110 THE VOYAGE OF H.M.S. CHALLENGER. 



late processes. The granules, which are of equal size, are arranged in rows at right angles 

 to the margins, but in a central triangular space they are disposed irregularly. The demar- 

 cation of this central area is clearly indicated by a few well-marked granules or denticules, 

 placed at intervals along its sides. In the area itself there are a few scattered minute 

 spines or apiculi. In these respects this frustule resembles the Triceratium armatum of 

 Eoper, 1 but it may readily be distinguished from the latter by the denticules referred to 

 above. Brightwell has already (Quart. Journ. Micr. Sci., vol. iv. p. 274, Plate xvii. figs. 

 9, 9b, 10, 11, 116, 12) notified several varieties of the typical species, and the present 

 form may be similarly referred to as var. S. 



Triceratium fimbriatum, "Wall., var. nov. (Plate IX. fig. 12.) 



This form resembles in its general characters the Triceratium fimbriatum of Wallich, 2 

 but its terminal processes are much more elevated, and its extremities somewhat more dilated. 



Triceratium incrassatum, n. sp. (Plate IX. fig. 10.) 



Trigonum, areolatum ; valva lateribus convexis tumida ; areolis hexagonalibus ; 

 apicibus obtuso processu terminantibus. In mari Japonico. • 



This form corresponds in general outline to the Triceratium grande of Brightwell, 3 

 and its hexagonal areolation is also similar. The extremities, however, are here remark- 

 ably depressed and obtuse, instead of being more acute and attenuated. The ocelli are 

 nearly in the plane of the valve, which is evidently tumid. The three sides are slightly 

 convex, and the hexagonal areolae vary somewhat both in size and shape even in the 

 central region of the valve. 



Triceratium grunowianum, n. sp. (Plate XVI. fig. 5.) 



Forma triangularis, latissime areolata ; apicibus aspero processu erecto instructis ; 

 areolis subhexagonalibus ; valvis finissime et radianter punctulatis ; margine convexo 

 lsevi. Ad insulas Philippinas. 



This Diatom is remarkable from the enormous size of its unequal hexagonal areolae, 

 its strong terminal processes, covered with inequalities, and its very delicate radiating 

 punctiform striation. The three sides of the valve are slightly convex outwards, and in 

 immediate contact with these is a hyaline belt which bears irregularly elliptical or clavate 

 granules. At the bases of each of the three terminal somewhat infundibuliform processes 

 there are also several irregularly scattered angular granules which serve to give greater 

 prominence to this region. The narrower and more distal parts of each process bears a series 

 of fine striae which radiate into the proximal and wider end of the funnel. The specific 

 name has been given in honour of Mr Albert Grunow, the well-known observer of Diatoms. 



1 Micr. Journ., voL ii. p. 283, fig. 1. 2 Micr. Journ., vol. vi. p. 247, pi. xii. figs. 4-9. 



3 Micr. Journ., vol. i. p. 249, pi. iv. fig. 8; =(1.) Triceratium oriental?., Harv. et Bail.; (2.) Triceratium 

 faints (large), Pritcliard, op. cit., p. 856. The original specimens of Ticeratium grande, Bright., were found on 

 Tridachnidoe'and other shells from the Indian seas. 



