50 



AViout half a mile from Meech's Lake, on the creek through which it finds 

 an outlet, are a few shallow ponds, with a bottom of coarse sand and gravel 

 washed down from the surrounding hills. In the warmer water of these ponds, 

 where food also must be more abundant, U. complanatus is three times as large as 

 in the neighbouring lake. It differs moreover in being proportionately less 

 depressed, and more equally rounded at both extremities. Its colour is a rich 

 dark brown with a silken lustre, and, not unfrequently, a tinge of bright orange 

 along the umbonial slope. 



Near Kettle Island there occurs a form of much interest on account of its 

 curious angular inflation. How extraordinary this is for a species whose most 

 constant characteristic is its flatness, may be inferred from the fact that a repre- 

 sentative specimen whose height is 1-6 in. measures 1-5 in. in diameter. The 

 inflation is greatest near the dorsal margin behind the hinge-ligament, where a 

 section of the shell would be an almost perfectly equilateral triangle with the 

 base and the angles at the base slightly rounded. A specimen found hv Mr. 

 Poirier is 3 in. high, 4-9 long, and weighs 7^ oz. Ten of the shells from Meech's 

 Lake weigh only 3 oz. 



At the same locality is found a still more remarkable variety and one of no 

 little beauty. In some respects it resembles U. Raleighensis, Lea, from North 

 Carolina, and in others V. turtuosus, Sowerby, from Maryland. It is like the 

 former in shape and in the numerous prominent rays which diversify its surface; 

 and like the latter in the strange peculiarity that its valves meet at the ventral 

 margin not in a straight but in a sinuous line. A correspondent writes that 

 under Dr. Lea's treatment it would be entitled to rank as a species. Whether a 

 A^ariety of U. complanatus or a distinct species, it is a most unique and interesting 

 shell. 



Unio ffibbosus, Barne", appears to be rare, having occurred to me only in the 

 Ottawa near Gilmour's Mills and at Templeton, always in deep water. It is a 

 brown, elongated shell, attenuated posteriorly, and with the dorsal margin 

 regularly curved. It bears a slight resemblance to some forms of U. complanatus ; 

 but may always be distinguished by its heavier shell, the deeper purple of its 

 nacre, and especially by the great thickness of the lamellar tooth in the right 

 valve. 



Unio ellipsis, Lea, is not uncommon on sand bars below Kettle Island, but 

 does not seem to occur in the Rideau or in the Ottawa above this City. It differs 

 from all other species here observed in having the beaks very near the anterior 

 end of the shell, where the muscular impression is of great depth and the shell 

 itself of great thickness. The cardinal teeth are paralled to the lateral teeth and 

 not at a right or oblique angle to them as in our other species. The nacre of 

 many specimens is beautifully iridescent, displaying the colours of the prism and 

 rainbow, chastened, softened, and made perpetual. 



Unio rectus, Lamarck, which is easily recognized by its dark colour and elon- 

 gated form, is found in considerable numbers in the Rideau near Billings' Bridge, 

 but is comparatively rare in the Ottawa. The ground colour of the epidermis, 

 which at first sight appears black, proves on closer examination to be yellow, 

 profusely rayed with broad lines of very dark gieen. Young shells occasionally 

 have a purple nacre, but in mature specimens only a trace of this is seen along 

 the lateral teeth and in the cavity of (he beaks. In the Rideau it is not unusual 

 to find f '. rectus almost six inches in length, and I have observed it quite as large 

 in the Ottawa near Arnprior. Though smaller in the Ottawa here, it compensates 

 for its inferior size by its finer form. The mantle of the animal is fringed with 

 long and delicate vibratile cilia more beautiful than tiie richest lace. 



Unio radiatus, Lamarck, is common almost everywhere in the Ottawa above 

 the Chaudiere. At the foot of the rapids near MechanicsvWle are a number of 

 islets along whose shores may be seen large heaps of ehellB, of which this species 

 constitutes no inconsiderable part. The muskrat lives chiefly on the Unionidie ; 



