278 BRITISH ENTOMOSTRACA. 



6. Lepeoptheirus Thompsoni. Tab. XXXIII, fig. 2. 



Female. Carapace round. Frontal plates small. An- 

 tennae well developed. Thorax about the fourth part the 

 size of the carapace. Penultimate segment very small. The 

 last nearly quadrilateral ; the posterior edge deeply lobed. 



Abdomen long ; the length of the thorax ; upper por- 

 tion narrow, and bulging out as it approaches the tail. 

 Caudal plates short, rather broad, and giving off three 

 long, plumose setse, and two shorter ones. Sternal fork 

 with sharp, simple branches. 



Male. — Carapace round, but rather broader than in 

 female. Thorax and abdomen both considerably shorter 

 than in female. 



TIab. — Taken from the turbot, March 1837, along with 

 Caligus Midleri and C. diaphanus ; W. Thompson, Esq. 



Genus 3— Chalimus. 



Chalimus, Burmeister, Nov. Act. Acad. Nat. Cur. Bonn., xvii. 



— M. Edwards, Hist. Nat. Crust., iii. 



— Kroi/er, Tidsskrift, ii. 



Character. — Feet, as in preceding genera. Thorax 

 exhibiting four distinct segments. Frontal plates without 

 lunules, or sucking-discs, but provided with a long and 

 slender appendage adapted for prehension, arising from 

 the centre of its anterior surface. 



The genus Chalimus was first established by Burmeister 

 in the 'Nov. Act. Acad. Nat. Cur. Bonn.,' in 1835, to 

 receive a small animal, closely allied to, and nearly 

 resembling the Caligi, but possessing a long and slender 

 appendage arising from the centre of the frontal plates, by 

 which it fixes itself to its prey. He found it attached to 

 a mackerel; but Kroyer afterwards discovered the same 

 species adhering to a Caligus ; and the only specimen I 

 have yet met with, I found also parasitic upon an indivi- 

 dual of that genus. 



