That is that He commanded us to check for the signs of beasts and animals that can be slaughtered - and that is that they chew the cud and have split hooves - and it is then permissible to eat them. And in that we are commended to check them for these signs, it is a positive commandment. And that is His, may He be blessed, saying, "These are the animals that you may eat" (Leviticus 11:2). And the language of the [Sifra] (Sifra, Chapter 3:1) is, "'Such may you eat' (Leviticus 11:3) - it may be eaten, but an unclean beast may not be eaten." This means to say, a beast that has these signs is permissible to eat; so it indicates that a beast that does not have these signs is not permitted to eat. And this is a negative commandment that is derived from a positive commandment - which is a positive commandment, as is a principle with us. And therefore, it said after this statement, "This tells me only of a positive commandment. From where [do we know that he also transgresses] a negative commandment? [Hence] we learn to say, 'the camel, etc.'"(Leviticus 11:4) - as I will explain in the Negative Commandments (Sefer HaMitzvot, Negative Commandments 172). Behold it has already been made clear that His saying, "such may you eat," is a positive commandment. And the content of this commandment is that we are commanded to check for these signs in the beasts and animals; and it is not permissible to eat them without this. And this law is the commandment. And the regulations of this commandment have already been explained in Tractate Chullin and in Bekhorot. (See Parashat Shemini; Mishneh Torah, Forbidden Foods 2.)

That is that He commanded us to check for the signs of birds, such that only some of them are permissible. And the signs of the birds are not stated in the Torah. They rather come from an investigation of our finding the birds that are written to be forbidden, and our [then finding] phenomena that they have in common - and these are the signs of an impure bird. And since also regarding birds are we involved with the issue of which is impure and which is pure, that [involvement] is a positive commandment. And the language of the Sifrei is, "'You may eat any clean bird' (Deuteronomy 14:11) - that is a positive commandment." Behold what we have hinted was made clear. And the regulations of this commandment have already been explained in Chullin. (See Mishneh Torah, Forbidden Foods 2.)

That is that He commanded us to check for the signs of locusts as well. And [the signs] are written in the Torah - "all [...] that have, above their feet, jointed legs" (Leviticus 11:21). And the content of this commandment is like that which we explained in the commandment before this; and the verse about it is His saying, "Of these you may eat the following - locusts" (Leviticus 11:22). And the laws of this commandment have already been explained in Tractate Chullin. (See Parashat Shemini; Mishneh Torah, Forbidden Foods 1.)

That is that He commanded us to check for the signs of [permissible] fish, which are written [in the Torah]. And that is His, may He be blessed, saying, "These are what you may eat from all that is in the water" (Leviticus 11:8). And in explanation, they said in the Gemara (Chullin 66b), "One who eats an impure fish transgresses a positive and a negative commandment." As its statement - "These are what you may eat" - [makes] me understand that one besides these may not be eaten. And a negative commandment that is derived from a positive commandment is a positive commandment. Behold it has been made clear that its statement, "These are what you may eat," is a positive commandment. And the content of our saying that this is a positive commandment is what we have mentioned to you; and that is our being commanded to administer these signs, and to say that this is permissible to eat and this is not permissible to eat - as it is stated (Leviticus 20:25), "And you shall distinguish the clean beast from the unclean." And their distinguishment is though the signs. And therefore each and every one of these four types and their signs is a separate commandment - meaning the signs of the beasts and the animals; the birds; the locusts; and the fish. And we have already explained their expressions in each of the verses as an individual commandment. And the regulations of this commandment - meaning the signs of the fish - have already been explained in Chapter 3 of Tractate Chullin. (See Parashat Shemini; Mishneh Torah, Forbidden Foods 1.)

For you are a people consecrated to your God יי: your God יי chose you from among all other peoples on earth to be a treasured people. You shall not eat anything abhorrent. These are the animals that you may eat: the ox, the sheep, and the goat; the deer, the gazelle, the roebuck, the wild goat, the ibex, the antelope, the mountain sheep, and any other animal that has true hoofs which are cleft in two and brings up the cud—such you may eat. But the following, which do bring up the cud or have true hoofs which are cleft through, you may not eat: the camel, the hare, and the daman—for although they bring up the cud, they have no true hoofs—they are impure for you; also the swine—for although it has true hoofs, it does not bring up the cud—is impure for you. You shall not eat of their flesh or touch their carcasses.

These you may eat of all that live in water: you may eat anything that has fins and scales. But you may not eat anything that has no fins and scales: it is impure for you. You may eat any pure bird. The following you may not eat: the eagle, the vulture, and the black vulture; the kite, the falcon, and the buzzard of any variety; every variety of raven; the ostrich, the nighthawk, the sea gull, and the hawk of any variety; the little owl, the great owl, and the white owl; the pelican, the bustard, and the cormorant; the stork, any variety of heron, the hoopoe, and the bat. All winged swarming things are impure for you: they may not be eaten. You may eat only pure winged creatures. You shall not eat anything that has died a natural death; give it to the stranger in your community to eat, or you may sell it to a foreigner. For you are a people consecrated to your God יי. You shall not boil a kid in its mother’s milk.

