f 
191 
to place it with Coelospira (see ref. those authors, footnote below). The 
Australian species possesses some definite characters which separate it from 
the northern form. In the first place, Coelospira hemispJicerica is not so 
typically hemispherical in the valve outlines as the Australian ; the figures 
given by Davidson^ tallying with his description “ ventral valve sub-hemi¬ 
spherical.” Another essential difference is the greater number of riblets 
in the British and American species, that is, 12 to 18 against 8 or 10 in the 
Australian. A third feature is the greater average dimensions, as compared 
with the Australian species, being very nearly twice the diameters. 
Coelospira acutiplicata, Conrad sp.^ has a similar ornament to the Australian 
species, but the valves are more circular in outline and not so widely trans¬ 
verse. This species, by the way, has lately been referred by E. M. Kindle^ 
to the genus Anoplotheca. 
Occurrence. —In calcareous shales ; Mitta Mitta River (Nos. 2547 holotype, 
2548, 2551). Also in dark mudstone ; Co wombat. Forest Hill, coll., by Dr. 
A. W. Howitt; specimens in the Nat. Mus. coll. (Nos. 792-3). Silurian 
(Yeringian). 
Class Pelecypoda. 
Earn. CoNOCARDiiD^. 
Genus Conocardium, Bronn. 
CoNOCARDiUM BELLULUM, Cresswell sp. 
Pleur^rhiinchus bellulus, Cresswell, 1893, Proc. R. Soc. Viet., vols.V. (N.S.), 
p. 43, pi. IX., fig. 6. 
Conocardium bellulum, Cresswell sp.. Chapman, 1908, Mem. Nat. Mus., 
Melb., No. 2, p. 45. Id., 1913, Rep. Austr. Assoc. Adv. Sci., vol. XIV., 
Melbourne, p. 226. 
Observations. —^A very finely preserved mould of the anterior and main 
part of both valves occurs here. The mode of preservation enables one to see 
the minute structure of the shell in this genus, as being composed of hollow 
prisms, which in the present mould are represented by limonite mud-casts. 
C. bellulum is apparently restricted to the Yeringian series in Victoria, 
and is therefore useful as an index fossil. It has not been previously recorded 
fromN.E. Gippsland, having been found only at Lilydale, the Upper Yarra 
(Junction of Woori Yallock and Yarra), and at Deep Creek, Thomson River, 
Gippsland. 
Occurrence. —In calcareous shales ; Mitta Mitta River (No. 2554). Silurian 
(Yeringian). 
Class Crustacea. 
OsTRACODA spp. (Plate XXXI., Fig. 34). 
Observations. —The majority of examples of sectional tests seen in the 
slides resemble those of Bythocypris hollii, Jones, a form which has already 
been recorded from the Silurian (Yeringian) of Victoria.'* The precise deter¬ 
mination of even the genus in such sections is unsafe, and we can only refer 
to the form in a tentative way. Other examples in section are more com¬ 
pressed than the above, and'may belong to bythocyprids of a type like 
Bythocypris phaseolus, Jones.^ 
Occurrence. —The Ostracods here under discussion occur in the pale grey 
limestone with Halysites from the Mitta Mitta River, N.E. Gippsland (No. 
2700, c.). Silurian (Yeringian). 
^ ?Atrypa hemisphcerica, Sow., Davidson, Mon. Brit. Foss. Brach., pt. VII., No. 11. (Pal. Soc. Mon.), 
1867, p. 136, pi. XIII., figs. 23-30ffl. See also Atrypa hemisphcerica, Sowerby, Sil. Syst., 1839, p. 637, 
pi. XX., fig. 7. Coelospira hemisphcerica. Sow. sp.. Hall and Clarke, Pal. N. York, vol. VIII., Brack., 
pt. I’., 1894, p. 1.36, pi. LXXXII., figs. 1-4. 
* See Hall and (darke, ibid., 1894, pi. LIII., figs. 32-39. 
* U.S. Geol. Surv., Bull. No. 508, p. 84, pi. VI., figs. 1-5. 
* Proc. R. Soc. Viet., vol. XVIII. (N.S.), pt. I., 1904, p. 310, pi. XIV.,figs. Qa-b ; pi. XV.. figs, la-e, 
2a-c. 
* See id., ibid., p. 311, pi. XV., figs. 5a-6. 
