72 
OhseriKitions . — The large number of specimens now before us con- 
forming to Morris’ upper single bgure, compels us to regard this as repre- 
senting the typical form of E. cordatiim. At the same time this umbonal 
fragment by no means conveys a correct impression of the actual outline of 
the species. The collection contains a number of such fragments (PI. XIX, 
figs. 4 and 5 ; PI. XX, figs. 2, 3, 4, 5), in excellent preservation, and similar 
])ortions in sitn on partially exfoliated individuals, the lower portions being 
represented by internal casts — the latter are identical in outline, and agree 
in proportion, with Sowerby’s original figure. The dissimilarity of these 
figures evidently struck Dana, for in referring to them in bis synonymy 
of E. cordalmn be said, “ pi. 12, the second and third figures ; also the 
first?” ; bis inter 2 )retation, however, is opposed to that expressed here. 
Considerable variation is represented by E. cordatnm ; from considera- 
tion of individual specimens from New South Wales it would be easy to 
establish three species separable from the type, agreeing with Dana’s 
terminology. If, however, a suite be studied, this separation is seen to be 
impracticable, the two supposed species, E. ellipticmn, Dana, and E. sacculum, 
Dana, merging imperceptibly into the species proper, Avhilst E. glohomm is 
merely the young form ; under these circumstances all have been brought 
together under E. cordatnm, but, as the cincture distinguishing E. sacculum 
does sometimes assume noticeable proportions, the name may be used in a 
varietal sense. To assist in this enquiry, replicas of Dana’s types have been 
made use of. 
The internal cast figured as Pachydomus Eonincki (?), by Mr. R. M. 
Johnston, is a Eurydesma, judging from the ap|)earance of the mantle scars, 
and in all probability belongs to this species. The partially exfoliated shell 
shown on Johnston’s PI. XVIII, fig. lb, is this species, but it appears to us 
that his Pachydomus globosus^ {non J. de C. Shy.) is in reality Eurydesma 
cordatum — the deeply excavated and corrugated lunule region differs from 
that of Sowerhy’s P. globosus. 
Leiornyalina antarctica, Prech (1891), is, as already pointed out, 
a Eurydesma, but it is not L. antarctica, Freeh (1902) — we have no 
specimens like it. 
Johastou — Op. cit., PI. XVIII, figs. 1, la. 
