CHIROCEPHALUS. 39 



and not divided into two plates. No appendages at the 

 base of cephalic horns. 



1 — Chirocephalus.* 



Chirocephalus, Prevost, 1803 ; Thompson. 



Branchipus, M. Edwards, Fischer, Latreille, Desmarest, Giierm, Lamarck. 



Ino, Schrank, 1803 ; Oken. 



Cai^cer, Shaw. 



Character. — Abdomen large, consisting of nine di- 

 visions, and terminated by two well-developed caudal 

 plates or lamellar appendages ; cephalic horns, of a cylin- 

 drical shape, and fm-nished with fan-shaped and digitiform 

 appendages in the male. 



BiUiograpldcal History. — A figure of the Chirocephalus 

 was given by Petiver, in his * Gazophylacion Natm'ae,' as 

 early as 1709. He mentions it as a native of England, 

 but merely describes it shortly, as " Squilla lacustris 

 minima, dorso natante." It was afterwards described at 

 greater length, as British, by Edward King, f.r.s., who 

 read, before the Royal Society, a short description of " a 

 very remarkable aquatic insect, found in a ditch of stand- 

 ing water, near Norwich, in the spring of the year 1762," 

 and which is published in the ' Philos. Trans.' for 1767. 

 " They were discovered," he says, " by a poor man now 

 dead, whose genius was very extraordinary, and much 

 superior to what is usually found in his rank. He was 

 indefatigable in his searches after everything curious, and 

 without ever having had any advantages of education, 

 had acquired a degree of knowledge by no means con- 

 temptible. ... In the ditch from which they were taken," 

 he continues, " there were a vast multitude of the same 

 kind, though they have not been found in any other place 

 that I know of. From their being prolific in this state, 



* From x*'P; a, liitud ; and Kii^cikov, head. 



