150 RECORDS OF THE AUSTRALIAN MUSEUM. 



plastic, I do not think it has undergone distortion. If the latter 

 be the case, it is remarkable for the breadth of the rounded 

 venter, and convexity of the flanks. The section, a transverse 

 broad oval, is more truly oval than any other of our forms, even 

 than that of C. plectoides. 



In possessing tubercle-united fasciculi of cost?e C. nautiloides 

 resembles C. axonoides, but whilst the tubercles of the latter 

 continue throughout life (so far as the shell is known), in the 

 present species they stop short at a certain period of growth, as 

 in C. jackii, and do not appear on the more mature whorls. 

 Were it not for the fasciculate condition of the costse, no objec- 

 tion could he raised to including this with C. jackii provisionally 

 on the ground of distortion arising from plasticity as a cast. 



Loc. — Aramac, Thomson River, Central Queensland [G.S.Q.] 



Crioceras axonoides," 4 sp. nor. 



(Plate xxxii., fig. 4 ; PI. xliv., fig. 1.) 



Sp. Chars. — Shell large, with a depressed discoidal appearance. 

 Whorls four (as far as known), close coiled, very gradually 

 enlarging and not greatly overhanging one another ; initial 

 whorl unknown ; venter comparatively narrow ; abdominal 

 margins rounded and tuberculated throughout life ; dorsum flat, 

 costate ; impressed zone imperceptible ; flanks very gently 

 rounded, inclined to be straight-walled; umbilical cavity wide, com- 

 paratively shallow, and open ; section longitudinally and obtusely 

 triangular (deltoid). Sculpture varies at different stages of 

 growth ; on the earlier whorls the costa? are oblique and both 

 simple and in fasciculi, the former one or two in succession, the 

 latter in groups of two or three ; on the later whorls all are 

 simple and non-fasciculate ; on the venter of the inner whorls 

 straight, and simple or fasciculate ; on the flanks of the outer 

 whorls oblique, and on the venter straight ; on the dorsum 

 throughout bent forwards. Tubercles in one row on each side 

 the middle line of the venter along the abdominal margins ; on 

 the inner whorls prominent, pointed, and conical, uniting the 

 fasciculate costse in bundles of two or three, usually the latter, 

 gradually lessening in size as the shell grew, and on the fasciculi 

 ceasing, one blunt tubercle to each cost a. 



Obs. — This species must have attained a large size; the figured 

 example possesses a diameter of ten and a half inches. One of 



ai a^d)v, ovos, a wheel. 



