234 Surg.-Capt. A. Alcock on 



65. Pentacheles gilha *, sp. n. 



Pentacheles, sp. remarkable for its hunch-backed thorax, Wood-Mason, 

 Admin. Rep. Marine Survey of India for 1890-91, p. 19. 



The carapace, which is inflated, elevated, and humped in 

 front, is everywhere tliin, spiny jrranular or carious, and 

 thickly setose, and its greatest breadth, which is just behind 

 the cervical groove, is not much more than half its greatest 

 (lateral) length ; the median carina ends in a double rostral 

 spine and has its crest irregularly serrated or eroded through- 

 out, in addition to which there is a row of 4 large spines, of 

 which the second may be double, between the rostral spine 

 and the cervical groove, and 10 or 11 spines or double spines 

 between the cervical groove and the posterior smooth, 

 narrowly-moulded edge of the carapace ; the frontal margin 

 is finely eroded ; the spines of the lateral margins are con- 

 cealed in setae of great length, they number about 25 on each 

 side, of which 5 are found in front of the hepatic groove, 3 

 between the hepatic and cervical grooves, and about 17 

 behind the cervical groove ; the usual dorsal sublateral 

 (branch iostegal) crests are quite wanting, but ventrally the 

 branchial regions are traversed fore and aft by the usual 

 finely serrated ridges. The abdominal terga have the surface 

 rough and spiny and the setae on the posterior margin 

 remarkably long and close-set ; all, including the telson in 

 its front part, are carinated, the edge of the carina in all 

 being irregularly and obtusely denticulated ; a broad shallow 

 groove traverses the terga obliquely outwards and backwards 

 on each side of the carina. 



The pleuree have the surface spiny and the setose margin 

 smoothly moulded. The edge of the telson is finely spinate. 



The orbital notches are broad and shallow, with the inner 

 edge eroded ; the optic peduncles have each a small scrobicu- 

 late spine at the frontal level. 



The basal joint of the antennules has a single spine at its 

 antero-external angle, and its scale is 4 or 5 times larger than 

 the antennal scale, both scales ending obtusely. All 5 pairs 

 of thoracic legs are chelate (in the female). 



The great chelipeds have the usual form and just exceed 

 the body in length ; tlie compressed meropodite has both edges 

 distantly and very finely serrated, the upper edge bearinir a 

 single terminal spine ; the prismatic carpopodite has a similar 



♦ This species is figured in ** Illustrations of the Zoology of the Royal 

 Indian Marine Steamer ' Investigator,' Crustacea," pt. ii, (pi. viii.), to bo 

 issued early this year. 



