BOPYRUS SQUILLARUM. 221 



the body. The respiratory scales on the underside of 

 the tail are short and transverse ; the basal segment of 

 the tail is much shorter than the following, the second 

 and three succeeding being of equal size, whilst the 

 sixth is rather narrow and nearly truncate, without any 

 appendages. 



The female when alive is of a pale greenish colour, 

 glossy above, with the head and oral plates black, and 

 those of the ovisac and under surface of the head black 

 or very dark at their edges. 



The young Bopyri, before they leave the incubatory 

 pouch of the females, are ovate in form, and dorsally 

 convex, resembling very minute wood-lice, with the 

 outer pair of antennae greatly elongated, composed of 

 four joints, of which the first is short and robust, and 

 the others elongated and terminated by one or two very 

 long and slender setse. The legs are broadly sub-cheli- 

 ferous, especially the four posterior pairs, the three 

 anterior pairs being rather more slender and directed 

 forwards, whilst the four latter pairs are directed back- 

 wards. The respiratory scales of the tail (pleopoda) are 

 strongly setigerous, the posterior pair being composed 

 of a very short basal joint, supporting two elongated 

 rami, pointed, and tipped with one or two terminal 

 setae. 



The females of this species are attached to the outer 

 lining of the branchial cavity of the common prawn, a 

 single parasite being found upon an individual prawn. The 

 fecundity of these parasites is very great, the eggs being 

 retained within the incubatory pouch where they are 

 hatched, and M. Risso states that he had counted as 

 many as eight hundred young ones nourished by a single 

 female. 



Mr. Adam White, upon the authority of Col. Mon- 



