358 MEMOIRS OF THE CARNEGIE MUSEUM 



Co.; Susquehanna River, Northumberland, Northumberland (Jo. ; Fishing Creek, 

 Bloomsburg, Columbia Co. ; Bald Eagle Creek, Milesburg, Center Co. ; Conooo- 

 cheague Creek, Chambersburg, Marion, and Williamson, Franklin Co. ; Maiden 

 Creek, Maiden Creek, Berks C'o. 



REiNIARKS. 



Camharus limosvs is the common river species of eastern Pennsylvania. Its 

 morphological characters are very constant, and give it a rather isolated position 

 within the genus, which is also expressed by, and very likely due to, its geograph- 

 ical isolation, the most closely allied species being found far to the west, in Indiana 

 and Kentucky, (see Ortmann, 1905//, p. 114, 127). The most prominent specific 

 chaj-acters are furnished by the male sexual organs, and the .spinosity of the sides 

 of the carapace. The description, as given above, does not indicate any important 

 variations, and the specimens are generally very uniform. The spino.sity of the 

 carapace, however, changes with age, yoving specimens being much less spinose than 

 old ones. In the spines of the chelipeds and of the anterior section of the telson, 

 there is some variation, but this is only slight and not subject to any rule. The 

 shape of the carapace and rostrum is very constant, the only differences of age no- 

 ticed are found in the acumen of the rostrum, which in young specimens is slen- 

 derer than in those which are older, and in the bulging out of the branchial regions 

 of the carapace, which is most marked in old individuals. The changes in the 

 pubescence of the wbole body are apparently due t(j wear. The short hairs gener- 

 ally present in newly moulted individuals slowly wear off, and specimens with a 

 distinct coat of dirt upon them, indicating age, generally have the pubescence more 

 or less, sometimes entirely, worn off. Only on the hands and fingers are traces of 

 it left. 



I niN'self have never found any freaks in this species. But Mr. W. R. jMcl.'oimell 

 found a male (first form), 66 mm. long, at Bloomsburg, Columbia County, (the only 

 specimen taken at this locality), in which the rostrum had two pairs of marginal 

 s[)ines. Tlie additional pair in this specimen is smaller, and stands about midway 

 between the normal pair and the base of the rostrum. 



2. Cambarus (Faxonius) i'kopixquus Girard. 

 (Plate XXXIX, Fig. 6a and 66.) 



C:inilmnis pni/iimpius, Uiiard, 1855, p. 88 ; Hagen, 1870, p. 67, PI I, f. 3-1-38, PI. 3, f. 1.j3 ; Siiiitli, 1874, p. 638 ; Forbes, 

 1876, p. 4, 19; Bundy, 1877, p. 171 ; Bumly, 1882, p. 181 ; Biinily, 1883, p. 402; Faxon, 1884, p. 147 ; Faxon, 1885.i, 

 p. 91 ; Faxon, 188oh, p 360; Underwood, 1886, p. 371 ; Faxon, 1890, p. 628 ; Hay, 189G, p. 497, Fig. 11 ; Ward, 

 1896, p. 15 ; Faxon, 1898, p. 651 ; Hay, 1899, p. 960, 962 ; Ortmann, 1905(i, p. 400. 



C'unbarus (Faxonius) pnijiini/Kus OrtmanVf 150r56, p. 112. 132. 



