59 



22. -Valves without terminal buttons (23). 



23.— A circlet (25). 



24. — No circlet (31). 



25.— Circlet formed by short, distinct, paired Lines. 



C. Kerguelensis, 1 )eby. 



26. Circlet formed by rounded dots (27). 



27. — Beads of circlet large. C. adornatus^ A. S 



28. — Beads of circlet minute (29). 



29.— Circlet interrupted at top and bottom. Rays few. 



C. peramplus, Cleve. 



30. — Circlet continuous. Rays numerous. (41). 



31. — Area nearly circular (33). 



32. — Area oval or oblong (37). 



33.— Valves with distinct double border. C. bimarginatus^ A, S. 



34. — No distinct double margin (35). 



35. — Centrally a smooth, elliptical space. C. Rabenhorstn, Jan. 



36. — No central, distinct, elliptical blank space. 



C. Pacificus, Grun. 



37. — Inter-radials and inter-striae finely punctato-striate. Central 



Area smooth. C. bicostatus. IV. Sm.* 



38. — Inter-radials and inter-striae smooth ; central Area, if any, 

 inconspicuous (39). 



* The typical Campylodiscus bicostatus of W. Sm. (Roper, Micr. Trans., 

 Vol. II., pi. 6, f. 4). I have from North-fleet, including original specimens 

 from W. Sm. and Roper's collections, from Mostyn. N. Wales, and from the 

 Baltic Sea, where it occurs along with Camp. Balticus, Cleve, in litt, and 

 Camp, echeneis. Many specimens in my collection, labelled C. bicostatus, rep- 

 resent a different Diatom, namely, the Camp, bicostatus of Grunow, oi Win 

 Heurck. and of the Atlas, as figured in ('.run.. Oest. Diat., 1862, pi. 10 (vii.), 

 f. 1 ; Van Heurck, Synopsis, pi. 75, I. 2, and types No. 450: and A. S. 



{Continued p. 60.] 



