A FOSSIL MARINE IHAT0MACEOUS DEPOSIT. 135 



absent in Dr. Greville's drawing, we give a figure from an excel- 

 lent specimen in the cabinet of Dr. Gray. (PI. XIV, Fig. 51.) 



B. lata, n. sp., Gr. and St. — Valve broadly oval, with four 

 slightly tapering processes close to the margin. The surface, 

 which is moderately convex, is covered with distinct puncta or 

 small spines. Length of valve •0055'; breadth •0047". 



Our figure is given from a magnificent specimen of this fine 

 diatom in the collection of Herr J. Kinker, of Amsterdam. (PI. 

 XIV, Fig. 53.) 



Cerataulus marginatus, n. sp., Gr. and St. — Valve circular, with 

 flat upper surface arising from a broad striated base. In the 

 centre is a group of dots surrounded by an annular clear space, 

 whence distinct lines of dots radiate to the margin, having between 

 them numerous subulate blank spaces. The processes, two in 

 number, are conspicuous, with obtuse ends, and between them, on 

 each side, on the margin of the elevated portion of the valve, is a 

 small spine seated on a small nipple-shaped projection. Diam. 

 •0033". (PI. XI, Fig. 21.) 



Triceratium oamaruense, n. sp., Gr. and St. — Valve large, 

 gibbous, sparsely dotted. The apices are covered with minute 

 dots, and are cut off from the central portion by curved lines, 

 which are very distinct at the margins and fade away towards the 

 middle. Length of side to -0085 ". (PI. X, Fig. 18.) 



Note. — This form was described by us in the first part of this 

 paper (" J. Q. M. C.," Vol. ii, Ser. ii, p. 327) as T. partitum. 

 Grev., but we have since ascertained from an inspection of 

 Greville's original examples that it is a quite distinct species. 



T. rectangulare, n. sp., Gr. and St. — Valve quadrangular, with 

 gibbous sides. A distinguishing feature of this form is the large 

 flat central rectangular elevation, terminating at each angle in a 

 prominent process or horn. The surface is covered with radial 

 lines of large granules, except in a small clear central place. 

 Breadth -004". (PI. X, Fig. 17.) 



Note. — Since the above figure was drawn, other specimens 

 have been observed, in which the processes are club-shaped and 

 conspicuously spinous. From this it appears that in this species, 

 as in T. rugosum, Gr. and St. (see below), the valves in each frus- 

 tule are dissimilar in the form of the processes. 



T. rugosum, n. sp., Gr. and St. 



Note. — Since describing and figuring this species {supra, p. 



