118 CONTRIBUTIONS TO CANADIAN PALEONTOLOGY. 



Plattostoma lineatum, Conrad. 



Platyostoma lineatum, Conrad. 1842. Journ. Ac- Nat. Sc. Phil., vol. VIIL, pt. 2, 



p. 276, pi. 17, fig. 7. 

 Hall. 1876. lllustr. Dev. Foss., pi. 9, flgs. 1-21, andPal. 

 State N. York, (1879) vol. V., pt. 2, p. 21, 

 pi. 10, figs. 1-21. 



Township of Bosanquet, Mr. J. Pettit, 1868, and near Thedford, Rev. 

 J. M. Goodwillie, 1882 : several well preserved and nearly perfect 

 specimens. The species is not uncommon in the Corniferous Limestone 

 of Ontario. 



In his Catalogue of "American Pateozoic Fossils," Mr. S. A. Miller 

 has changed the name of Conrad's genus Platyostoma to Platystoma, 

 but Zittel, in his " Handbuch der Pateontologie," retains both names 

 on the ground that the latter had previously been proposed by Homes 

 for a totally distinct genus or rather subgenus of gasteropoda, from 

 the Triassic roO.ks of Europe. 



Platyostoma plicatum. (JST. Sp.) 

 Plate 16, fig. 6. 



Shell turbinate, about as broad as high, whorls certainly three (and 

 perhaps fom" when perfect, the nuclear portion being broken off in 

 the only specimen collected) ino'easing rapidly in size, the later ones 

 ventricose, flattened above and step-shaped but with a rounded shoulder ; 

 suture distinct and nearly rectangular ; spire moderately elevated but 

 much shorter than the height of the aperture; body whorl strongly 

 inflated, its base apparently imperforate or nearly so ; aperture sub- 

 circular. 



The only part of the test that happens to be preserved is a rather 

 large piece of the upper part of the body whorl immediately at and 

 behind the outer lip. In this region there are indications of faint spiral 

 grooves with low rounded spiral ridges between them, and these are 

 crossed by prominent, distant and very distinct transverse plications. 



Maximum height of the only specimen collected, allowing for the 

 nucleus, two inches and a quarter ; maximum breadth, also two inches 

 and a quarter; height of spire, near the aperture, not quite one inch. 



Township of Bosanquet, Mr. J. Pettit, 1868: a nearly perfect cast of 

 the interior of the shell, with a jjortion of the test preserved near the 

 aperture. 



In general shape this shell is extremely similar to some specimens 

 of the Platyostoma affine of Billings (Geol. Surv. Can., Pal. Foss., vol. 



