XX. NOTES ON CRUSTACEA DECAPOD A 

 IN THE INDIAN MUSEUM. 



VI. Indian Crangonidae. 



By Stanley Kemp, B.A., Superintendent^ Zoological Survey 



of India. 



(Plate VIII.) 



The number of Crangonidae known from Indian seas has been 

 considerably increased by recent work in shallow water on various 

 parts of the coast. In dealing with the additional material that 

 has come to hand I have thought it useful to include references to 

 all the known Indian forms and to construct keys to facilitate the 

 identification of the species of Pontophihis and Aegeo7i. 



Six species hitherto unknown are described, all belonging to 

 the genus Pontophilus, while, thanks to the assistance of Dr. W. T. 

 Caiman, I have been able to rectify certain errors in the nomen- 

 clature of two species of Aegeon. 



In a previous paper in this series ' I expressed the view that 

 Philocheras, Stehhmg{ = Cher aphilus, Kinahan, partim) could not 

 be sustained as a distinct genus, but must be merged in Pontophilus. 

 In examining the new forms of this genus a point hitherto over- 

 looked has come to light, namely, that in certain species there 

 are considerable differences between the sexes in the form of the 

 pleopods. The modifications of these appendages are not only of 

 interest as evidence of the affinities of the different species, they 

 also, as it appears to me, afford a valuable clue to the origin of 

 the various genera of the family and point to lines of descent 

 very different from those suggested by Ortmann in 1890. I have 

 thought it best to discuss the structure of these appendages and the 

 phylogenetic conclusions which may be derived from them under a 

 separate heading at the end of the paper. 



In all eighteen species of Crangonidae are now known from 

 Indian waters, ten belonging to the g^nns Pontophilus, six to Aegeon 

 and one each to Prionocrangon and Crangon. 



Genus Pontophilus, lycach. 



The six undescribed Indian species of this genus were obtained, 

 two from Kilakarai at the northern end of the Gulf of Mannar 



1 Rec. Ind. Mms.,YI, p. 5 (19") 



