58 Art. 6. — M. Yokoyama: 



According to Tryon (Man. Conch., IV, p. 46), Nassa dcuti- 

 dentata Smith is a synonym and Nassa dealbata A. Adams is only 

 a narrower variety. 



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

 Zone (Naganuma). Upper Musashino of Kazusa and Shimosa. 



Living. — Northern, Central and Western Japan. 



49. Nassa (Niotha) livescens, Philippi. 

 Pl. III. Fig 18. 



Nassa Nvesce)is. Philippi, Zeitschrift für Malakozoologie, 1848, p. 135. Donker, Moll. 

 Jap., p. 7. Lischke, Jap. Meerescouch., II, p. 52, pl. IV, figs. 1-3. Dunker, Index Moll. Mar. 

 Jap., p. 35. Brauns, Geo!. Ear. Tokio, p. 29. Tokunaga, Foss. Euy. Tokyo, p. 9. 



Nass ( kieneri. Tryon, Man. Conch., IV, p. 53, pl. 16, figs. 301-303. 



Rather frequent and also found in several localities. Pilsp.ry 

 states in his ' ' Catalogue of Marine Mollusks of Japan ' ' (p. 35) 

 that the Nassa kieneri Desi-i. mentioned in Tryon' s Manual (I.e.) 

 is probably identical with Philippi' s species above mentioned and 

 indeed quite rightly, for the two species are connected by many 

 intermediate forms. The typical specimens of Nassa livescens 

 show a lower spire than those of Nassa kieneri, which character is, 

 however, not at all constant. But there is one constant character 

 invariably found in both species, and that is the callus of the inner 

 lip, which may be thick or thin and has the outer edge always 

 free, at least in its anterior portion. 



Nassa marginulata Lam. (Pilsbrys Catalogue p. 35) is said to 

 be a synonym of Nassa kieneri Desii. (Tryon Man. IV. p. 54) 

 which is again m synonym of Nassa livescens Phil. And this is 

 probably the case also with Nassa cremata Hinds (Tryon's Manual,' 

 IV, p. 53, pl. 16, tigs. 295-300). 



The largest of the perfect specimens measures 20,5 milium, in 

 height and 13 millim. in greatest diameter. But there is also a 

 specimen lacking the spire and measuring 15 millim. in its great- 

 est diameter. 



Fossil occurrence. — Miyata Zone (Iwaiguchi and Matsubara- 

 Mizufuka-no-fuchi in Kami-Miyata, and Shimo-Miyata); Yoko- 

 suka Zone (Yokosuka and Otsu); Naganuma Zone (Naganuma); 

 Upper Musashino of Musashi. 



