«HiTEAV6B,J DEVONIAN FOSSILS OF MANITOBA, ETC. 327 



(S.) Omphalocirrus Manitobensis. 



Plate 43, figs. 5, C c-ind 7. 



Euompkahis Manitobensis, Whitea\i'«. 1890. Trans. Royal Soc. Canada, vol. VIII, 

 Sect. 4, 1). 100, pi. vi, figs. 2, 2a-b and 3, .Sa. (Separate 

 copies. ) 



Shell large, discoidal, concave on both sides, luit rather more deeply 

 concave aboxe* than below : spire .sunk : umbilicus extremely wide and 

 open. Volutions five when perfect, though the nuclear one is not jii-e- 

 served in any of the specimens collected, in contact but very slightly 

 embracing, coiled on nearly the same plane, those of the sunken spire 

 depressed convex above, the last whorl but one subangular below and 

 encircled on its outer margin with a row of tubercles close to the suture. 

 Outer volution angular or subangular and encircled by from thirteen to 

 nineteen, or, in unusually large specimens, by as many as twenty-six, 

 large, arched and more or less spout-shaped nodes or tubercles at the 

 shoulder above and on the umbilical margin below, the rather broad and 

 comparatively smooth Eone between these two rows of nodes being com- 

 pressed obliquely inward and downward : suture deeply impressed on both 

 sides : aperture suboircular : test apparently rather thick. 



Surface marked with flexuous lines of growth, which curve obliquely 

 and concavely forward both above and below and very gently but con- 

 A-exly forward across the zone between the two rows of tubercles on the 

 outer volution. In well preserved specimens these incremental lines are 

 so prominent, numerous and close-set upon the upper surface as to give it 

 a distinctly costulate appearance, while in half-grown testifei-ous speci- 

 mens the outer zone between the two rows of tubercles is minutely and 

 densely but very regularly granulose. 



Operculum calcareous, moderately thick, nearly flat internally, slightly 

 con\ex externally, circular in outline and multispiral. 



In the Stringocephalus zone at Pentamerus Point, Lake ^Manitoba, at 

 many exposures on the shores and islands of Dawson Bay, Lake Winni- 

 pegosis, and on the Red Deer River, Ijetween the Lower and Upper Salt 

 Springs, where it was collected by J. B. Tyrrell, J. F. Whiteaves and D. 

 B. Dowling in 1^88 and 1889. 



In the limestone iunnediately above the Stringocephalus zone at Onion 

 (7iot Monroe) Point, Steep Rock Point and at an e.xjiosure north of Steep 

 Rock Point, Lake Manitoba ; at Lake AVinnipegosis, on its southern shore 

 two miles west of Meadow Portage, — on Charlie, Snake and South Manitou 



' As the nucleus is unknown, it is uncertain whether the shell is dextral or sinistral. 

 In the above description it is assumed to be dextral, but, should it prove to be sinistral, 

 the terms ''above" and "below," "spire " and " umbili(?as," will, of course have to be 

 reversed. 



