Whether the unnatural vice is a species of lust?

Objections

Objection 1 : It would seem that the unnatural vice is not a species of lust. For no mention of the vice against nature is made in the enumeration given above (Article [1], Objection [1]). Therefore it is not a species of lust.
Objection 2 : Further, lust is contrary to virtue; and so it is comprised under vice. But the unnatural vice is comprised not under vice, but under bestiality, according to the Philosopher (Ethic. vii, 5). Therefore the unnatural vice is not a species of lust.
Objection 3 : Further, lust regards acts directed to human generation, as stated above (Question [153], Article [2]): Whereas the unnatural vice concerns acts from which generation cannot follow. Therefore the unnatural vice is not a species of lust.