Pah iahO eS ON DE CAP ODA EN sh ie 
INDIAN MUSE UM, 
IV.—OBSERVATIONS ON THE PRIMITIVE ATYIDAE WITH 
SPECIAL REFERENCE TO THE GENUS Xiphocaridina. 
By STANLEY Kemp, B.A., Assistant Superintendent, Indian 
Museum. 
For the last few years efforts have been made to improve 
the collection of Atyidae in the Indian Museum and, thanks 
to the energy displayed by numerous correspondents, the series 
will, it is hoped, shortly become thoroughly representative of this 
important part of the Indian freshwater fauna. In course of time 
a full report on this family and on the Palaemonidae will be 
issued, forming a part of the Museum Catalogue of Indian Deca- 
pod crustacea. 
The Atyid fauna of the Indian Empire comprises, so far as is 
at present known, only three genera, Atya, Caridina and Xiphoca- 
vidina. Ortmannia (Atyotda) does not seem to occur, and this, in 
view of Bouvier’s theory of the mutational origin of that genus 
and of Atya, is a most unfortunate circumstance. It is, however, 
still hoped that specimens will be found which will provide 
material for some further consideration of this interesting question. 
Atya appears to be very scarce. A few specimens from the 
Andamans are the only Indian representatives of the genus in the 
collection, while in addition there is a single example from Ceylon. 
Candina, the prevalent genus, occurs in great abundance in every 
suitable locality, inhabiting both fresh and brackish water and 
ascending to altitudes of at least 6,000 ft. Of Xzphocaridina a single 
species only is known, obtained at Tezpur, on the north bank of 
the Brahmaputra R. in Assam, and in the native state of Manipur 
further to the east. It is with this last form that the present 
note is concerned. 
The Atyidae as a whole must be regarded as a very primitive 
family of Caridea, in spite of the fact that the peculiarly modified 
chelae indicate a considerable degree of specialization. Xiphocan- 
dina is one of the most primitive of the known genera, and it is 
through such forms as this and Xzphocaris that the common 
ancestry of the Atyidae and the deep-sea pelagic shrimps of the 
family Hoplophoridae has been traced. Bouvier (1g09@), follow- 
ing Ortmann (1895), has laid great stress on this interesting feature 
of Caridean evolution, and his careful researches leave no room 
for doubt on the point. 
