202 



LETTER XIII. 



ON THEIR CIRCULATING SYSTEM. 



Aristotle divides animals into those which have blood, 

 and those which have none ; and these primary classes were 

 appropriately named the sanguineous and exsanguineous. 



Fig. 36". 



ilpgL 



•4 



a, Veil ; b, tentacula ; c, neck ; d, organs of generation ; e, anus and another excre- 

 tory orifice ; /, greater branchiaj ; </, lesser branchia; ; //, margins of foot. 



Among the latter, he places the mollusca, as all naturalists 

 did for a long time afterwards, and as all, except naturalists, 



