28 CALIFORNIA ACADEMY OF SCIENCES. 



Carapace subtriaugular and furnished with tubercles aud granulations; 

 a tubercle on the posterior portion of the tumid median region; a large, 

 pointed tubercle on the cardiac, and a smaller one near the posterior mar- 

 gin of the carapace; branchial regions with several small tubercles; tuber- 

 cles on the sides of the carapace prominent. Rostrum acute. Postocular 

 spine pointing obliquely forwards and a little exceeding the eyes. Basal 

 antenual joint with its outer edge produced forwards into a spine and its 

 lower side furnished with a longitudinal ridge which is nearer the inner 

 than the outer edge. Chelipeds in the male rather stout, the outer edge 

 of the merus furnished with small tubercles and coarse granulations; inner 

 edge of the carpus coarsely granulated; palm of the hand inflated and 

 having a short row of small tubercles on the proximal portion of the outer 

 surface near the middle line; fingers slender, silicate. Legs long and 

 slender. In the male the first abdominal segment is large and bears a 

 large spine-like tubercle; the second segment is short aud bears a smaller 

 tubercle; the third segment is the widest and bears three rounded eleva- 

 tions in a transverse row; behind the third segment the abdomen tapers 

 rapidly to the fifth, which is but little wider than the succeeding one; the 

 last segment is subtriangular and fused with the one before it. In the 

 female the first segments are short and furnished with small median tuber- 

 cles. In the male the sternum is coarsely granulated, and on the segment 

 which bears the chelipeds there is a pair of transverse, granulated ridges. 



The measurements of Lockington's specimens which 

 I have had the opportunity of examining are as follows: 



Length. Breadth. Length of first 



ambulatory leg. 



Male 75 in 55 in 1 .55 in. 



Female 56 in 38 in 94 in. 



The rostrum varies much in length; in old males it is 

 often produced into a sort of spine; in females and 

 young males it is often quite broadly triangular. 



San Diego! Magdaleiia Bay (Lockington)! Gulf of Cali- 

 fornia (Rathbun)! Panama Bay (Rathbun). 



I have seen the types of both tuberculatus and mexi- 

 canus. 



