304 Mr. F. M'Coy on the Fossil Botany and Zoology 



responding with it, those parts being oppositely inclined in No- 

 tomya. The oblique mesial or post-mesial furrow from the beak 

 in the cast of Notomya does not exist in the other two genera, 

 but in Pleuromya there exists a somewhat similar furrow, but 

 different in position, arising in front of the beaks, and extending 

 directly to the ventral margin close to the anterior end. Cardinia 

 (Ag.), which somewhat resembles the present genus, is distin- 

 guished by its entire pallial impression #nd dental characters. 



Notomya securiformis (M'Coy). PI. XV. figs. 5 & 5 a. 



Sp. Char. Transversely ovate, flattened; length two-thirds the 

 width, thickness rather less than half the length ; beaks small, 

 flattened, rather more than one-third the width from the an- 

 terior end; anterior end narrowed, rounded; posterior end 

 narrow, subtruncate, nearly square ; anterior two-thirds of the 

 ventral margin very convex, a shallow concavity in the poste- 

 rior third; muscular impressions very large, anterior one 

 deepest, ovate, posterior one shallow, broad, reniform ; pallial 

 scar strongly marked, parallel with the ventral margin as far 

 as the anal angle, then a small subangular sinus before joining 

 the adductor impression ; retractor impression small, deep, 

 narrow, oval ; in the cast the oblique furrow from the beak 

 towards the ventral sinus wide, shallow ; remains of a cardinal 

 tooth under the beak of the right valve. 

 Length 1 inch 6 lines, width 2 inches 2 lines, thickness 11 lines. 



The figures of this species display most of the generic characters. 



Sandstone of Wollongong, N. S. Wales. 



Notomya clavata (M'Coy). PI. XV. fig. 4. 

 Sp. Char. Transversely clavate; length two-thirds the width, 

 evenly convex, greatest thickness towards the posterior half; 

 beaks very small, compressed, rather more than one-fifth the 

 width from the anterior end ; anterior end very broad, evenly 

 rounded; anterior third of the ventral margin very convex, 

 middle portion widely concave ; posterior end narrowed, ob- 

 liquely subtruncate, rounded; muscular impression shallow, 

 anterior large ovate, posterior broad lunate ; retractor small, 

 broad, oval ; oblique longitudinal furrow from the beak deep, 

 narrow above, widening nearly to the marginal concavity ; im- 

 pression of one simple cardinal tooth beneath the beak of the 

 right valve ; the long spoon-shaped hollow extending from the 

 beaks to the posterior muscular impressions, and its lateral 

 bounding ridges obscurely marked. 



Distinguished from the N securiformis by its broadly rounded 

 anterior side, smaller beaks, thinner shell, and consequently more 

 faintly marked ridges and impressions on the cast, and by the 



