A CAVE ISOPOD 377 



(Linn.) is a species distributed almost all over Europe in 

 great abundance. The details of its organisation, external 

 and internal, are explained, with a clearness of language 

 and drawing which leaves nothing to be desired, in the 

 'Histoire naturelle des Crustaces d'eau douce de Norv^ge' 

 by G. 0. Sars, 1867. M. Dollfus says that aquaticus is 

 completely displaced in Palestine by his new species, 

 Asellus Goxalis. Harger mentions AseUas communis, Say, 

 as common in the fresh-water ponds and streams of New 

 England. For other species, and the bibliography of the 

 genus, the ' Notes on the Family Asellidae,' by Dr. Boval- 

 lius, should be consulted. 



Mancasellus, Harger, 1876, was named to take the 

 place of ^seZZopsis, Harger, 1874, preoccupied. This genus 

 is exceptional in regard to the mandibles which have no 

 ' palp,' being otherwise very like Asellus. Mancasellus 

 tenax (S. I. Smith) and Mancasellus brachyurus^ Harger, 

 are found in the fresh waters of North America. 



Ccecidotea, Packard, 1871, is without eyes, has the 

 seventh joint of the limbs not bifid, and the uropods elon- 

 gate, with two unequal branches. The species Goecidotea, 

 stijgia is found in the Mammoth and Wyandotte Caves and 

 in wells in Indiana. The absence of eyes does not distin- 

 guish it from Asellus, for some of the species of that genus 

 are also blind. 



Janlra^ Leach, 1814, is a marine genus, dorsally not un- 

 like Asellus, but the second antennas have a small scale or 

 exopod ; the first limbs of the pergeon have the sixth joint 

 scarcely expanded ; the first pleopods in the female form 

 a subcircular operculum. The uropods are two- branched. 

 The only British species is Janira maculosa, Leach. In 

 regard to the American species, Janira alta (Stimpson), 

 Harger says of the pleopods in the male : — ' The thickened 

 opercular plates are three in number, viz., a pair of semi- 

 oval plates at the sides, and a more slender median plate 

 presenting traces of a suture along the middle.' This 

 formation is probably characteristic of the genus, and no 

 doubt, as explained by Hansen for Eurycojpe, the fused 

 plates represent the first pleopods, and the semi-oval plates 



