P. T. CLEVE ON SOME FOSSIL MARINE DIATOMS. 175 



(1863.) I Lave seen one valve ; it lias a small central space with- 

 out granules. Row of granules 9 in "01 mm., margin with short 

 granulated striae 'lG-'Ol mm. Diameter -055 mm. The arrange- 

 ment of the lines of puncta agrees very [well with Greville's 

 figure, but differs from that in Van Heurck (Syn., PI. 132, f. 1), 

 which has also very much coarser marginal stride. The " Tegel " 

 specimen also differs very much from figures 13 and 14 (PI. 58 in 

 Schmidt's Atlas), which have coarser granules, and the margins are 

 not striate. 



C. elegans, Grey. T.M.S. xiv, p. 3, PL 1, f. G (1860). A. Schm. 

 AtL, PL 58, f. 7. Several specimens from -05 to -08 mm. in 

 diameter. Rows of puncta 3 to 4 in -01 mm., marginal striae 12 

 in '01 mm. I regard as a variety C. biradiatus, Grev. (T.M.S. 

 ix, p. 42, PL 4,f. 7 (1861)., and A. Schm. AtL, PL 58, f. 2). This 

 form also occurs in the Tegel. 



C. Thumii, Cle., n.sp. Valve *075 mm. in diameter; lines of 

 granules radiant, unequal in length, not reaching the centre ; 

 crowded near the margin, where they are 6 in '01 mm. PL 13, 

 f. 17, 4 -f-°. 



C. nitidus, Greg. (1857). A. Schm. AtL PL 58, f. 18. Valve 

 •088 mm. in diameter. The puncta exhibit a tendency to form 

 radiating lines. 



C. radiatus, Ebb. (1839), Gran. Diat. Fr. Jos. Land, p. 

 19. Cellules about 2*5 in -01 mm., in the margin about 4 in -01 

 mm. Diameter *12 mm. Some varieties approach near to C. 

 crassus, C. heteroporus. 



C. Argus, C. marginatus, and C. Oculus Iridis, but they 

 are not typical specimens of these species. 



C. robustus, Grev. (T.M.S. xiv., p. 3, PL 1, f. 8, 1866). 

 Specimens from the Tegel are -09-'01 mm. in diameter, and have 

 2 cellules in '01 mm. Some of the Tegel specimens very much 

 resemble A. Schm., figure 3, PL 62, in AtL Others having smaller 

 cellules (3--01 mm.) approach closely to C. marginatus, C. bi- 

 marginatus, and C. radiatus. 



C. Asteromphalus Ebb. (1844 ). Some splendid specimens 

 occur in the Tegel of the varieties eximia, Grun. (A. Schm. AtL, 

 PL 63, f. 12), and var. liybrida, Grun., Fra. Jos. Land Diat. 79, 

 PL c, f. 9. C. centralis (AtL, PL 63, f. 1.) 



Xanthiopyxis oblonga, Ehb. (Mg. ; PL 33, 17, f. 17). This 

 curious form is probably an auxospore of some Diatom, perhaps a 



