21s CONTRIBUTIONS TO CANADIAN PALyEONTOLOGY. 



Although here referred provisionally to four nominal species, it is 

 most proliable that the throe last enumei-ated, if not the whole four, are 

 nothing more than mere local varieties of P. subaculeata. 



Ortiiis striatula, Schlotheim. 



OrtJiis xlridltila (Schlotheim). Davidson. 1865. .Mon. Brit. Dev. Bracli., p. 87, 

 (which see for a full list of the synonyms of tliis species) 

 pi. xvii, fi^s. 4-7. Tomp. especially with .Schnur's fiuures of 

 0. fitrialvia hom the Eifel. 



Ortliii lovmxi.i, ISillings. ls,5!). In Hind's Rep. Expl. Assinib., Saskatcb., Sic, p. 

 187, woodcut, iig. la. 

 Meek. 1808. Trans. Chicago Ac Sc, vol. I, p. 90, pi. xii, figs. 

 'I a-h. 



Abundant on the east bank of the Clearwater iJiver, live miles below 

 the Pembina, where it was collected by Pi'ofessor Macoun in 18*75 and by 

 Mr. A. iS. Cochrane in 1881. Hay Eiver, forty mi[os above its mouth, 

 E. G. McConnell, 1887: anumbei- of line Kpecimens. Mackenzie Eiver, 

 at the ''Eamparts," E. (x. Mc(jonnell, 1888: four specimens. Athabasca 

 Eiver, three miles below the Calumet and thirty miles below Eed Eiver, 

 E. G. McConnell, 1890: apparently common at each of these localities. 

 In Manitoba the same species is said to have been collected at Snake 

 Island, Lake Winnipcgosis, by Pi'of'essor II. Y. Hind, and several fine 

 examples of it wci'e obtained by Pi-of Macoun in ISSl on the noi'th 

 shore of the Eed Deer Eiver, about half way between Ucd Deer Lake 

 and Lalve Winnipcgosis. 



Adult specimens of this shell from the Hay Eivci' and the ''Eam- 

 parts" a]'e in some i-ospects intermediate in their characters between 

 the hij-gc, broad and comy)ressed form of 0. striatula, from the Clear- 

 water which Meek described and figured as O. foirensis, and 0. McFar- 

 lanei. They I'csemble the latlor species in the great conv(!xity of their 

 dorsal valves and in the dee]) marginal sinus of the ventral, but are 

 never so nari-owly elongated immediately behind thi; midlenicth. Other 

 specimens, again, from the Matdvonzio liixer disti-ict, are strikingly 

 similar to the largo variety of 0. Tii.Ui('n.\is of Ilall, as figured by Prof 

 IJ. S. Williams on Plato 12, fig. 3, of bis |)a]>or on the " ( !nboides Zone 

 and its Fauna."* 



In the "American Geologist" foi' A]iril, issl), Prof. Williams says 

 that Orthis loioensis is but a woslern variety of the 0. impressa of the 

 New York faunas, both of which are but varieti(5s of the European <). 

 Striatula of Schlotheim, and if is most probable that 0. jMcFarlanei is 

 only another local variety of the same species. 



• Ijnlletin Geol. Soc. Amorica, May, 1890. 



