366 M. YOKOYAMA. 



as casts, one of which is figured on tlie plate. It shows two strong, 

 striated, divero'ino; teeth. 



Quite as numerous as Trig niia Kikucliiana at Tanno ; occurs also 

 near Sakawa at Ninomiya, Yamanukami, and Sendachino. 



Helicoeeras sp. 

 PL XL, Fig. 10, 10a. 



A fragment of the body-whorl of a snail-like Ammonite, elliptical 

 in section, somewhat higher than broad, and with the body-chamber 

 occup3àng about one half of the entire volution. The external 

 sculpture consists in fine, rounded, transverse ribs, slightly undulatory 

 in tlieir course, and weakest on the umbilical side of the whorl, where 

 some of them even disappear. Their number is about 50 in one 

 circuit. The sutures on the external side of the whorl are indistinct, 

 lîut as flir as they are seen in our specimen, they are deeply and much 

 incised, with saddles and lobes bipartite ; the siphuncle seems to lie 

 on the outer side, so tliat our fragment is that of a Helicoeeras which 

 is, at least, closely akin to Helicoeeras indicum, Stol. (Cret. Cephalo- 

 poda of Southern India, p. 184, pi. 86, Fig. 1-2). But as the 

 specimen is imperfect, its exact specific determination is not possible. 



Helicoeeras indicum occurs in the Arrialoor Group of India. 

 . Our specimen was found in a very fine-grained shaly sandstone 

 of Oumi, Ouchigori, Prov. Sanuki. 



