140 BULLETIN 129^ UNITED STATES NATIONAL MUSEUM 



Lat. 24° 16' 00" N., long. 110° 22' 00" W.; 21 fathoms; gy. S. brk. 

 Sh.; station 2822; 2 males, 3 females (18143). 



Subfamily Acanthonychinae 



Epialtidae + Huenidae M'Leay, in Smith, Illus. Zool. S. Africa, Annulosa, 



1838, p. 56. 

 Acanthonychinae Alcock, Journ. Asiat. Soc. Bengal, vol. 64, 1895, pp. 160, 



164, 190. 

 Acanthonychidae Stebbing, Ann. S. Afr. Mus., vol. 6, 1910, p. 286. 



Eyes without true orbits; eyestalks little movable, either short and 

 more or less concealed beneath a forwardly-directed supraocular 

 spine, or obsolescent and almost or completely sunk either in the sides 

 of a huge beak-like rostrum, or between low preocular and postocular 

 excrescences; a distinct postocular spine, which is not cupped 

 (except in Sphenocarcinus) may be present. Rostrum either simple 

 or two-spined. Basal antennal article truncate-triangular. Ex- 

 ternal maxilhpeds with the merus as broad as the ischium and with 

 the palp arising from the antero-internal angle of the merus. Dactyli 

 of ambulatory legs often prehensile or subchelate, the legs of the first 

 pair often disproportionately long compared to those of the last three 

 pairs. (After Alcock.) 



KEY TO THE AMERICAN GENERA OF THE Sl'BFAMILY ACANTHONYCHINAE 



A^ Carapace broadly oval, smooth. Rostrum subtriangular, bidentate. Post- 

 orbital tooth wanting or small Taliepus, p. 162. 



A^. Carapace subpentagonal, oblong or pyriform, or, if oval, not smooth. 



B^ Carapace subpentagonal or oblong, with only two lateral lobes (one 

 hepatic, one branchial), postorbital tooth lacking or minute, rostrum 

 simple or bilobed at tip only. 

 C. Eyestalks short, immovable, without the shelter of a supraocular eave 



or postocular tooth. Carapace lumpy Mooosoa, p. 158. 



C^. Eyestalks longer, movable. 



D^. Some strong tubercles on dorsal surface of carapace. A strong 

 thumblike process near proximal end of propodites of ambulatory 



legs Eupleurodon, p. 100. 



D2. Carapace nearly smooth. Preorbital tooth usually lacking; when 



present, small Epialtus, p. 144. 



B2. Not as in Bi. 



C. Ambulatory legs subchelate. Carapace suboblong, with three lateral 

 teeth or lobes. A blunt preorbital lobe; no postorbital tooth. 



Acanthonyx, p. 141. 

 C^ Ambulatory legs not subchelate. 



Di. Carapace oval. Postorbital tooth present. Preorbital tooth ab- 

 sent. Carapace lumpy. Front tuberculiform, broader than long. 



Esopus, p. 191. 

 D2. Carapace subpentagonal or suboblong. 



E^. Antennae visible in dorsal view at sides of rostrum. 



