10 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vol. 50 



Until specimens preserving the nuclear whorls are obtained the de- 

 cision must rest in abeyance. 



We now come to the Cretaceous of the Pacific slope, where, in the 

 Chico series, we have the typical species of Volutoderma, V. cali- 

 f or nica Dall 1 ; a larger and more robust species, figured and de- 

 scribed by Dr. C. A. White 2 under the name of Fulguraria gabbi, 

 and V. (Rostelliiida) dilleri White. 3 A fourth species occurs in the 

 Cretaceous of Sucia Island, British Columbia, which I have named 

 Volutoderma suciana.* 



This species is most nearly related to V. gabbi White, and not to 

 V. texana (-f- navarroensis) ; it differs from V. gabbi in its more 

 slenderly fusiform shape, its higher and more acute spire, more deli- 

 cate spiral ridges, the more anterior periphery to the last whorl, and 

 in the absence of marked axial ribbing. 



I am indebted to Dr. J. F. Whiteaves, of the Dominion Geological 

 Survey, for the opportunity to examine the original specimens from 

 Sucia Island. It may be added that the figure above cited gives an 

 insufficient idea of the strength and disposition of the spiral sculp- 

 ture, the specimen from which it was made having evidently been 

 more or less decorticated. 



In the lowest Eocene of the Martinez horizon in California was 

 collected Retipirula crassitesta Gabb, before alluded to, but, with the 

 exception of Ficulomorpha (Glyptostyla) panamensis Dall, from the 

 far south, no relatives of the genus Volutoderma have yet been made 

 known from the Californian or Oregonian Eocene. Retipirula differs 

 from Ficulopsis by having a sculpture reticulate with rather wide in- 

 tervals and stronsr nodulation at the intersections. It also resembles 



1 Gabb, Pal. Cal. 1, p. 102, pi. xix, fig. 56, ( 1864) . New name for V. navar- 

 roensis Gabb, not Shumard. 



2 Bull. U. S. Geological Survey, No. 51, pi. in, fig. 1, 1889. 



s B-liII. U. S. Geological Survey, No. 51 (as Scobinella dilleri), pi. iv, figs. 

 I, 2, 3. 



4 Whiteaves, in Mesozoic Fossils, Geol. Survey of Canada, vol. I, part II, 

 1879, p. 117, pi. xv, figs. 3, 3a, under the name of Fulguraria navarroensis 

 Shumard, the true navarroensis being identified with Volutoderma texana 

 Conrad, a sufficiently distinct species. 



The following notes will indicate the distinctions : 



V. suciana has seven whorls; three strong plaits, of which the anterior is 

 weakest; an appressed suture; an evident posterior sinus; and sculpture con- 

 sisting of four simple spirals in front of the suture; then two nodulous spirals, 

 a peripheral nodulous spiral with wider interspaces on each side of it; then 

 eleven more or less nodulous spirals, followed by two faint simple ones on the 

 canal. The axial ribbing found in several other species is obsolete or absent. 

 Length 120; spire behind the posterior sinus 44; max. diam. 45 mm. 



