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 ; \ 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 

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

 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. 



N. 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. j-. 



H 



