CERITHIUM. 151 
67. Crrtraium verustum, var. seminuda, Hudl. Plate VIII, fig. 7. 
1882. “CHEMNITZIA” veTUSTA, var. seMINUDA, Hudl. Geol. Mag., dec. ii 
vol. ix, p. 249, pl. vi, fig. 13. 
, 
Description.—This is a subulate variety, about 23 mm. in length, and with a 
spiral angle of 14°. The spire is composed of about a dozen whorls, which are 
flat to subconvex, increasing with perfect regularity. The subapical whorls are 
ornamented with numerous delicate longitudinal ribs, very slightly curved. Lower 
down this ornament becomes very faint, and expires in the body-whorl or is merely 
represented by obscure sinuous lines. 
Base rounded and smooth; aperture ovate: other indications wanting. 
Relations and Distribution.—Differs from C. vetustwm in being more slender 
and in the failure of ornamentation on the anterior whorls. Rare in the Yorkshire 
Dogger. 
68. CEritHium suBscALARIFoRME, D’Orb., var. spinicostata, Wright, MS. Plate VIII, 
figs. 8 a, 8 b, 8c, 8d, 
S eyoms 
1850. Crrirntum supscatartrormE, D’Orb. Prod., vol. i, p. 271. 
Compare also 
1842. Menanta ScALARIFoRMIS, var. a, Des]. Mém. Soe. Linn. Norm., vol. vii, 
p. 218, pl. xi, fig. 63. 
1842. — UNDULATA, var.B, Desl. Vol. cit., p. 217, pl. xi, figs. 59—62. 
Bibliography, §¢.—This species may be regarded as the principal representa- 
tive of the vetustwm-group in Dorsetshire. There are, it would seem, objections 
to both Deslongchamps’ names, hence collectors usually fall back upon Cerithiwm 
subscalariforme, D’Orb., for a set of fossils which are well known in the Bayeux- 
beds. Although we cannot use Deslongchamps’ names, we can at least apply his 
generalizations as follows : 
“ Melania undulata, var. 8. TestA longiori, costis striisque frequentioribus. 
Lias supérieur.’ His Upper Lias I take to comprehend the Maitre (see 
Introduction to the present Monograph), which is included in our Lower Division 
of the Inferior Oolite. 
“ Melania undulata, var. a. Testa breviori, costis et striis crassioribus 
varioribusque. Oolite ferrugineuse,” i. e. our Upper Division. 
Deslongchamps’ generalisation, as above stated, holds good throughout the 
Dorsetshire-beds, the varieties of C. subscalariforme having a tendency to become 
