330 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



(S.) PSEUDOPHORUS TECTIFORMIS. (N. Sp.) 



Plate 44, tigs. 1 & la. 



Shell subconical, spire elevated, outer volution widely expanded, sharply 

 angulated below and truncated very obliquely at the aperture : base 

 flattened, imperforate. Number of volutions unknown, only the outer 

 one and a portion of the last but one beini;- preserved in the most perfect 

 specimen collected, the penultimate one considerably elevated, moderately 

 convex, rounded above, slightly compressetl in the centre, and faintly 

 concave next to the suture below. Outer voluticjn nearly three times as 

 broad as high, also rounded above and obli(iuely compressed below : aper- 

 ture large and apparently somewhat triangular in outline : outer lip thin, 

 produced above and receding beneath, its lower portion concavely emar- 

 ginated. 



Surface marked with close-set imbricating lamellar striie of growth, 

 which curve somewhat convexly and very obliquely backward and down- 

 ward on the apical side of the outer volution, and obliquely but concavely 

 backward below. 



Dawson Bay, Lake Winnipegosis, about two miles west of Salt Point, 

 J. ii. Tyrrell, 1889 : one imperfect specimen with the test pi'eserved. A 

 specimen of essentially similar shape and size, but whose surface is encir- 

 cled by numerous small spiral ridges, in addition to the oblique lines of 

 growth, and which therefore may not belong to the same species, was 

 collected by Mr. Tyri-ell in the same year on a, small island in Dawson 

 Day, about half way between Salt and Whiteaves Points. 



The name PNendap/ijirus was proposed by Meek in 1H73* for an " unde- 

 scribed group of shells," the type of which is a remarkable species from 

 the Corniferous limestone of Ohio, which he provisionally described and 

 figured under the name Xi'nojihora'l (Pseudophorus) antiqua, Meek. 

 This shell, Mr. Meek writes, " is almost certainly not a Trochi/ic, because 

 the broad underside does not have the character of a mere spii-al lamina 

 within the margin, but is really the lower side of the body volution. It 

 seems to be morenearly related to A'enop/ioni, Fischer( = P/iorn.% Montfort) 

 or O'inisfiis, Humphrey ; but diflers from both in not having the habit of 

 attaching foreign bodies around its periphery, as well as in wanting the 

 distinct umbilicus of the latter." 



The comparatively elevated form together with the much more convex 

 and almost dome-shaped volutions, of P. ferti/'unnis, will at once enable 

 that species to be distinguished from I' a idiqniix. 



Rej). Geol. Surv. Ohio, vol. T, pt. 2, Pahcontology, p. 222. 



