326 MisceUanea. 



large, tumid, much incurved into the anterior cordiform' space, 

 which is unusually deep ; anterior side short, rounded ; posterior 

 end rounded ; ventral margin very convex ; ligament very large, 

 external ; muscular impressions large, anterior deep oval, poste- 

 rior impression shallow, lunate, pallial impression entire ; shell 

 thick, surface rough with strong concentric imbricating lines of 

 growth. 



This curious little species resembles an Isocardia ; but from the 

 great size of tiie external ligament, thick shell and general habit, I 

 have placed it in the present genus, but not without doubt, from its 

 diminutive size and peculiar proportions. Length 10 lines, width 

 11 lines. 



Common in the sandy schists of "Wollongong, N. S. Wales. 



Cardtma (?) eccilts (M'Coy). PI. XV. fig. 1. 



Sp. Char. Transversely ovate, compressed, cuneiform, slender, 

 twice as wide as long ; dorsal margin convex ; beaks small, one- 

 sixth of the width from the anterior end ; posterior end attenu- 

 ated, obtusely jiointed ; anterior side small, rounded; anterior 

 half of the ventral margin convex, posterior half slightly con- 

 cave ; surface with strong irregular imbricating laminee of growth 

 and close intervening imbricating strioc. 



This reminds us of the Unio (C'ardhiia) acuta (Sow. sp.) of tb.e 

 European coal-fields, but is distinguished by its greater thickness, 

 more clavate form, and arched dorsal margin. The muscular and 

 pallial impressions correspond with those of the lias species of the 

 genus generally, but the dental impressions are obscure. Length 

 1 inch 1 line, width 2 inches 2 lines. 

 From the sandstone of Wollongong, N. S. Wales. 



Notomya (M'Coy), new genus. 



Gen. Cltar. Shell transversely ovate, equivalve, inequilateral, com- 

 pressed, greatest thickness behind the middle of the shell; 

 gaping slightly at both ends ; beaks small, compressed ; cardinal 

 slope not distinguished from the sides of the shell ; shell thick, 

 surface concentrically lineated ; ligament external, large. Cast : 

 a wide shallow furrow runs obliquely from the beak about half- 

 way towards the ventral margin ; a shallow spoon-shaped hollow 

 extends from the beak to the impression of the posterior adduc- 

 tor muscle, bounded by a low ridge on each side in each valve ; 

 traces of a simple cardinal tooth beneath the beak of the right 

 valve; muscular impressions deep, anterior adductor large ovate, 

 not attenuated above ; posterior adductor broadly lunate; re- 

 tractor of the foot small, oval, immediately over the anterior 

 adductor ; pallial impression with a small rounded sinus before 

 joining the posterior adductor. 



It is with those Muschelkalk Myacitcs of Schlotheim and Bronn' 

 and such like forms, of which M. Agassiz, in his 'Etudes Critiques 

 sur Ics Mollusques Fossiles,' has composed his genus Pleuromya, 

 and with those forming his genus Gressi'i/a, that the present fossils 

 have the strongest affinity. They are, however, perfectly distinct 

 from those essentially Jurassic and Triassic types, by the small size 

 of the sinus in the pallial impression. In minor characters it diifers 

 from the Gresshjos in the small size of the beaks, and the m.ore 



