KONGL. SVENSKA VET. AKADEMIENS HANDLINGAR. BAND. I8. n:0 5. 25 
6. Triceratium leve Cur. N. Sp. 
Triangular or quadratic, with straight sides and acute not produced angles. The 
surface perfectly smooth, no structure being visible on balsam-specimens. In F. V. 
the centre of the valve is elevated, and the angles are produced into processes, forming 
right angles with the transverse diameter. 
Distance between angles 0,02—0,0285 mm. 
Pls Vi, fie. 70, oe Be Vig Oy Fs Ve 
Gallapagos Islands (Eugenie Exp.). 
7. Tricerattum (productum Grev. var.) Balearicum Cx. et Gron. (in Cx. et Mou. Diat. 
N:o 154—155). 
This form is closely allied to Amphitetras producta GREVILLE and Triceratium An- 
tallarum Cu. Its outline is 4—5 angular, with the angles produced into short processes. 
The centre of the valve is elevated and by a depression separated from the margins. 
The structure consists of rounded puncta arranged in lines, radiating from the centre 
to the angles, about 5 in 0,01 mm. 
Greatest diamcter 0,06—0,08 mm. 
Pl: Vly ie. 73, 
Balearic Islets (Dr. F. SépERLUND). 
There can be not doubt that A. producta Grev. (Micr. Journ. II, p. 94, Pl. 9, 
fig. 2) and TJ. Antillarum Cu. (Bih. till K. Sv. Vet.-Ak. Handl. Bd. V, N:o 8, Pl. V, 
fig. 29) belong to the same species, which seems to be nearly allied also to Amphitetras 
elegans Grev. from Monterey stone, in which form the depression between the centre 
and the margins form an inscribed quadrate. 
Allied to these forms seems to be Am. nobilis Grev. (Trans. Micr. Soc. 1865, 
p. 105, Pl. IX, fig. 27) from the Red Sea. This species is however larger and seems 
to be only the pentagonal form of Am. antediluviana. It occurs in RaBrnnorst, Alg. 
Eur. N:o 2264 from Livorno together with Am. antediluviana, and Mr. Kirron informs 
me that he has found it in samples from Orkney Islands and Southampton; he also 
remarks that the processes are much exaggerated in GREVILLES figure. Another form 
related to A. antediluviana is A. tessellata Suapp. (T. M. S. 1854, p. 16, Pl. 1, fig. 11), 
of which a variety with very coarse cellulation and large processes occurs in Moron 
Deposit. 
The Triceratium productum Grev. from Barbados Deposit is a quite different form 
(see T. M. S. 1863, IX, p. 69, Pl. VII, fig. 9). 
8. Triceratium Gallapagense Cu. N. Sp. 
Triangular, with acute angles, not provided with processes. Structure: distant 
puncta, scattered over the disc of the valve, closer near the margins, where they form 
K. Sv. Vet-Akad. Handl. Band. 1». Nio 5. 4 
