NEREIDS. 255 



two tentacles, two palpi, and four eyes. First segment devoid of a foot, with two 

 pairs of tentacular cirri on each side, and two cirri below the anus. Proboscis with 

 two regions in extrusion, furnished with paragnathi, rarely naked, and with two jaws, 

 which in retraction fall behind the two regions. 

 He divides the family Lycoridea as follows : 



1. Feet single — Lycastis, 1 Aud. & Edw. 



2. Feet bifid : 



(a) With simple dorsal cirri. 



1. With dorsal and ventral lamellae — Nereis, Cuvier. 



2. Devoid of dorsal lamellae — Cevatocephale, Malmgren. 



3. Devoid of central lamellae — Tylorhynchus, Grrube. 



(b) With plumose dorsal cirri — TJendronereis, Peters. 



Ehlers did good service in showing that many of the generic terms used by 

 Kinberg, Malmgren, and others, were due either to sexual variations or were other- 

 wise unnecessary. 



He grouped the species as follows : 



A. The dorsal lobe of all the feet simple, that is, without an enlarged lamella. 

 I. The feet on all the segments uniform or only little altered. 



1. Paragnathi complete, including the British Nereis cultrLfera. 



2. Paragnathi incomplete, comprising Nereis jpelagica, N. longissima. 

 II. The feet unequal. 



1. Four or five of the anterior segments have the lobes of the feet little 



developed, the following feet with prominent lobes. 

 (a) Paragnathi conical. 



Nereis irrorata, N. Dumerilii. 



2. The posterior feet elongated, with long lobes and processes. 



3. The posterior feet elongated, the dorsal border, from which springs the 



cirri, very convex. 

 Nereis fucata. 



4. The dorsal lobe of the posterior feet broadly triangular. 



Nereis diversicolor. 



B. The upper lobe with the cirrus bearing a large lamella. 

 I. The upper lobe in the first feet not leaf-like. 



Nereis virens, Sars. 

 II. The upper lobe only in the middle, and posterior feet foliaceous. 



1. The dorsal cirrus terminal. 



(a) Paragnathi complete, conical. 



Nereis Marionii, Aud. & Edw. 



2. The dorsal cirrus prominent in the posterior feet (no British form). 

 Claparede, in 1868, placed the Nereidae under the sub-genera Leontis, Malmgren, 



Lipephile, Malmgren, Oeratonereis, Kinberg, Nereilepas, Blainville, Johnston, Malmgren, 

 making a special genus of Beteronereis. The same author, in an elaborate investiga- 



1 Vide G-rube's view, p. 256. 



