292 MEMOIRS OF THE CARNEGIE MUSEUM. 



Crystal Lake, Benzie Co., Michigan (B. Walker, donor). 



Lake Michigan, off Kenosha, Kenosha Co., Wisconsin (P. E. Nordgren). 



Lake Superior, Nipigon Straits, St. Ignace Island, Ontario, Canada (0. E. Jennings). 



Six Mile Lake, Silver Island, Thundercape Peninsula, Ontario, Canada (0. E. Jennings). 



Lake Nipigon, Ombabika Bay, Ontario, Canada (0. E. Jennings). 



Sheyenne River, Argusville, Cass Co., North Dakota (S. M. Edwards). 



Moose River, South of Moose Factory, Ontario, Canada (W. E. C. Todd). 



Distribution and Ecology (See fig. 30) : Type locality, Seneca Lake, New York 

 (DeKay). 



As Simpson says, this race is found in the St. Lawrence area, and is common in 

 the lakes. However, its exact distribution is not very well known, since it often has 

 not been kept apart from the typical form. In addition our records show, that, in 

 northern Indiana, it is also in some lakes belonging to the Ohio (Wabash) drainage. 



Walker (1913) has it from Lake Erie, and he was the first to use the name 

 rosacea for the lake-form. Sterki (1907o) reports it from Lake Erie in Ohio, but 

 he also gives typical luteola from this lake. It may be, that he understood by 

 rosacea only specimens with red nacre. But I have never seen such from Lake 

 Erie. Walker (1898) reports borealis and superiorensis from northern Michigan, 

 but not rosacea. What I have from Lake Huron and central and northern Michi- 

 gan, is indistinguishable from the Lake Erie form. This variety certainly also 

 occurs in Lake Michigan and Lake Superior. 



A form very close to this is found in Moose River, near Hudson Bay. It also 

 turns up again, although not quite typical, in the drainage of the Red River of the 

 North in North Dakota. 



The ecological preference of this form is certainly for the lake environment, 

 and it is best developed in the larger lakes. In Presque Isle Bay in Lake Erie, 

 where it is a common shell, it is found everywhere on the sandy and gravelly shores, 

 in shallow water, and down to a depth of about fifteen feet in sand and mud. It 

 also is found in the beach-pools of Presque Isle, upon sandy-muddy bottom, and 

 is one of the few shells existing in the open lake, being frequently thrown out alive 

 by the surf. 



Lampsilis radiata (Gmelin) (1792). 



Lampsilis radiata (Gmelin) Simpson, 1914, p. 64.^'^ 



Plate XVII, figs. 6, 7. 

 Records from Pennsylvania: 



Gabb, 1861 (Schuylkill and Wissahickon, and League Island, Philadelphia). 

 Bruckhart, 1869 (Lancaster Co.) 



'" The figures given by DeKay (1843, PI. 19, figs. 2.37, 238) as of Unio ochraceus, have always been 

 taken for L. ochracea (Say), even by Simpson (1914, p. 50), but they actually represent L. radiata, and 



