1914-] W. M. Tattersall : Indian Brackish Water My sidae. 77 



lately fresh water, beyond suspicion of saline contamination as at 

 Madpur or in the Zoological Gardens at Calcutta, or in water 

 almost as salt as the sea as at L. Chilka. 



I have seen no specimens at all from the west coast of India. 



Potamomysis assimilis, Tattersall. 

 P. assimilis, Tattersall, loc. cit. 



(Plate xiii, fig. 14.) 

 Complete list of localities. 



(i). Chittagong town, brackish ponds near river (A^. Annan- 

 dale and 5. W . Kemp). 



(2). Dhappa, near Calcutta, brackish ponds (iV. Annandale). 

 Type locality. 



(3). Garia, Lower Bengal, brackish ponds {N . Annandale and 

 S. If. Kemp). 



(4). Sar Lake, near Puri, Orissa, fresh water {N . Annandale). 



(5). Edge of the Mahanadi River, Cuttack, Orissa, fresh water 

 (A^. Annandale). 



I have seen specimens from all these localities. This species 

 has a general distribution very closely agreeing with that of 

 Macropsisoricntalis. It is generally found in company with the 

 latter, but is apparently as a rule not nearly so abundant. More- 

 over, it seems to prefer brackish water, since it has not yet been 

 taken in water as salt as the sea and onh^ twice has it been found 

 in fresh water. It has not 3'et been found on the west coast of 

 India. 



The additional material that I have been able to examine of 

 this species has enabled me to supplement m}' original description. 

 I find that m mature males, 6 mm. in length, there is a prominent 

 hirsute lobe oq the antennules, similar in form to but shorter than 

 the same appendage in Macropsis orientalis. At the time of 

 describing the species, my largest male specimen measured onlv 

 4 mm. and in specimens of that size, the appendage is just begin- 

 ning to show itself as a small hirsute tubercle. 



The female has two pairs of incubatory lamellae. 



In the specimens from the Mahanadi River, I find that the 

 small spines arming the truncate apex of the telson show a 

 tendency to an arrangement in series of shorter spines with a 

 longer spine between each series (see plate xiii, fig. 14). This 

 arrangement was shown to a much less extent in the type speci- 

 mens but is probably characteristic of the species. 



Most of the specimens have a row oi black chromatophores 

 on the inner margin of the outer uropod. 



Genus Indomysis, nov. 



Form of the body comparatively slender. 

 Eyes well developed. 



