498 Records of the Indian Museum. [Voi,. XXIV, 



the length of the carpus. Tarsus of the remaining thoracic limbs 

 five-jointed, at least equal to the merus which is one and a half 

 times as long as the ischium ; nail small and setiform. Telson 

 slightly longer than the last abdominal somite, not quite one and 

 a half times as long as broad at the base, cleft for one quarter of 

 its length, the cleft armed on each side by ten coarse teeth, apex 

 about one quarter of the breadth at the base, each lobe at the 

 apex armed with an inner small spine and an outer larger and 

 stouter spine which is twice as long as the small spine and about 

 one-eighth of the length of the telson, lateral margins straight, 

 distal half armed with 10-12 spines, proximal half of the margins 

 smooth, without spines. 



Inner uropod slightly longer than the telson plus the termi- 

 nal spine at the apex, a single spine on the lower inner margin 

 near the statocyst. 



Outer uropod about one quarter as long again as the telson. 



Remarks: — Of the three Indian species of Heteromysis here 

 recorded, this species approaches most closely to H. harpax (Hil- 

 gendorf). I was inclined at first to regard my specimens as be- 

 longing to Hilgendorf's species, but after an examination of the 

 unpublished drawings of Bonnier, illustrating the structure of 

 Gnathomysis gerlachei which I regard as identical with H. harpax, 

 I have decided that the Ceylon specimens represent a distinct 

 species differing mainly in the form and armature of the third 

 thoracic limbs. 



In H. harpax as figured by Kossmann and also by Bonnier 

 among his unpublished drawings, the ischium of the third tho- 

 racic limbs has the inner distal corner produced and acute and 

 the distal margin minutely toothed or serrate. The carpus is 

 armed on its inner margin with a group of four spines distally 

 and two spines proximally, with a distinct gap, unarmed, between 

 the two sets of spines. The distal spines are truncate at the apex 

 and microscopically toothed. The proximal spines are bluntly 

 pointed and bear two or three small blunt teeth. The inner distal 

 angle of the propodus is bluntly produced. 



In H. -proxima the ischium of the third thoracic limbs is not 

 produced at its inner distal angle and the distal margin is not 

 serrate. The carpus has the inner margin armed with two rows 

 of eight or nine peculiar spines with a seta inserted near the tip, 

 extending in a continuous line, without gap, along the greater 

 part of the margin. Between these two rows of peculiar spines, 

 on the distal part of the margin, are three or four stouter, blunter 

 spines and at the extreme distal angle one or two stout spines 

 with a truncate apex. The inner angle of the propodus is more 

 acutely produced than in H. harpax. 



The close agreement between Kossmann's and Bonnier's 

 drawings of the third thoracic limbs of the specimens they ex- 

 amined is strong evidence of the identity of these specimens and 

 also of the probability that the Indian specimens represent a 

 distinct species. The differences I have noted are not sexual, 



