WHITEAVE8 J DEVONIAN FOSSILS OF iMA^MTOBA, WVC. 343 



The only surface markings that are preserved in any of tlic specimens 

 are a few lines of growth on the dorsal side parallel to the outer lip. 

 Operculum unknown. 



Onion Point and Little Sandy Point, Lake Manitolja, J. B. Tyrrell and 

 J. F. Whiteaves, 1S88 : Lake Wiunipegosis, on the east shore at Point 

 Brabant, and on the south-west shore of Dawson Bay, at two small points, 

 one about half a mile and the other three miles north of the mouth of 

 Bell River, D. B. Dowling, 18SS : one or two specimens from each of these 

 localities. A few specimens, also, were collected by Messrs. Tyrrell and 

 Dowling, in 1889, at Lake Winnipegosis, on Snake and South Manitou 

 islands, at Devils Point, in Cameron Bay, and at ten different exposures 

 on the islands and shores of Dawson Bay ; also, on the Red Deer River, 

 half a mile above the Lower Salt Spring. The species appears to be rare 

 in and below the Stringocephalus zone, and to be most abundant in the 

 beds above that zone. 



In the foregoing description the flattened side of the shell is regarded 

 as the dorsal, and the strongly convex a7id angulated portion as the venti'al, 

 in accordance with the terminology used by Sowerby, Morris and Salter' 

 and by Walcott in his later publications. 



Most of the specimens collected are either separate casts of the interior 

 of the shell, or casts with the corresponding mould of the exterior, from 

 which the intervening test has decayed. The outline of the transverse 

 section of the shell, as represented by tig. 4, is well shown in manj^ speci- 

 mens. The test is rarely preserved, but indications of it are shown in 

 three or four specimens, particularly in the original of fig. 3 , which coji- 

 sists of the anterior moiety of a specimen, in which the central portion 

 and one of the broad lateral wings of the dorsal surface are well exhibited, 

 with the lines of growth and shape of the lip on that .side. 



j\[r. Walcott says* that the //. princepn, Billings, " is the largest species 

 of Hi/o/itlien known," Ijut some of the specimens of //. alatus collected by 

 IMessrs. Tyrrell and Dowling are considerably larger than any of Billings's 

 types of I/, princepa in the Mu-seum of this Survey. 



The present species is only referred to Hyolithes provisionally, as it seems 

 to differ from that genus in its Ijroad latero-basal alation, and more particu- 

 larly in the deep central sinus of the lip on the dorsal side. It is most 

 probable that a new genus will have to be constituted foi' its reception, 

 but the specimens so fai- collected are too imperfect to admit of an accurate 

 or sufficiently explicit generic description. 



♦Bulletin U. S. Geological Survey, Washington, No. 30, 1885, p. ia5. 



