What are the words "es Zeh Lo Sochlu" coming to preclude?
Bechoros, 7a: It precludes from the prohibition of a Tamei species whose mother and father are both Tahor (a donkey whose mother and father are both sheep or if one of them is a goat). 1
Refer to 11:5:0.2:1.
Having presented the Simanim of a Tahor nimal, why does the Torah need to list the species of Tamei animals?
Oznayim la'Torah (citing Tana de'Bei R. Yishmael): To teach us that the camel, the rabbit and the hare (and the Shesu'ah according to Chazal) are the only creatures in the world that chew their cud and are Tamei because they do not have split hooves, and the Chazir is the only creature in the world that has split hooves nd is Tamei because it does not chew its cud. 1
See Oznayim la'Torah.
What is the definiton of a "Shesu'ah"?
Rashi: It is an animal with two backs and two spines. 1
Targum Onkelos: "Mafisei Parsah Shesu'ah" simply means 'animals whjosee hooves are completely split'. 2
Targum Yonasan: It is an animal with two heads and two spines. 3
Nidah 24a: Accoring to Shmuel it is a species, and if such a fetus is found inside a Shechted Tahor animal, it is permitted. Rav however, maintains that there is no such species - It is a mutation (like Siamese twins), and it is forbidden. See also Oznayim la'Torah, who concurs with the first opinion and elaborates.
See Oznayim la'Torah.
Targum Yonasan: Which is forbidden because it cannot survive.
How could Moshe Rabeinun know about the Shesu'ah?
