WHITEAVES ] APPENDIX. 421 



Page 158. 



For " Placenticeras (Perezianum ? var.) Liardense " — 

 read : * 



Desmocebas (Perezianum? var.) Liardense. 



The systematic position of the four specimens upon which this species 

 was based is stili doubtful, and they are now only provisionally referred 

 to Desmoceras. Their previous reference to I'lace^iticeras was based upon 

 Zittel's extension of the chaiacters of that genus so as lo include the 

 Clypeiformes, and has not proved satisfactory. 



Page 159. 



For " Discina pileolus. (N. Sp.)" — read: 



Obbiculoidea Dawsoni. (Norn, nov.) 



Discinii pileolus, Whiteaves, 1889. This volume, p. 15il, pi, 21, figs. 3 and 3 a, but not 



D, pileolvii. Hicks, 1866, which is probably also an Orbiculoidca. 

 Discina Dawsoni, Whiteaves. 18H3. Trans. Royal. Soc. Canada, vol. XI., sect. 4, p. 17. 



Page 172. 



For "Placenticeras glabrum. (N. Sp.)" — read : 

 Desmoceras affine, var. glabru.m. 



Placenticeras fflobrum, Whiteaves. 1889. This volume, p. 172, pi. 24, figs. 1 and 1 a-b. 

 Desmoceras affine, var. glabrum, Whiteaves. 1892. Trans. Royal Soc. Canada, vol. X., 

 sect. 4, p. 115, pi. 9. 



The type of Placenlicpran glabrum is a small and perfectly smooth cast 

 of the interior of the shell, collected by Mr. W. Ogilvie, in 1885, from 

 the Cretaceous rocks of the Peace Ptiver, a few miles below Fort Ver- 

 milion. Nlimerous other specimens, from rocks of similar age on the 

 Peace River and its tributaries, collected by Mr. McConnell in 1889, 

 were described and figured in the Transactions of the Royal Society of 

 Canada for 1892. As the surface of none of these specimens can be 

 called smooth, or even very nearly smooth, the species was redefined 

 under the name Desmoceras affine, on account of its close re.semblance to 

 D. Beudanti, and the name glabrum retained in a varietal sense and 

 restricted to those specimens in which the distant periodic arrests of 

 growth are not developed. 



