VII. NOTES ON CRUSTACEA DECAPODA 

 IN THE INDIAN MUSEUM. 



VIII. The genus Acetes, Milne-Edwards. 



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



of India. 



In attempting to determine a large collection of Decapod Crus- 

 tacea recently made by Dr, Annandale in J apan, China and Lower 

 Siam, I found it impossible to come to a satisfactory decision 

 regarding the identity of a species of Acetes, and it was only after 

 examining the series of unidentified specimens in the Indian 

 Museum that any definite conclusion was reached. It is with the 

 results of this examination that the present short paper is con- 

 cerned. 



In the first of his classical memoirs on the genus Sergestes 

 Dr. Hansen remarked,^ '' Of Acetes 2 species are known (one of 

 which has not been examined since 1837), ^^^ we possess 6 species, 

 the distinctive characters of which are very curious ; it is, however, 

 impossible to give a good idea of the species. . . . without a consider- 

 able number of figures." Twenty years have elapsed since this 

 statement was made, but Dr. Hansen has unfortunately not made 

 any further contribution to the subject. Although two additional 

 species have been described, their characters are very imperfectly 

 known and no fresh account of A. indicus, the species for which 

 Milne-Edwards founded the genus Acetes, has appeared. Acetes 

 indicus has indeed been several times recorded from various locali- 

 ties, but it is, I believe, quite impossible to recognize the species 

 from the original description : all definite specific records are 

 therefore open to doubt. 



The collection in the Indian Museum is not so rich as that in 

 the University of Copenhagen, but comprises four distinct forms; 

 three of these — all occurring in Indian waters — are in my opinion 

 to be referred to known species, to A. indicus, Milne-Edwards, 

 A. japonicus, Kishinouye, and A. erythraeus, '^oh\\\; the fourth, 

 obtained in Borneo, is undescribed. One described species, A. 

 americanus , Ortmann.'^ is not represented in the collection. 



The four forms examined show the closest affinity with one 

 another and all agree in the complete suppression of the last two 

 pairs of peraeopods — the character on which Milne-Edwards estab- 

 lished the genus. 



' Hansen, Proc. Zool. Soc. London, 1896, p. 937. 



"^ Ortmann, Decap. Schizop. Plankton- Exped., p. 39, pi. ii. fig. 2 (1893). 



