172 RALPH TATE. 
the posterior angulation gives the posterior part of the aperture a 
truncated outline; the margin of the aperture is only feebly 
denticulated anteriorily. The anterior groove is broad and deep, | 
and the columella-expansion is broadly concave and not horizontal. 
The ornament consists of linear grooves unequally placed, divid- 
ing-up the surface into flat ridges, which become somewhat angu- 
lated towards the front ; the whole crossed by growth-iines, giving 
place to slight lamellae in the neighbourhood of the basal rib. 
There is a total absence of a fenestrate ornament as in most 
individuals of C. Peruviana. Length 26, breadth 22, height 14mm. 
Genus Distortio. 
D. INTERPOSITA, sp. nov., Pl. x., fig. 3. 
This genus is represented in living creation by three species, 
one of which D. anus, Linn., of the Indian Ocean, is a familiar 
shell, remarkable for its ringent aperture. Among described 
species D. septemdentata, Gabb, from the Hocene of Texas is the 
most ancient ; in the European Tertiary beds, it is represented by 
D. tortuosa, Borson, in the Piedmontese Miocene. Our Australian 
species is from the Eocene at Bird-rock Bluff near Geelong, whence 
a few examples have been obtained ; it has the general aspect and 
latticed ornament of D. cancellina, Roissy, but has a very short 
canal, the spiral ribs are flat and alternate with riblets (there are 
about seven on the penultimate whorl, the third, fifth, and seventh 
more prominent), subgranose at the intersections of the primary 
spirals and costze (most prominent in the early whorls). D. septem- 
dentata has three spirals on the penultimate whorl. Length 25, 
breadth 15, length of aperture and canal 13-5 mm. 
Genus Argobucconum. 
If this name is accorded generic rank, then it should replace 
fanella, as the only species in the Australian Eocene, &. Pratt, 
Ten.-Woods, has the distinctive characters of Argobucconum as 
already implied by me when redescribing the species. 
Genus 7ritonidea. 
IT here refer Pisania obliquecostata and P. brevis, Tate; whilst 
LP. rostrata and P. semicostata, Tate,. are’ better placed under 
