116 



140. PLATYCERAS, sp. 

 (Plate II., Fig. 6.) 



Our collection includes a single very well preserved specimen of the body-whorl of a 

 Platyceras of the type of P. bisulcatum (Hall). It is apparently new, but with such meagre 

 materials I do not venture to describe it. The body-whorl is free, and the apex has evidently 

 been small, and has apparently been sinistrally rolled up. The aperture is expanded, and the 

 tip is strongly sinuated. Along the convex side of the body-whorl run two longitudinal fur- 

 rows, of which one is very deep, whilst the other is quite shallow and obscure. Between 

 these is a strong rounded longitudinal riJge or plication. The entire surface is marked with 

 strong, close-set, lamellose, transverse striae, which do not become any stronger towards the 

 aperture than they are near the apex. 



Locality and Formation. Corniferous Limestone, Lot 6, Con. 1, Wainfleet. 



141. PLATYCERAS, sp. 

 (Plate II., Fig. 7). 



This is a much crushed specimen resembling P. tenuiliratum (Hall), but the true affini 

 ties of which cannot be determined. It consists of two or three volutions, the first and second 

 being extremely minute, and the body-whorl being greatly expanded and lengthened. The 

 minute, inrolled apex is not two lines in diameter, whilst the elongated body-whorl has a length 

 of nearly an inch and a half. The specimen is decorticated, and the surface-characters cannot 

 be made out. 



Locality and Formation. Corniferous Limestone, Ridgeway. 



142 PLATYCERAS UNISERIALE (Nicholson). 

 (Plate II., Fig. 5.) 



Spire small, unknown, but evidently of few volutions. Body-whorl very large, vontri- 

 oose, expanded towards the aperture. Aperture rounded, its margin sinuated. The margin 

 of the aperture is somewhat oblique, and the spire would appear to have been in contact with 

 the body-volution. The convex aspect of the body-whorl carries upon one side, not mesially, 

 a single row of large remote spines. Surface marked with tolerably conspicuous transverse 

 striae, which become stronger towards the aperture, and also with very fine longitudinal 

 striae. 



I have only a single specimen of this singular form, but its characters are so distinct 

 from those of any species of Platyceras known to me, that I feel justified in describing it as 

 a new species. The specimen exhibits only the body-whorl, with the margin of the aperture 

 and the commencement of the spire. The most noticeable feature, apart from the surface- 

 ornamentation, is the existence of a single row of spines upon one side of the body-whorl, 

 these spines being of large size, and r laced very far apart. The specimen only shows two of 

 these spines, and only the bases of these, but they have a diameter of a line and a half, and 

 are placed at four lines apart. As almost the entire surface of the body-whorl is shown, and 

 as the shell itself is preserved, it is certain that no other spines could have been present ex- 

 cept those belonging to this series. It thus differs very materially both from the Devonian 

 species of Platyceras, with spines irregularly disposed over the whole surface, and also from 

 the carboniferous species, P. biseriale (Hall), in which the body-whorl is provided on loth sides 

 with a row of long spines. 



Locality and Formation. Corniferous Limestone, Port Colborne. 



] 43. PLATYCERAS DUMOSUM (Conrad) ? 



A smnll gpiniferous species of Plntyceras is not uncommon in the Hamilton Formation of 

 "Western Ontario, which belongs to the group of which P. dumosum (Conrad) is the type, 

 and ^hich appears to be in nil probability a variety of this variable species. It is much 



