OBSERVATIONS ON THE ASTACIDM— FAXON. 657 



The first pair of abdominal appendages of the first form of the male 

 are short and stout, reaching forward only to the base of the antepe- 

 nultimate pair of thoracic legs. They end in two short, recurved 

 sfyles, the inner (or posterior) of which is slender and more strongly 

 recurved than the outer one. In males of the second form, these 

 appendages are split for only a short distance from the tip, and the free 

 ends are stouter, blunter, and less strongly recurved. The anterior 

 wall of the annulus of the female is depressed to the level of the ster- 

 num so that there is no distinct central fossa. The posterior wall, on 

 the other hand, is very thick and protuberant, forming a transverse 

 tubercle across the hind margin of the penultimate thoracic sternum. 

 The chela of the female is shorter and broader than that of the first 

 form of the male, and the dactylus less bowed. The chela of the second 

 form of the male is similar to that of the female. 



Length 93 mm.; carapace 46 mm.; rostrum 11.5 mm.; from tip of 

 rostrum to cervical groove 30 mm.; from cervical groove to hind border 

 of carapace 16 mm. ; antenna 106 mm. ; cheliped 90 mm. ; merus 20 mm. ; 

 carpus 13 mm. ; chela 48 mm. ; dactylus 36 mm. ; width of palm 19 mm. ; 

 length of inner border of palm 14 mm.; length of first pair of abdom- 

 inal appendages 12 mm. 



McAlister, Indian Territory. (Coll. Mus. Comp. Zool., from S. E. 

 Meek.) Twelve males, Form I; five males, Form II; eleven females. 

 Prairie Grove, Washington County, Arkansas. (Coll. S. E. Meek.) 

 One male, Form I. 



This species bears the closest possible resemblance to Gambarus 

 palmeri longimanus, with which it would surely be confounded if it 

 were not for the peculiar form of the sexual appendages of the male. 

 These organs consist of a stout peduncle terminating in two very short 

 recurved spines. In G. palmeri longimanus the two terminal spines are 

 represented by two very long slender branches, equal in length to the 

 peduncle itself. The annulus ventralis of the female also differs from 

 that of G. palmeri inasmuch as the central fossa is well-nigh obliterated. 



The upper side of the wrist and hand display the same spots of dark 

 color which are seen in G. palmeri longimanus. 



CAMBARUS MEEKI, new species. 

 (Plate LXV ; figs. 5-9.) 



Cephalo-thorax cylindrical, polished, conspicuously punctate, except 

 in the middle of the gastric area, granulated on the anterior portion of 

 the sides, lateral spine small or obsolete, anterolateral border bluntly 

 angulated below the orbit, postorbital ridges armed with a sharp ante- 

 rior spine. Eostrum deeply excavated, often very faintly carinated 

 near the tip; margins thickened, concave, strongly divergent at base, 

 each with a longitudinal row of impressed dots; lateral spines and 

 acumen horny-tipped, strongly upturned; acumen reaching to distal 

 end of anteunular peduncle. Areola narrow, punctate. Anterior 

 Proc. 1ST. M. vol. xx 42 



