ON THE NEW GENUS OF BIVALVE, l03 



Our next figure shows the nature of the teeth. 



FIO. III.— INTERIOR OP LEFT VALVE, SHOWING THE TEETH OF THE HINOB. 



The Shell is about two inches long, and a little more than 

 an inch deep, it is distinguished by its peculiarly incurved 

 umbones, and its finely striated external markings. 



This shell was first discovered at Half-way House in a thin 

 bed of ferruginous marl, which separates the so-called zones of 

 Sowerbyi and Humphresianus beds. 



A similar bed occurs in Gloucestershire, separating what we 

 had distinguished as the Trigonia (upper) and Grypliitc — grits — 

 (lower beds). 



This thin band is remarkable both in Dorsetshire and Glouces- 

 tershire for peculiar fossils, among which we may now reckon 

 the Curvirostrum, 



We have as yet only found it in Dorsetshire — a single speci- 

 men from Bradford Abbas, the same from Half-way House, 

 while several specimens have been obtained from a quarry on 

 Wyke Farm, and it is not uncommon at Louse-hill Quarry. 

 These are stations in Dorsetshire, but it has been found at East 

 Coker, in Somersetshire, in a similar position to that of the 

 Dorset beds. 



