P. T. CLEVE ON SOME FOSSIL MARINE DIATOMS. 169 



Syringidium, sp. I have seen one imperfectly developed frustule 

 which seems to belong to S. Americanum, Bail. (Van Heurck 

 Syn., PI. 106, f. 2.) PI. 12, f. 3, if*. 



Triceratium Favus, Ehr. Type form. 



T. Favus, var. maxima, Grun. Van Heurck Syn., PI. 107, f. 

 5. Distance between the angles '15-'25 mm. Cellules (1-P4 in 

 •01 mm.) very regularly arranged in lines parallel with the 

 margins ; surface of valve covered with coarse granules (10 in '10 

 mm.), radiating from the centre to the margins. Although the 

 form of the valve and the arrangement of the cellules are the same 

 as in the typical T. Favus, the presence of the radiating granules 

 seems to be sufficient to constitute it a distinct species. 



T. arcticum, Brightwell, 1853. A. Schm. Atl. PI. 79, f. 

 12-13. Large triangular ("15 mm. between the angles) cellules 

 in lines radiating from the centre angles ; obtuse, with rows of 

 smaller cellules, 8 in '01 mm. In addition to the coarser eellula- 

 tion the surface is covered with very small cellules, as shown in 

 figures 5, 6, 7, PL 79, of the Atlas. 



T.Moronense, Grev. (T.M.S. xiii., p. 9, PI. 4, f. 18, 1865). 

 Of this species I have seen two specimens. Distance between the 

 angles '08--15 mm. So far as 1 know this species has only been 

 found in the fossil deposits of Moron and Nankoori. 



T. latum, Grev. (T.M.S., xiii, p. 103, PI. 9, f. 20, 1865). A. 

 Schm. Atl., PI. 77, f. 38-39. One specimen. Distance be- 

 tween the angles *075 mm. In all respects identical with A. 

 Schmidt's figures ; this species has been found living at Singapore 

 and Celebes. 



T. turgidum, Ch. n.sp. Valve in s.v. triangular, with very 

 broad angles ; outline orbicular, very convex ; centre with 

 scattered puncta, which become closer as they approach the 

 margin. In s.v. the centre is very turgid, and the angles produced. 

 Distance between the angles *07 mm. PI. 12, f. 4, a b, 12 f. 



T. Stokesianum, Grev. (T.M.S., xiv., p. 8, PI. 2, f. 23, 1866). 

 The form found in the Tegel, and which I refer to the above 

 named species, differs from Greville's figure, the veins not form- 

 ing transverse bars ; they are also shorter and more irregular. In 

 a small specimen they are very short, but I do not think these 

 differences are of any specific value. I have examined four speci- 

 mens. Distance between the angles '1-'16. The centre of the 

 valve has a few puncta (?) differing from the ordinary cellulation ; 



