iç)i5-] Fauna of the Chilka Lake : Stomatopoda. 195 



and more strictly triangular in outline, the lateral margin of the fifth thoracic somite 

 is scarcely at all produced and the telson still possesses between the marginal teeth 

 the fine widely-separated spinules characteristic of the larval stages. 



The single post-larval specimen of the typical S. scorpio, an individual 21 mm. 

 in length, is easily distinguished from examples of the var. Immaculata measuring 16 

 and 25 mm. by the same characters that serve to separate the adults. All post-larval 

 specimens of 16 mm. in length and under apparently belong to the variety, lacking 

 the characteristic features of the typical form. It appears to me probable that the 

 two are to be distinguished even in the earliest post-larval stages and that such stages 

 of the typical S. scorpio, a form comparatively rare in the Chilka L,ake, are absent 

 from our collections. There is, of course, a possibility that the two are inseparable 

 until they have reached a length of about 2 cms. 



Larval Forms. 



The larval forms found in the Chilka Lake are all of one type and the majority 

 are doubtless those of 5. scorpio var. immaculata. The larvae of the typical form 

 were either not obtained or are inseparable from those of the variety. 



The largest larvae in the collection (text-figs. 2a-c) are from 11 "5 to 12*0 mm. in 

 length from the tip of the rostrum to the apex of the telson. The rostrum is not as 

 long as the carapace, the anter o-lateral spines are shorter, in length scarcely equal to 

 half the anterior breadth of the carapace, while the postero-laterals are long, about 

 two-thirds as long as the distance between the antero-lateral angles and the posterior 

 margin. The carapace is carinate in the mid-dorsal line, the carina terminating pos- 

 teriorly in a spine, directed obliquely upwards and backwards, that is fully one-third 

 the length of the postero-laterals. The lower edge of the rostrum, a little behind its 

 middle point, is provided with one, less commonly with two, spinules. On the lateral 

 margin of the carapace are three spinules, one close to the antero-lateral spine and 

 two in the posterior quarter of its length (text-fig. 2c). On the inferior aspect of 

 each postero-lateral spine is a sharp spinule and another, which appears to be highly 

 characteristic of this particular larva, is found on each side of the posterior margin 

 midway between the postero-median and postero-lateral spines. 



The eyes are comparatively large, the basal portion of the stalk being very slen- 

 der. The penultimate segment of the raptorial claw bears, on the margin opposed 

 to the dactylus, two stout basal teeth, beyond which is a series of fine pectinations. 

 The dactylus shows 110 trace of teeth (text-fig. 2b). 



The appendages of the last three thoracic segments are well developed and 

 biramous; only the last segment is exposed in dorsal view. The postero-lateral 

 angles of the abdominal somites are not provided with spines and there are no spines 

 on the posterior margin of the last segment. The pleopods are well formed but do 

 not bear gills. 



The telson is a trifle broader than long and is carinate mid-dorsally. There are 

 eight pairs of spinules between the submedian teeth, five to seven spinules between 

 the submedians and intermediates and one between the intermediates and laterals. 