It is a positive commandment to know the signs that distinguish between domesticated animals, beasts, fowl, fish, and locusts that are permitted to be eaten and those which are not permitted to be eaten, as [Leviticus 20:25] states: "And you shall distinguish between a kosher animal and a non-kosher one, between a non-kosher fowl and a kosher one." And [Leviticus 11:47] states: "To distinguish between the kosher and the non-kosher, between a beast which may be eaten and one which may not be eaten."

The signs of a [kosher] domesticated animal and beast are explicitly mentioned in the Torah. There are two signs: a split hoof and chewing the cud. Both are necessary.Any domesticated animal and beast that chews the cud does not have teeth on its upper jaw-bone. Every animal that chews the cud has split hoofs except a camel. Every animal that has split hoofs chews the cud except a pig.

Therefore if a person finds an animal whose hoofs are cut off in the desert and he cannot identify its species, he should check its mouth. If it does not have teeth on its upper jaw, it can be identified as kosher, provided one can recognize a camel. If a person finds an animal whose mouth is cut off, he should check its hooves, if they are split, it is kosher, provided he can recognize a pig.When both its mouth and its hoofs are cut off, he should inspect the end of its tail after he slaughters it. If he discovers that [the strings of] its meat extend both lengthwise and widthwise, it is kosher, provided he can recognize a wild donkey. For [the strings of] its meat also extend both lengthwise and widthwise.

There are no other domesticated animals or wild beasts in the world that are permitted to be eaten except the ten species mentioned in the Torah. They are three types of domesticated animals: an ox, a sheep, and a goat, and seven types of wild beasts: a gazelle, a deer, an antelope, an ibex, a chamois, a bison, and a giraffe. [This includes the species] itself and its subspecies, e.g., the wild ox and the buffalo are subspecies of the ox.All of these ten species and their subspecies chew the cud and have split hoofs. Therefore, a person who recognizes these species need not check neither their mouths, nor their feet.

Although all these species are permitted to be eaten, we must make a distinction between a kosher domesticated animal and a kosher wild beast. For the fat of a wild beast is permitted to be eaten and its blood must be covered. With regard to a kosher domesticated animal, by contrast, one is liable for kerais for partaking of its fat and its blood need not be covered.

According to the Oral Tradition, these are the distinguishing signs of a [kosher] wild beast: Any species that has split hoofs, chews its cud, and has horns which branch off like those of a gazelle are certainly kosher wild beasts. [The following laws apply with regard to] all those whose horns do not branch off: If they are curved, like the horns of an ox, notched, like the horns of a goat, but the notch should be embedded within them, and spiraled, like the horns of a deer, it is a kosher wild beast. Its horns, however, must have these three signs: They must be curved, notched, and spiraled.

The distinguishing signs of a kosher [species of] fowl are not mentioned explicitly by the Torah. Instead, the Torah mentions only the non-kosher species. The remainder of the species of fowl are kosher. There are 24 forbidden species. They are:a) the eagle,b) the ossifrage,c) the osprey;d) the kite, this is identical with the rayah mentioned in Deuteronomy,e) the vulture, this is identical with the dayah mentioned in Deuteronomy,f) members of the vulture family; for the Torah states "according to its family," implying that two species [are forbidden],g) the raven,h) the starling; since the Torah states "according to its family" with regard to the raven, the starling is included,i) the ostrich,j) the owl,k) the gull,l) the hawk,m) the gosshawk, for this is among the hawk family; and the verse says "according to its family,"n) the falcon,o) the cormorant,p) the ibis,q) the swan,r) the pelican,s) the magpie,t) the stork,u) the heron,v) members of the heron family; for the Torah states "according to its family,"w) the hoopie, andx) the bat.

Whoever is knowledgeable with regard to these species and their names may partake of any fowl from other species. A kosher species of fowl may be eaten based on tradition, i.e., that it is accepted simply in that place that the species of fowl is kosher. A hunter's word is accepted if he says: "The hunter who taught me told me that this fowl is permitted," provided that [teacher] has an established reputation as being knowledgeable with regard to these species and their names.

Whoever does not recognize these species and does not know their names must check according to the following signs given by our Sages: Any fowl that attacks with its claws and eats is known to be among these species and is unkosher. If [a fowl] does not attack with its claws and eat, it is kosher if it possesses one of the following signs: a) it has an extra claw, b) a crop; this is also referred to as a mur'ah, c) [the membrane of] its craw can be peeled by hand.

There are two signs of [kosher] fish: fins and scales. Fins are used by the fish to swim and scales are those which cling to its entire body. Any fish that possesses scales will have fins. If it does not have them at present, but when it grows, it will have them or if it has scales while in the sea, but when it emerges it sheds its scales, it is permitted.When a fish does not have scales that cover its entire body, it is permitted. Even if it has only one fin and one scale, it is permitted.