496 T. H. Withers—Pollicipes levis, Shy. 
Since it cannot be ascertained that the specimens figured by Sowerby 
are still preserved, it is proposed to describe and fioure some similar 
valves from the same horizon and locality, formerly in the collection 
of the late W. Vicary, F.G.S. They were recorded by the Rev. W. 
Downes, F.G.S8., in List of Fossils from Blackdown (Q.J.G.S., 1882 
vol. xxxviii, p. 86), and are now preserved in the British Museum 
(Natural History). 
C. Darwin (1851, p. 80) says of the valves figured by Sowerby 
‘«... the P. Jevis from Blackdown . .. seems to be certainly 
a distinct species, and possibly a Scalpellum: no details are given” 
Darwin apparently did not see the actual specimens, or he would at once 
have recognized that they did not belong to Scalpellum but to Pollicipes. 
The parietes of the carina are not separated by any defined ridge or 
angle from the tectum as in Scalpellum, neither is the tergo-lateral 
margin of the scutum divided into two distinct lines, as is the case in 
Scalpellum, owing to the abrupt ending of the upturned lines of growth. 
Since there is a general similarity in the characters of these valves, 
and since no other Cirripede remains have as yet been found associated 
with them in the Blackdown Beds, it seems safe to regard them as 
belonging to a single species, namely— 
PoLLICIPES IMBRICATUS, sp. nov. Figs. 1-3. 
1836. Pollicipes levis, J. de C. Sowerby, Trans. Geol. Soc., ser. 11, vol. iv, p. 340, 
pl. xvi, fig. 1 (non pl. xi, fig. 5). 
Diagnosis. — Valves thin, composed of a number of consecutive 
and slightly imbricate segments, the lines of junction being marked 
on their external and inner surfaces by shallow obtusely V-shaped 
grooves. Scutum trapezoidal in outline; apex blunt; occludent 
portion twice as wide as the tergo-lateral portion; basal margin 
nearly at right angles to the occludent margin, and to the lower 
part of the tergo-lateral margin; there is no deep pit on the inner 
surface for the adductor scutorum muscle. Carina triangular in 
transverse section, with basal margin angular (about 92°). 
Material.—A nearly perfect carina on a hard shelly matrix (B.M., 
I. 5392). A portion of a. carina (B.M., I. 13518), portions of two 
scuta (B.M., I. 13519, I. 18520), and portions of two terga (B.M., 
so 2T 0. 18522) ; ; all these are free from matrix. The whole of 
the material is silicified. 
Holotype.—The right scutum (Figs. 1a, 6). 
Horizon and Locality. — Albian, Upper Greensand : Blackdown, 
Devonshire. 
Description of Specimens.— Right scutum (Figs. 1a, 6; B.M., 1.13519) 
convex, valve thin, divided unequally by a ridge extending from the 
apex to the basi-lateral angle; occludent margin slightly convex ; 
basal margin nearly straight; basi-lateral angle blunt; tergo-lateral 
margin convex, and protuberant near the middle. The unequally- 
spaced surface-grooves, which represent the growth periods, are 
very slightly sinuous on the occludent portion; on the tergo- 
lateral portion they are sharply upturned, and on nearing the margin 
curve inwards towards the apex. Occludent margin (from apex to 
rostral angle) 7°5 mm., tergo-lateral margin (from apex to basi-lateral 
augle) 8mm., basal margin 5mm. 
a 
