SILURIAN BIVALVED MOLLUSCA OF VICTORIA. 
Measurements.—Smallest specimens, length, 4.5 mm.; 
height, 3mm. A large example, length, 12 mm.; height, 7.5 
mm. The largest specimen in the present series has a length 
of 15 mm. 
A ffinities—The Nuculites oblongatus of Conrad* from the 
Hamilton Group in North America is, in general features, 
closely comparable with our species, but differs in having a rela- 
tively greater length and a straight ventral margin. With re- 
gard to the posterior adductor impression nearly alw ays present 
in the Victorian species, comparison may be made with a simi- 
larly marked fossil shell, Nuculites colonicus Reedt from the 
Bokkeveld beds of Cape Colony. 
Horizon and Locality—Silurian (Melbournian). Very 
abundant in the ochreous and blue mudstone at the Yarra Im- 
provement Works, 8. Yarra, and the Swanston-street sewer near 
Collins-street; in brown mudstone N. of Yan Yean, Geol. Surv. 
Vict., coll. B>- 11; and in pale grey mudstone, Merri Creek, Kal- 
kallo, Geol. Surv. Vict., coll. B> 3; also Silurian (Yeringian), 
junction of Woori Yallock and Yarra. Geol. Surv. Vict. B 23 
[7887 (type), 7888-9, 969-75. | 
Nuculites coarctatus, Phillips, sp. Pl. I1., Figs. 24, 25. 
Nucula coarctata, Phillips, 1848, Mem. Geol. Surv. Gr. 
Bri, Vol ii Pt. it; Paleont: Append, ip: 3665 Pl XO Xar, 
Figs. 1-4. 
Cucullella coarctata, Phill. sp., McCoy, 1852, Brit. Pal. 
Boss5aPt. 1p: 284. 
Observations.—This species was originally described from 
the Ludlow Rocks of Great Britain, and it is therefore interest- 
ing to find it also in the Silurian rocks of Victoria. N. coarctatus 
is a somewhat variable species, but is distinguished from the 
allied form N. triqueter, Conrad,t from the Hamilton Group of 
N. America, by the beaks being less pronounced, and the 
posterior area not so obliquely produced. 
Horizon and Locality—Silurian (Melbournian). In the 
mudstone of 8. Yarra, specimen presented by Mr. F. P. Spry; 
west of Mount Pe coll. Geol. Surv., Vict., B®: 17. 
(See note on $ sheet 3 N.E., “Cucullella sp.”) {7890-1.] 
* J. Hall, Pal. N. York, Vol. V., Pt. I., 1885, Lamellibranchiata IT., P- 324, Pl. 
XLVII., Figs. 1-12. 
+ Annals S. African Museum, Vol. IV., Pt. VI., No. 11, 1904, p. 259, Pl. XXXII., 
Fig. 1. 
“t Geol. Surv. New York, ae Rept., 1841, p. 50. See also J. Hall, Pal. N. York, 
1885, Vol. V., Pt. I. Lamell. II, 326, Pl. XLVII., Figs. 17-28, Pl. XCIII., Figs. 8-r0. 
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