CAMBARUS. 57 



base to near the tip, where they suddenly converge to form the short, acute, 

 broadly triangular acumen; the acumen is slightly margined. Post-orbital 

 ridges unarmed in front, with posterior callosities. Cephalothorax long, lat- 

 erally compressed. Carapace smooth and sparsely punctate above, granular 

 on the sides; cervical groove sinuate, no branchiostegian spine; sub-orbital 

 angle moderately developed, rounded ; areola linear, with a small anterior 

 and a larger posterior triangular space. Abdomen shorter than the cephalo- 

 thorax by the length of the rostrum, lateral margins of the pleurae nearly 

 straight, basal segment of the telson one- or two-spined on each side, poste- 

 rior segment short, rounded ; rib on inner blade of the swimmeret ends 

 inside the margin. Basal segment of antennule with a spine beneath. An- 

 tenna? short, scale short and of moderate width. Epistoma triangular, sides 

 convex and setose, anterior angle truncate in some specimens. Third max- 

 illipeds furnished with long hairs within. Chela broad, inflated, punctate. 

 squamoso-tuberoulate on the inner part of the upper face of the hand ; 

 inner margin of hand serrato-dentate ; fingers laterally compressed, punc- 

 tate ; movable finger tuberculate on the outer margin at the base ; inner 

 margins of fingers tuberculate. Carpus triangular, obliquely truncate, armed 

 on the internal side with a long strong tooth and one or two smaller teeth 

 and low tubercles ; on the lower face there are a small external spine, a 

 strong median anterior spine, and two or three small tubercles between the 

 median spine and the internal tooth. Distal half of superior margin of 

 meros tuberculate, lower face biserially spinulose. Third pair of legs hooked. 

 Sternum hairy. First pair of abdominal appendages long, slender, twisted; 

 internal part cylindrical, straight, apex acute, longer than internal part, bent 

 somewhat outward; external part truncate, terminated by two horny teeth. 



Length, 80 mm. Carapace, 45 mm. Width of carapace, 20 mm. Length 

 of metaearapace, 19 mm. 



Female. — Abdomen broader, annulus ventralis composed of two cres- 

 cents flattened and interlocked behind, the anterior horn of each crescent 

 making a prominent denticulated tubercle. 



1 have not seen the second form of the adult male. Very young males 

 have the first pair of abdominal appendages unarmed at the tip. In the 

 larger male specimens the movable linger is somewhat excised at the base 

 within, and the index has a very prominent tubercle opposite the excision. 

 In younger specimens the antennal scale is broader and more convex within 

 than in mature specimens. Very young ones, taken from the parent, have 



6 



