103 



There is a thin brown epidermis ; the ornament consists of 

 concentric lines and a few distant growth-folds and obscure 

 radial lines. 



Umbo- ventral diam., 2*25 ; antero-posterior diam., 2 ; sec- 

 tional diam., 1*25 mm. 



Derwent Estuary, Tasmania (W. L. May). 



Comes nearest to C. polita, Tate, an Eocene species, but is not 

 produced anteriorly. It differs from C. Atkinsoni by its acutely 

 trigonal outline, and is not so convex. 



Carditella pectinata, spec, nov. 



Triangularly oval, inequilateral, rather convex. Antero- 

 dorsal margin straight and steeply inclined ; post-dorsal margin 

 convexly sloping to the narrow rounded posterior side ; ventral 

 margin slightly curved, distantly crenulated within. 



Umbones obtuse, prominent, approximate, situated consider- 

 ably in front of the centre. 



Colour yellowish-brown. The ornament consists of numerous 

 (fifteen or more) radial broad ridges (most conspicuous anteriorly)^ 

 separated by linear sulci ; and intersected by growth-lines. 



Umbo-ventral diam., 1*5; antero-posterior diam., 1*5; sec- 

 tional diam., 1 mm! 



Derwent Estuary, Tasmania ( W. L. May). 



Genus Thraeiopsis, nom. mutand. 



Alicia, Angas, 1867, non Johnson, 1861. 



Type : — T. angustata, Angas (sp.) 



New South Wales, Tasmania, and South Australia. 



