444 ANIMAL NATURE OF DIATOME^!. 



The partial tubes are very evident, and so is their 

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

 multifid ramification. 



Schizonema apiculatum, Ag. 



The ^th of a line, which Kiitzing assigns as the length 

 of the Naviculse, 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 0*01, of the secondary 0*012, and the figure of 

 both perfectly corresponding with the description and the 

 delineation of Kiitzing. 



Schizonema medusinum, Kiitz., (Micrornega.) 



In specimens so denominated by the author, I find the 

 Naviculae 0'036 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. 



Schizonema 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, Kiitz., (Micromega.) 



Found in Venice, byZanardini. The Naviculae (0-042 

 millim. long, and 0*0062 broad,) differ little from the 

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

 about twice the size of the figure (9'6 millim. 4 f = 022). 



