60(5 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxi. 



deflexed for its distal third and terniiuating in a short digital spine 

 which serves as the pollex ; distal margin transverse and armed with 

 two tnbcrcles, one near the insertion of the dactylus and the other at 

 the middle. Dactylns transverse, a tubercle at the middle of the pre- 

 hensile margin which fits against the margin of the propodus. The 

 first and se(!()nd i)airs of ambulatory legs are narrow, the second the 

 longer and larger and reaching to the extremity of tlie propodus of 

 the third pair. The nierus of the third pair is very little dilated at tlie 

 middle. The fourth pair reaches the middle of the carpus of the third 

 pair. 



The entire surface of the crab is covered with a dense pubescent 

 coat. 



Dimensions. — Male: Length, 5.5mm.; width, 11mm. Female: Length, 

 (J.G mm.; width, 12.5 mm. 



Typefi.—^o. 21593, U.S.N.M. One male, two females. Off Gulf of 

 San Matias, Argentina, 4.) fathoms, station 2768. 



This species bears apiiareatly considerable resemblance to the little- 

 known Pinnixa monodactylus (Say),' which is a narrower sjiecies. 



128. PINNIXA AFFINIS, new species. 

 (IMatf XLIIl, ligs. 7-i>.) 



Louder margin of palm of female convex; pollex short; posterior margin 

 of merits of third ambulatory ley armed with spinnles or small spines. 



Allied to /*. californiensis Bathbuu, with whicli it might easily be 

 confounded. 



Female. — Carai)ace broader than in californiensis, regions distinctly 

 indicated, cardiac region crossed by a blunt, transverse, bilobed crest; 

 surface punctate, the puncta' largest on the branchial regions. A 

 granulate line marks the an tero lateral border of the branchial region. 

 The front is not advanced beyond the line of the subhepatic region. 

 The third Joint of the palpus of the maxillipeds is articulated near 

 the proximal end of the inner side of the second. 



The chelipcds are smooth and pubescent; lower margin of palm con- 

 vex ; pollex short, very broad and deflexed, its prehensile edge irreg- 

 ularly dentate, terminating in a short, acute spine; the dactylus has a 

 large tooth at one- third the distance from the base; the fingers when 

 closed do not gape. The first two pairs of ambulatory legs are slender, 

 the margins of the propodal joints subparallel; the first pair reaches 

 to the end of the propodus of the second; the second to the end of the 

 propodus of the third. The third leg is the broadest; the nierus is 

 very hairy along the margins; the posterior margin is armed with 

 spinnles, those near the middle being larger and spine-like; anterior 

 margin granulous. The fourth pair of ambulatory legs reaches about 



» Jour. Phila. Acad. Sci., 1818, 1, p. 454. 



