ABT. 6 NEW EOeEKE CRABS FROM TEXAS RATHBUN 6 



Family XANTHIDAE 



Genus HARPACTOCARCINUS A. Milne Edwards 



Harpactocareinus A. Milne Edwaeds, Ann. Sci. Nat., Zool., ser. 4, vol. 18, 

 1862, pp. 46 and 64; type, H. punctulatiis (Desmarest) from the Eocene 

 of Priabona. 



HARPACTOCARCINUS AMERICANUS, new spscies 



Plates 2 and 3 



The specimens were obtained chiefly from the interior of con- 

 cretions, but the material was so friable that the fossils broke into 

 many pieces. One female and one male were in a layer 10 feet be- 

 low the concretions ; they are used as holotype and paratype. 



Diagnosis. — Lateral teeth behind the orbit five, very small. Sur- 

 face of carapace uneven in posterior two-thirds. Chelipeds similar 

 and of moderate size in the female, unequal in male, the major one 

 of enormous size, the fingers greatly elongate. 



Description. — Carapace of female holotype (pi. 2, fig. 3) very 

 little broader than long; chord of antero-lateral margin nearly as 

 long as postero-lateral margin, and amply rounded; postero-lateral 

 margin slightly sinuous, nearly straight. Surface very convex, more 

 so from front to back than from side to side; punctate and very 

 finely granulate. From either side of the widest part of the meso- 

 gastric region a broad, nearly longitudinal furrow runs back to 

 the intestinal region stopping short of the posterior margin. A 

 large but low swelling occupies the inner angle of the branchial 

 region, and a larger but less well defined one adjoins it in an antero- 

 lateral direction. From the lateral tooth a very blunt ridge runs 

 backward and inward and upward on to the dorsal surface. At 

 the end of this ridge and a little above and within the postero-lateral 

 margin there is a round shallow depression. The postero-lateral 

 margin is very thick and not clearly defined, the antero-lateral is 

 thin but blunt and furnished with five small teeth behind the orbit; 

 their tips are for the most part broken off; the anterior or first 

 tooth is very slight, scarcely a tooth but a very oblique angle in 

 the margin; the other teeth appear to be normal to the margin, the 

 second one very small, the third and fourth larger and perhaps 

 subequal, the fifth probably considerably larger, judging from a 

 section of the base. The intervening sinuses are unequal and in 

 the order of their length on the left side are 1.3.2.4.5, the first sinus 

 longest, the fifth shortest. On the right side the first tooth is nearer 

 the orbit. The upper margin of the orbit is approximately a semi- 

 circle viewed from above, the outer angle narrow and well advanced ; 

 at the lower inner angle there is a strong, conical, subacute tooth, 

 more advanced than the outer tooth. 



