270 Proceedings of the Royal Society of Victoria. 



I., Fip;s. 1 und 2). It differs, however, in having a more slender 

 cusp and a lower and more elongate base. 



Locality and Horizon. — Orphanage Hill, Geelong (T. S. Hall 

 CoU.)^ — Balcombian. 



Family Cestraciontidae, 

 Genus Cestracion, Cuvier. 



Cestracion cainozoicus, sp. nov. (PI. XI., Figs. 5-8. 

 PL XII., Fig. 2). 



Description. — Various lateral teeth showing variation com- 

 parable \\'ith that of the crushing teeth of the recent C. 

 philippi. In shape the specimens vary from almost semicircular 

 through subrhomboidal to elongate-oblong ; the latter form 

 usually showing a stronger incurvation of the outer lateral 

 edge. In the best preserved specimens the surface towards the 

 outer lateral edges shows the submedian ridge as a fine elevated 

 band from AvMch proceed anastomosing ridges giving rise to 

 the pitted appearance at the extremities of the teeth. The ar- 

 rangement of the ridges running off the submedian ridge is 

 generally parallel and at right angles to it. As in common 

 with other Cestraciont teeth, the base of the outer concave 

 side is usually excavate, giving rise to an articulating ridge at 

 the junction of the crown with the root. 



The surface of the cro^vn is, generally speaking, strongly 

 convex, and is apparently much smoother than that of the 

 living species. An interesting point of agreement, however, is 

 shown in one specimen which has flaked off superficially from 

 the rest of the crown, a feature w^hich may be readily tested in 

 the living species. 



Dimensions. — Specimen (a) (semicircular form)— Length, 13 

 mm.; breadth, 7 mm.; height, 5 mm. 



Specimen(b) (subrhomboidal form) — Length, 18.5mm.; breadth, 

 11 mm.; height, 7 mm. 



Specimen (c) (elongate oblong form) — Length, 18 mm.; breadth, 

 7 mm. ; height, 5 mm. 



1 Since presented to the National Museum. 



