FAMILIES, GENERA, AND SPECIES, OE THE BRITISH MARINE 



ANNELIDS. 



(ANNELIDA POLYCELETA, continued.) 



Family VI. — Nephthydid^e, 1 Grube, 1851. 



Head flattened, quadrangular or rhomboidal, rarely nearly hexagonal, a short tentacle 

 at each anterior angle, and one (palpus, Kinberg, tentacular cirrus, Ehlers) a little 

 posterior (1st segment) and ventro -lateral in position, or both may be absent. Eyes two 

 or none. A small ciliated organ at each lateral groove posteriorly. 



Body elongate, almost tetragonal in section, though convex dorsally and flattened 

 ventrally. Segments similar. Vent terminal with a single cirrus (rarely two, Ehlers) 

 beneath. Peristomial segment fused with that behind. Proboscis large, sub-cylindrical, 



dv. 



Vrn. 



Fig. 34— Section of NepMhys caeca, about the anterior third. Id, dorsal division of the foot ; bv, ventral division ; 

 d, alimentary canal ; dm, dorsal longitudinal muscle ; dv, dorsal blood-vessel ; nc, nerve-cord ; om, oblique 

 muscle ; vm, ventral longitudinal muscle. 



ovate or obovate with or without a double arch of bifid papilla, a pair of horny teeth or 

 none. Alimentary canal simple — slightly moniliform. 



Divisions of the foot widely separated, flattened, bearing a spine and double row of 

 diverse bristles (barred and serrated or rarely with lyriform tips) in each in front, the 

 dorsal lobe, further, having superiorly a lamella and other processes, and a small dorsal 

 cirrus in connection with the branchia; the ventral lobe has a lamella with or without 

 other processes and a ventral cirrus. 



1 The title Nephthya was used by Savigny for a group of Alcyonaria including Spongodes. 



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