444 ANIMAL NATURE OF DIATOME^. 



The partial tubes are very evident, and so is tlieir 

 confluence at the apex, from which is derived the digitato- 

 multifid ramification. 



Schizonema apiculatum, Ag. 



The Jjth of a Une, virhich Kiitzing assigns as the length 

 of the Naviculae, corresponds to 0'0492 millim. As usual, 

 the figure gives a measurement of half the size. In speci- 

 mens from Lenormand and Brebisson, I find the length 

 of the Naviculae 0'04 millim., the breadth of the primary 

 surfaces O'Ol, of the secondary 0-012, and the figure of 

 both perfectly corresponding with the description and the 

 delineation of Kiitzing. 



ScJdzonema medusinum, Kiitz., (Micromega.) 



In specimens so denominated by the author, I find the 

 Naviculse 0036 millim. long, 0'0047 broad in the primary 

 surfaces, and a millimillimetre more in the secondary. 

 Kiitzing does not state the dimensions; from his figure, 

 I infer the length only to be 0'0262, and the breadth in 

 proportion. 



ScJdzonema chondroides, Kiitz., (Micromega.) 



I regret that I have been unable to study this species, 

 on account of the peculiar mode of prolification at the 

 extremities. 



Schizonema spinescens, Klitz., (Micromega.) 



Found in Venice, by Zanardini. The Naviculse (0042 

 millim. long, and 0-0062 broad,) difier little from the 

 dimensions indicated by Kiitzing (^th of a line), being 

 about twice the size of the figure (9 '6 milUm. T = 022). 



