Holotype of Scalpellum angustum. 659 
rather narrow and separated from the intraparietes by a 
ridge; the intraparietes are comparatively wide and form 
a thin wall on each side of the valve. 
None of the characters shown by this valve of S. angustum 
seems to justify its separation from the species S. angustatum 
(Geinitz, 1843, Versteim. von Kieslingwalda, p. 7, pl. iv. 
fig. 10), which was based on a single carina from the Pliner- 
kalk of Strehlen, Saxony, but better figures of the carina, 
together with scuta and terga, were later given by Geinitz 
(1875, Paleontogr. Bd. xx. Abth. ii. p. 202, pl. xxxvil. 
figs, 14-20). Further, there seems little doubt that 
S. guadricarinatum (Reuss, 1646, Verst. der Bohmischen 
Kreidef. p. 105, pl. xlii. fig. 18; 1864, Sitz. d. Akad. d. 
Wiss. Wien, Bd. xlix. Abth. i. p. 238, pl. i. fig. 14) is also 
the same species. SS. guadricarinatum, which occurs in the 
Planer-kalk of Bohemia, was likewise established on a carina. 
Darwin evidently accepted this as a separate species, mainly 
because of the truncated base shown in the figure (Reuss, 
1846, pl. xlii. fig. 18); but surely this figure represents 
merely the apical part of a carina, and the truncated base is 
where the lower part has been broken away, for the growth- 
lines indicate that the parietes and intraparietes are incom- 
plete at the base. 
It is the later figure of S. quadricarinatum given by Reuss 
(1864, pl. ii. fig. 14) that best brings out the agreement both 
with S. angustatum (Geinitz) and S. angustum (Dixon), 
and, since it is evident that one species only is represented, 
this must be known as S. angustatum (Geinitz). Valves 
referable to S. angustatum are known to me from the 
Cenomanian and Turonian of England, and there is every 
reason to suppose that S. angustatum is the ancestor of the 
Senonian S. fossu/a, Darwin. 
Scalpelium angustum, G. O. Sars (1879, Archiv. Math. og 
Naturv. Christiania, Bd. iv. p.466; olim S. stremzi, C. Heller, 
1878, Denkschr. k. Akad. Wiss. Wien, Bd. xxxv. p. 39, 
pl. iv. figs. 18, 14, non S. stremii, M. Sars, 1859, Forhandl. 
Vidensk-Selsk. Christiania (1858), p. 158), is a recent species 
that appears to be generally accepted as distinct, and, since 
its name is preoccupied by S. angustum (Dixon, 1850), it 
may be re-named S, sarst, nom. nov. 
I am indebted to Mr. Henry D Roberts, Director of the 
Brighton Museum, for the loan of the specimen, and also to 
Mr. C. T A. Gaster for information with regard to the chalk 
pits in the neighbourhood of Southeram, Lewes. 
