BY JOHN MITCHELL AND VT. S. DUN. 



275 



Western Australia. 



A. H. Foordt records Atrypa reticularis from Mt. Piene, Kimberley Dis- 

 trict, associated with Ulnjiichonella pleurodnn and RhijnclioneUa cuboides, in the 

 Stroraatoporoid horizon which Nicholson considered to be Upper Devonian. To 

 our knowledg-e, no specimen of this species from a similar horizon in Eastern 

 Australia has vet been collected. 



Figs. 



Figs. 



Fig. 

 Figs. 



Fig. 

 Figs. 



1 — 4 



S. 



9 —11 



12. 



13— IS 



19. 



Fig. 



Pigs. 20-21 



Figs. 

 Pigs. 



Fig. 

 Fig. 



22—26, 



27 28 . 



EXPL.\N.\TION OF PL.\TES XTV.-XVI. 

 Plate xiv. 



(.-Ml figures natural size.) 



Alrvf>oiiiea aiistnilis. Mitchell and Dun. 

 Ventral, profile and dorsal view? nf two perfect young specimens. 

 Molong. Coll. Mitchell. 

 Front, profile and ventral view of a mature specimen. Molong, 



ing. Coll. Mitchell. 

 Front view of a nearly mature specimen. Molong. Coll. Mitchell. 

 Front, profile and ventral views of the largest specimen from Down- 

 ing. Coll. Mitchell. 



Ventral view of specimen shown in figure S. Molong. Coll. Mitchell. 

 Specimens from Hatton's Corner, Yass River. Fig. 13 shows the 

 largest shell from that locality; fig. 18, a small, square-shouldered 

 form with inconspicuous umbo. Coll. Mitchell. 



Atrvpa pulchra Mitchell and Dun. 

 .\ perfect specimen, dorsal aspect.. Silverdale, near Bowning. Coll. 

 Mitchell. 



Atrvpoidea aiigiisfa ^litchell and Dun. 

 Oblique profile and front view of largest specimen from the Bowning 

 series. This shows, in the original where the brachial valve is weath- 

 ered slightly, faint outlines of one of the spirals. Gurnett's fann, 

 three miles west of Bowning. Coll. Mitchell. 

 29. Specimens from Molong, at various stages of growth. 

 Front and profile views of two specimens from Hatton's Corner, Yass 

 River . 



Plate XV. 



Atrvpa rciicnhiris Linn . 

 A beautifully weathered transverse section of a large shell, showing 

 the spiral cones and great inflation of the brachial valve. Wellington 

 Caves. Coll. Mining Museum. Sydney. 



Same specimen as fig. 3, but enlarged to show the surface ornamen- 

 tation. 



JGeol. Mag., Dec. 3, vii., 1890, pp.lOO-l. 



