92 ASTACID^. 



2. ASTACUS NIQRESCENS Stimjjson. 



Astacus nigrescens Stimpson, Proc. Boston Soc. N. H., T. 6, p. 87 (Separat p. 52). 



Figures on PI. III. 

 Antcnnal lamina, fig. 168, a; epistoma, b ; spine- of the second joint of the exterior antenna, c. 



Mas. Obesus, obscure olivaceus ; rostro longo, valido, basi latiori, 

 antice fere parallelo, acumine triangulari, longiori acuto, subrecurvo ; 

 supra medio canaliculato basi callo obsolete in fovea antice angulata; 

 mar"-inibus calloso-iuflatis, sex vel octo-dentatis ; loco cretarum denti- 

 bus ntrinque tribus acutis. Antennis validis, corpore brevioribus, ar- 

 ticulis duobus basalibus dente extemo acuto ; antennis internis articulo 

 l)asali dente infero anteapicali acuto ; lamina valida trigona, rostri 

 longitudine, modice lata, margine externo crasso, inflato, apice spina 

 longa acuta. Epistomate lato, subtus carinato, antice triangulari ; pedi- 

 bus maxillaribus externis subtus sjiinulosis, intus barbatis. Thorace 

 ovato, depresso, densius et fortitcr punctato, lateribus granulosis ; linea 

 lata profunda, ntrinque subsinuata; areola lata, plana, antice latius 

 dilatata. Postabdomine lato, fere la^vi, segmentorum angulis externis 

 elongatis acutis ; lamina media parte basali quadrangulari ; apice ntrin- 

 que spinis duabus validis, subrejectis ; parte apicali minori, angustiori, 

 elliptica, margine antico exciso; lamina laterali vix costata, spina media 

 anteuiarginali, externaque marginali. Pedibus anticis validis, longis, 

 corpore paulo brevioribus ; chela magna, elongata, subplana, margini- 

 l3us subacutis, densius punctata, margine interno fere recto, subtus 

 paulo depresso ; digitis validis, rectis, cliela^ longitudine, conicis, apice 

 spinulosis. Carpo lato, granuloso, antice truncato, subtus spina media 

 valida. Brachio Itevi, margine antico et superiori spinoso, spina apicali 

 majori, subtus biseriatim spinuloso, spina antica aliaque ntrinque ad 

 articulationem majori])us. Pedibus alxlominaliljus, brevibus, rectis, 

 dimidio apicali cylindrico circumvolutis, apice truncatis. 



Femina differt ventre inter pedes quartos la3vi, canaliculato ; anuulo 

 bifido laminato. 



(Maxim.) Long. corp. 4.6; antenn. 3; ped. antic. 4.2. 



Habitat : San Francisco, California. 



I have seen eight males and one female ; the fifth pair of legs has 

 branchiae. Male and female type communicated by Professor Stimpson. 



This species and A. Gambelii are separated fi'om the others by the 

 denticulated rostrum. 



Cat. No. 228, San Francisco, Cal., Mr. T. G. Cary. Male. Spec. 4. 



Cat. No. 1851, California, Mr. T. G. Cary. Male. Spec. 1. 



