PLATE CVI. 

 Figures magnified 500 diameters. 



Fig. 1. TRICKRATITJM SCITTJLUM, Bright, M. J., 1853, p. 250, 4, f. 9; 



Schm. At., 83, f. 11-16. Gulf of Mexico. 

 " '2. ALTERNANS, Ehrb. Camp. Bay. S. B. D., o, f. 



45; V. H., 113, f. 6; Schm. At., 78, f. 9-20. 



Figs. 3-5. SCULPTUM, Shadb., T. M. S., 1854, p. 15, 2, f. 4; 



Schm. At., 76, f. 9-12; V. H., 109, f. 7, 8. Camp. 

 Bay. Granules hardly prominent enough. 

 " 6. CONSIMILE, Grun.; V. H., 108, f. 2; Schm. At., 84, 



f. 13, 14. Santa Monica. 



" 7. ABCTICUM, forma Campeachiana. Camp. Bay. 



V. H., 112, f. 1. Cellules hexangular, not so 

 rectangular. 



" S. QUADRANGUL.ARE, Grev. Santa Monica, Cal. 



Probably only a quadrangular form of T. arc- 

 ticurn. The cellulae are really radiate. 



l-'itrs. 9, 11. FRAGLICH? Schm. At., 86, f. 9, 10. Crescent 



City, Oregon. Figures only slightly mag- 

 nified. 

 Fig. 10. OBLIQUUM, Grun.; V. H., 110, f. 11. Cal. 



