THE NAUTILUS. 57 



posterior and iijiper portion, wliere it is loosely wrinkled ; color 

 deep grass green, dusky above and behind, radiated ; nacre silvery 

 or bluish-Avhite, margin greenish. Length given by authors, 4i 

 inches; height, 2} inches; breadth, li inch. 



When shells are figured in books the specimens selected for the 

 purpose are always the largest and finest ones to be had. When 

 Say described this species in 1816, he gave its length as 2f inches. 

 Gould gives it Ah inches, but I have frequently seen specimens over 

 five inches in length and have one myself six inches long. Gould 

 considers the species very rare, found only in ponds in the central 

 and western parts of Mass., but Perkins finds it near New Haven, 

 in Conn., and we have at least two localities in R. I., and one in 

 Attleboro, near the line. 



194. — Anodonta implicata, Say. 



Shell transversely oblong, almost as broad as high, very variable 

 in proportions, thick and strong in some, thin and fragile in others]; 

 epidermis yellowish olive (darker above and behind), with dark 

 brown zones; young shells grass green, resembling A. catarada, 

 middle aged resembling U. radinta ; nacre silvery white until after 

 the middle age, Avhen it becomes flesh colored or salmon. Length 

 about four inches, height, 21 inches ; breadth 2 inches. Gould says 

 it inhabits ponds in Essex and Middlesex counties in Mass., and 

 has been found in Maine. Whether it occurs southward or not is 

 uncertain. AVe find them in R. I., extremely common in all our 

 ponds and rivers. 



195. — Anodonta undidatn, Say. 



Shell transversely oval, thick ; beaks prominent, the points in 

 contact, and when not eroded they exhibit four or five undulations 

 upon them ; epidermis dark brown, radiated ; hinge with a vestige 

 of a tooth, this peculiarity forming a connecting link between 

 Anodonta and IMargaritana ; nacre salmon colored, granulated in 

 the centre, bluish-white outside the pallial impression, with a broad 

 margin of olive. Length, 3] inches; height, 2 inches; breadth, 

 li inch. 



The locality given by Gould is the Blackstone River and its 

 tributaries in Mass., and as this river flows through several miles of 

 R. I. territoiT, I include it here although no specimens have been 

 obtained within our limits. 



