AEENICOLANA. 97 



SUB-TRIBE II. ARENICOLANA. 



Arenicola (Lamk.). Body round, swollen behind; 

 gills in branched tufts, arranged on the central 

 segments ; mouth terminal. 



A. piscatorum. Fig. 154 ; 3 n. s. 

 branchialis. 

 carbonaria ? 

 ecaudata. 



Travisia (Johnst.). Body somewhat flattened, 

 swollen in front; gills a pair of simple filaments 

 on each of the hinder segments ; mouth beneath. 



T. Forbesii. Fig. 155 ; n. s. 



Nerine (Johnst.). Feet alike, two -branched; 



each branch consisting of a membranous lobe, and 



i a short bristled foot-stalk ; gills short, thread-like, 



I bent up over the back, with a small cirrus at the 



base of each : two long tentacles on the back of 



the head : eyes four. Burrowing in mud. 



K vulgaris. 



coniocephala. Fig. 156 ; |. n. s. 



Spio (Gmelin). Gills thread-like, simple; two 

 very long tentacles ; four eyes. Inhabiting tubes, 

 which are built up of grains of sand. 



S. seticornis. Fig. 157 ; mag. -. 

 crenaticornis. 

 calcarea ? 



Leucodore (Johnst.). Feet of two kinds, dis- 

 similar ; those behind the fourth pair carrying leaf- 

 like gills bent over the back : tentacles two on 

 the back of the head : eyes four. Burrowing in 

 mud. [N.B. This seems not sufficiently distinct 

 from Spio.] 



L. ciliatus. Fig. 158 ; mag. -&. 

 H 



