88 Proceedings of the Royal Society of Victoria. 



Lithophagus latecaudatus, sp. nov. (PI. XIV., Fig. 4). 



Description. — Shell suiootli, thin and fragile, digitiforni, narrow 

 and tumid at the anterior end, but leinarkably broad and 

 depressed at the posterioi* end, the posterior being more than 

 twice as broad as the anterior. Umbo incurved anteiiorly and 

 depressed dorsally. Anterior end very short, but strongly 

 ■convexly i-ounded, ventral margin sloping downwards to the 

 posterior; dorsum immediately behind the umbo slightly concave, 

 thence ascending to the posterior, posterior margin broadly 

 convex. Surface smooth and shining, showing faint irregular 

 undulations or ridges conforming to the lines of growth, and very 

 faint finer parallel stiiations, very close radial striatioiis may also 

 be detected, particularly on the upturn towards the post-dorsal 

 margin forming a microscopic reticulation. The nacreous interior 

 shows where the shells are decorticated or worn, especially on 

 the umbonal region. 



Dimensions. — Antero-posterior diameter, 42 mm.; width at 

 umbo, 11 mm.; median width, 17 mm.; greatest posterior width, 

 22 mm.; thickness through one valve, about 6 mm. 



Locality. — Lower beds of the Spring Creek series, or Bird Rock 

 Bluff, near Geelong. Jan Jukian, — Eocene. 



Observations. — The genus Lithodomus has pieviously been 

 recorded from "casts and crypts" in a coral from the Miocene 

 beds of Hallett's Cove, by Professor R. Tate' in 1885, but the 

 species was not described till 1886,- under the name of L. brevis. 

 The present species is evidently distinct from the above-mentioned 

 representative as judged by the dimensions and the few brief 

 particulars given. 



Mytilus mooraboolensis, sp. nov. (Plate XIV., Fig. 1). 



Description. — Shell small, elongately triangular, undjo some- 

 Avhat twisted, incurved, and terminal, strongly keeled fi-om the 

 umbo to the posterior margin, posterior area much expanded and 

 depressed, sculpture on the anterior portion of the shell strongly 

 marked off", and distinct from that on the posterior. 



1 Trans. Roy. Soc. South Australia, 1S8C, vol. viii., Lam., i>t. i., p. 124. 



2 Op. cit., 1887, vol. ix., Lam., pt. ii., p. 186 (4.t in author'.s reprint). 



