156 T. H. Withers—New Chalk Cirripedes. 
more pronounced, and some of the remaining ridges on the tectum and 
parietes are more irregularly placed and a little less coarse. 
Comparison with other Species.—The Albian Scalpellum areuatum, 
Darwin (1851, p. 40, pl. i, fig. 7), a common Gault species, also has 
longitudinal ridges, which, however, are finer and confined to the 
tectum. SS. cyphum is at once distinguished from that species by its 
greater transverse convexity and by the presence of intraparietes. It 
agrees in some of its characters with S. aduncatum, sp. nov. (see 
infra), but the far more numerous and much coarser longitudinal 
ridges give it an entirely different appearance. It is also more convex 
transversely, has less obliquely inclined parietes, more pointed apex, 
curved inner margin, and the ridge that separates the parietes from 
the intraparietes is much more strongly rounded and conspicuous. 
4, ScaLPELLUM ADUNCATUM, sp. nov. Figs. 10-138. 
Diagnosis.—Carina narrow, moderately bowed inwards, inner margin 
nearly straight, widening gradually from the apex, divided into 
parietes and intraparietes, apex very sharply pointed and a small por- 
tion of it probably projected freely, basal margin angular (about 75°). 
Tectum moderately arched transversely, ornamented with about ten 
sharply raised longitudinal ridges, all of which can be seen with the 
naked eye; one strong ridge runs down the middle, followed on each 
Fie. 10. Sealpellum aduncatum, T. H. Withers, sp.nov. External view of carina, 
x 2 nat. size. Cenomanian, upper part of Holaster subglobosus-zone : 
Oxted Lime Works, Oxted, Surrey. (B.M., I. 7235.) 
», Ll. Id. Side view, x 2 nat. size. 
;, 12. Id. Transverse section at one-third from apex, x 2 nat. size. 
», 13. Id. Transverse section at one-third from base, x 2 nat. size. 
side by two or three finer ridges, which are bounded on either side by 
a pair of stronger ridges, close together, dividing the tectum from the 
parietes. Parietes narrow, obliquely inclined from the tectum, 
concave, about half the width of the tectum, widening slowly to the 
basal margin, and ornamented with extremely fine longitudinal strie, 
which can only be seen with a lens. Intraparietes set a little inwards, 
separated from the parietes by a well-marked ridge, measuring in their 
widest part slightly more than the rest of the valve at that point, 
widening rapidly from the apex, and then narrowing rapidly until 
they reach little more than half the length of the valve, where they 
