26 G PROCEEDINGS OF THE 



duced by two or three very large and irregular concentric undula- 

 ations, the elevated but not incurved beak, and the wide area, 

 with its convex deltidium. Similarly the dorsal valves of these 

 specimens exhibit the straight hinge line, and evenly convex 

 surface. The situation of the valves likewise appears to be iden- 

 tical, and there also appears to be the same concentric lamination 

 of the area and deltidium as seen in some British specimens. 

 The most interesting point, however, is the structure of the shell 

 itself. This is seen to be distinctly punctate, and when the surface 

 is at all worn the punctae are everywhere visible, more especially 

 on the area. I believe this feature in Orthotetes ( = Strepto- 

 rhynchus) has not been generally recognised, for in the generic 

 description given by the best authorities the shell is said to be 

 impunctate. Professor William King, however, has not omitted 

 to notice this peculiarity in a Permian species, 0. pelargonatus 

 (Schlotheim). On mentioning the existence of these perforations 

 to Mr. T. Davidson, he informed me that he had recently seen the 

 same structure in some British Orthotetes. The punctae on the 

 exterior of the shells appear as small rugosities scattered at random 

 over the surface of the ribs or striae and intervening valleys, but 

 when the surface is to any extent worn, their perforate character 

 at once becomes apparent. 



Locality and Horizon. — Havilah-Byerwin Road, one mile south 

 of Rosella Creek Crossing, Bowen River coal-field, N. Queensland ; 

 a marine band intercalated in the " fresh- water " or upper series 

 of the Permo-Carboniferous formation (Mr. R. L. Jack, F.G.S.). 



6. On a small, distorted, and probably young form of Chonetes, 

 from the Carboniferous beds of the East of Scotland, PL V., figs. 1 

 and 2; PI. VI., figs. 4 and 5.— Only one valve of this shell is known 

 to me — the ventral. When the normal form is preserved the shell 

 is convex, markedly so in the middle line, giving rise to a rather 

 prominent fold of greater or less dimensions. The specimens 

 undergo curious contortions of outline, due perhaps, to a certain 

 extent, to accidental crushing ; in some there is a pinching up of 

 the mesial fold or visceral region, in others a puckering in of one 

 of the lateral margins, giving to the valve that irregular appearance 

 assumed by Mollusca which live in crevices and cracks of rocks. 

 One individual is of a very peculiar form — much elongated laterally, 

 and correspondingly narrowed across tne valve from the dorsal to 

 the front margin, and somewhat obliquely twisted. The hinge 



