402 MEMOIRS OF THE CARNEGIE MUSEUM 



Other freaks are occasionally found, as for instance a specimen without an acumen 

 on the rostrum, the latter being evenly rounded off; a specimen with the immov- 

 able finger of the left hand with a doaljle tip, the outer one the larger, and a spec- 

 imen with the movable fingers of both liands only half as long as usual, thick, short, 

 and conical. Such cases apparently are due to some previous injury, and suggest 

 nothing of special intei'est. 



All the variations mentioned above are rare and are not restricted to certain 

 parts of the range of the species, so that we do iiot distinguish any regional varieties. 



7. ( 'amp..\rus (Bartonius) diogenes Girard. 

 (Plate A, Fig. 3 ; Plate XXXIX, Fig. 11 ; Plate XL, Figs. and 7.) 



Camhmvfi (liog<7Hx Girard, 1852, p. 88-, Faxon, 1884i, p. 144 ; Abbott, 1884. p. 1157; Faxon, 1885", p^ 71 ; Fa.xon, 

 ISesfc, p. 359 ; Faxon, )885f, p. 140 ; Underwood, 1886, p. 368 ; Faxon, 1890, p. 624 ; Ortmann, 1891, p. 12 ; 

 Hay, 1896, p. 489, Fig. 7 ; Faxon, 1898, p. 650 ; Osburn it Williamson, 1898, p. 21 ; Williamson, 1899, p. 20, 48 : 

 Hay, 1899, p. 959, 961 ; Harris, 1900, p. 267 ; Williamson, 1901, p. 11 ; Hay, 1902«, p. 235 ; Ortniann, 1905o, p. 398. 



Cambarvs nbiKvs Haf;en, 1870, p. 8], pi. 1, T 39-42, pi. 3, f. 163, pi. 9 ; Smith, 1874, p. 639 ; Foibes, 1876, p. 5, 19 ; 

 Bnndy, 1877, p. 171 ; Bnndy, 1882, p. 183; Bnndy, 1883, p. 403. 



Cambarus dioqenes ludovidamis Faxon, 18846, p. 144 ; Hay, 1899, p. 959, 962. 



Cambarus dubins Osburn and Williamson, 1898, p. 21, ( non dubiiis Faxon). 



Cambanm {Biirlonhis) (/inycnf.s Ortmann, 190.56, )>. 120, 135. 



Bodi/ robust, smooth, except for short hairs, chiefiy on the cheke in fresh shells; 

 the hairs also to a certain degree persist upon the hand and fingers in older indi- 

 viduals. 



(Airapace subovate, not depressed, but rather compressed. G' : H: B = 1 : 0.88 to 

 1.0:1.06 to 1.2; that is to say, the transverse diameter of the carapace is very 

 slightly greater than the vertical, at the hepatic region sometimes even less. Great- 

 est width of branchial regions well forward, not far from the cervical groove. 



Cervical groove deep, not interrupted on the sides. 



uircola distinctly longer than half of the anterior section of the carapace (a :/> = 

 1 :0.6l to 0.75), very narrow, and generally obliterated in the middle; that is to 

 .say, the two lines bordering the branchial regions are in contact in the middle of 

 the carapace. In rare instances a small space is left between them, upon which 

 there is no room for punctures. 



Rodrum more or less lanceolate, rather narrow, but not very long, reaching 

 hardly beyond the distal end of the second joint of the peduncle of the antennula, 

 being often shorter. Upper surface slightly concave, with elevated margins. Mar- 

 gins not much swollen, the swelling gradually disappearing toward the tip, con- 

 verging, straight, or slightly convex, contracted to form a short triangular acumen. 

 Basal angles of acumen indistinct, rounded, without any trace of marginal spines. 



