952 MR. T. H. WITHERS ON. 
recent group of asymmetrical sessile Cirripedes forming the 
family Verrucide, and in its structure clearly shows its origin 
from the symmetrical pedunculate forms of the family Polli- 
cipedide. 1t presents further evidence that the sessile condition 
has been arrived at independently on several different lines of 
descent during the evolution of the Cirripedia. The Verrucide 
have a phylogenetic history widely different from that of the 
Balanidee (sensu lato), and evidence is not wanting to show that 
the Balanide also are at least diphyletic. The Chthamaline 
have almost certainly arisen from some such form as Brachylepas, 
while it is extremely difficult, if not impossible, to derive the 
Balanine from that source, or indeed from any form as yet 
known. 
Family PoLLICIPEDIDS. 
SCALPELLUM VIMINEUM *, sp.n. (PI. I. figs. 10-12.) 
Diagnosis.—Seutum subtrapezoidal, with no apico-basal ridge, 
the apex rounded, the growth-ridges arranged in concentric lines 
from the apex; occludent margin forming a right angle with the 
basal margin. 
Material.—Portions of a right and a left seutum, and a com- 
plete right tergum which might or might not belong to the 
same species. 
Holotype.—The left scutum (figs. 10 a, 6). 
Horizon and locality Lower Senonian, wpper part of WM. cor- 
testudinarium-zone: Slines Oak Pit, Worms Heath, Wolding- 
ham, Surrey. 
Measurements.—Length of left scutum, 2°9 mm.; length of 
left tergum 1°9 mm., breadth, 1-2 mm. 
Scutum.—The left valve (PI. I. figs. 10 a, 6), which is more nearly 
complete, has the tergo-lateral portion almost entirely broken 
away, and is gently convex transversely. When complete the 
valve was subtrapezoidal in outline, and there is no apico-basal 
ridge. Apex rounded ; basal margin convex, and forming aright 
angle with the lower part of the convex occludent margin. Outer 
surface ornamented with a number of concentric ridges termin- 
ating each zone of growth, and these ridges are broken up into 
bead-like prominences where crossed by the longitudinal ridges. 
The middle portion of the valve has the bead-like prominences 
much more numerous and crowded. A wide portion of the inner 
surface on the occludent side, and so far as preserved on the 
tergal side, is marked with growth-lines which meet on a raised 
ridge below the apex. A deep pit for the adductor muscle is 
situated in the middle of the basal portion of the valve. 
Tergum (Pl. I. figs. 124, 6) subrhomboidal, with a delicate 
apico-basal furrow ; apex slightly curled towards the scutum, 
basal portion narrow and pointed. Upper carinal margin slightly 
* vimineus, made of wicker-work. 
