HISTOBY OF THE SUBJECT. 37 



(a) Bhochmocephalidce without the lobe-shaped snout. 



Gen. 7, Lineus, Sowerby, 1804. Head easily distinguished from the body, somewhat 

 broad. Mostly without eyes. Cephalic fissures extending to the mouth. Posterior part of body 

 almost pointed, flat, very long and contractile, sometimes knotted. 



Gen. 8. — Cerebratulus, Benier, 1807. Head not distinguished from the body, somewhat 

 smaller, but ending bluntly. Cephalic fissures extending to the mouth. Body not smaller 

 towards the posterior end, flat, moderately long and slightly contractile. 



Gen. 9. — Nemertes, Cuv. (char, reform). Head not distinguished from the body. Cephalic 

 fissures long, extending to the mouth. Mostly with eyes. Body flat, moderately long and con- 

 tractile. 



(b) — BhocJimocephalida with the lobe-shaped snout. 



Gen. 10. — Opkiocephalus, Delle Chiaje, 1829. Head distinguished from the body, some- 

 what smaller, but ending bluntly, the snout having a deep median groove on the dorsal and 

 vcxitral surfaces, so that it appears bilobed. Cephalic fissures long, extending to the mouth. No 

 eyes. Body long. 



Fam. 3. — Gymnocephalim:. 



The cephalic fissures entirely lost. Brain like that in Folia, but the superior ganglion covers 

 the inferior much less. The lateral nerve proceeds from the entire side of the inferior ganglion, 

 or is almost a continuation thereof. 



Gen. 11. — Cephalothriac, (Ersted, 1844. Head not distinguished from the body, very long 

 and pointed. The mouth lies more than the breadth of a head from the anterior end. Body 

 rounded, very long, filiform, and very contractile. 



No fault can be found with the primary subdivisions or sub-orders (after Max Schultze), and 

 the family-name Tremaceplialid(B, as applied to the Amjjfdporini, is not seriously wrong, but the 

 sub-families and genera of this portion require complete reformation. His criterion of the " absence 

 of the lobe-shaped snout" does not stand the author in good stead if we may judge from the 

 genera he has thrown together in the sub-family. The first of his genera (Folia) seems to me 

 to be in a questionable position, since the Nemertean described by Delle Chiaje under the name of 

 Folia sipkunculm is, so far as I can make out, one of the Anopla. The second genus, Forlasia, 

 has a very unfortunate name ; for, while I agree with the author as to the propriety of preserving 

 the title commemorative of the early English naturalist, it certainly ought not to be bestowed on 

 a group of Nemerteans totally different in structure from that form (Lineus marinus) to which 

 the name was originally given by Oken. The author has simply followed De Quatrefages in the 

 formation of the third genus (Erstedia, the anatomy of which, especially the position of the nerve- 

 trunks, differs in no respect from the type of the Enopla. A still more serious error has been 

 committed with the fourth genus, Micrura, this being a true member of the Anopla, and having 

 no connection with Tetrastemma, Ehrenberg, or other representative of the Enopla. The fifth 

 genus, Frosorhochmus, may be allowed to stand, as descriptive of a curious example of the 

 Enopla, closely allied to Tetrastemma, discovered by the author. The sixth genus, LobUabrum, 

 was constituted by De Blainville for a form pertaining to the Anopla, and, therefore, is quite 

 out of place in its present position. There are, perhaps, fewer errors of commission in his second 



