46 



crowded setae, which may attain a considerable length, rendering those limbs 

 well adapted for assisting the anterior antennae in the swiming motion of the 

 animal, these setae being however in some instances much reduced in size or 

 even wholly wanting; apical claws more or less slender, and generally 4 or 5 

 in number. Maxillipeds with the basal part produced in front to a well defined 

 masticatory lobe armed on the tip with curved spines or setae, and in most 

 cases carrying behind a more or less developed vibratory plate; palp, as a 

 rule, in female of inconsiderable size and in male transformed to a grasping 

 organ. Legs more or less dissimilar, the posterior one being as a rule, not 

 ambulatory, but upturned within the cavity of the shell. Caudal rami in some 

 cases much reduced, but in the great majority of the forms well developed 

 and very mobile. Germinal part of the genital organs in both sexes generally 

 lodged between the lamellae of the valves. A pair of more or less complicated 

 ejaculatory tubes added to the genital apparatus in male. 



Remarks. In the sense in which the family is here taken, it comprises 

 a considerable number of genera, both marine and freshwater, the former 

 deviating more or less conspicuously from the usual type prevailing in the 

 freshwater genera, though retaining most of the characteristic features disting- 

 uishing the present family from the Cytheridce. Yet a grouping of the genera 

 within subfamilies would seem to be fully justified. 5 such subfamilies will 

 be treated of in the sequel. 



Subfam. 1. Pontocyprinae. 



Characters of the subfamily. Shell of somewhat varying shape, with the 

 valves nearly equal and more or less hairy. Antennae in some cases rather 

 slender and distinctly natatory, in other cases very short and stout and scarcely 

 adapted for swimming; the posterior ones 6-articulate; with the sensory appendage 

 ,of 3rd joint very fully developed. Mandibles with the bristle attached outside 

 the masticatory part remarkably strong and distinctly pectinate; cutting teeth 

 simple, claw-like; palp comparatively large. Maxillae with the masticatory lobes 

 short and stout; palp however rather prominent and bowed in front. Maxillipeds 

 without any trace of a vibratory plate at the base; palp in female distinctly 

 3-articulate, sub-pediform, in male transformed in the usual manner. Anterior 



