ANNALS OF NATURAL HISTORY. 



XXXIII. — Miscellanea Zoologica. By George Johnston, 

 M.D., Fellow of the Royal College of Surgeons of Edin- 

 burgh. With Plate VI.*. 



VII. The British Nereides. 



Class Annelides. Order Errantes. 



Character. Head usually distinct and antenniferous : pro- 

 boscis very large, with one or two pairs of jaws in most : seg- 

 ments numerous, co-ordinate ; the feet highly developed, fur- 

 nished with spines and bristles : branchice either obsolete or 

 in the form of lobules or papillae inserted generally at the apex 

 of the feet : the tentacular cirri rarely wanting. 



1. Nereis, Linnceus. 



Char. Head antenniferous, the antennae small; palpi two, 

 larger, mammillate ; proboscis with two horny falcate jaws ; 

 segments numerous, the first with four tentacular cirri on each 

 side \feet bizamous, variously lobulated, furnished with a dor- 

 sal and ventral cirrus. 



Observations, The body of the Nereis is always vermiform, 

 insensibly tapered towards the tail, somewhat truncate in front, 

 and composed of numerous narrow segments : the back round- 

 ish, but the ventral surface is flattened, and marked down the 

 middle with an impressed line. The head is distinct, a little 

 contracted in front, and furnished with two pairs of eyes placed 

 on the occiput, the one before the other. The small subulate 

 antennae are inserted on its frontal margin (Plate VI. fig. 1 a, 

 a.) ; and, in general, we find two of these organs, which are 

 guarded, on each side, by a thick palpus distinctly formed of 

 two articulations, the apical capable of being retracted within 

 the other (fig. 1 a, p) . The large cylindrical exsertile pro- 

 boscis is divided into two rings, and its surface is roughened 

 with minute corneous prickles, more or less numerous in the 



* This plate will form part of the Supplement to the present volume. 

 Ann. Nat. Hist. Vol. 3. No. 18. July 1839. y 



