of Microscopical Organisms. 331 



hyaline. Aa no name was assigned by its discoverer, I 

 have ventured to propose the above, taken from the name 

 of the vessel by which these soundings were collected. 



Figs. 2, 3. Amphitetras cuspidata, Bail.., nov. sp. 

 Sides concave ; lateral view quadrangular, with angles 

 produced and rounded ; cellules distinctly hexagonal ; con- 

 necting membrane minutely and decussately punctate. 



Hab. Para River, and Lat. 0° 45' 50' S. Long. 48° 11' 

 25 ' W. 



I have detected several specimens of this species, and 

 compared them carefully with Triceratium favus, of which 

 several varieties occur in these soundings. Although the 

 hexagonal areolations are somewhat smaller than usually 

 represented in Tr. favus, yet in this locality there are sev- 

 eral varieties of this species, which differ considerably in 

 this respect; and as a five-sided variety or Amphipentas 

 also occurs with similar areolati^n, I am disposed to re- 

 gard these forms as all of one species. It is probable, also, 

 that Amphitetras favosa, H. et B., which differs only in the 

 sides being straight instead of concave, may be another 

 variety of the same species. This form was found at the 

 depth of thirty-three fathoms. 



Figs. 4 and 5. Cyclotella Kijtzingiana ? . This 



species, which, in the list of forms detected by him, my 

 father doubtfully refers to Discoplea Kutzing-ii, is probably 

 a variety of C. Kutzingiana of Smith. The central por- 

 tion is large, elevated, and irregularly punctate ; the striae 

 are minute and closely radiant, reaching the margin, but 

 interrupted before reaching the margin by a finely undu- 

 late circle. 



I would here remark, as this species of Cyclotella is de- 

 scribed by some as with a punctate, and by others as with 

 a striate margin, that either appearance may be produced, 

 in this variety at least, by a simple change of focus ; the 

 undulate line when in focus appearing as if made up of 



