iz.] 340 [October 4, 



As far as anatomical features are concerned, we have information no 

 where more full than in the fourth volume of Cuvier's Lectures on 

 Comparative Anatomy. In reviewing the accounts given by various 

 observers, we find that Aristotle really knew more about the process 

 than all other zoologists since his time. He says the cartilaginous 

 fishes in copulation " hang together after the fashion of dogs, ' uoneq 

 xwagf the long-tailed ones mounting the others', unless the latter 

 have a thick tail preventing this, when they come together belly to 

 belly." Before my late illness I had the good fortune to be able to 

 observe and study the subject among the sharks and skates, with re- 

 sults which satisfactorily settle this question ; no opportunity to in- 

 vestigate the Trygons has yet occurred to me. One ray of each 

 posterior fin is capable of erection and rotation, and is covered with 

 erectile tissue, far too delicate to allow it to be used as a clasper 

 around a body covered with sharp, rough spines. In the act these 

 two organs are rotated inward and forward, bringing the furrows on 

 their inner surface into parallel contact, and in apposition with the 

 testes. Being then introduced into the body of the female, their ex- 

 tremities diverge in the two oviducts, and the glans being uncovered 

 exposes a sharp cutting instrument, which would injure the organs 

 of the female if she resisted ; the male has her, therefore, in com- 

 plete subjection, and has been observed to strike and wound her 

 with this spine. What was formerly supposed to be the penis is too 

 small, and of insufficient length to accomplish fecundation. The 

 penis consists of the two long flexible finger-like fins, furnished with 

 two projectile spinous appendages, as in vipers. (In Chimaera the 

 surfaces of the organs are also spinous, as in snakes.) The two 

 spines found in cartilaginous fishes are homologous with the os penis 

 of mammals. In man this bony part has disappeared, and we have 

 only the soft spongy portions of the organ remaining ; the quivering 

 of the legs during connection seems the echo, as it were, of the sen- 

 sitiveness of the flexible posterior limbs of the skates. 



The fins of the male skate resemble those of the female, having 

 only in addition the sexual organ. We are led here to consider the 

 connection between posterior limbs and sexual organs. In the 

 snakes we find the latter organ, but no limbs. The examination of 

 the homologies of the penis shows these various forms, the long 

 erectile, the smaller pointed, and the mere tubercle. We may 

 therefore conclude that the more lascivious animals have gradually 

 developed these organs, or, as seems to me far preferable, that this 



