ExpLAXATiox OF Plate 23 



Figs. 1-8. — Liocyma fluctuosa (Gould): 1, from 80 feet (Aug. 21, 1948), a fairly typical 

 L. fluctuosa close to L."v{rid{s" in shape, from 80 feet (Aug. 21, 1948); 2, a specimen 

 intermediate in shape between 1 and 3, from 246 feet; 3, a specimen that approaches 

 the shape of L.^beckiV but lacks sufficient height, from 246 feet; 4-6, from 453, 80, 

 and 341 feet, respectively, showing further variations in shape; 7, from 453 feet, show- 

 ing concentric waves more widely spaced than in the preceding specimens; 8, from 341 

 feet, showing concentric waves very widely spaced. 



Fig. 9. — Thracia myopsis (Moller): From 341 feet, interior view, showing difference in 

 shape of sinus in right and left valves. 



Fig. 10. — Alacoma moesta (Deshayes): Interior view of specimen from 147 feet, showing 

 difference in size of sinus in right and left vah'es, and the extent to which the perio- 

 stracum cov'ers the interior, especially on the anterior end. 



M.VGXIFICATIOX: All X 1.2. 



