NEW MICROSCOPIC ALG^. 323 



A second most remarkable form is named 



Attueya, nov. gen. T. W. 



Frustules quadrangular, compressed, annulate; annuli inde- 

 finite ; valve elliptical lanceolate, with a median line ; a spinous 

 process from each angle. 



A. DECORA, n. sp. T. W. (Plate XVI., fig. 8.) 



Annuli 12 to 28, 20 in -001 ; septa alternate. Width of 

 frustule, -0009 to -0015. Breadth of valve, -0003, with 

 a median line and distinct central punctum. 



This was found by Mr. Atthey plentifully on Cresswell sands, 

 in June, 1859, free from admixture; and again equally clear in 

 May of the present year (1860). Also with Podosira (^?) com- 

 pressa, and other diatoms of similar habitat, by the Rev. R. Tay- 

 lor and Mr. A. in the same place, and by the latter in Druridge 

 Bay. The appearance of this pretty little species is precisely 

 like Striatella unipunctata in miniature, the arrangement of the 

 endochrome being also much the same in both. From Striatella, 

 however, it is separated by the presence of spinous processes at 

 the angles, and the entire absence of stipes or attachment of any 

 kind. Of the propriety of instituting a new genus for it there 

 can be no question, and I have much pleasure in dedicating it to 

 Mr. Atthey, as a slight mark of my regard for him as a very 

 acute and diligent observer. It is not so easy to decide on its 

 true place in a natural system, for it appears to unite Striatella 

 with ChcBtoceros ; next to which latter I feel disposed to place it 

 on account of the spinous processes at the angles; and the dis- 

 covery of the structure of Bhizosolenia, a near ally, in which I 

 ascertained the existence of indeterminate, alternately arranged 

 annuli, seems to diminish the difficulty that might otherwise be 

 felt in allying it with Chcetoceros. 



Since the above was printed, I have had the gratification of 

 receiving, in a letter from Dr. Greville, the following : — " I am 

 glad to see that you have settled Attheya ; I was completely 

 puzzled with it." 



