500 
moderately straiglit, but as tbe shell grew they became rounder, flatter, further apart, 
abrupt on their front sides, gradually shelving off into the concave sulcus, and sigmoidal 
in direction on the flanks. In this condition the shell becomes G. australe, Moore. 
The tubercles are occasionally retained to the fourth whorl before they disappear, but in 
most examples they are not visible beyond the second or second and a-half whorl. In 
no less than four specimens there is no sign of tubercles at all, even in the flattened, 
rounded ribs in advanced age, which gradually become further apart as the mouth is 
approached, even to the extent of a quarter of an inch. The costae bearing tubercles 
are always larger and thicker than the non-tuberculate. The number of secondarj- ribs 
between those, bearing tubercles varies from two to five. Much variation also took place 
in the contiguity of the whorls, some being inrolled much more closely than others, and 
frequently the whorls to all appearance look as if touching, but on fracturing the 
specimens they are all found to be separate. 
Crioceras australe attains to very large dimensions. The subject of PI. 81, 
fig. 1, measures twelve and a-quarter inches in one direction by nine and a-half in the 
other. Another before me is nine inches by seven and a-half, the breadth of the last 
whorl from the middle of tho back to the umbilical edge being three and a-half inches. 
But in the Australian Museum is a huge specimen described by the late Mr. E. Eatte, 
consisting of about half the entire shell, showing the following measurements : — 
Ft. in. 
Diameter ... 
Circumference of periphery 
G-irtli of older portion ... 
Distance apart of the costae at the younger end 
Depth of valleys between the cost® at the younger end 
1 Hi 
3 9i 
2 2i 
0 4 
0 1 
Mr. G. Sweet obtained another very large example from the Maranoa Eiver, 
with a diameter of two feet nine inches and even then imperfect. The cost® or 
ribs are from two to three inches apart. 
Mr. Moore states that in his specimen the mouth measured seven and a-haH 
inches in depth by seven in breadth. The dorsal side of each whorl is flattened, with a 
space in the middle line corresponding to the dorsal lobe, and bounded by two impressed 
lines. 
One word more about Crioeoras Jachii. Moore’s description and figure are quite 
inadequate for the poper recognition of O. uia'fmZe, and I believe I should, therefore, 
have been justified in retaining mine. But it is difficult to believe that two large species 
could have existed in the same area, so very alike and only known to differ in the young 
state. The figure, however, given by Dr. Waagen is probably conclusive, for in this 
case there arc portions of the large outer whorls of C, australe^ embracing an inner 
fragment resembling O. Jachii. Such conditions arc seen in other Crioceri, such for 
example as G. Emerici* a JMeocomian species. Ilis statement that when complete the 
shell attained nearly twice the dimensions of the huge G. Botverhanki, of the British 
Lower Greensand, would appear to be borne out by the size of the shell already 
referred to as in the Australian Museum. Mr. E. Etheridge, E.E.8., also recognised 
a large Crioceras in Mr. Daintree’s Collection, measuring little less than twelve or 
fourteen inches in diameter, which may possibly be this species. 
The subdivisions of the septa have been excellently figured by Mr. Eatte, from 
the large specimen in the Australian Museum, but from advanced age they are more 
complicated than those shown in PI. 32, fig. 4. 
Quenstedt, Handb. Petrefaetenkunde, 1885, Atlas, t. 45, £. 21. 
