40 ASTACID^E. 



tubereulato, spina media majori; eubtus spinis duabus majoribus anticis, 

 aliisque minoribus intends. Brachio rostro longiori, extus laevi, intus 

 ante apicem et margine supero tubereulato. spinis duabus anteapicali- 

 bus oblique positis; subtus biseriatim spinoso, spinis intends apicali- 

 bus validis. Pedibus tertiis et quartis articulo tertio onguiculato ; 

 pedibus quartis et quintis capitulo basali, quartis oblongo-ovali. 

 quintis compresso, laminato. 



Pedibus abdominalibus brevibus, reetis. cylindricis, basi et ante 

 apicem attenuatis, vix bifidis; parte externa margine postico dente 

 medio obtuso, apice dentibus brevibus duabus compressis, corneis, latis, 

 rotundato-incurvis ; parte interna apiee spina fusiformi, acuta. 



Forma II. difFert antennis chelisque brevioribus, unguiculis pedum 

 minoribus ; pedibus abdominalibus basi artieulatis. minus attenuatis. 

 parte externa apiee fere obtuso. bitubereulato. dentibus obscurioribus, 

 nee fusco-corneis ; parte interna spina conica breviori. 



Mares forma? secundae variant bracbio rostro breviori. lateribus 

 cephalothoracis minus tuberculatis ; spina laterali ad lineam transversam 

 (semper fere nulla in Forma I.) ; forma et latitudine rostri et acuminis 

 variabili, vel marginibus reetis, vel subrotundatis ; acumine busi dis- 

 tinctius dentato. 



Femina differt antennis ebelisque brevioribus, minoribus. minus tuber- 

 culatis; ventre inter pedes quartos nudo. non tubereulato: annulo ovali, 

 obtuse conieo, fissura longitudinali, labiis antice inflatis, sulcatis, fere 

 bituberculatis. 



Long. 3 and -i une. Mas maximus ; long. 4.2; ped. ant. 4.7 ; antenn. 

 4.5 ; chelae, 2.6. 



Patria : New Orleans. Between San Antonio. Texas, and El Paso 

 del Norte. Vidi specimina multa, adulta et juniora. 



Tins species is very similar to C. acidus, but it differs surely ; the 

 rostrum is more evidently dentated before tbe acumen, and the obso- 

 lete impression at its base is terminated anteriorly by two oblique 

 elevated lines ; tbe epistoma is truncated and sinuated anteriorly and 

 laterally; tbe thorax is laterally compressed, the areola linear in tbe 

 middle ; tbe penultimate segments of tbe postabdomen with the ex- 

 terior angle are more obtuse; tbe apical part of the intermediate 

 lamina is as long as tbe basal a little attenuated at the base; tbe 

 chelae are shorter and broader ; the legs of tbe postabdomen different ; 

 the venter of the fourth legs in the female is without tubercles. 

 There is rarely one spine at tbe sides of the thorax. 



C. Clarkii Girard. I have most carefully compared male and female 

 types collected by the U. S. Mexican Boundary Commission, communi- 

 cated by Professor Stimpson. They belong, without doubt, to this 

 species. Tbe male is a young specimen of the Forma II. (1.8 unc. 



