ECOLOGY OF ISLE ROY ALE. 293 



44b.* var. royalensis Walker. 



(Nautilus, XXII, p. &-10, PI. I, fig. 11, (1909). 



Isle Eoyale : V, 6, South shore of Siskowit Lake, No. 210. 



This novel and very distinct form, characterized by its very acute 

 carinse and rough, irregularly corrugated surface, was one of the most 

 interesting discoveries of the expedition. 



In the mud among loose stones at a depth of about 1 foot. 



45. PlanorMs campanulatus Say. 



Range : "Atlantic, Mackenzie and Hudson Bay water sheds and north 

 to Great Slave Lake." (Dall). 



Michigan: Generally distributed. 



Isle Eoyale: III, 5, Sumner Lake, Nos. 78 A, 79 A; V, 6, South shore 

 of Siskowit Lake, Nos. 210, 211. 



In mud and among loose stones at a depth of about one foot (Nos. 

 210, 211) and in small pools in the Sedge Zone (Nos. 78 A, 79 A). 



The specimens from Sumner Lake are the usual form. Those from Sis- 

 kowit Lake are a peculiar variety resembling the rare PlanorMs multi- 

 volvis Case, in having apparently the apical whorls elevated above the 

 line of the body whorl. Unfortunately the upper surface of all the speci- 

 mens collected is so eroded that it is impossible to determine just what 

 degree of elevation the spire of the perfect shell attains. 



46. PlanorMs exacuous Say. 



Range: "Northern United States, east of the Rockies; Canada, etc., 

 south to New Mexico." (Dall). 



Michigan : Generally distributed. 



Isle Eoyale: III, 2, Small Island in Rock Harbor, No. 89; III, 3, 

 Bulrush Zone at the western end of Rock Harbor, Nos. 159, 160, 161, 

 162. 



In the muddy bottom of a small stream flowing into Rock Harbor and 

 in the Harbor itself, at a depth of 2-5 feet (Nos. 159 to 163). 



47. PlanorMs parvus Say. 



Range: "Eastern North America from Florida to North Lat. 67°, 

 and the Yukon Drainage System." (Dall). 



Michigan : Generally distributed. 



Isle Royale: I, 1, Rock Pool, No. 2, Light-house Peninsula, No. 59; 

 III, 2, Small Island at Rock Harbor, No. 89; III, 3, Bulrush Zone at 

 western end of Rock Harbor, Nos. 159, 160, 163, 164; III, 5, Sumner 

 Lake, No. 79 A; III, 6, Southwest Coves of Rock Harbor, No. 91. 



As with the last species (Nos. 159, 160,, 163 and 164). 



48. PlanorMs Jiirsutus Gld. 



Range: "Washington, D. C, northward east of the Mississippi." 

 (Dall). 

 Michigan: Generally distributed. 

 Isle Royale : Not collected in 1906. See Report Exped. 1904, p. 98. 



49. Ancylus sp? 



Isle Royale: I, 3, Balsam-spruce Forest, No. 140. 



"In the damp leaf mold in the dense shade of the balsam-spruce 

 forest." 



A single broken specimen, too much damaged to identify specifically, 

 was the only one obtained. There is apparently some mistake in regard 

 to the locality where this specimen was found. 



50. Valvata trioarinata Say. 



