P. KITTON ON DIATOMACEARUM DILLWYNII. 167 



dissepimentis solutis articulis prismaticis alternatum refractis. — PI. 

 VI., f. 2. 



C. flocculosa, Roth., " Catalecta Botanica " i. ; " Fl. Germ." iii., 

 part 1, p. 523. 



This singular plant was found for the first time in Britain by 

 my friend Joseph Woods, jun., and myself, growing in a pool on 

 Hampsteacl Heath, since which time I have observed it in various 

 other places. Its structure is so extraordinary that, notwithstand- 

 ing the figures and descriptions in the " Catalecta Botanica" and 

 my own repeated observations, I can hardly now allow myself to 

 assign it a place among the perfect productions of Nature. At first 

 I considered it as C. pectinalis broken to pieces, but a little exami- 

 nation rendered that idea inadmissible. It certainly has every 

 appearance of a broken plant, but J. Woods, jun., has observed it 

 in a state in which the joints cannot be so disposed as to make the 

 two parts of the line, which one might otherwise imagine continued 

 originally the whole length of the plant, coincide. 



It is a very small species, seldom exceeding a quarter of an inch 

 in length, and varying in colour from a pale to a greenish-brown. 

 The filaments are rarely branched. Their form is not easily ascer- 

 tained, but they always appear to me to be very much compressed, 

 and the joints only adhering to one another by single points, look 

 like a string of parallelograms united at the corners. Each joint 

 has a double line running through the middle of it, and some very 

 faint transverse bands frequently appear. In some cases, however, 

 this is entirely wanting, or has escaped the power of my glass. 



(This form was first figured and described but without name in 

 the " Abridgment of the Philosophical Transactions," 1703, both 

 of which have been reproduced in my article on the " Early History 

 of the Diatomaceaa." " Science Gossip," vol. xvi., p. 77, 1880. 

 It is the Tabellaria flocculosa of modern authors. — F. K.) 



C. pectinalis. — C. filis simplicibus pellucidis, acuminatis com- 

 pressis cinereis plerumque accuminatis, dissepimentis saepe solutis ; 

 articulis brevissimus medio-crystallino-pellucidis = C. pecti7ialis 

 Miiller, in " Nov. Act. Pet." iii. ; C. broncliialis, Roth., " Cat. Bot." 

 i., p. 186 ; " Fl. Germ." iii., p. 520.— PI. VI., f. 1. 



Miiller, who first found this singular species, and published an 

 excellent figure of it, observes that it is abundant in the ditches 

 about Pyrmont. 



The filaments are of a dirty green colour, seldom exceeding half 



