94 ASTACIDJE. 



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 vei'sus decrescentc, 

 Isevi, 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, chelae non longioribus, apice spinulosis, non dentatis. Carpo lato, 

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

 Brachio sublajvi, spina anteapicali majori, subtus biseriatim spinoso, 

 utrinque ad articulationem spina interna valida. Ventre inter pedes 

 quartos laevi, annulo transverse, cylindrico, bipartite. 



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. Troivhridgii 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. 11. Philad , T. 6, p. 20. — U. S. Exploring Expcd. 

 Crustac, T. 1, p. 524, t. 33, fig. 1. — Stimpson, Proc. Boston Soc. N. H., T. C, p. B7. 



" Rostrum tridentatum, dentibus acutis, medio tenuiter elongate. 

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

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

 tici cempressi, inermes, non tuberculati, manu laevi, punctulata, carpo 

 paulo ol)longo, intus recto, inermi, apice interno acuto excepto ; brachio 

 antice denticulate, apice interno elongate acuto, dorse unispinose. Pedes 

 sequentes uudiusculi. Segmentum caudale parce oblonguni, lateribus 



