359 



those of the spire rounded, but slightly compressed laterally, the outer 

 one somewhat inflated, but obliquely flattened next to the suture, sub- 

 angular and lightly shouldered a little behind its midheight or midlength, 

 and narrowing rapidly to the base anteriorly ; outer lip expanded and 

 alate, its posterior margin, the only part of the wing that is clearly shewn, 

 being broadly and shallowly concave ; columella incrusted by a large callus, 

 which forms quite a thick rounded projection anteriorly. 



Surface marked by rather distant, obtuse and not very prominent 

 plications or rib-like folds, which cross all the volutions transversely and 

 are themselves crossed by numerous small acute, spiral ridges, the 

 shoulder of the outer volution being distinctly nodose. 



The foregoing is a description of the imperfect specimen from the 

 Trent River, figured, of the natural size, on Plate 15 of the second part 

 of this volume. This specimen was referred by the writer to the Rostel- 

 laria stenopiera of Goldfuss, but this reference seems to be no longer 

 tenable. In the Canadian specimen the whorls can scarcely be des- 

 cribed as minutely and spirally striated, the ribs on the last volution are 

 not all strongly granulated, and it is by no means certain that its wing, 

 when entire, was narrow and sword shaped. Moreover it does not seem 

 probable that a fossil from the Nanaimo group of the Vancouver 

 Cretaceous is identical with a species from the Upper Greensand of 

 Westphalia. For these reasons it is now thought desirable to distinguish 

 the specimen from the Nanaimo River by a new specific name. 



Among the fossils of the California Cretaceous, Anchura transversa of 

 Gabb * would seem to come nearest to A. callosa, but the former is re- 

 presented as being wider than long, and of comparatively diminutive size 

 i. e., only ten millimetres in length, by thirteen mm. in width. 



Mesostoma Suciense. (N. Sp.) 



Plate 44, fig. 7. 



Cerithiuni Lallierianiim, var. Suciense, Whiteaves. 1879. This volume, pt. 2, p. 122, pi. 

 15, figs. 10 and 10 a ; but apparently not a true Cerithiuni, nor a 

 var. of the C. Lallierianum of d'Orbignj' and other European 

 authors. 



Shell imperforate, elongated and about twice as long as wide ; 

 volutions six in the most perfect specimen collected and probably 

 seven when perfect, those of the spire rounded and ventricose ; suture 

 well defined ; outer volution strongly convex at or about its midheight, 

 narrowing abruptly into the rounded base below ; aperture broadly and 



*Geological Survey of California, Palaeontology, volume ii, p. 165, pi. 27, fig. 45. 

 Ah — M. F. 



