IN THE MUD OF THE LEVANT. 15 



by germs or spores, or, as appears to be the case in 

 many species, by the formation of two new siliceous 

 cells, in the interior of the old one, each cell thus 

 becoming the germ of a new and self-increasing 

 organism. There are many reasons for referring 

 these curious and elegant creatures also to the 

 vegetable world ; but on the other hand, many 

 points of their history bring them so near to the 

 Coscinodisci, and other supposed siliceous Infu- 

 soria, that it appears almost impossible to come 

 to a definite conclusion on the subject. 



I havedweltthe longer on these families because 

 of their growing importance to geologists. Most 

 modern geological works contain some allusion to 

 them under the terms Gallionellse, Baccillarise, 

 &c.* ; but very few doubt for a moment their 

 animal character. The extensive discovery of 

 their siliceous cases amongst tertiary strata, 

 especially by Professors Ehrenberg, Bailey, and 

 Rogers, has given them an important position 

 amongst the organic remains of a former world ; 

 and, consequently, it is desirable to bear in mind, 

 in our generalizations, that the question of their 

 real nature is yet suh judice. 



* Lyell's Elements, p. 52. — Dr. Bailey's valuable Papers 

 in SilHman's American Journal. 



