260 Dr. J. Allan Thomson — Tlie genus Bouchardia, 



follow in order B. zifteli, von Ihering, from the lower Patagonian, 

 B. transplatina, von Ihering, from the Entrerian of Patagonia, along 

 with Buckman's Antarctic species, next the New Zealand Upper 

 Oamaruian species described below, and finally B. rosea. 



As a matter of fact, however, no such biological argument for the 

 age of the Seymour Island beds was necessary, since a direct zoological 

 comparison could have been made between B. transplatina, von 

 Ihering,/ and B. angusta, Buckman, which are hardly distinguishable 

 from the published figures. In the absence of other evidence, this 

 would justify the age of the younger beds of Seymour Island being 

 placed as Entrerian, i.e. distinctly younger than the Patagonian and 

 probably Upper Miocene, which is practically where Buckmtin 

 placed them. 



A New Species of Bodchardia fkom New Zealand. 

 Bouchardia minima, sp. nov. (Eig. 1.) 



Shell elongate oval or elliptical, generally much longer than wide, 

 greatest width about the middle, sides rounded in the broader forms, 



a b c 



Fig. 1. — Bouchardia minima, Thomson. Mt. Brown Beds, Waipara District, 

 North Canterbury, New Zealand, [a] Holotype, dorsal view ; (6) holotype, 

 lateral view ; (c) paratype, interior of dorsal valve, ventral view. Enlarged 

 6 diameters. 



nearly straight in the narrower forms, front rounded, commissures 

 with a low broad anterior sinuation. Valves rather depressed, the 

 ventral slightly more convex than the dorsal and obscurely carinated. 

 Hinge-line short and curved, beak short, acute, not incurved, beak 

 ridges rather blunt, foramen minute, epithyrid, deltidial plates 

 obscure, a groove running between the umbones of the two valves. 

 Surface of valves smooth with a few moderate lines of growth, 

 indicating development from a subcircular through an oval to an 

 elliptical shape. 



Interior of ventral valve : — Hinge teeth prominent, bifid, consisting 

 of upper and lower processes separated by a well-marked groove ; 



^ H. von Ihering, " Les mollusques fossiles du Tertiaire et du Cretac^ 

 sup^rieure de I'Argentine " : Ann. Mus. Nac. Buenos Aires, t. xiv, pp. 480-1, 

 1907. Buckman unfortunately overlooked this reference in drawing up his 

 bibliography. 



