CHAROPINTJS RAMOSUS. 193 



deen (T. Scott). Irish Sea (A. Scott). This appears to 

 be a moderately rare species in British waters. 



Genus 40. ACHTHERES Nordmann, 1832. 



Female. Cephalothorax short and broadly ovate, 

 separated from the genital segment by a tolerably dis- 

 tinct constriction. Genital segment oval or subglobose, 

 and sometimes exhibiting a more or less segmented 

 structure. The two pairs of antennae and the mouth- 

 appendages not differing much from those of Lernseo- 

 poda ; second maxillipeds short, stout, free, but united 

 at the tip to a circular chitinous disk, which is expanded 

 in front. Genital segment usually furnished with two 

 small processes at the distal extremity. Egg-strings 

 short, dilated or saccate ; ova tolerably large. 



Male. Very small ; first maxillipeds short, very 

 robust, strongly uncinate; second maxillipeds elongated, 

 stout; terminal claws small. 



Parasitic for the most part on freshwater fishes. 



1. Achtheres percarum Nordmann. 



(Plate L, figs. 6-8 ; Plate LIX, figs. 7, 8; Plate LXIV, 



figs. 1-3.) 



1832. Achtheres percarum Nordmann. (89) p. 63, pi. iv. 

 1838. Achtheres percarum Kroyer. (70) ii, p. 143, pi. iii, fig. 6. 

 1840. Achtheres percarum M. Edwards. (43) p. 511, pi. xl, fig. 8. 

 1861. Achtheres percarum Claus. (32) p. 287, pis. 23, 24. 

 1899. Adheres percarum Bassett-Smith. (8) p. 498. 

 1901. Actheres percarum T. Scott. (113) p. 132. 

 1904. Achteres percarum Pehr Gadd. (47) p. 21. 

 1906. Achtheres percarum Brian. (21) p. 101. 



Female. Cephalothorax of moderate size, narrower 

 in front than behind. Genital segment sub-globose, 

 rather longer than broad, separated from the Cephalo- 

 thorax by a distinct constriction ; the posterior end of 

 the segment slightly angular, bearing two minute pro- 

 cesses one on each side of the median line. Abdomen 

 obsolete. Egg-strings short, stout, saccate, scarcely 

 equal in length to the genital segment. Ova large. 



VOL. i. 13 



