THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE III. VOL. VII. 



No. VI.— JUNE, 1890. 



OIK-ia-ZEUST-A^Xi ARTICLES. 



I. — Further Notes on some Mollusca from South Australia. 



By W. H. Hudleston, M.A., F.R.S., F.G.S. 



(PLATE IX.) 



IN the Geological Magazine for 1884 l some Mesozoic fossils, 

 obtained from near Mount Hamilton and the Peak Station, were 

 noticed by me with figures and descriptions where the specimens 

 were fairly well preserved. Since then additional specimens have 

 been procured from adjoining districts. 2 The general character of 

 the facies is fairly similar to that already noticed in 1884; but on the 

 whole, perhaps, the specimens are scarcely so well preserved. 

 According to the opinion of those who have had most experience, 

 these fossils may be regarded as of " Cretaceo-Jurassic " age, though 

 I am not aware that such undoubted Cretaceous forms as Ancyloceras, 

 etc., have been discovered in the beds whence the fossils forming 

 the subject of these notes have been derived. 



With the materials before us, mostly in the state of casts, and 

 sometimes only single specimens, a really good specific diagnosis is 

 almost impossible. In those cases where I have ventured to give 

 a name, it must be regarded as mainly for convenience of reference. 

 To constitute species on a sound basis we require better specimens, 

 and more of them, and these it is to be hoped that the collectors 

 will ere long supply. 



Ammonites fontinalis, sp.nov. PI. IX. Fig. 1. 

 Shell compressed, carinated, involute. Owing to the raising of 

 the umbilical margin the whorls are slightly concave towards the 

 centre; umbilicus deep with steep walls, restricted yet showing 

 portions of each of the inner whorls in succession. In the early whorls 

 and more central portions of the body-whorl the ornaments consist 

 of numerous fine flexuous lines, which have a tendency to pass out- 



1 Dec. III. Vol. I. p. 339 and Plate XI. 



2 The fossils described in this paper form part of a small collection of geological 

 specimens which was exhibited in the South Australian Court of the Colonial Exhi- 

 bition in 1886, and subsequently presented by Henry Y. Lyell Brown, Esq., F.G.S., 

 Government Geologist for South Australia, to the Trustees of the British Museum 

 (Natural History). They have now been figured and described at the request of 

 Mr. H. Y. Lyell Brown. The collection comprises in addition, some Tertiary 

 Plant-remains, some Tertiary Mollusca, and some Palaeozoic Corals and fragments 

 of Trilobites ; the latter are from Yorke's Peninsula, and it is hoped that these will 

 shortly be described with the kind assistance of Dr. G. J. Hinde, F.G.S., and other 

 palaeontologists. — Edit. Geol. Mag. 



DECADE III. — VOL. VII. NO. VI. 16 



