442 ANIMAL NATURE OP DIATOMEA. 



greatest breadth of primary, as well as of the linear- 

 lanceolate secondary surfaces, 0-004 millim. 



Schizonema lenellum, Kiitz., (Micromega.) 

 Schizonema Hyalopus> Kiitz. , (Micromega.) 

 Schizonema ramosissimum^ Agardh. 



Kiitzing says that the Naviculae are ith of a line long, 

 or 0'045 millim., but he figures them only as 7'T = 

 0-0183, and the very small 0'0024. In a specimen from 

 Lenormand, and in some from Dalmatia, collected by 

 Vidovich, corresponding in external appearance, and other 

 characters, with Kiitzing's figures and description, I also 

 find the greatest length 0'028, the breadth of the primary 

 surfaces 0'005, and that of the elliptico-elongate obtuse 

 secondary surfaces 0064 millim. 



In an authentic specimen from Chamin, obligingly 

 sent to me by Desmazieres, with the name of Schizonema 

 apiculatum, which is cited by Agardh himself as belonging 

 to S. ramosissimum, and which differs a little from the 

 preceding, the Naviculae attain 0'054 in length; more 

 frequently they are only 0-042. The primary surfaces 

 are linear ; the secondary, elliptico-elongate, rather larger, 

 are a quarter of the length in breadth. Many smaller 

 ones (0'02) are mingled with the others. 



Under the same name of S. ramosissimum I received 

 from Harvey and Berkeley a species entirely different 

 from Kiitzing's, and corresponding perfectly with the 

 description and figure given by Kiitzing of his S. strio- 

 latum. In this the transverse striae upon the external 

 surface are very evident. Although Kiitzing does not 

 state the dimensions of the Naviculae in his definition, those 

 represented in his plate, and calculated by the usual rule 

 as equalling half the indicated amplification, would be 

 twice as large. In our own, the greatest length is O'OIS 

 millim., and is not quite three times the breadth of the 

 primary surfaces. In the figure of S, striolatunt,i\\Q greatest 



