75 

 Pleurotomaeia perlata, Hall. 



Pleurotomaria perlata. Hall. 1852. Pal. N. York, vol. I, p. 349, pi. 34, figs. 

 5, a, b, t. 



Pleurotomaria solaroides, Billings (probably by inadvertence). 1863. Geol. Can- 

 ada, p. 341, fig. 347. 



Gait, A. Murray, 1847, and Professor J ames Hall, 1 848; Gait and Hespeler, 

 E. Billings, 1857 ; Elora, T. C. Weston, 1867 ; Belwood, J. Townsendand 

 J. F. Whiteaves, 1893. A fine large species of which only casts of the 

 interior of the shell have yet been found. It is, however, distinguishable 

 at a glance from all the other Pleurotomarise of the Guelph formation, by 

 its compressed lenticular form, acutely angulated periphery and deep 

 but rather narrow umbilicus. 



Pledeotomaria Galtensis, Billings. 



Plate 11, fig. 7. 



Pleurotomaria Galtennis, Billings. 1862. Geol. Surv. Canada, Pal. Foss., vol. I., 



p. 154, fig. 136. 

 1863. Geol. Canada, p. 334, fig. 349. 



The types of this species are two imperfect casts of the interior of the 

 shell, collected at Gait by Dr. R. Bell in 1861. The apices of both of 

 these specimens are broken off, and only the three outer volutions are pre- 

 served in the more perfect of the two. In September, 1893, Mr. Town- 

 send and the writer obtained at Belwood two casts of the interior of a 

 shell which is evidently referable to P. Galtensis, with corresponding 

 moulds of the exterior of each, from which the intermediate test has long 

 ago disappeared. The figure on Plate 1 1 is a representation of a gutta- 

 percha impression of one of these natural moulds. It shows that the 

 volutions of the spire are angulated and subcarinate at or near their base, 

 that the outer portion of the last volution is angulated a little above the 

 mid-height and encircled by a spiral ridge which is concave on the apical 

 side and convex on the umbilical, also that the very convex umbilical side 

 is imperforate when the test is preserved. On each side of tjie spiral 

 angulation the whole surface of the shell appears to have been smooth. 



Pleurotomaria Deiopeia, Billings. 



Plate 12, fig. 1. 



Pleurotomaria Deiopeia, Billings. 1862. Geol. Surv. Canada, Pal. Foss., vol. I, 



p. 155. 



This insufficiently defined species, which is now figured for the first 

 time, was based upon a very imperfect cast of the interior of the shell, 



