19C THE GENERA OF NEMERTEANS. 



ters taken from the cephalic fissures. One family (the 

 Tremacephalidae) contains all the Nemertinea enopla , ar- 

 ranged in the genera Polia , Borlasia , Oerstedia , Micrura, 

 Prosorhochnus and Lohilahrum. His two other families: 

 the Gymnocephalidae and Rhochmocephalidae both belong 

 to the Nemertinea anopla. The former contains only one 

 genus: Cephalotrix , the latter four: Linens, Cerehratulus , 

 Nemertes and Ophiocephalus . Total eleven genera. The 

 number of species which he examined was much less 

 than those which Quatrefages disposed of. He largely con- 

 tributed to our knowledge of the anatomy of the group 

 but I do not think his systematic arrangement was a 

 very successful one, although it has found its way into 

 numerous textbooks. So for instance he does not seem to 

 have noticed that four of his six genera of armed Ne- 

 merteans were established by their authors for unarmed 

 species {Polia , Borlasia , Micrura , Lohilabrum). Quatre- 

 fages had commenced to create a confusion by applying 

 those generic names in a wrong sense; still Keferstein 

 might have corrected the error instead of extending it. 



Mac-Intosh (Ray Society Publicat. 1873, '74) who has 

 limited his researches to the British Nemerteans (of which he 

 describes 31 species) has distributed them in twelve genera, four 

 of which [Aynphiporus Tetrostevima, Prosorhochmus and Nemer- 

 tes) belong to the family of the Amphiporidae, five {Lineus, Bor- 

 lasia, Cerebratulus , Micrura, Meckelia) to the family Lineidae, 

 two {Carinella, Valencinia) to the family Carinellidae , 

 whereas the genus Cephalotrix forms by itself the family 

 of Cephalotricidae. The first family again coincides with 

 the suborder of Nemertinea enopla, the three last with 

 that of the Anopla. It is a pity that before fixing upon 

 his final arrangement, which must be recognized as a 

 most decided advance upon his predecessors , the author 

 had no occasion personally to examine the principal medi- 

 terranean species , which might have induced him to a 

 reduction in the number of his genera as will presently 

 be proposed. His families are very well chosen; here at 



Notes from the Leyden Museum. 



