REPORT ON THE DIATOM ACEvE. 65 



and irregularly striated, and the intercostal areas are punctated ; while in the latter, in 

 addition to the intercostal quadrately arranged puuctations, the margin is denticulated 

 and ornamented with a distinct corona of minute granules. As serving still more conclu- 

 sively to determine the independence of the two organisms, it may be noted that while 

 the symmetry of the radial costules of Campylodiscus lepidus indicate that augmentation 

 must go on all round the periphery, in the present frustule somewhat larger intercostal 

 areas are found at the diametrically opposite points, so that it is manifest that increase 

 takes place in these regions. 



Campylodiscus oceanicus, n. sp. (Plate XI. fig. 4.) 



Valvis flexuosis ; costulis longiusculis, quorum apicibus cellulce vel costulse inter- 

 ponuntur ; area centrali tereti subrotunda. In mari Pacifico. 



This fiexuous Diatom was collected in the Pacific Ocean. In it the radiate costules 

 encircle a smooth and almost round area. At their summit these alternate with another 

 order of costules, which seem to be elongated cellules. These are continued to the 

 extremity of the submarginal wing, for which they form a support. 



Campylodiscus nitens, n. sp. (Plate XL fig. 6.) 



Forma parva, flexuosa ; costulis subradiantibus grandiusculis aream hyalinam 

 limitantibus ; costulse superius rotundo-complanatse brevi spatio veluti granulo terminato 

 distinctae. Ad Zebu, ex insulis Philippinis. 



This small discoid form was collected in the neighbourhood of Zebu in the Philippine 

 Islands. It is distinguished by possessing a series of subradiate costules, whose outer 

 extremities are somewhat rounded, and separated from one another by small interspaces 

 that are bounded by small round granule-like bodies, which more centrally are replaced 

 by simple lines. In the centre there is a smooth area of moderate size. 



Campylodiscus wallichianus, Grev., var. thaitiensis, nov. (Plate XVI. fig. 6.) 



This magnificent frustule, of which several specimens were collected at the port of 

 Tahiti, surpasses all the others in the elegance of its ornamentation. It consists of a large 

 and slightly folded disc, the curve being reversed with respect to the two axes. Almost the 

 entire surface is occupied by subradiating canaliculi, which terminate marginally in rows 

 of distant erect spines. The canaliculi gradually disappear as they approach the centre, 

 where a biconcave smooth area exists. Around the two rounded extremities of this area 

 there are a number of more sharply defined punctations, the most external of which form 

 a semicircle, a circumstance which serves to give greater prominence to the area in these 

 regions. 



On comparing this frustule with others previously known, it is found to be most closely 

 (bot. chall. exp. — part iv. — 1886.) D 9 



