172 Art. 6. -M. Yokoyama: 



The largest specimen (left valve) measures 18,5 millim. in 

 height, 18 millim. in length and 6 millim. in depth. 



Tins species strongly reminds of Limopsis aurita Brocchi 

 (Conch. Foss. Subap., p. 485, pi. XL fig. 9) from the Pliocene of 

 Italy and England, from which it differs only in the greater size 

 and a very broadly triangular ligamental pit. Perhaps a discovery 

 of a greater number of specimens may reveal a closer relationship 

 between the two. 



Limojïsis woodwardi A. Adams (Dunker, Ind Moll., p. 237, pi. 

 XVI, figs. 5,6.) living in our seas is also closely allied to the pre- 

 sent species. In fact, some of its specimens greatly resemble the 

 latter in being more trigonally ovate than one figured by Dunker. 

 Put the more narrowly triangular pit and the radiating riblets of 

 the surface easily distinguish it from the the fossil form. 



Fossil occurrence. — Kanazawa Zone (Nojima). 



223. Limopsis tokaiensis, Yokoyama. 

 Pl. XVIII. Figs. 14, 15, 16, 



Limojisis tolaiensis. Yokoyama, Species of Limopsis found in the Xeogene of Koshiba, Jour. 

 Geol. Soc. Tokyo, vol. XVI£, no. 205, Oct. 1910, p. 1, pl. IX, figs. J-3, 5-7. 

 Limopsis tol;aiemii var. elongala. Yokoyama, Ibid. p. 2, pl. IX, fig. 4. 



Shell moderately thick, compressed, obliquely oblong, strong- 

 ly inequilateral. Anterior margin rounded, passing insensibly into 

 the arcuate ventral margin. Postero-dorsal margin sloping, more 

 or less straight, hardly forming an angle with the rounded posterior 

 margin. Postero-ventral angle mostly rounded, very rarly obtuse- 

 ly pointed. Surface with only distant radiating impressed lines, 

 crossed by coarse irregular lines of growth. Inner surface with 

 fine, dense, raised, radiating lines most distinct along the mantle- 

 line. Hinge-line slightly bent, with about twenty teeth in full- 

 grown specimens, vertical in the middle, oblique and curved out- 

 ward toward the sides. Ears small and indistinct. Area rather 

 wide, with a very broadly triangular, shallow ligamental pit, whose 

 base is usually about three times as long as its height. In the 

 middle of this pit, there is generally a space which is either some- 

 what deepened or bounded by two shallow grooves corresponding 



