68 Proceedings of the Royal Society of Victoria. 



Messrs. Hall and Clarke have further advocated the advisa- 

 bility of separating the known types of Orbiculoidea into two 

 groups ; Orbiculoidea sensu stricto would then include the forms 

 which have the pedicle valve convex or flattened, and the 

 brachial valve conical ; the sub-genus Schizotreta of Kutorga 

 embracing those forms in which the pedicle valve is conical, and 

 the brachial depressed convex. 



The above species is named in honour of the late Dr. A. R. C. 

 Selwyn, under whose auspices this and many other specimens 

 in the Museum were collected, and whose early mapping of Vic- 

 toria remains as a splendid testimony of conscientious pioneering 

 work. 



Occurrence. — The specimens of Orbiculoidea selwyni in the 

 National Museum are from the Geological Survey collections 

 from Merri Creek, Pai-ish of Merriang Bb 6 [613-4]; and from 

 Merri Creek, Kalkallo, Bb 3 [612]. 



In the former instance they are found in an ochreous coloured 

 sandy and micaceous rock, and in the latter in a tine blue-grey 

 sandstone. 



Horizon.— i^WuvvAW (? Yeringian). 



Genus Craniella, Oehlert. 



Craniella lata, sp. nov. (PI. X., Figs. 4, U). 



Specific characters. — Shell sub-quadrangular, moderately large, 

 broader than long. Dorsal surface rising from behind forward to 

 two-thirds the length when it curves steeply to the anterior 

 border. Sides somewhat steeply sloped. The surface of the 

 dorsal valve rather depressed in the central area ; marked by one 

 or two striae parallel with the posterior border. The upper valve 

 in the type specimen is practically represented as a cast of the 

 internal surface. The impressions of the posterior adductors are 

 shown as small trigonal depressions ; the two sub-centrals are 

 apparently confluent, though not well seen in the specimen, being 

 represented by a crescentic excavation. Faint indications of the 

 vascular sinuses on the steep lateral margins of the specimen, 

 nearly concentric with the lateral shell-margin and emitting 

 secondary branches from both sides. 



