382 CRAYFISHES. 



Middlesex County, Mass., by Professor G. H. Barton. Boone Pond drains 

 into the Assabet River. Walden Pond has no visible inlet or outlet. 



Dr. D. L. Belding, of the Mass. Fish Commission, collected several speci- 

 mens in East Washacum Pond, Sterling, Worcester Co., Mass. (Nashua River 

 drainage), Oct. 10, 1912; Mr. W. F. Clapp found many in the Blackstone River, 

 at Uxbridge, Worcester County, Mass., Sept. 29, 1913, and there is a specimen 

 in the United States National Museum collected in 1913 in Lake Winnepe- 

 saukee, N. H. 



In colour as well as in all other characters the Walden Pond and Blackstone 

 River specimens agree perfectly with those from Berkshire County. Those 

 from Boone Pond, Sterling, and Lake Winnepesaukee I have seen only after they 

 had been immersed in alcohol and lost their colour; in other respects they too 

 are conformable to the Berkshire County variety, i. e., C. i. spinirostris. 



Cambarus validus, sp., nov. 

 Plate 7, Fig. 3, 4, S; Plate 13, Fig. 1. 



Male, form L — Similar to C. immunis Hag., but differs as follows: — the 

 rostrum is relatively narrower, less tapering from the base to the lateral angles 

 at the proximal end of the acumen, its margins are more distinctly raised so that 

 the upper surface of the rostrum appears to be more deeply hollowed out. The 

 foveola at the base of the rostrum in C. immunis is scarcely evident in C. validus. 

 The chela is very much larger, more powerful and of a different form from that 

 of C. immunis; the immovable finger is curved strongly outward at the base, 

 giving a convex outline to the external margin of the hand ; the movable finger 

 is furnished with a double row of tubercles running along its external margin, 

 while the inner margin is not excised at the base and is armed with a row of eight 

 or nine round bead-like tubercles; the chela is as long as the carapace, and broad 

 and inflated. The lower face of the carpus is furnished with only a rudimentary, 

 blunt, median spine or tubercle. The sub-orbital angle is less prominent, the 

 posterior wall of the orbit forming a perpendicular straight line. The anterior 

 process of the epistome is much broader, with the anterior end truncated l^iit 

 not notched. In other regards, including the form of the sexual appendages 

 it agrees with C. immunis. The rostrum is devoid of lateral teeth or spines, 

 like the typical form of C. immunis. 



Length, 68 mm.; length of carapace, 33.5 nun.; length from tip of rostrum 



