96 
Dimensions. — Length, about nine millimetres; diameter of the base, 
twenty-seven millimetres. 
Relations and Differences . — This species has several points of re- 
semblance to the preceding, from which it is easily distinguished by its size, 
spiral angle, and above all by tiie shape and disposition of the double carina. 
Ohservation. — It is only l)y the examination of several fragments of 
the same species that I have been aide to gras]3 the different characters. By 
chance it happens that these different pieces fit together so well with one 
another that I feel as confident in dealing with them as if I had a perfect 
specimen before me. 
Horizon and Locality. — All the specimens come from the Yass District. 
3. MuiiCHisoNiA GEANiFERA, L. G. dc Kouinck. 
PI. IV, Pig. G. 
Shell very small, elongate, regularly conical, composed of eight spiral 
whorls, slightly arched, the successive growth of which is very regular. The 
suture is shown by a well-marked prominence. The spiral angle is 16°. The 
surface is ornamented with five rows of small granulations parallel to one 
another, as well as to the suture. The two rows closest to the anterior suture 
are a little more distinct from one another than those that succeed them ; it 
is between these two rows that the band of the sinus, represented by a small 
furrow, is situated. The base is faintly depressed. The aperture is oval, and 
the columella is straight and thickened. 
D imensions. — Length, six millimetres ; transverse diameter of the base, 
two millimetres. 
Relations and Differences.- — ‘I know no species of the same genus that 
can be compared to it and with wdiich it could be confused. 
Horizon arid Locality. — This pretty little species was collected in a 
greyish argillaceous limestone in the Yass District. 
Genus — ^PLEUBOTOMARIA, Defrance. 
Pleurotomaeia subconica, L. G. de Koninck. 
PL IV, Pig. 7. 
Shell small, of conical form, of which the spiral angle is 45°. It is 
composed of six or seven spiral whorls, angular at their anterior margin, and 
