124 TRANS. OF THE ACAD. OF SCIENCE. 
it does not rise so abruptly from the general. surface. This 
latter variety of our shell resembles somewhat Tnoceramus 
onvecus (Hall eek), from which it is easily distinguished 
by the concentric lines of the surface, which are much wit 
apart. e I. Vancouverensis is also much less oblique, and : 
this inticken also separates it from Z. Sagensis (Cue 
which : bears some resemblance. : 
nsions.—The measurements of the best specimen in 
the collection are—length, 4 inches; height, 4 inches ; thick 
ness of left valve, 2 inch. There are, ‘however r, some fragments _ 
which show that this species attains a much greater size, per 
haps more than double the dimensions here given. 1 
Form. & Loc—Occurs in the dark argillaceous, compact A 
limestone of Nanaimo River, Vancouver's Island. Dr. Evans: 
placed fragments of this shell in my hands for investigation 
several years since, from the same locality, along with a No : 
tilus which appears to be identical with ekayt (M 
-~ other forms of the Cretaceous system. But, notwi 
‘their seed 
Baxi CALAMITOIDES, Shumard. i - 
: ene nel gla compressed gb et 
uated 3 i 
