OBSER ] A TIOXS OX THE J S TA C IDJi—FA XON. 653 



lected at Irondale, and in Reyuolds County, Missouri.^ Botli in the 

 shape of the claws and in the character of the male appendages the 

 Cabool specimens are transitional forms connecting G. vlrilis with C. 

 rusticus and allied species. 



CAMBARUS LONGIDIGITUS, new species. 

 (Plate LXII, figs. 6-9.) 



Dorsal surface of the carapace flattened, thickly and coarsely punc- 

 tate; lateral walls granulate. Rostrum long, concave above, sides par- 

 allel from base to the lateral pair of si^ines, which are sharp and directed 

 forward; acumen long, acute, reaching to the distal extremity of the 

 antennular peduncle, and to the middle of the distal segment of 

 the antennal peduncle, Postorbital ridges curved inward at the pos- 

 terior end, armed at the anterior end with a sharp spine. Antero- 

 lateral margin of carapace bluntly angulated beneath the orbit, but 

 not armed with a spine. There is a prominent spine on each side of 

 the carapace on the hinder border of the cervical groove; a small 

 branchiostegian spine is also present. The areola is very narrow for 

 the greater part of its length; its narrowest part is well forward, close 

 to the small, but broad, triangular held that borders upon the cervical 

 groove; from this point it widens gradually and slightly to the hinder 

 end. 



The abdomen presents no distinctive characters; the pleurte are 

 punctate, tlieir posterolateral angles rounded. The telson is rather 

 long, armed with a pair of spines on each side of the transverse suture; 

 its hind margin truncate. 



The anterior process of the epistome is broadly triangular, its antero- 

 lateral margins slightly convex, its anterior angle rounded, truncate, 

 or (in a few examjiles) slightly notched. The basal segment of the 

 antenna bears no spine, but the so-called olfactory turbercle is ])romi- 

 nent just in front of the orifice of the green gland; the second seg- 

 ment of the antenna is armed with a small but sharp lateral spine. 

 The antennal scales are about as long as the rostrum, of moderate 

 width, widest at the middle. 



The merus of the chelipeds is armed, as usual, with spines bise- 

 rially disposed on the inferior margins, and with two obliquely placed 

 spines on the superior border near the distal end; the carpus is longi- 

 tudinally furrowed, punctate, and slightly tuberculate above; there 

 is a small spine near each point. of articulation with the manus, two 

 spines besides on the inner border — one median and one smaller one 

 near the posterior end of the segment; the lower surface presents, 

 moreover, a prominent acute median spine together with a minute 

 spinule lying between the inferior median and the internal median 

 spines (the smaller si)inule is sometimes obsolete). The palm, or basal 

 part of the propodite, is flattened and very short; its upper face is 



' Rev. Astacidie, p. 98, autl Proc. U, S, Nat. Mus., XII, p. 630, 



