Ott Some Fossil Shells from the Island of Saishu. 3 



one-half or 3 are quite new, while the other half has already been 

 found in the Musashino formation near Tokyo. The former are 

 Turritella saishuensls, Venericardia nakamurai and Terebratella ? 

 excelsa, and the latter Anomla lunula, Pecten tohjoensis and Pecte/ii 

 cosibensis. The remaining 15 are all recent as well as fossil and 

 found in Japan, save one, Thracia pubesce7is, which was hitherto 

 known only from Europe where it is living and also fossil in the 

 English Crag. The formation in which the other 14 are fossil 

 is the MusasJiino found in the region surrounding Tokyo 

 Bay. 



From these considerations I deem the shell-layers of Seikiho 

 as of the 3Ivsashhio Age, that is to say. Upper Pliocene. 



Description of the Species, 



1. Turritella saishtiensis n. sp. 



(PI. I., Pig. 2.). 



Shell turrete. Whorls numerous, somewhat convex, weakly 

 angulate a little above the suture, three-ridged. Ridges elevated, 

 more or less sharp on the younger whorls, and flattened on the 

 older; the lowest occupies tlie angle and is the largest, the middle 

 is nearly as large and in tlie middle of the whorl, while the upper 

 is the weakest of all and somewhat more distant from the middle 

 one than the middle one is from the lower. There is also a fourth 

 ridge close to the lower suture which, though usually small and 

 inconspicuous, is on the body- whorl nearly as large as the others 

 and forms the angulate periphery. The spaces between the ridges 

 are usually provided with a few unequal spiral striae. Base flat- 

 tened, with about two spiral ridges near the periphery and dimi- 

 nishing in size toward the caudal end. Spiral striae also present 

 not only between the ridges, but also beyond the last one. Aperture 

 roundly subquadrate. Outer lip thin, sinuous, with a broad and 

 shallow notch below the suture. 



There are only a few specimens, all lacking the apex. The 

 entire number of the whorls may be about eighteen. Apical angle 



