836 Transactions of the Society. 



The definition of tlie genus Eucampia Ehr. as given in ' Sm. 

 Brit. Diat.' vol. ii. p. 25, is — 



" Friistides cuneate, quadrangular or oblong, united into a 

 spii-al filament ; valves dotted, elliptical." 



This definition slightly extended, so as to include my new 

 form, obviates the necessity of creating a new genus : — 



Frustiiles cuneate, quadrangular or oljloug, united into a spiral 

 filament ; valves dotted or costate, elliptical or circular. 



Eucamjna striata n. sp. Breadth of the whole plant circle 

 about '01 of an inch. Valves hyaline. Side view, circular, "002." 

 Front view, trapezoidal, and about four or five times longer than 

 broad. Marked with fine costte extending across, 14 to the •001". 

 A small spine at the angles terminating the convex border, and 

 situated at the edge of the circular side view. Endochrome green. 



Habitat, marine ; estuary of the Dee, Chester, July 14th, 

 1879, and Hong Kong Harbour (Dr. Palmer). 



In the same gathering I found another form, which I take to 

 be a variety — Eucampia striata n. sj>. var. maxima. 1 have never 

 seen a complete circle of the whole plant, only five or six frustules 

 together forming a curve. Valves hyaline. Side view, circular, 

 • 004". Front view nearly square, marked with costse 7 or 8 to the 

 •001". No spine. Endochrome green. In the dry state the ends 

 of the valves fold over, as seen in d. 



Habitat, marine ; estuary of the Dee, Chester. July 14th, 

 1879, and Hong Kong Harbour (Dr. Palmer). 



The variety maxima may only be a stage of growth, but it is 

 constant in its appearance, and I do not find intermediate states 

 of growth. 



I have added the locality Hong Kong on the authority of my 

 friend, Laurence Hardman, Esq., who pointed out to me the exact 

 similarity between my form and that found in the Hong Kong 

 gatherings, and which he believes has never yet been described 

 owing to the want of fresh material. 



