GrkvillEj on New Diatoms. 69 



depressed, with a broadly expanded hyaline margin ; areola- 

 tion large; connecting processes robust, spine-like, situated 

 nearer to the margin than the apex. Diameter •0024" to 

 •0354". (PI. VIII, figs. 3, 4, 5.) 



Hab. Barbadoes deposit ; frequent. 



A splendid species, with very large areolation. Average 

 specimens possess from six to eight connecting processes, but 

 examples occur with from four or five, up to the giant repi'e- 

 sented at fig. 5, with nineteen. I have never seen Ehrenberg's 

 Stephanopyxis diadema ; but if Kutzing^s definition be 

 connect, " disci medii depressi annulo dense denticulato" — my 

 present diatom must be distinct. Kutzing, besides, gives the 

 number of teeth in the crown as thirty, whereas it is a very 

 rare circumstance indeed to see so many in Cresswellia su- 

 per ba as appear in fig. 5. 



EUODIA. 



Euodia Barbadensis, n. sp., Grev. — Frustules semilunate, 

 ends slightly produced, lower margin straight ; surface cellu- 

 lose, with a small, irregular, central blank space. Distance 

 between the angles -0015" to -0020". (Figs 6, 7.) m /, 

 Hab. Barbadoes deposit ; extremely rare. / 



Valve yellowish ; short, vein-like lines are given off from 

 the margin, sufficiently conspicuous in the larger specimens, 

 but less so in small ones. The upper margin is conical-con- 

 vex, so as to give the frustule very much the outline of a 

 cocked hat. Cellulation rather large, but under a low power 

 appearing as granules. 



Trice RATiUM. 



Triceratium cornutum, n. sp., Grev. — Valve (4-angled?) 

 with straight sides and sharp angles furnished with strong, 

 horn-like processes ; surface minutely granulose, in lines ra- 

 diating from the centre, on which are three spines ; granules 

 at the margin 15 in -001". Distance between the angles 

 •0015". (Fig. 8.) 



Hab. Barbadoes deposit ; excessively rare. 



The only frustule, a very perfect one, which has come under 

 ray notice, has four angles with exceedingly strong, horn- 

 like processes, which, as they cast a dark shadow, render the 

 frustule conspicuous. The granules are very minute in the 

 centre, but increase in size as they radiate to the margin. It 

 is quite distinct from the few species already described, having 

 spinous lateral surfaces. 



Triceratium productum, n. sp., Grev. — -Valve punctate ; 



