Upper Silurian.] PALZAONTOLOGY OF VICTORIA. [ Mollusca, 
Priate LVII., Fia. 6. 
ORTHOCERAS LINEARE (Monst.). 
Descriprion.—Very gradually tapering, at the rate of 14 lines in 1 inch from 
a diameter of 10 lines, at which size the septa are 2 lines apart; surface girt with 
excessively fine, close, equal, very slightly oblique, transverse striee, 29 in a space of 
2 lines, without distinct interspaces. 
REFERENCE.—Orthoceratites linearis (Miinster), Beitrige zur Petrefactenkunde, 
Heft 3, t. 19, f. 1. 
The excessive fineness and regularity of the microscopie trans- 
verse close thread-like lineation renders this species easy of recog- 
nition. Count Miinster originally described it from the Upper 
Silurian of Elbersreuth, and M. Barrande subsequently found it in 
limestone of the same age in Bohemia. I do not think it has been 
found elsewhere until I now find it in Victoria in strata of the 
same age. 
Not uncommon in the olive mudstones of the junction of Woori 
Yallock and the Yarra. 
EXPLANATION OF FIGURES. 
Plate LVII.—Fig. 6, fragmeni, natural size. Fig. 6a, striation highly magnified to show 
the closeness of the rounded strize without defined interspaces. Fig. 66, a few striz across the 
whole width of the shell, magnified three diameters to show their slightly oblique wave. 
Pirate LVII., Fries. 7 anv 8. 
ORTHOCERAS STRIATO-PUNCTATUM (Mtnst.). 
Drscrirprion.—Short conical, rapidly tapering, at the rate of 5 lines in 2 inches 
from a diameter of about 2 inches; surface covered with strong, slightly unequal, 
longitudinal ridges, about 4 or 5 in a space of 2 lines at 2 inches in diameter ; 
between each pair is a longitudinal row of strong oval puncta, about two in a length, 
equalling the transverse distance of the rows; slightly oblique, sigmoid, transverse 
fine lines of growth. 
REFERENCE.—Orthoceratites striato-punctatus (Miinster), Beitrige zur Petre- 
factenkunde, Heft 3, t. 20, f. 1 to 3. 
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