THE SPIDER CRABS OF AMERICA 95 



Genus EUPROGNATHA Stimpson 



Euprognatha Stimpson, Bull. Mus. Comp. ZooL, vol. 2, 1871, p. 122; type, 

 E. rastellifera Stimpson. — A. Milne Edwards, Crust. R^g. Max., 1878, 

 p. 182. — INIiERS, Journ. Linn. Soc. London, Zool., vol. 14, 1879, p. 645. — 

 Rathbun, Bull. U. S. Fish Comm., vol. 20, for 1900, pt. 2 (1901), p. 57. 



Carapace pyi'iform. Rostrum short, with two small teeth or horns. 

 Interantennular spine usually present, pointing forward and down- 

 ward at a much lower level than rostrum. Basal antennal article 

 narrowly triangular, with an outer and an inner granulate or dentate 

 crest; armed at anterior extremit}" with a slender spine reaching 

 forward as far or nearly as far as do the rostral horns; movable part 

 of antennae exposed from its insertion. A spine or tubercle on orbital 

 arch. Eye peduncle short, with a tubercle at the emargination of 

 cornea. Postocular spine reaching beyond extremity of eye. Merus 

 of external maxillipeds somewhat L-shaped, strongly produced beyond 

 insertion, of palpus in front and at postero-inner angle. Abdomen 

 of male with last two segments coalesced. 



Chehpeds with palms dilated; fingers in the male slightly gaping. 

 Ambulatory legs of first pair much the longest, the others decreasing 

 regularly in length. Dactyli long and slender, more than half the 

 length of the propodal joints. These crabs are almost naked, the 

 ambulatory legs with a few ciu^led setae above. 



Restricted to American waters. Distributed on the Atlantic coast, 

 from south of Nantucket (lat. 40° 13' N.) to south part of 

 Gulf of Mexico and the West Indies as far as Grenada and Barbados; 

 and on the Pacific coast from Lower California, Mexico, to Panama. 



KEY TO THE SPECIE3 OF THE GENUS EUPROGNATHA 



A^. Interantennular spine present. 



B'. Antennal spines about equaling, or falling short of, the pair of rostral 



spines. 



C. Interantennular spine long. Sternum forming a narrow border 



around postero-lateral portions of carapace. Antennal spines 



diverging anteriorh". Immovable finger without a noticeably 



enlarged tooth. 



D'. Gastric, cardiac and branchial regions each surmounted by a 



tubercle. Legs without spinules rastellifera marthae, p. 96. 



D^. Gastric, cardiac and branchial regions each surmounted by a spine. 

 Legs spinulous above. 

 E*. Dorsal spines stout. Legs finely and sparingly spinulous above. 



rastellifera, typical, p. 96. 

 E'^. Dorsal and other spines slender. Legs more spinulous. Cara- 

 pace closely and finely roughened rastellifera acuta, p. 96. 



C^. Interantennular spine ver\' short. Sternum forming a wide border 



around postero-lateral portions of carapace gracilipes, p. 101. 



B^. Antennal spines considerably overreaching the pair of rostral horns. 



Anterior margins of postocular spines laciniated granulata, p. 104. 



A2. Interantennular spine absent. Two spines on intestinal region. Gastric, 

 cardiac and branchial regions each surmounted by a spine. 

 Antennal spines as advanced as pair of rostral spines bifida, p. 103. 



