IN THE MUD OF THE LEVANT. IQ 



freshwater species ; but Mr. Ralfs kindly informs 

 us that he has occasionally found it brought down 

 by the rivers into marine marshes. 



Arranged along with the Diatomacsee, by many 

 authors, are the singular group of Naviculacese, 

 small siliceous boat-like bodies, whose affinities 

 are even yet more doubtful than those organisms 

 already noticed, containing a peculiar green 

 internal organization ; not forming chains like 

 most of the preceding genera, but each being 

 independent ; possessing great powers of loco- 

 motion ; manifesting all the phenomena of fissi- 

 parous generation, and exhibiting, when treated 

 with iodine, well-marked traces of the existence 

 of the vegetable product starch ; connected 

 with the preceding group by the genus Coc- 

 conema, in which, as in Gomphonema, the sili- 

 ceous frustules contain a granular endochrome, 

 and are supported on long flexible pedicles ; 

 and yet, when detached, the frustules being 

 distinguishable by any known character from 

 true Navicula ! Altogether, we are involved in 

 a labyrinth of difficulties, from which we cannot 

 easily extricate ourselves. 



Ehrenberg believes that he has observed in 



