102 Withers. — Ncoscalpellum in Cretaceous of W ester n Australia. 
2. — Scalj)cUum (NcoscalpcUum) diclicloplax Pilsbry. 
(After Pilsbry). Recent. Lateral view of lioTotype. 
Two-thirds nat. size. 
C, earina ; CL, earinal-latus ; IL, infra-median latus; 
RL, rostral-latus ; S, sentum; T, tergiim; UL, upper latus. 
in tlie tergum of any Seal})ellid barnaede, the scutal margin is 
liollowed out to some extent, and this varies in the ditferent species, 
so that a deep eniarginatioii of the scutal margin is not an unex- 
})ected modifiention. Tlie present terga are normal in growth to 
a.liout half tlieir length, and then there i.s an abrupt change of 
gro:\'tli, tlie eniarginatioii of the scutal margin becoming rapidly 
(leeiter. In its early stage the valve is very like that of Calaniica 
{Scillaelepas} piii(ji)icnsis, for it has a similar, Avide, flat-topped 
ridge as in that s])ecies, and, in fact, at the base the Avhole of the 
carinal liml) of the valve is formed by the ridge. This Avidc, flat- 
topped ridge is characteristic of Scillaclepas, and it may be that the 
present form is a derivative from some species of SciUaeJepas such 
as C. (S.) giupinensis. 
Scalpellum (Neoscalpellum) glauerti sp. n. j 
(Plate XI, figs. l-(i.) | 
t. 
Diagnosis.— Tcvgmn Y-shaped, Avith a prominent, Avide, flat- i 
to}»ped apico-basal ridge, forming almost the Avhole of the base of | 
the carinal liml.) of the A’’ulA’’e. 
Distribution.- Upper Cretaceous, Middle Senonian (Santonian) ; 
Hound Hill, Dandarragaii, oO miles north of Gingin, Western Austra- } 
lia. Also probably at One Tree Hill, Gingin. 
Material.— Two right terga. One, the holotype (PI. XI, figs. 3, 
I) is in the Western Australian iruseum. registered 4194, and the 
