658 Mr. T. H. Withers on the 
Foss. Lepadidee, p. 37, pl. i. fig. 2), included the species in 
the genus Scalyellum, but, since he had not the holotype or 
other specimens before him, had to rely on Dixon’s figure, 
which he reproduced. 
The original of Dixon’s Xiphidium angustum was not in 
the Dixon Collection, now in the Geological Department 
of the British Museum, and, in spite of several attempts to 
trace the specimen, it was not tillrecently, when on a casual 
visit to the Brighton Museum, that I noticed it on exhi- 
bition there. It was then found that the specimen was 
mentioned in H. Willett’s Catalogue (1871, Cat. Cret. Foss. 
Brighton Mus. p. 45, No. 35), with a reference to Dixon’s 
pl. xxviii. fig. 9, together with the locality and horizon, “ m.e. 
[=Middle Chalk], Southeram, Lewes,” which were other- 
wise unknown. Willett was a keen collector of Chalk 
Fossils, aud several of his specimens were figured by Dixon, 
although in the present instance Dixon gave neither the 
locality nor collection. 
There are two large quarries at Southeram—one, 
Southeram Grey Pit, cut in the Lower Chalk, zones of 
A, varians and H. subglubosus (Mem. Geol. Surv., Cretaceous 
Rocks of Gt. Britain, 1903, vol. ii. pp. 69, 70), and the 
other, Southeram Limekilu Quarry, cut in the Middle and 
Upper Chalk, zones of R. cuviert to M. cor-anguinum (tom. 
cit. pp. 401, 402 ; vol. ii. 1904, pp. 46,48). Judging from 
the chalk in which the specimen is embedded, and still more 
from the fact that Willett gives “m.c.” [= Middle Chalk | 
as the horizon, there can be little doubt that it came from 
the second quarry, and either from the R. cuviert or Tere- 
bratulina-zone. 
The authorities of the Brighton Museum kindly allowed 
me to borrow the specimen, and since it agrees in measure- 
ments with Dixon’s figure, and what is more important has 
the pecuharity that the intraparietes are broken off as indi- 
cated in the figure, there is no doubt that it is the type. 
Darwin (1851, p. 38)—relying on the accuracy of J. de C. 
Sowerby’s drawing (Dixon’s pl. xxvii. fig. 9), which depicts 
the lower end of the intraparietes as abruptly and obliquely 
truncated, and also on the sharply pointed basal margin— 
believed the species to be new. Kxamination of the type, 
however, shows that the abrupt truncation of the intra- 
parietes is due to the valve being broken across near the 
base of the intraparietes (sce Pl. X. fig. 8). The valve is 
comparatively narrow, the tectum only moderately arched 
transversely, and on each side of the tectum there is a com- 
paratively narrow but protuberant ridge; the parietes are 
