94 astacid^:. 



canaliculato, antice angustiori, utrinque marginato, acumine modico, 

 acuto, spinis lateralibus parvis ; cretis brevioribus, spina antica perparva, 

 postica nulla. Antennis corpore brevioribus (apex deest) articulo primo 

 dente valido, secundo subnullo ; antennis internis articulo basali dente 

 infero subapicali, lamina valida, trigona, rostro breviori, lata, margine 

 externo crasso, apice spina brevi, acuta. Epistomate triangulari ; pedi- 

 bus maxillaribus externis intus barbatis. Thorace ovato, antice angus- 

 tiori, densius punctato, lateribus granulosis ; linea profunda, sinuata ; 

 areola lata. Postabdomine thorace latiori, apicem versus decrescente, 

 lsevi, angulis segmentorum externis rotundatis, lamina intermedia qua- 

 drangulari, apice subangustiori, utrinque spinis duabus validis rejectis ; 

 parte apicali breviori, rotundato ; lamina laterali vix costata. Pedibus 

 anticis modicis, brevibus ; chela modica, punctata, subplana, marginibus 

 subacutis, margine interno recto, subtus excavato ; digitis validis, sub- 

 rectis, chela? non longioribus, apice spinulosis, non dentatis. Carpo lato, 

 truncato, punctato, intus mutico ; subtus spina media antica parva. 

 Brachio sublaevi, spina anteapicali majori, subtus biseriatim spinoso, 

 utrinque ad articulationem spina interna valida. Ventre inter pedes 

 quartos lsevi, annulo transverso, cylindrico, bipartito. 



Long. corp. 3"; ped. antic. 2.1". 



Habitat : Klamath Lake, California ; in all streams east of the Cas- 

 cades. Sp. Bates. 



I have seen only one female type, in bad condition, communicated 

 by Dr. W. Stimpson. 



It may be distinguished from A. Troivbridgii by its stronger and more 

 punctulated thorax, its tapering rostrum, with less developed spines, 

 the shortly spined antennal lamina, the smaller hands, the carpus with- 

 out internal apical spine ; the annulus between the fourth pair of legs 

 divided in the middle. 



The accurate determination of this species requires the examination 

 of more specimens; the antennal lamina on the right side is accidentally 

 abnormal, perhaps the other is also a little changed in shape. 



5. Astacus LENiuscuLus Dana. 



Aslacus leniusculus Dana, Proc. Acad. N. H. Philad , T. 6, p. 20. — U. S. Exploring Exped. 

 Crustac, T. 1, p. 524, t. 33, fig. 1. — Stimpson, Proc. Boston Soc. N. H., T. 6, p. 87. 



" Rostrum tridentatum, dentibus acutis, medio tenuiter elongato. 

 Carapax lasvis, punctulatus, lateraliter pone rostrum utrinque bi-spi- 

 nosus ; areola inter suturas longitudinales postdorsales lata. Pedes an- 

 tici compressi, inermes, non tuberculati, manu lsevi, punctulata, carpo 

 paulo oblongo, intus recto, inermi, apice interno acuto excepto ; brachio 

 antice denticulato, apice interno elongate acuto, dorso unispinoso. Pedes 

 sequentes nudiusculi. Segmentum caudale parce oblongum, lateribus 



