132 -A-rt. 6.— M. Tokoyama: 



This species resembles the preceding, but is distinguished 

 from it by the smaller size, the more straight hinge-line and 

 the greatest length being in the upper half of the shell near the 

 hinge-line. Also the concentric costellae of the surface often con- 

 sist of rows of elongated granules, especially in the middle portion 

 of the shell. 



Fossil occurrence, — Naganuma Zone (Naganuma). Upper 

 Musashino of Shimosa. 



Living. — Central Japan. 



165. Diplodonta gouldi, Yokovama. 

 Pi. X, Fig. 5. 



Shell small, moderately thick, roundly oval, somewhat oblique, 

 only slightly inequilateral, anterior and posterior margins roun- 

 ded, the latter more broadly than the former; dorsal margin sloping 

 on both sides, the antero-dorsal passing gradually into the anterior 

 margin, while the postero-dorsal forms a rounded obtuse angle with 

 the posterior margin. The broadest part of the shell is nearly in 

 its middle. The sculpture consists of unequal incremental lines. 

 Main teeth two, the anterior tooth in the left valve and the pos- 

 terior in the right being bifid. Muscular impressions more or less 

 elongated, longly pear-shaped. Length 15 millim., height 18 

 millim., thickness (two valves together) 7 millim. 



This species resembles Diplodonta scmiaspera in outline, but 

 is much flatter. 



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



Living. — Central Japan (Sagami Bay). 



Family Lucinidae. 



Genus L/ucina. Bruguiere. 



166. Lucina pisidium, Dunker. 



Pl. X. Fig. 6. 



Lucina pi^idium. Dunker, Moll. Jap., p. 28, pl. Ill, fig. 9. Index Moll., p. "216. Lisohke, 

 Jap. Meeresconch-, II, p. 133. Pilsbkv Cat. Mar. Moll. Jap., p. 133. 



Lucinz parvula. Gould, in ProC. Boston Soc. Nat. Hist., vol. VIII, p. 36 (April, 1861) ; 

 Otia Conch., p. 174. 



