342 Di\ S. Woochcard — New Trilubites from 8. Australia. 



valve and equilateral. Posterior region compressed, anterior rather 

 fuller, the shell being thickest a short distance from the umbones. 

 No wing can here be traced, and it is probable that it must have been 

 very short. In one of the valves of the smaller specimen what I 

 take to be the ligamental groove with its nacreous lining may be 

 seen. The surface bears traces of an ornamentation which consisted 

 of numerous fine radiating ribs, which appear to have been pretty 

 nearly equal in prominence. There are also traces of concentric 

 costai which seem to have been the strongest anteriorly. 



There are so many features in these shells that fail to correspond 

 with the general diagnosis of Avicula, which is usually inequivalve 

 and very inequilateral, that the determination is open to doubt. The 

 two specimens in question seem to belong to a group of Lima-like 

 Aviculas, such as Avicula ecJiinata of the Cornbrash, and A. ovalis of 

 the Corallian. 



III. — Note on the Eejiains op Thilobites eeom South Attstealia. 

 By Henry "Woodward, LL.D., F.E.S., etc. 

 (PLATE XI. Figs. 2 and 3.) 

 AYING, some time since, been favoured by Professor Ealph Tate, 

 A.L.S., P.G.S., of the University of Adelaide, South Australia, 

 with two fragments of Tribolites from the Parara Limestone, Yorke's 

 Peninsula, I venture to place the same on record, and to add a few 

 notes on their probable affinities 



"The Parara Limestone" (writes Prof. Tate) "is apparently un- 

 conformable to the Chloritic and Micaceous Schists and associated 

 rocks constituting the elevated tracts of this Colony containing our 

 chief metallifei'ous deposits. The determination of the horizon is 

 therefore of great importance." 



Mr. Henry Y. Lyell Brown, F.G.S., Government Geologist for the 

 Colony, has also kindly sent me some specimens of the same limestone 

 from Yorke's Peninsula, containing what appears to be the remains 

 of a Coral, the calicos of which are about 12 millimetres in diameter. 

 The septa are numerous and very short, with a thickened spongy 

 columella ; the corallites are irregular, and few in number, and appear 

 to be united by a cellular coenenchyma. It is difficult to pronounce 

 upon the nature of these specimens, owing to their highly meta- 

 morphosed and mineralized condition ; it is to be hoped therefore that 

 other and better-preserved specimens may be met with, from which 

 an accurate determination of the fossil may be arrived at ; especially 

 as these fossils do not appear to be of very rare occurrence. 



In his " Introduction to the Cliffs and Pocks at Ardrossan, Yorke's 

 Peninsula," by Mr. Otto Tepper (Corr. Memb.), see Trans, and Proc. 

 and Peport of the Phil. Soc. of Adelaide, South Australia, for 1878-9, 

 pp. 71-79, the author observes: — "Both varieties of the upper 

 marbles contain distinct fossils and abundantly minute fragments of 

 such, but the upper one by far the most ; conspicuous among which 

 occurs a trilolite, and cor«/-structure appears to perfection in sea-rolled 

 pebbles, when the fossil shows in beautiful contrast of colour upon 

 the smooth surface. Professor Tate holds the tentative opinion that 



