170 Carcinological Fauna of India. 



ii. Gastric region with a sharp tubercle or 



spine ... ... ... A. spinosus. 



II. Carapace with a long post-ocular neck: dactyli of 

 last pair of legs hardly curved : — 



1. Lobes of rostrum with a spinate carina: median 



tubercles of carapace low and blunt ... A. cadelli. 



2. Lobes of rostrum with a smooth carina : median 



tubercles of carapace sharp and elevated A. tenuicollis. 



AcJi&us tenuicollis, Miers. 



Achmus tenuicollis, Miers 'Challenger' Brachyura, p. 9, PI. I. fig. 3. 



" The body is thinly clothed with short curled hairs ; the limbs 

 with similar hairs, interspersed among which are some longer ones. 

 The carapace is subtnangulate, little longer than broad, with a neck-like 

 constriction behind the orbits, and armed with spines as follows : — Three 

 conical spines upon the gastric and another upon the cardiac region, two 

 shorter conical spines or tubercles whereof the anterior is the smallest, 

 on each branchial region, behind these one very small on the posterior 

 margin of the carapace, and another on the sides of the branchial regions 

 above the bases of the chelipedes; also a small spine upon the 

 rounded, lateral, hepatic protuberance, and another behind this, on the 

 pterygostomian region ; there is also a strong spinule on the upper 

 margin of the orbit, above the eye-peduncles. The lobes of the rostrum 

 are short, and terminate each in a spine. The sternal surface of the 

 body bears a few spinules. The post-abdomen of the male, is as usual, 

 six-jointed (the two last joints having coalesced). The eye-peduncles 

 are robust, with the corneas protuberant ; a small spinule exists on the 

 inferior margin of the eye-peduncle, and another on the upper margin 

 of the eye, near the distal extremity. The antennules are lodged in 

 deep longitudinal fossettes ; the very slender basal joint of the antenna? 

 is joined with the front at its distal extremity and bears several small 

 spinules on its inferior surface, the following joint is short, the next 

 about as long as the basal joint, flagella slender ; the ischium-joint of 

 the outer maxillipedes is produced at its inner and distal angle which 

 is rounded and bears several spinules on its outer surface, as does also 

 the merus-joint which is rounded, not truncated, at the distal extremity 

 where it bears the next joint. The chelipedes (in the male) are rather 

 slender, and longer than the body ; with the joints clothed with rather 

 long hairs; ischium and merus-joints with a series of spinules on their 

 antcro- and postero-inferior faces, wrist about as long as palm, with a 

 few spinules hardly discernible amid the hairs which clothe this joint, 



16 



