JITKAS.SIC FOSSILH FROM KIKUZEN. 11 



3. CYRENA ELLIPTICA x. «r. 



PL I. Fig. 4. 



Shell elliptical, In'uader than high, somewhat inequilateral, 

 with anterior and posterior margin rounded and ventral margin 

 curved. Beaks submedian, prominent, touching. Surface only 

 with fine concentric striations. Pi'oportions of length, height and 

 thickness, 10 : (S : 4. 



This form is a, little larger than the preceding one, and 

 seems to have been com^jaratively thin shelled. There are 

 specimens larger than the one figured. 



, Locality : — Hosouia. Earer than the foi'egoing species. 



4. TRIGONIA HOSOURENSIS n. sp. 



PI. I. Fig. 3. 



A few specimens of a Trigonia belonging to the Group of 

 Costatœ were obtained from the Cyrena slate of Hosoura which, 

 though imperfect, show sufficient characters to be created into a, 

 new species. 



The shell is ovately triangular, flattened and strongly inequi- 

 lateral. The anterior side is very short with its border rounded. 

 The posterior side is long and produced. Beaks prominent, and 

 recurvate. The surface is ornamented with about 17 smooth 

 concentric ril)s Avhich near the marginal carina descend with a 

 veiy steep slope so that the curvature is stronger than in any 

 of the known species of this group. Escutcheon narrow and. 

 lanceolate. Area depressed, and smooth. 



The group of Trigonia costaia has occurretl hitherto only in 

 the Oolite. 



