THE GENERA OF NEMERTEANS. 497 



last the internal structure of these worms, which exter- 

 nally present so little difference, is taken into considera- 

 tion and an arrangement into more natural groups is the 

 immediate result. 



If we apply the rule that generic names may not stand 

 when applied in a sense different from what they were 

 intended for by their author (as may be judged from the 

 species on which he primitively established the genus: the 

 type species, or typical specimens), three of Quatrefages' 

 genera {Polia, Borlasia, Cerebratulus) must be cancelled 

 and his species divided over other genera to which they more 

 properly belong. To Keferstein's Polia and Borlasia the 

 same rule should be applied, as well as to Mac-Intosh's 

 Meckelia. Rigidly speaking the name Nemertes Cuv. was 

 applied to a worm quite different from those which later 

 authors united under that name. However not only Quatre- 

 fages and Mac Intosh but KöUiker (Verb. Schweiz. Naturf. 

 Gesellsch. Chur 1844) and many others have all applied the 

 name Nemertes to armed species and so here we may feel 

 justified in maintaining it in this modified sense. Then 

 of course the species to which Keferstein and v. Beneden 

 applied this name must reappear in another genus. And 

 if we separate Keferstein's genus Micrura from the Tre- 

 macephalidae , again placing it amongst the Anopla we 

 have only the genera Ophiocephalus and Lohilahrum to 

 account for in order to bring the arrangements of Kefer- 

 stein and Mac Intosh in accordance. Now Opldocephalus 

 was established by Blainville for a worm brought by Quoy 

 and Gaimard from their voyage of circumnavigation and 

 had it not been brought from Sydney Blainville himself 

 would not have hesitated in placing this species in the genus 

 Cerebratulus. Such at least may be understood from his 

 text (Diet, des Sciences Nat. Paris 1828. Vol. 57). Delle 

 Chiaje further discredited this generic name by employing 

 it in 1829 (Descr. e Not degli Anim. invertebr. etc. Vol. 

 Ill, p. 127) for three species very heterogenous among 

 themselves and of which we will have occasion to speak 



Notes from the [Leyden Mluseuin. 



