Greville, on New Diatoms. 85 



no undulating line in the border. Distance between the 

 angles -0029". (Fig. 11.) 



Hab. Barbadoes deposit ; excessively rare. 



A fine species, coming nearest to T. Abercrombieanum, but 

 wanting the undulating border line. The fork referred to in 

 the specific characters here assumes a Patera-like form. 

 Whether any dependence can be placed on the two little 

 spurs at the base of the pseudo-nodule^ a character I have 

 not observed in any other species of the group, it is impossible 

 at present to say. The puncta are numerous. 



Triceratium gratiosum, n. sp., Grev. — Valve with slightly 

 convex sides, obtuse angles, and striated margin; centre a 

 triangular, blank space ; border divided by transverse costse 

 into closely punctated compartments ; a short line from each 

 angle of the inner triangle terminating in a fork, from the 

 centre of which spring two other lines^ curving outwards to 

 the margin. Distance between the angles^ -0029' to "OOSS". 

 (Figs. 12, 13.) 



Hab. Barbadoes deposit ; extremely rare ; George Norman, 

 Esq., Dr. Greville. 



A very elegant species, closely and conspicuously punctate. 

 The arrangement of the vein-like lines at the angles is pecu- 

 liar, and serves at once to distinguish it from all its allies. 

 Two lines spring from a point within the fork already men- 

 tioned, near its base, and curve gracefully outward until they 

 reach the margin. In the examples which I have examined, 

 the lateral costae alternate more or less regularly with im- 

 perfect ones, extending about half-way across the border. 



Triceratium variegatum, n. sp., Grev. — Valve with straight 

 sides, obtuse angles, and striated margin ; centre a blank, 

 triangular space ; border divided by transverse costse into 

 very minutely punctated compartments ; a short line from 

 each angle of the central triangle terminating in a deep, 

 campanulate fork, the lines of which reach the margin. 

 Distance between the angles, •0027". (Fig. 14.) 



Hab. Barbadoes deposit; excessively rare; George Nor- 

 man, Esq. 



Of this beautiful diatom I have seen only a single specimen ; 

 but it differs so materially from all the preceding, that no 

 doubt whatever can exist regarding its claim to being ranked 

 as a distinct species. It will be recognised at once by the 

 graceful campanulate or vase-like compartment at each 

 angle of the valve, which is very minutely, yet more dis- 

 tinctly punctate than the border. A very minute, deflexed 

 line may also be seen given off externally on each side from 

 near the base of this compartment. 



