308 



Records of the Indian Museum. 



[Vol.. VIII, 



the propodus and is armed with from 40 to 50 close-set serrated 

 spines (figs. 34, 35). 



The branchial formula is as follows : — 



The epipod on the third peraeopods is sometimes present, 

 sometimes absent : more usually it is suppressed. 



The telson bears two pairs of dorso-lateral spinules ; there is 

 a small spinule on either side of the apex and the margin between 

 them is rounded and bears eight spines, the outermost slightly 

 the largest. 



Large specimens reach a length of about 25 mm. In an 

 ovigerous female (onl}^ one example obtained) the eggs average 

 i"o mm. X '68 mm. in longer and shorter diameter. 



A characteristic feature in the colouration of living specimens 

 is the presence of a broad vertical band of pigment on the side- 

 walls of the carapace immediately over the pleurobranch at the 

 base of the third peraeopods. 



In many species of Caridina the branchial formula is unknown ; 

 but in all cases in which it has hitherto been examined epipods 

 have been found at the bases of the first four pairs of peraeopods. 

 The absence of these appendages from the fourth pair and their 

 occasional absence from the third seems therefore to consti- 

 tute a very important feature of C. excavata. Apart from this 

 character its nearest ally appears to be C. acutirostns , Schenkel/ 

 from Celebes. 



A single example of C. excavata was found at Sadiya in the 

 Dikrang river, while numerous other specimens were obtained in 

 January, 191 r, in the Tezpur district on the Assam-Bhutan 

 frontier. These were taken, for the most part, in a small back- 

 water of the Rowta R. in the Brahmaputra drainage system 

 (Regd. no. ~^), and in this particular spot the species was found 

 to the exclusion of C. weheri var. and C. hodgarti which were 

 abundant in other parts of the district. A few specimens were 

 found in the Rowta R, itself (^{^) and in irrigation channels at 

 Mazbat in the same vicinity (4^), but the species was for the most 

 part decidedly rare. 



1 Verhandl. naturf. Ges. Basel, XIII, 1902, p. 496, pi. viii, fig. 3. 



