PLATE VIII. 
Fig. ‘ 
11. Trigonotreta cristata, Schlothem. Cast showing area and fissure, natural size. 
Humbleton Hill. 
12. — = Young specimen. Humbleton Hill. 
13. — — Enlarged view of the test, showing openings of the punctures. 
14. — — Longitudinal section of the test, highly magnified, showing 
casts of the punctures. 
15. Trigonotreta multiplicata, J. de C. Sowerby. ‘'Testiferous specimen, a little enlarged, 
of large valve. Tunstail Hill. 
16. — — Small valve of last specimen. 
Mis = — View of the area and fissure of the last. 
KS == = Interior of the large valve, showing the ventral median 
plate (a). Tunstall Hill. 
19. Trigonotreta Jonesiana, Avmy. Large valve of a young specimen, twice the natural 
size. Ryhope Field-House Farm. 
