ORTMANN: monograph of the naiades of PENNSYLVANIA. 309 



common in Lake Erie (Walker, 1913), and is also in Lake Huron. Whether it 

 extends farther west, remains to be seen.'^' 



In the Lake Erie region L. ovata canadensis is restricted to the lake proper, 

 and does not go into the tributaries. In the lake this form is found in protected 

 bays as well as in the open lake, and it is one of the few species, which are found 

 in the surf, where I repeatedly picked up living specimens thrown out by the 

 waves. In Presque Isle Bay it is common everywhere, among rushes, and on 

 open shores, going down to a depth of about fifteen feet. It is here mostly on 

 sandy bottom. I never found it in the beach-pools. 



Lampsilis fasciola Rafinesque (1820). 

 Lampsilis multiradiala (Lea) Simpson, 1914, p. 55.^°" 



Plate XX, figs. 1, 2. 

 Records from Pennsylvania : 



Ham, 1891 (western Pennsylvania). 

 Marshall, 1895 (Allegheny River, Warren Co.) 

 Rhoads, 1899 (Beaver River, Wampum, Lawrence Co.) 

 Ortmann, 19096, p. 189. 



Characters of the shell: The species is best described in terms of comparison 

 with L. ovata ventricosa. It is much smaller, and relatively a little thicker. It has 

 a more regularly ovate or elliptical outline. The posterior ridge is quite indistinct. 

 But the chief difference is in the color-pattern of the epidermis. This is yellowish 

 or greenish, or light brownish olive, with very numerous and crowded rays. The 

 latter may be rather broad, or they may consist of bundles of fine (capillar}') raj'S, 

 and they are more or less wav)' or interrupted. There are always many fine rays 

 between the wider ones, and often onlj^ fine rays are present. The interrupted and 

 wa\n>' character is especially noticeable in the posterior part of the shell. Generally 

 the rays are distinct, but sometimes they are indistinct in the anterior part of the 

 shell. I have never seen a shell in which rays were entirely absent. According to 

 my experience, the nacre is always white. 



"' I have two specimens (male and female) of a form of ventricosa from Sheyenne River, Argusville, 

 Cass Co., North Dakota (S. M. Edwards), which repreisent a depauperate form, but differ from L. cana- 

 densis by the more elongated shape and the more compressed valves. The material is too insufficient 

 to permit the expression of an opinion. L. ventricosa has been reported from the Red River of the North 

 and from Nelson River, but little is known about these forms. 



-°° According to Vanatta (1915, p. 552), Lampsilis fasciola of Rafinesque is L. luteola (Lamarck). 

 Nevertheless in this case I do not accept the determination of the so-called (but questionable) " type," 

 since Rafinesque's description is unmistakable, and refers to an ovate (not elongate) shell, with wavy, 

 unequal rays. This fits only the present species. 



