51 



and these heaps are the remains of his nightly viipxst.s. To the collector they 

 should generally serve only to point out that living specimens occur in. their 

 immediate vicinity ; still, by presenting to liim larger suites trom which to choose 

 than he could possibly obtain by dredging, they may sometimes afford good and 

 even rare shells. I have obtained from them some of my best specimens of 

 O. radiatuH. It seldom attains a greater length than three inches, and is a very 

 flat, obovate shell, of a green, olive or reddish color, with numerous narrow 

 rays. 



Unio luteolus^ Lamarck, abounds in the Eideau Canal from the Sippers' Bridge 

 upward, and is not uncommon ia the Uideau Rivrr. Its color is from a yellowish 

 green to a dark olive, with distinct dark gr-^en rays. In thape it varies much 

 more than in color. Some shells are so infl ited as to be almost cylindrical ; 

 others so depressed thit they cannot, when the beaks are eroded, be distinguished 

 by any external character from U. radiatm. Having probably studied only tlie 

 exterior of the two species, a western correspondent writes that they merge intO' 

 one another in Toronto Bay. Now they cannot possibly be more alike in Lake 

 Ontario than they are s")metimes here; and however great their outward resem- 

 blance, I find that they always differ internally, especially in the form of the 

 cardinal teeth. In U. rudiatus these are short, erect, and triangular. In U^ 

 luteolus, they are long, curved, compressed and oblique. 



Unio cariosus, Say, occurred to me near Black Biy, Eardley, Quebec, 

 where I was searching for nodules and fossils in the Champlain Clays, which 

 there form the north shore of the Lac des Chenes. It is a thin, small, ovate, 

 inflated shell, of a yellowish color, with a few indistinct rays. Some specimens 

 of an accompanying species of Le da, which lived when the clays were deposited 

 ii the post glacial period, would be taken for recent shells, so well hive they 

 preserved their thin, delicate epidermis and fragile teeth through the many 

 thousand years that have elapsed since then. 



Unio occidens, Lea, is quite abundant in the Ottawa, near the mouth of the 

 Gatineau, and along the sandy shores of Kettle Island. Its shape is remarkably 

 uniform, varying only with the sex. It is an ovate and very much inflated sbell, 

 Avith large prominent umbones and closely approximate recurved beaks. The 

 females are more broadly inflated than the males and are of an almost triangular 

 shape, on account of which peculiarities they are liable to be considerel forms oi 

 U. ventricosus, Barnes. 



For beauty and diversity of coloring, there is not probably found in the 

 world a fresh water shell which surpasses the Unio occidens of the Ottawa River. 

 When young io is of soft and varied shades of yellow, green and red, the primary 

 spectral colors, and sometimes of all three together, producing an effect of 

 chromatic harmony that a painter might study with advantage. Mature 

 specimens are rich as an autumn landscape in tints of yellow-brown and olive- 

 green. All — but especially the young shells — have a porcelain-like lustre, 

 which is seen at its best, when on a sunny day they lie on the clean, white sand, 

 with just enough water to cover them. Then they shine and glow like opals in 

 the fluent light. Moreover, their changeful colours are so differently combined 

 with rays, sometimes few and sometimes many, fine as a hair or broad almost as 

 an iris leaf, that, among hundreds of specimens collected, no two were alike 

 in every respect. Each is, accordingly, a unio, in the sense that Pliny tells ns- 

 the word was coined to express — a unique production — " from the circumstance,' 

 he says, "that no two unionis — pearls — are ever found alike.' The biirbarians 

 who found the pearls called them margarHn: 



That U. occidens, under exactly the same conditions of life, should secrete in 

 almost infinite variety so many different pigments is a fact which challenges 

 ittention. • 



Unio subovatus, Lea, which is found in the Rideau Canal and River and in 

 the Des Chenes Lake, is chiefly remxrkable for the large size to which it some- 



