of the Rocks associated with the Coal of Australia. 299 



five nearly equalling the primary ridges in thickness. The pre- 

 sent fossil has however much finer striae than the Irish species 

 alluded to, and the arrangement is much less definite, becoming 

 confused in size and number towards the sides ; it is also distin- 

 guished by its greater convexity. Length 2 inches 9 lines, width 

 the same. 



Rare in the greenish, fine sandy, beds of Harper's Hill, N. S. 

 Wales. 



Avicula tessellata (Phil.). 



I cannot distinguish the specimens occurring in the soft green- 

 ish schists of Dunvegan, N. S. Wales, from those in the precisely 

 similar shale at the base of the carboniferous series at Lisnapaste 

 in the north of Ireland. 



Pterinea macroptera (Mor.). 

 Rare in the white rock of Port Arthur, V. D. Land. 



Eurydesma cor data (Mor.). 

 Common in the arenaceous limestone of Arthur's Hill, N. S. 

 Wales. 



Inocer annus Mitchellii (M'Coy). PI. XIV. fig. 1. 



Sp, Char. Longitudinally ovate, one-fifth longer than wide, 

 slightly oblique, inflated ; hinge-line oblique, nearly equalling 

 the width of the shell, forming a slightly compressed wing ; 

 beaks pointed, prominent, incurved, close to the anterior end ; 

 anterior side nearly straight, abruptly subtruncate; surface 

 with numerous strong, concentric, irregular wrinkles of 

 growth. 



The hinge-margin of this species is much thickened, which 

 removes it from Posidonia, while, as in many of the German cre- 

 taceous Inocerami, it is not possible to observe any traces of the 

 transverse ligamentary pits, nor can we be sure whether those 

 species possessed them or not ; meanwhile I shall leave the pre- 

 sent species in the same genus as its obvious allies alluded to ; 

 and even if future research should prove that ligamentary pits 

 did not exist, we should form a distinct genus for those species, 

 which, like the present and the /. vetustus (Sow.) of the moun- 

 tain limestone, are distinguished from the true semimembranous 

 Posidonice of the lias and palaeozoic shales with which they have 

 been confounded, by their thick shells, general form, and thick- 

 ened hinge-margin. Length 2 inches 3 lines, width 1 inch 

 9 lines, thickness about 1| inches. 



Common in the sandstones of Glendon and Wollongong, N. S. 

 Wales. 



Dedicated to Sir T. Mitchell, one of the first to make known 

 the existence of fossils in those rocks. 



