THE SPIDER CKABS OF AMERICA 531 



region; branchial regions very swollen, bordered outwardly by a 

 sharp crest which extends to the lateral angle. Front trilobed, 

 medially much produced. Antero-lateral margins cut into many 

 small teeth furnished with short hahs. Chelipeds long and strong; 

 the arm has on its posterior border two or three large tubercles which 

 are compressed and clothed with hair, and on its anterior border a 

 sharp denticulated crest. The inner border of the hand bears a 

 dentate crest, outer border sharp and cut into four large and well 

 separated tfteth. Two crests on upper border of movable finger. 

 Fingers touching only at the tips, widely gaping. Legs entire, merus 

 cristate above and below, carpus and propodus above. 



Measurements. — Male, holotype, length of carapace 14, width of 

 same 17, total width of crab with arms extended 74 mm. 



Range. — Pourtales Plateau, Florida Straits; St. Vincent, Wind- 

 ward Islands. Depth, 124 to 200 fathoms. 



Material examined. — Pourtales Plateau; lat. 24° 16' N.; long. 81° 

 22' W.; about 200 fathoms; June 27, 1893; station 56, State University 

 of Iowa Expedition; 1 specimen (Mus. S. U. I.). 



Genus THYROLAMBRUS Rathbun 



Thyrolambrus Rathbux, Proc. U. S. Nat. Mus., vol. 17, Mar. 30, 1894, 

 advance sheet, p. 1; July, 1894, p. 83; type, T. astroides Rathbun. 



Parthenomerus Alcock, Journ. Asiat. Soc. Bengal, vol. 64, 1895, p. 280; 

 type, P. efflorescens Alcock. 



Carapace broader than long, deeply eroded. Frontal and antero- 

 lateral regions strongly deflexed. Surface covered \nth irregular 

 pits. Basal joint of antenna elongate, reaching or nearly reaching 

 level of inferior orbital hiatus. Maxilhpeds broad, fitting close to- 

 gether and filling the buccal cavity; ischium subrect angular pos- 

 teriorly, inner anterior angle produced; merus broader than long, 

 with a slight notch at antero-internal angle in which the first joint 

 of palpus is fitted transversely; remainder of palpus concealed by 

 merus. Chehpeds of moderate length; manus less stout than merus 

 and armed on inner side ^^^th two rows of spines or long tubercles 

 which are continued on the fingers. 



West coast of Mexico; off Havana; Indian Ocean; East Indian 

 Archipelago; Australia. 



KEY TO THE AMERICAN SPECIES OF THE GENUS THTR0LAMBRU3 



AK Reticulation of surface very rough, frost-like. Chelae slender, armed with 

 two rows of long spines astroides, p. 532. 



A2. Reticulation of surface nearly smooth. Chelae stout, armed with two rows 

 of short spines or pointed teeth erosus, p. 533. 



Analogous species on opposite sides of the continent: astroides 

 (Atlantic) ; erosus (Pacific) . 



