300 HISTORY OF BRITISH CRUSTACEA. 



in Berwick Bay. He describes its motion as very peculiar ; 

 it generally swims on its back, and instead of darting for- 

 ward through the water, like the other species of the family, 

 it springs with a bound from the bottom of the vessel, 

 where it remains when undisturbed, up to the surface of 

 the water. It effects this by curling its body into a ball, 

 and then suddenly assuming a straight position. 



Alteutha depressa, Baird. — Body depressed, flat, broad; 

 eye of a fine ruby colour. 



Hab. Berwick Bay. 



Fam. II. DIAPTOMID^, Baird. 



Head generally distinguishable from the body, though 

 firmly articulated with first ring of thorax. Three pairs of 

 well-developed foot-jaws. Five pairs of legs, last pair of 

 different structure from the others, and differing from each 

 other in the two sexes. One eye. In the male, one of the 

 antennae alone is furnished with a swollen hinge-joint, with 

 which he seizes and holds the female. 



Gen. 161. DIAPTOMUS, Westwoocl. 

 Head distinguishable from the thorax; thorax and ab- 



