ORTMANN : MONOGRAPH OF THE NAIADES OF PENNSYLVANIA. 307 



artificially and accidentally in recent times (see Ortmann, Nautilus 26, 1912, p. 51, 

 and 1913«, p. 318, and Marshall, Nautilus 31, 1917, p. 40). On the other hand, 

 L. ovata ventricosa is reported to cross over, in the northwest, into the Red River 

 and Nelson River systems in Canada, but little is known about the form of this 

 region (See below, under canadensis) . 



In a southerly direction, records from Kentucky are scarce, and Wilson & 

 Clark (1914) report it only from two tributaries of the Cumberland (Harpeth & 

 Stones R.) in Tennessee. But it certainly is found in the upper Tennessee-drainage, 

 where it has a similar relation to L. ovata as elsewhere, being preeminently found 

 in smaller streams and in the headwaters. 



Westward it goes through Missouri (Utterback, 1916) to southeastern Nebraska 

 (Trj^on, 1868; Call, 1885) and eastern Kansas (Scammon, 1906), and southwest- 

 ward, it is found in Arkansas and Oklahoma. But in this region it passes into the 

 southwestern race called satura Lea (Scammon, 1906). In the Alabama-drainage 

 it is represented by allied forms, which require closer investigation. 



Baker (1898) and Scammon (1906) say that it is generally found on muddy 

 bottoms, and with some qualification this agrees with my observations in Penn- 

 sylvania. 



Lampsilis OVATA CANADENSIS (Lea) (1857). 



Lampsilis ventricosa canadensis (Lea) Walker, 1913, p. 21; Lampsilis ventricosa 

 lurida Simpson, 1914, p. 41. 



Plate XIX, figs. 4, 5. 

 Records from Pennsylvania: 



Ortmann, 19096, p. 202 (as the lake-form of ventricosa). 



Characters of the variety: This form differs from L. ovata ventricosa, of which 

 it is a local race, by its smaller size, and verj' light-colored epidermis, which is 

 light-3^ellow, or light grayish or greenish yellow, with or without greenish rays. 

 In some specimens, the color of the epidermis inclines toward reddish brown or 

 chestnut, chiefly so near the beaks. 



In other respects this form agrees with L. ovata ventricosa, but old specimens 

 of the male sex are often more elongated than the average ventricosa (slightly 

 over one-and-one-half times as long as high) . 



L 

 Size: (Males) 1. Erie, Cat. No. 61.3989 101 mm 



2. do. " " 61.3982 93 



3. do. " " 61.4883 68 



(Females) 4. Erie, Cat. No. 61.3982 (gravid) 97 



5. do. " " 61.4884 83 



6. do. " " 61.4882 72 



