Pranizafuscdta, 521 



taceous insect winch Montagu had discovered on the shores 

 of Devon, and described as a species of Oniscus. It is yet, 

 so far as I know, the only member of its genus recognised in 

 systematic works ; and, I think, there are among your readers 

 some who will be gratified by having another native one 

 brought under their notice. 



The Pranizae are marine Crustacea of minute size. By 

 means of their legs, they can creep on the bottom, which 

 they do slowly; but they swim with greater rapidity, pro- 

 pelling themselves forwards by the quick motions of a series 

 of ciliated fins placed beneath the tail. Of their economy, 

 nothing is known. They are characterised by having four 

 unequal antennae ; two sessile eyes ; an elongated body 

 divided into three segments, of which the two anterior, or 

 thoracic, are very small, and the third, or abdominal, very 

 large. They have ten legs, a pair to each segment of the 

 thorax, and three pairs to the abdomen ; while the jointed 

 tail is armed beneath, and at its end, with foliaceous append- 

 ages, that appear to be both motive and respiratory organs. 



The species may be distinguished thus : — 



1. P. cseruleata. — Abdominal segment blue {Lamarck y Hist. Nat., vol. v. 



p. 168.). Oniscus cxrulektus {Montagu, in Lin. Trans.^ \o\.xi. p. 15. 

 tab. iv. fig. 2.). — Hab. Shores of Devon. 



2. P. fuscata — Abdominal segment reddish brown [Johnston, in Magazine 



of Natural History, Vol. V. p. 521 .]. — Hab. Coast of Berwickshire. 



The latter is two lines long, subcylindrical. The head, 

 thorax, tail, and legs colourless and transparent ; eyes black ; 

 the great segment of a reddish brown. Head pointed. An- 

 tennae lateral, four-jointed, the ultimate joint long, and divided 

 by many transverse lines. Eyes lateral, large, compound like 

 those of insects. Thoracic segments very small, with a pair 

 of legs to each: abdomen ovate, with a translucent edge, fur- 

 nished with three pairs of legs; one from the anterior margin, 

 one from the middle, and one from a projecting tubercle at 

 the base. Legs taper, five-jointed, armed with a simple nearly 

 straight claw. Tail straight, five-jointed ; joints equal, dis- 

 tinct, armed on the under side with four rows of compressed 



