400 PROCEEDINGS OF THE ACADEMY OF [Sept., 



advanced stages of development. The ova were of oval form, and the 

 heads of the sperms were bacillus-shaped. Even under very high 

 powers no filaments could be detected, though the}- may probably 

 have been destroyed by reagents. The material, it should be added, 

 was collected early in October, while the breeding season does not begin 

 until some time in January or February. From the above it is evident 

 that II. cracherodn does not commence to breed until it is more than 

 9 cm. in length, and it is certain that sexual activity begins at a some- 

 what earlier period with the males than the females. 



In large specimens the gonad may attain as much as half an inch in 

 thickness along the posterior border of the columellar muscle. And 

 the cavity, only potentially present in early stages, becomes now very 

 clearly defined and of considerable size. Tracing it posteriorly and 

 then to the left one may discover the fimnel-shaped gonoduct {GO' , 

 figs. 2, 3, 4, 5, text fig. A). It bends somewhat to the left and narrows to 

 a flattened tube from 3 to 6 mm. in diameter. This opens into the cavity 

 of the kidney, at the left border of the gonad, and the mouth is provided 

 with a flexible valve-like flap, which may serve to prevent the entrance 

 of any sulistances from the kidney. I have found ripe eggs and sperms 

 in the gonoducts of specimens taken the last of December. Perrier 

 ('89) states that the gonoduct of IlaJiotis is closed except at the breed- 

 ing season, but this is certainly not the case in the two species studied 

 by me. In all stages the duct has been open and there was a free 

 passage from the gonad to the kidney. There was no organic obstruc- 

 tion even in specimens 2 cm. long. Fleure ('02) found ova in the peri- 

 cardial cavity of H. tuhcrculata, but this is probably an accidental 

 occurrence, since in the western species the sex products pass from the 

 kidney directly to the exterior. 



The renopericardial canals of prosobranchs have of late been the 

 subject of much controversy, and at the present time the results of 

 various authors are decidedly conflicting. Working upon the Eu- 

 ropean species Wegmann ('84), Perrier ('89) and Erlanger ('92), besides 

 other investigators, found a left renopericardial canal only. Fleure 

 ("02) examined the same species very carefully, but curiously could 

 find no left canal, though he did demonstrate the existence of a right 

 canal. About the same time Totzaur ('02) found both canals, but 

 neither of these investigators has given us any figures nor a detailed 

 account of these much discussed organs. Some time previous to the 

 reports of the above named authors, Haller stated that he had found 

 both canals in H. glabra, and was thus, so far as I am aware, the first 

 to report such a state of affairs for any species of Haliotidoe. 



