INVERTEBRATE FAUNA OF LAKE SUPERIOR. 705 



were dredged in 40 to 50 fathoms off Raciue. In Lake Superior, it was 

 commou in the cove at the eastern end of Saint Ignace, on a sandy and 

 muddy bottom, in 4 to 6 fathoms, and abundant among Cladopliora^ in 

 8 to 13 fathoms, on the south side of that island ; among the Slate 

 Islands, in G to 8 and 12 to 14 fathoms; at 13 to 15 fathoms on a sandy 

 bottom in Simmons' Harbor; near Copper Harbor, in 17 fathoms, clear 

 sand; in 32 fathoms, very soft clayey mud, in Neepigon Bay ; off Cop- 

 per Harbor, in 62 fathoms ; and north of Keweenaw Point, in 82 fathoms, 

 soft reddish clayey mud and sand ; aud in all the deep dredgings down 

 to 159 fathoms. Below 100 fathoms, however, it was never abundant, 

 and all the specimens from deep water were much smaller and more 

 fragile than the majority of those from shallow water. Apparently, 

 great depths are not favorable to its growth, aud it never reaches its 

 full development in such ijlaces. It was found in great abundance in 

 the stomachs of white-fish taken at Outer Island. 



" PisUUum ahysomns Stimpsou," mentioned, without description, by 

 Hoy, (Transactions Wisconsin Academy, vol. i, p. 100, 1872,) is undoubt- 

 edly this variety. 



PisiDiUM ROTUisDATUM Prime. 



Op. cit., p. 72. 



Eegion of Lake Superior, (Prime.) 



Unio radiatits Lamarck. 

 North shore, (Gould.) 



Anodonta Pepiniana Lea. 



Transactions Amer. Philosophical Society, vol. vi, pi. 16, fig. 51. 

 Xorth shore, (Gould.) 



EADIATA. 



Hydra carnea Agassiz. 



Proceedings Boston Society Nat. Hist., vol. iii, 354, 1850 ; Ayres, Proceedings 

 Boston Society Nat. Hist., vol. v, p. 104, 1855 ; A. Agassiz, Illustrated Cata- 

 logue Mus. Comparative Zool., North American Acalephte, p. 197, 18G5. 



A beautiful Syclra, agreeing with Ayres' description of this species, 

 was very abundant at the eastern end of Saint Ignace, upon rocks along 

 the shore and near the surface, frequently completely covering quite 

 large surfaces where they were protected from the direct sunlight, and 

 was also brought up in many of the dredgings from 8 to 148 fathoms. 

 In 32 fathoms, Neepigon Bay, and in 59 fathoms, off' Simmons' Harbor, 

 it was brought up in abundance from a soft clayey bottom. In the 

 deep dredgings it frequently came up near the bottom of the clay in 

 the dredge, and was evidently not caught while the dredge was near 

 the surface. 



S. Mis. 74 45 



