50 ASTACID^. 



8. Cambarus angustatus LeConte. 



Astacus angustatus LeConte, Proc. Acad. Philad., T. 7, p. 401. 



Figures on PI. I. and III. 

 First abdominal legs of the male. 



First form, fig. 65 in front, fig. 66 outside, fig. 67 inside. 

 Antenna! lamina, fig. 146, a; epistoma, b; spine of the second joint of the exterior antennae, c. 



A little dry typical specimen, communicated to the Museum of the 

 Philadelphia Academy by Mr. LeConte, is very difficult to identify 

 with any specimen before me. It is a male (Forma I.), 1.95 inch long, 

 hands 1.2 long, and agrees with the description. It seems to be a 

 young male of 0. spiculifer or a new species. The differences quoted 

 in the descriptions of C spiculifer and 0. angustatus are not decisive. 

 The rostrum in C. angustatus is described : " valde acuminatum, utrin- 

 que versus apicem fortiter et acute unidentatum " ; in C. spiculifer : 

 " longissime acuminatum, denticulo parvo utrinque ad acuminis basin." 

 The two types show no difference, except that in C. angustatus the 

 rostrum is not so narrow before the acumen. I have seen similar 

 differences in C. spiculifer. C. angustatus is " linea ordinaria apice spina 

 armata," but the same spine exists in C. spiculifer. The thorax has but 

 one lateral spine (not at all noticed in the description), and two in 

 C. spiculifer. But I have seen C. spiculifer with two, with three, and 

 even with one spine. The lamina intermedia of the postabdomen has 

 sometimes three apical spines in C. spiculifer as well as in C. angustatus. 

 I should not hesitate to unite the two species (C. spiculifer as Forma II., 

 and C angustatus as Forma I. of the male), did I not find two differences 

 not so easy to explain. 



1. The hands are longer and narrower, not so tuberculated in C. 

 angustatus ; the fingers a little shorter than the hands, and inside always 

 spongiose. I have seen hands nearly of the same shape in young C. 

 spiculifer, but the fingers were always as long as the hands or longer, 

 and not always spongiose, although sometimes a little so at the tip. 



2. The first pair of abdominal legs are a little more obtuse at the 

 tip, with the posterior border a little more dilated, and are sulcated on 

 the inside. I confess that these differences are perhaps rather too 

 minute, but the two together seem more important. I should ex- 

 pressly remark, that the type of C. angustatus seems well developed, 

 and the hooks in the third and fourth legs strong. Finally, as Mr. 

 John LeConte has seen and observed the species alive, and I have only 

 two single specimens, I prefer to separate C. angustatus ; a further ex- 

 amination may perhaps bring out more strongly the differences of the 

 two nearly allied species. 



" C. angustatus is found in Georgia inferiore, in aquae purae rivulos 

 inter colliculos arenosos, C. spiculifer in Georgia superiore." 



