376 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



Distributed from Atlantic America (Boston to Uruguay) east- 

 ward, including the Mediterranean, to Pacific America (San Diego, 

 California, to Chile). 



KEY TO THE AMERICAN SPECIES OF THE GEXOS CCA. 



A 1 . Front between the eyes narrow and spatuliform, less than one-tenth width 



of carapace. 



B*. Eyes without terminal stylets. 

 C 1 . Lateral margins either granulate or unarmed. 



D 1 . Dactylus of large claw of male wider in the middle than at the 

 proximal end. 



E 1 . Surface of fingers rough maracoani, p. 378 



E*. Surface of fingers smooth monilifcra, p. 380. 



D*. Dactylus of large claw of male more slender, nnd tapering from the 

 proximal end to the tip (except for the tooth ut the middle of its 

 prehensile edge). 



E 1 . Fingers of large claw of male gaping to the extremity. Carapace 

 broad, width one and four-fifths times its length. 



heterochelos, p. 381. 



E*. Fingers of large claw of male partially in contact in their terminal 

 half. Carapace narrower, width less than one and four-fifths 



times its length princeps, p. 382. 



G*. Lateral margins armed with large spiniforra tubercles in both sexes. 



Merus joints of legs armed with tubercles or spines insignis, p. 385. 



B'. Eyes with terminal stylets. 

 C*. Oblique ridge inside palm continued to upper margin. Ocular stylet 



longer than peduncle stylifcra, p. 383. 



C". Oblique ridge inside palm ending at carpal cavity. Ocular stylet as 



long as cornea hcteroplevra, p. 385. 



A*. Front between the eyes wider, increasing in width from below upward, pos- 

 teriorly more than one-tenth width of carapace. 

 B 1 . Carapace not semicylindrical. 



C 1 . Anterior part of side margins convex and curving gradually backward. 

 D*. An oblique tuberculate ridge on inner surface of larger palm of male 



extending upward from lower margin. 

 E 1 . Front less than one-fifth width of carapace. 

 F 1 . Carapace coarsely granulate or tuberculate. Immovable finger 



flat, lower edge acute tangeri, p. 387. 



F". Carapace nearly smooth. Immovable finger convex, lower edge 

 rounded. 



G 1 . Carapace strongly convergent posteriorly thayeri, p. 406. 



G 1 . Carapace moderately convergent posteriorly_,_recft7af, p. 405. 

 E*. Front more than one-fifth width of carapace. 



F*. Front wide, at least one-third of fronto-orbital width. 

 G*. Oblique ridge inside palm a single row of tubercles; the two 

 rows of tubercles at base of dactylus are parallel and near 

 together. Eyebrow nearly vertical and scarcely visible in a 



dorsal view . minax, p. 389. 



G*. Oblique ridge several tubercles in width; the two rows of tu- 

 bercles at base of dactylus diverge from below upward and 

 leave a considerable space between them. Eyebrow inclined 

 and visible in a dorsal view mordax, p. 391. 



