786 



AV. T. (JALMAN. 



^94, and BoLivier '05). Some of the members of the family 

 show very primitive characters, having, for instance, swim- 

 ming branches or exopodites on all the thoracic limbs, as in 

 the so-called " Schizopods." In this and in other features 

 they resemble the deep-sea Hoplophoridse, from which, or 

 from some allied forms, most authorities are agreed in con- 

 sidering them to have been derived. 



Other members of the family, however, are considerably 

 specialised. In some characters this specialisation has pro- 

 ceeded along lines parallel to those followed in other series of 

 the Caridea — for example, in the progressive disappearance 



Text-fig. ]. 



Atya bisulcata. Ovigerous female of the Atya-form. X 3. From 

 a specimen in the " Challenger " collection from Honolulu. 



of the exopodites and, later, of the epipodites of the legs, and 

 a diminution in the number of the branchiae. In other 

 characters specialisation has followed lines peculiar to the 

 family, and this is especially the case with the modifications 

 of the chelate first and second pairs of legs. In nearly all 

 Atyidae these limbs are comparatively small, not dissimilar in 

 size, and have the fingers each tipped with a brush of long 

 hairs (Text-fig. 1). Fritz Muller ('92) has described how these 

 brushes are used in collecting pellets of mud on which the 

 animal feeds.^ Among the more specialised members of the 



1 I do not unclevstand Bordage's statement that the chelse are vised 

 for excavating bm-ro-ws in the mud, for which their structm-e would 

 appear to be ill-adapted. 



