170 Zoological Notices. 



have hitherto been considered as hermaphrodites ; nevertheless 

 we have found no difhoulty in satisfying ourselves, that in 

 these mollusca the sexes are perfectly distinct. The males 

 and females even differ by the most evident external charac- 

 ters. In fact, in the males, we discover on the right side 

 (the animal lying on its abdomen), underneath the visceral 

 nucleus, a very distinct copulating apparatus, an organiza- 

 tion which is wholly wanting in the female ; but she, on the 

 other hand, presents near the anus a genital organ of which 

 the male is destitute. The testis occupies the same posi- 

 tion as the ovaria, and very much resembles it, but instead 

 of ovules characterized by the presence of a vitellin sac and a 

 vesicle of Purkinje, it contains membranous capsules full of 

 zoosperms. These animalcules have a very long tail, and are 

 very rapid in their movements. The same observations apply 

 to the Pterotrachea. — Milne Edwards and Peters, 



5. Echini. (Les Oursins.) — Males and females perfectly 

 distinct, also exist among these animals. Externally the tes- 

 ticles of these Echinodermata differ in nothing from the ova- 

 ries ; but the liquid they enclose is white Hke milk, instead 

 of being of an orange colour as in the females : and crowded 

 with zoosperms whose tail cannot be seen without difficulty, 

 although their movements are quite characteristic. — Milne Ed- 

 wards and Peters. 



6. Hydrostatic Acalephw. — M. Edwards states, that he is 

 convinced that these singular productions, which have been 

 drawn under the name of Physophores, and which resemble 

 long garlands of flowers intermixed with roundish bay leaves 

 and stipules spirally contorted, are not simple animals ; but on 

 the other hand, aggregations of a great number of individuals 

 produced by buds, and living united together as a compound 

 polypidom. It is also probable that they possess a distinction of 

 sex, for in some, in which it was impossible to perceive any 

 trace of ovaries, organs were discovered full of spermatic ani- 

 malcules. — Milne Edwards and Peters. 



7- Holothuria. — The circulation in these creatures differs from 

 the description given by M. Tiedemann, and very nearly ap- 

 proaches to the sketches given of it by M. Delle Chiaje. 



8. Gircuhtion in Beroe ovatm. — In this medusa there exists a 



