Fossils from the Miura Peninsula and its Immediate North. 9| 



Genus Marr/ttrita. Leach. 



101. Margarita umbilicalis, Bkodebip et Sowérey. 



Pl. V. Fig. 29. 



Margarita umbilicalis. Broderip and Sowerbt.. Mai. and Conch. Mag-., 'I, p. 20, 1836. 

 Conch. Ulust., fig. 5. Pilsbry, in Tryon's Man. Conch., XI, p. 288, pl. 39, figs. 61, 62, 64, pl. 

 64, figs. 39h11. 



Trochus umbilicalis. Philippi in Syst. Conch. Cab. Mart. u. Chein.,*vol. II, part 3, Trochus, 

 p. 245, pl. 37, fig. 2. 



Two badly preserved specimens, the one with the diameter 

 of about 9 millim. and the other with that of 8 millim. The 

 shell is widely umbilicate, depressed-conic thin, composed of 

 about six convex whorls whose upper ones are close!}' spirally 

 striated, the striae becoming obsolete on '"the lower whorls. 

 Sutures deeply impressed. Aperture oblique, subcircular. Peris- 

 tome simple. Umbilicus deep, funnel-shaped. 



Though the greater part of the shell is broken, there is no 

 doubt of its being the well-known arctic species. 



Fossil occurrence. — Kamakura Zone (Kcwaizaka in Kama- 

 kura). 



Living. — Polar seas (Greenland, Melville Island, etc.). 



102. Margarita cinerea, Couthony. 

 Pl. V. Fig. 30. 



Margarita cinerea. Pilsbry in Trton's Man. Conch., XI, p. 291, pl. 44, rigs. 20, 25, pl. 60, 

 fig. 29. Gould, Invertebr. Massach., p. 252. Loven, Index Moll. Scandin. p. 20. 



Trochus cinereus. Philippi in Syst. Conch. Cab. Mart. u. Chem., vol. II, part 3, p. 252, pl. 

 37, fig. 15. 



Turbo cinereus. Coüthony, Bost. Journ. Nat. Hist., II, p. 99, pl. 3, fig. 9. 



A single example. 



The shell is small, only 4 millim. in height and about 3,8 

 millim. in diameter, thin, turbinate, umbilicate. The whorls are 

 about six. shouldered, weakly convex on side, and flattened and 

 horizontal above, spirally Urate, and obliquely striate. The line. 

 except on the body-whorl, are four in number, subequal, the 

 uppermost being on the flattened upper surface close to the suture, 

 the next one forming the angular shoulder and the two remaining 

 ones being on the lateral surface, dividing it into three subequal 



