138 Art {! -— M - Yok.^yama: 



In 1889, I described a series of Cretaceous fossils from the 

 Hokkaido among which there happened to be a species of Veneri- 

 cardia which I then took for Cretaceous and named Venericardda 

 compressa, but which I subsequently found out to be a Tertiary 

 fossil mixed up by chance with the Cretaceous ones. A few speci- 

 mens of the same species also occur in the Lower Musashino of the 

 Miura Peninsula which I characterize as follows: 



Shell rather small, solid, more or less compressed, inequila- 

 teral, somewhat variable in shape from roundly trigonal to sharply 

 trigonal; anterior margin rounded; posterior margin subtruncate, 

 making the postero- ventral corner subangula te ; ventral margin 

 broadly convex to nearly straight. The sculpture consists of round- 

 ed radiating ribs fourten to sixteen in number, wider than their 

 intervals and often subgranose on account of coarse incremental 

 lines crossing them; these ribs are sometimes much flattened, 

 especially toward the ventral margin where they are usually smooth. 

 Beaks small, pointed. Anterior muscular impression bean-shaped, 

 posterior oval;pedal sear semicircular, just above the anterior mus- 

 cular impression. Lunula small, but distinct, hounded by sharp 

 edges, ovate, rather smooth. Inner margin coarsely crenate. 



The largest specimen at hand is a left valve of a sharply tri- 

 gonal shape, 20 millim. in length, 1(> in height and 6 in depth. 

 Another left valve more roundly trigonal in shape is 1!) millim. in 

 length, 15 in height and 5 in depth. 



This species is very closely allied to Venericardia subaffinis 

 TomtN. (Cossmann at Peyrot, Conch. Néog. de l'Aquitaine, vol, 

 II, pt 1, p. 70. pi. Ill, figs. 21-"24) from the Miocene of France 

 from which it is hardly distinguishable but for the flattened pos- 

 terior side of the latter. Therefore it is not at all impossible that 

 these two may turn out to be the same species. 



The reason why the original name compressa has been changed 

 to a new one is because the former is preoccupied by Reeve for a 

 recent speciesjrom ('bile. 



Fossil occurrence. — Miyata Zone (Shimo-Miyata); Naganuma 



