LOWER CRETACEOUS FOSSILS — ETHERIDGE. 237 



Dr. F. Stoliczka commented on the variability in the number 

 of rows of tubercles in Indian specimens of this species. The 

 same instability appears to exist in the present specimens, one of 

 the matrix casts exhibiting three rows, two others two rows 

 only ; the coiled cast (Pi. lxvii., fig. 1) one row on the concealed 

 whorls, and two on the exposed volutions ; the testiferous 

 example reveals only two, but between these rows, the inter- 

 section of the costaa and lyrse become prominent and sub-echinate. 



The sigmoidal curvature of the costse is far more noticeable on 

 the youug than the more mature individuals, and the sharpest 

 curve of each sigmoid is always in the ventral channels where 

 it practically forms a continuation or extension of the tubercles, 

 and is directed forwards. 



The largest matrix cast represents a perfect shell of one foot in 

 diameter. 



The resemblance between the Australian examples of S. ros- 

 tratus and Stoliczka's figures of specimens from the Ootatoor 

 Group of the Indian Cretaceous, particularly that represented in 

 his Plate xxvii. is very strong. 



S. ROSTRATUS, J. Sby.. Val\ ANTIPODEUS, Eth. fil. 



Hystrichoceras, sp., Eth. fil., Mem. K. Soc S. Austr., ii., 1, 1902 

 p. 47 



Hystrichoceras antipodeus, Eth. fil., ibid, pi. vii., fig 6. 



Obs. — In my account of the South Australian Cretaceous 

 fossils I placed a few small fragmentary Ammonites provision- 

 ally in Hystrichoceras, Hyatt-. These shells, I have since learnt, 

 occur at Point Charles in incredible numbers, and never appear 

 to attain to more than a small size, as I now find through the 

 reception of successive collections. At the time I wrote the 

 fragmentary specimens before me did not reveal what I now 

 believe to be their close relation to the inner, or younger 

 whorls of S. rostratus. Hyatt selected Ammonites coupei, Brong., 

 as the type of his proposed genus, but figured A. varians. 3 



Our Point Charles Cephalopods present a most unmistakable 

 resemblance to the latter, but less to the former. Now, Mr. A. 



2 Hyatt— Zittell's Handb. Pal. (Eastman ed.), i. 1900, p. 589. 



3 Hyatt— Lor. cit., p. 589, fig. 1233. 

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