650 Memoirs of the Indian Museum. [Voi,. V, 



It is with some hesitation that the numerous specimens of Sternaspis from 

 the Chilka Lake are referred to the species from Japan, described by Marenzeller, 

 and rediscovered at Batavia by Sluiter. According to Marenzeller, it agrees closely 

 with the widely distributed 5. scutata (Ranzani) of European seas, the most marked 

 difference being in the shape of the posterior ventral shield. In the latter respect 

 the Chilka Lake specimens show a fairly close agreement with the description and 

 figures given by Marenzeller. 



Not one of the 316 specimens which I examined showed any trace of an 

 elongate proboscis such as Sluiter found in 5. spinosa, and it is obvious that 

 the latter species should be removed to a new genus. The prostomial lobe is 

 small and rounded, exactly as in 5. scutata. The largest specimens were 8 mm. 

 long, and the greatest width was 3-3*5 mm. The largest specimen examined by 

 Marenzeller was 12 mm. long and 5 mm. wide. Sluiter examined three specimens, 

 18 mm., 22 mm., and 35 mm. long respectively. In the smallest of these, the 

 ventral shield closely resembled that of 5. costata in shape and colour, but the 

 largest individual varied considerably in the direction of 5. scutata, the other 

 specimen being intermediate in size and structure. European specimens of 5. scutata 

 which I have been able to examine were larger than those from the Chilka Lake, 

 and differed in the shape of the ventral shield. Some of the specimens, taken 

 in the outer channel in September, had the body cavity full of ripe eggs, so that 

 apparently the Chilka Lake species does not attain a much greater size than 8 mm. 



The body as a whole is brownish yellow in colour. The yellow pigment is 

 specially marked on the gills, the intersegmental areas, and in the area surrounding 

 the mouth and prostomial lobe. The wide posterior part of the body is more 

 deeply coloured than the narrow anterior part, and the body-wall of the former 

 is also thicker and less transparent. The prostomial lobe is quite transparent. 

 The ventral shield (fig. 5 a) is brightly coloured, the colour ranging from rusty 

 red to scarlet. There is a narrow colourless margin on the lateral and posterior 

 borders. It easily separates into two halves, and each half is slightly longer 

 than broad. It has a series of ridges radiating from the centre, each ridge forming 

 a groove over one of the bundles of setae, which emerge from the body-wall 

 beneath the shield. A series of concentric markings is also obvious. The anterior 

 and posterior borders are apparently deeply indented, the indentations, which 

 are not so rounded as in Marenzeller' s figure, being occupied by paired triangular 

 plates. The anterior pair, which Marenzeller calls accessory plates, and which 

 are absent in 5. scutata, really form part of the large plates, being only differentiated 

 by their delicate transparency and smoothness, and by the conspicuous ridge 

 which separates them from the large plates. They only occupy part of the anterior 

 concavity. The posterior triangular plates make the posterior border almost 

 straight. * They show the same ridges and concentric markings as the large plates, 

 and five pairs of bundles of setae emerge from beneath them. From beneath 

 the large plates 9-1 1 pairs of bundles of setae emerge. There are thus 14-16 pairs 

 altogether, those at the outer posterior angles being the largest and longest. All 



