394 



may be specifically, or at any rate varietally distinct from the true C. 

 truncata." "Through the kindness of Prof. Pilsbiy, the writer has 

 recently been able to examine and study ten authentic examples of that 

 species, from Cottonwood Creek, the property of the Academy of Natural 

 Sciences of Philadelphia. The largest of these specimens, however, is 

 only forty-nine millimetres in length, by thirty-six mm. in height, inclusive 

 of the umbones." " They seem to diflfer from the Maud Island specimens," 

 (there described and figured by the writer under the name C. ponderosa) 

 and from those from Vancouver and the Sucia Islands that have been 

 referred to C. truncata, in their uniformly smaller size, and more parti- 

 cularly in their proportionately narrower and more pointed umbones. 

 The specimens from the Vancouver Cretaceous may not be distinct from 

 the still larger and thicker fossils from the Queen Charlotte Islands, which 

 the writer has called C. ponderosa, but it is quite possible that both may 

 be only geographical and stratigraphical varieties of C. truncata. 



Mytilus pauperculus, Gabb. 



Mytilus pauperculus, Gabb. 1864. Geol. Calif., Palteont., vol. I, p. 183, pi. 2.5, fig. 165. 

 H „ Whiteaves. 1879. This volume, pt. 1, p. 167. 



A few detached valves of a small smooth Mytilus, that are probably 

 referable to M. pauperculus, were collected on the Trent River, V.I., by 

 Mr. Richardson in 1872 ; at the Sucia Islands, by Mr. Richardson in 

 1874 and Dr. Newcombe in 1894; and at Texada Island by Mr. Harvey 

 in 1901. As compared with Mr. Gabb's figure of 31. pauperculus, the 

 specimens from these localities are proportionately a little higher, more 

 angular at the termination of the cardinal border above, and a little less 

 elongated. 



MoDiOLA SiSKiYOUENSis, Gabb. 



Plate 48, fig. 2. 



Modiola Siskiyouensis, Gabb. 1864. Geol. Sur., Calif., Palseont., vol. i, p. 184, pi. 30, 

 fig. 260. 



Brennnan Creek, V.L, Rev. G. W. Taylor, 1901 : a small but perfect 

 and well preserved left valve, which is probably referable to this species. 

 It is, however, less than half the size of the type of that species, being 

 only eighteen millimetres and a half long, by nine and a half high, and 

 its posterior umbonal ridge is not very clearly defined. A very imperfect 

 and badly preserved but much larger specimen, from the roof of the coal 

 at the Nanaimo mines, collected by Mr. Harvey, in 1901, is also probably 

 referable to M. Siskiyouensis. 



