272 The Philippine Journal of Science ms 



dementia papyracea Gray. Plate VII, fig. 5. 



It is very difficult to tell whether this is a dementia or a 

 Cytherea from the cast. The Philippine forms resemble the 

 above in many respects — shape, sculpture, etc. 



dementia is a recent genus according to Zittel, and, therefore, 

 either it has a longer vertical range or these forms should not 

 properly be referred to this genus. 



Another internal cast is shown in Plate VIII, fig. 3. 



Locality: About 0.5 kilometer west of the Tribunal, Baguio, 

 Mountain Province, Luzon. 



Formation: Tuffaceous sandstone. 



Elevation : Nearly 1,500 meters. 



venerim: 



MACROCALLISTA Meek 



(Cytherea) 



External form and curve of the shell the same as in Venus, 

 edges smooth; hinge with 3 dividing, frequently cleft teeth and 

 in the left valve beneath the lunule a fourth, generally recumbent, 

 anterior tooth, which corresponds to a long groove in the right 

 valve ; sometimes also there is a lateral tooth situated farther to 

 the rear; pallial sinus large, triangular or tongue-shaped, some- 

 times quite lacking. This genus contains over 150 recent and 

 at least as many fossil species which are widely distributed 

 from the Jura to the older Tertiary. (Zittel.) 



Macrocallista ventricola K. Mart. (?). Plate VII, fig. 6. 

 Martin, Tertiarscht. auf Java (1880), PI. XVI, fig. 10. 



This form resembles exteriorly C. ventricola described from 

 the Tertiary of Java and it is also very similar to Meretrix sub- 

 pellucida found in Luzon waters by Cuming. 



Locality: Agusan River, Mindanao. 



Formation : Recent deposits. 



. CHI0NE Gray 



(Venus) 



Shell oval, roundish to triangular or heart-shaped, thick, 

 smooth, or lined with ribs, striations, furrows, leaves, etc. ; edges 

 of shell finely crenulated, seldom smooth; a lunule usually is 

 present; hinge area wide with 3 strong, diverging hinge teeth 

 in each valve; ligament prominent; pallial sinus short angular. 

 (Zittel.) 



