154 RECORDS OK THE AUSTRALIAN MUSEUM. 



Sp. Chars. — Shell attaining a large size, robust. Whorls, at 

 least four, close coiled, rapidly enlarging and overhanging one 

 another ; crozier .sharply and shortly curved ; shaft often with a 

 compressed and lank or lean appearance ; initial whorl vermiform, 

 with an acute apex ; venter of the whorls narrow and much 

 arched in the young state, broadening and less arched in the 

 older condition, narrow and gently rounded on the crozier and 

 low convex or almost truncate on the shaft ; abdominal margins 

 rounded ; dorsum flattened, costate , impressed zone very faintly 

 indicated, more apparent in the young state, not visible on the 

 shaft and crozier ; flanks of the whorls and shaft compressed, 

 llattened, on the crozier slightly rounded ; umbilical cavity wide 

 and open ; section longitudinally oval. The nature of the cos tie 

 and tubercles varies according to growth and position; in the 

 young state the cost* are obtuse and rounded, some more pro- 

 minent and obtuse than others, single, or bifurcate low down on 

 the flanks ; as growth progressed the costs? became sharp and 

 angular, and either single (venter, dorsum, and flanks), larger and 

 smaller alternately, bifurcate as before, or fasciculate (flanks and 

 venter) in bundles of two to four (usually three) on whorls, 

 shaft, and crozier; on the venter straight, on the flanks sigmoidal, 

 varying only in degree, and bent forwards on the dorsum ; inter- 

 costal spaces, or valleys, very narrow in the young condition, wide 

 and concave on the old whorls. Tubercles very prominent and 

 well marked, one row on each side the middle line of the venter 

 along the abdominal angles, and at irregular distances apart in 

 the young, but on the maturer whorls, shaft, and crozier on 

 nearly every costa or group of costal ; those of the simple costse 

 node-like, those uniting fasciculi on the whorls cristiform, 

 elongated in the direction of the coil, those on the shaft low and 

 conical ; mid-lateral and dorso lateral nodes absent. 



Obs. — This is one of the three Australian Crioceras in which 

 I have been able to trace the various parts of the entire shell, 

 whorls, shaft, and crozier ; the nature of the sculpture is so 

 characteristic, little or no mistake can be made, the retention of 

 strong fasciculate bundles of costse and prominent nodes through- 

 out life being very characteristic. 



No doubt this shell attained to a very large size, although T 

 have not the means of saying how large, but McCoy compared it 

 with the C. gigas, J. de C. Shy., of the British Cretaceous, and 

 speaks of it as a "gigantic" species. The largest portion of a 

 whorl to come under my notice, as elsewhere recorded, is eight 

 inches long by four and a half wide (i.e., transversely), but this 

 is only a portion of a Sank, or side of a whorl the circumference 



