668 
by^ no means so massive a shell, and some of the internal characters are different ; still, 
it is undoubtedly closely allied to Krauss’ species. It does not in any way agree with the 
other Soutli African Cretaceous shell, Trigonia Sliepstotiei, Grieshach.* 
I think it quite likely that the present shell may be an elongated variety of 
T. mesemlria. Ton. Woods, but as the figure of this species represents an individual with 
the shell on, and the present fossil is only a east, it is difficult to compare them. On 
the difficulty of dealing with Trigonia casts, the late Dr. Lycett made the following 
remarks, which are very applicable to these Australian forms. He said It rarely 
happens that any of the externa] ornaments are visible upon them; and even under the 
most favourable conditions the impressions of these ornaments are only faintly and 
insufficiently shown, so that by means of these alone the external aspect even of a 
single species could never be fully ascertained, and even when both the mould and test 
have been obtained it is not in every instance that the mould can with certainty be dis- 
criminated from those of other allied species. The practice of authors, therefore, who 
have described supposed new species even partially, and have named them from internal 
moulds alone, is objectionable, as tending to create doubt and hesitation in the minds of 
students, and encumbering the list of species with things which for all practical purposes 
are little more then mere names.” 
Loc. Maryborough {Hon. A. 0. Gregory). 
Family— CTPRINID..I:. 
Genus — GYPB.IN'A, Lamarch, 1818. 
(Hist. Anim. sans. Verteb., v.) 
CrraiNA Ciaekei, Moore, PI. 27, fig. 9; ?P1. 26, figs. 18 and 19. 
(For description see under “ Boiling Downs,” p. 47-i.) 
Ods. This shell appears to have attained considerable dimensions in the 
Australian Cretaceous seas, being much larger than the Cyprina planata of the Lower 
Tertiaries of Britain and France. In form and habit G. expansa is closely allied to G. 
planata, possessing also the compressed ventral border, deep lunule, and expanded 
anterior or pedi-lateral margin. {Etheridge.) 
C. expansa is a very characteristic species of the North Queensland Cretaceous 
deposits. In the Maryborough Beds it has invariably been met with in casts, but in 
the nodular limestone of the Walsh Eiver portions of the shell arc usually attached to 
the specimens. In some individuals the anterior side is longer, and the dorsal margin 
very much more oblique, than represented in Mr. Etheridge’s figure. The umbones are 
much incurved, and the lunule deep. The anterior end rather compressed and flattened 
towards the margins. The pallial line is strongly marked, but the sinus is not deep. The 
shell, where preserved, is thick and concentrically coiTugated, with fine intervening 
concentric lines. 
Loc. and Horizon. Maryborough {The late B. Baintree ; T. W. E. David — 
Colin. David, Sydney ; G. Sweet — Colin. Sweet, Melbourne). 
In connection with this genus may be mentioned a shell (PI. 27, Fig. 1) 
figured t by Mr. Etheridge without name. The following is his description “ Shell 
apparently smooth, semicircular, nearly equilateral, equivalve ; umbones central, slightly 
acute and anterior ; posterior and ventral margins equally rounded and smooth ; hinge- 
line straight, rounded at the angles, giving the shell an almost circular appearance.” 
* Quart. Joum. Geol. Soc., 1871, -xxvii., t. 3, f. 11. 
t Ibid., 1872, xxviii., p, 330, t. 19, f. i. 
