500 F. W. GAMBLE. 



vary in number and arrangement. In front of the brain are 

 usually two distinct patches of loosely arranged eyes at the 

 bases of the nerves (corresponding to the eyes at the bases of 

 the tentacles in Planoceridse). Opposite the bases of the fifth 

 pair of nerves is a compact group of larger, chiefly reuiform 

 eyes. In some specimens, however, the tentacular and ce- 

 phalic groups of each side are continuous with one another. 

 The genital apertures have already been noticed. From the 

 numerous scattered testes, vasa efferentia arise. These gra- 

 dually unite to form the pair of vasa deferentia which run 

 at the sides of the pharynx, and before uniting at the base of 

 the penis give off a posterior branch, which joins the one of 

 the other side behind the female genital pore. The male 

 copulatory organ consists of a ductus ejaculatorius, and the 

 strongly muscular vesiculse seminales and granulorum. The 

 ova scattered throughout the body accumulate after fertilisa- 

 tion in the long uterus, which completely (in adult specimens) 

 surrounds the pharynx and genital-apparatus. The uterus 

 communicates with the exterior by a median duct, which in 

 its lower portion is surrounded by the voluminous '' shell- 

 gland." 



Habitat.— Firth of Forth (Dalyell) ; Cultra, Belfast Bay 

 (W.Thompson); Rothesay (Johnston); Firman Bay, Guernsey 

 (Ray Lankester) ; St. Andrews (Mcintosh) ; Jersey, Guernsey, 

 Herm (Koehler); Plymouth Sound and neighbourhood, from 

 littoral zone to 20 fms. (W. Garstang, F. W. G.) ; Hilbre 

 Island, mouth of the Dee, Port Erin, Isle of Man (F. W. G.) ; 

 Aberystwyth (J. H. Salter). 



Distribution. — Black Sea, Mediterranean, west coast of 

 France, coast of Holland, Denmark, Baltic, North Sea, 

 Red Sea. 



The distinctive peculiarities of this species are the possession 

 of a**sucker^' and the simplicity of the female copulatory organ. 

 Thus the " antrum femininum," or cavity into which the 

 female genital pore leads directly, remains simple, while in 



