374 MEMOIRS OF THE CARNEGIE MO.SEUM 



REMARKS. 



CariiJianis (;/*.sTv/rv/.v is tlie river species of tlie Upper ()hit) drainage. It is widely 

 distributed in western Pennsvlvania. Compared with the allied species C. propin- 

 quus. which occupies a much wider area, it is ratlier uniform in its characters all 

 over its known range. It nowhere reveals a tendency to vary in the direction of 

 ('. propiiKinn^i, or of propliKjuns sanhonii. This is the more remarkaljle because C. 

 prnpuKpxus distinctly inclines toward this species in Erie and Crawford ( 'ounties, (in 

 the lake drainage), and likewise because C pnijiiiujnin^ Hunhomi shows such a ten- 

 dency in Wetzel (bounty, A¥est Virginia. 



The variations observed in our abundant material have been briefly indicated 

 above. However, it deserves special mention that the specitic charactei's are 

 scarcely subject to any variation. 



Very interesting conditions are offered liy the spines of the outer lower margin 

 of the meropodite of the cheliped. One or two spines ma_y be present, the prox- 

 imal one smaller and often represented only by a small tubercle. Looking over our 

 material, I find that only one spine is present in all individuals from the upper 

 Alleghany drainage, including all the tributaries from Red liank ( 'reek northward 

 (sixty-one specimens are at hand). In Armstrong, Indiana, Westmoreland, and 

 Allegheny Counties, in the drainage of the Alleghany River, and in the whole 

 drainage of the INIonongahela, the Beaver, and ( Jhio proper, a second spine may be 

 present, but such cases are not frec|uent, and generally this spine is f(_)und only on 

 one of the two chelipeds. There is a tendency of this character, more frequentlj' 

 dis})layed in the southwestern extremity of the range. Two such .spines on either 

 side (right and left) are very rare, and I have found them only in twenty speci- 

 mens; fifteen of which Ijelong to the ( )hio drainage: two to that of the Monongahela, 

 six to that of the Beaver, and seven to that of the Ohio below Beaver. Two cases 

 were discovered in Wills Creek, ^Maryland, and three in Conneaut Creek at All)ion, 

 Erie County, Pa. 



The latter specimens are interesting inasmuch as in Erie and Crawford Counties 

 two drainage areas come together with that of Lake P]rie, namely, that of the 

 Shenango River, a tril)utary of the Beaver, and that of French Creek, a tributary 

 of the Alleghany. In the latter ci'eek and its trilmtaries I have never seen 

 an individual with two spines (seventeen specimens arc at hand). Among the 

 material from the Beaver River di-ainage (fifty-six specimens) there are twenty- 

 one with two spines. Thus the tendency to develop two spines is markedly present 

 in the drainage of the Beaver, while it is apparently absent in Fi'ench Creek. 



