XXII. — DESCRIPTION OF A NEW SPECIES 



OF THE CxENUS S E S A R M A, SAY., FROM 



THE A N D A M A N I S L A N D S . 



By Dr. J. G. clE Man. 



A collection received from Dr. Annandale of the Indian 

 Museum, Calcutta, comprises a new species of the genus Sesarma, 

 Say. It is represented by one male and two females that were 

 collected at Mount Hamet, Port Blair, Andaman Island, in fresh- 

 water streams in dense forest at a height of 700 feet, b}^ Mr. B. B. 

 Osmaston, in January, 1907. The larger of the two females, which 

 are a little smaller than the male, carries a Sacculina. 



Sesarma thelxinoe, sp. nov, 



(Plate xi.) 



A new species of the subgenus Sesarma, related to Sesarma 

 sylvicola, de M., from Sumatra, to 5. ocypoda, Nob., from Benkoelen 

 and to 5. celehensis, Schenkel, from Celebes. 



Both in the male and in the female the distance between the 

 outer orbital angles appears a little larger than the length of the 

 carapace, the proportion being nearly as 13 : 12. Upper surface de- 

 pressed, very slightly arcuate transversely at the level of the 

 mesogastric area, whereas the gastric region slightly slopes down 

 forward towards the frontal lobes ; posteriorly the upper surface 

 is more flattened, whereas the epibranchial regions are deflexed 

 downward. Regions indicated, but incompletely defined. Of the 

 cervical groove the transverse furrow that defines the gastric 

 region posteriorly is well developed and rather deep only in its 

 lateral parts ; the mesogastric furrow is shallow, though reaching to 

 just behind the middle of the gastric region. The protogastric 

 areas that slope down laterally to the lower situated, hepatic 

 region, are not separated at all from the anterior branchial areas, nor 

 from the mesogastric area which is also undivided. The intestinal 

 region is bounded laterally by shallow depressions. 



The front, which is vertically deflexed, is just half as broad as 

 the distance between the outer orbital angles. Of the four post- 

 frontal lobes, which are separated from each other by narrow, moder- 

 ately deep incisions, the inner are just twice as broad as the outer ; 

 the post- frontal lobes are prominent and hide the front, though the 

 lower margin is visible when the carapace is looked at from above. 

 The free edge of the post-frontal lobes is rather sharp, though very 



