630 NOTES ON PROSOBRANCHIATA, 



female reproductive complex is very much shrunken, and the 

 parts are very difficult to dissect out. At such times the glands 

 are restricted to the main branches of the visceral arterial system, 

 these branches forming the centres around which the lobes are 

 grouped when fully developed. The extensions of the female 

 gland around the outer side and on to the inferior face are 

 invariably along the course of an artery. This variation in the 

 size of the gland is noted by R. J. Harvey Gibson (6) in Patella 

 vidgata ; it doubtless occurs in all molluscs. I have myself 

 noticed it in Lotoriura and Purpura. 



The peculiar form of the genitalia is the character on which it 

 has been thought fit to found this family. In the male there is 

 no sperm-groove as in Liltorina, its place being taken by an 

 anterior prolongation of the vas deferens ; and, further, the 

 seminal fluid passes through the penis, not along a groove on its 

 side; nor are any glands to be detected on the penis. In the 

 female we have an equally important difference — namely, the 

 existence of an ovipositor C?) similar to that found in Stromhus 

 and Pterocera. The former of these differences is one of the 

 most important anatomic differences between the Lotoriidce and 

 Muricidai. 



Moore has stated (12, p. 162) that he has found this 

 ovipositor (?) slightly developed in Littorina. This is an observa- 

 tion that needs contirmatiun. The most careful examination 

 of innumerable fresh and spirit specimens of L. scabra, Linn., 

 (some of large size), and L. maurittaiia, Lamk., has proved to the 

 writer that it does not exist in either of these two species. 

 Moreover, Souleyet (21), in his excellent account of the anatomy 

 of L. littorale, Linn., does not mention its presence. If, therefore, 

 it does exist in one species of so-called Littorina^ I would suggest 

 that species of two genera are grouped under one name. 



Tenison- Woods (23) has stated that although the species of 

 Riselia are organically hemaphrodite, functionally the sexes are 

 separate, and may be distinguished by the form of the shell. 

 Both these statements are at variance with facts; it is probable 

 that he mistook the ovipositor (i) for the male organ; of twenty 



