No. IX._ON CARIDES FROM THE WESTERN INDIAN OCEAN. 



By L. a. Borradaile, M.A. 



{Lecturer in Zoology in the University of Cambridge, Fellow, Dean, and Lecturer 



of Selwyn College.) 



(Communicated by Prof. J. Stanley Gardiner, M.A., F.R.S., F.L.S.) 



(Plates 58, 59.) 



Read 2nd November, 1916. 



The prawns which are enumerated in this paper are the residue of several large 

 collections, a great part of which has already been described elsewhere. They were 

 gathered by Professor J. Stanley Gardiner's two expeditions to the Islands and Banks 

 of the Western Indian Ocean, and by Mr J. C. Fryer in Aldabra. I have dealt with 

 the Ponseides and Stenopides of these collections in an article in the Transactions of 

 this Society which . appeared in February 1910 ((2) Zool. xiii. pt. 2, p. 257), and with 

 the freshwater Carides in other articles in the same publication ((2) Zool. xii. pt. 1, p. 63, 

 and xiii. pt. 3, p. 405) and in Gardiner's Fauna of the Maldives (vol. i. p. 64). The 

 Alpheidse have been reported upon by Professor Coutifere in Gardiner's Fauna of the 

 Maldives (vol. ii. p. 852) and in the present volume, and the Pontoniidae by myself, also 

 in this volume (pp. 323 — 396). Only 26 species remain to be dealt with here, but these 

 are by no means the least important part of the collections. Twelve of them were 

 new to science, including one for which it has been necessary to found a new genus*, 

 and there is an exceptionally large proportion of interesting forms. The common but 

 remarkable species Saron marmoratus is of course included, and this allows me to 

 make some remarks concerning Mr Kemp's recent discoveries with regard to the 

 seeming dimorphism of the males, to which I first called attention in the year 1898. 

 There is a new species of the genus Thar, hitherto only known to contain T. paschalis 

 (Heller). The rare Ligur uvece, hitherto only known by the specimens described by 

 myself from the Loyalty Islands, has reappeared, and I am enabled to add some 

 details to my original description. Lysmatella is a new genus related to Hippolysmata 

 but, somewhat strangely, unprovided with mastigobranchs upon the legs. The specimens 

 which I have referred to Leander debilis throw some light upon the meaning of the 

 great variability of this species and upon the nature of the numerous forms related 



* Short definitions of the new species and of the new genus have already appeared in the Annals 

 and Magazine of Natural History for February, 1915. 



