ici 5-] Fauna of the Chilka Lake : Mysidacea. 151 



broad ; lateral margins of the telson armed with 4-7 



spines, apex with numerous quite small spines or teeth 



much shorter than the terminal spines of the lateral 



margins . . . . . . Indomysis annandalei, W.M.T. 



(d) Apex of the telson between the terminal spines of the lateral 

 margins produced into an obtuse serrated process ; third 

 pleopod of the male biramous though small ; exopod of the 

 fourth pair elongate ; antennal scale setose all round and two- 

 jointed ; eyes rather large on long stalks . . . Macropsis orientalis, W.M.T. 



One species (Gastrosaccus simulans) described in this paper, was not found in 

 brackish water, but on the sea -shore a few miles up the coast from the mouth of the 

 Chilka I,ake. 



Dr. Annandale and Mr. Kemp have supplied notes on the natural colouration, 

 habits, etc., of the different species. These notes I have added in each case at the 

 end of my own observations. 



Family MYSIDAE. 



Sub-family RHOPALOPHTHALMINAE, Hansen. 



Genus RHOPALOPHTHALMUS, Illig. 



Rhopalophthalmus egregius, Hansen. 



R. egregius, Hansen, 1910. R. egregius, Nakazawa, 1910. 



This interesting species was first described by Hansen (1910) from specimens 

 taken on the Siboga expedition in the Sangkapoera Roads, Bawean Island, in the East 

 Indies. It has since been recorded by Nakazawa (1910), from Port Shimizu, Suruga 

 Bay, Japan. Its occurrence on the coast of India therefore marks a considerable 

 extension in its known geographical range, and it is evidently an abundant and 

 widely distributed form. 



Hansen's description was based on mutilated specimens, and is therefore incom- 

 plete. I am able from the present material to supplement his description and to add 

 some points not hitherto noticed. 



The most interesting feature of the species, not noticed by Hansen but described 

 and figured by Nakazawa, is the reduced condition of the endopod of the eighth pair 

 of thoracic limbs in both sexes. In the female, the endopod of these limbs is hardly 

 as long as the basal joint of the exopod, papilliform in shape, obscurely two- 

 jointed, with one or two setae on the outer edge at the obscure junction of the two 

 joints, but otherwise unarmed. In the male, the endopod is more distinctly two- 

 jointed, and the basal joint bear six long setae on its outer margin. 



The remainder of the thoracic legs are as described by Hansen. They increase 

 in length and slenderness from the third to the seventh pair and have the sixth 

 joint or tarsus four-jointed in the third pair, five-jointed in the fourth to the sixth 

 pair and seven-jointed in the seventh pair. The carapace is exceedingly short, leaving 

 entirely exposed the last three thoracic segments. The antennular peduncle appears 

 to me to be somewhat stouter than shown in Hansen's figure and has the outer distal 



