THE CANCROID CRABS OF AMERICA 91 



Description. — A small species. Carapace very broad, lateral spine 

 very long, an erect spine at posterior angles. Width of carapace two 

 and a half times length. Two tubercles on mesogastric region form 

 a quadrilateral with two on cardiac region which are farther apart; a 

 protogastric tubercle is in oblique line with two branchial tubercles. 

 Behind these but smaller and less evident is a tubercle at the begin- 

 ning of a branchial ridge which is formed of a single row of granules. 

 There is a low posterior median cardiac tubercle. The long branchial 

 ridge running from the lateral spine to the inner angle is high, blunt 

 and forms a single arch reaching forward to the level of the sixth 

 tooth. A hepatic arch of granules nearly parallels the branchial ridge. 

 Front arcuate, teeth triangular, blunt, similar, submedian more ad- 

 vanced, median sinus deepest. Inner end of upper margin of orbit 

 oblique, divided into two low blunt teeth; upper fissures closed in 

 large part; outer tooth large, subacute. Lateral teeth 2 to 8 sharp, 

 the first 5 shallow, seventh and eighth longer and more outstanding; 

 fifth larger than third; second, fourth and sixth smaller than their 

 neighbors; lateral spine transverse, as long as the width of the five 

 spines or teeth in front of it, its anterior margin fringed with hair. 

 Posterior spines curved, directed upward, outward, and forward. 



Four spines on anterior margin of arm and one terminal posterior 

 spine. Outer spine of carpus of good size, shorter than inner spine 

 and longer than proximal spine of manus; superior spine of manus at 

 distal fourth of margin. Merus of last leg unarmed. 



Measurements. — Male (22040), total length of carapace 12.4, width 

 of same 31, width at anterior base of lateral spine 20.5, fronto-orbital 

 wadth 10, width of front 3.6 mm. 



Young. — Usually in this genus the lateral spine is longer proportion- 

 ally in young or small specimens than in full grown. Such is not the 

 case in tuber culatus; in one 14.4 mm. wide the spine is equal to the 

 width of the next four teeth, and in one 12 mm. wide the spine is equal 

 to the width of only two teeth. 



Range. — From Cape St. Lucas, Mexico, to Panama. 



Material examined. — Cape St. Lucas, Lower California; John 

 Xantus; 1 male cotype (19679) from British Museum; 8 specimens, 

 cotypes (1626, M. C. Z.); 7 specimens, cotypes (Brit. Mus.). 



Maria Madre Island, Tres Marias Islands, Mexico; 4-10 fathoms; 

 1925; Hanna and Jordan, Cahfornia Academy of Sciences Expedi- 

 tion; 1 young (Cal. Acad. Sci.) 1 young (62706). 



Bay of Panama; 1888; Albatross: Lat. 8° 44' 00" N., long. 79° 

 09' 00" W.; 29).^ fathoms; gn. M.; March 6; 1 male (22041). Lat. 

 8° 10' 30" N., long. 78° 50' 30" W.; 18 fathoms; gy. S. brk. Sh.; 

 March 5; 1 male (22040). 



