216 THE AMERICAN MONTHLY [September, 



shall do the same with a seemingly more difficult but really more 

 easy ^roup or genus of Diatottiaceoe^ the Schizo7ienia. The 

 genus Schizone7na was founded by C. A. Agardh in 1S24 (Bot. 

 Zeit.), and forms naviculoid frustules commonly existing in the 

 ocean or salt water in fronds or tubes. But they can, for the 

 same reason which I have shown in Hom<xocladia^ be classified 

 as Navic7ila. Then we come to the species. As W. Smith 

 says, " the fronds of this extensive genus were among the earliest 

 Diatomaceous organisms recognized by naturalists, and have been 

 the perplexity of all subsequent observers." He points out that 

 " their external form, size, and color vary with age, season, and 

 locality, and in consequence any characters based alone upon these 

 particulars are uncertain and deceptional." The genus must be 

 grouped together under Sckizonefna^ C. A. A., 1S24. By R. K. 

 Greville, 1826, under SchizoKe7na and Motiema ; by C. A. 

 Agardh, 1830, under Schlzonema and Microniega ; by C. G. 

 Eherenberg, 1838 (Infr. ), under A^«o?z<?wa, and now as A^azi/cz^/a. 

 With the exception of Schizoncma cniciger^ W. S., 1856, 

 which is now classed under Pleurosigfna^ W. S., by most ob- 

 servers, we can group the twenty-four ]\Iicromega^ F. T. K., 

 1844, under one head or species of JVavicjila fcctida^ J. E. S., 

 1790-1814, which is Ulva fcetida^ J. E. S. That we will class the 

 Colletonema^ A. de B., under this group along with Berkleya^ 

 R. K. G., and Dickieia^ J. R., is most certain, I think. For 

 they are formed in fi'esh water as Colleto7ie77ia neglectum or C. 

 vulgare or C. subcohcerens. These are placed under Pl7t7iu- 

 la7'ia {Navicula) radiosa ?Lnd JVavicula crassi77tervia. But this 

 part of the subject I do not wish to go into at the present time. 



I have the very large, middling, and small forms grow- 

 ing in one tube at the Passaic river, Newark, N. J., and Hudson 

 river at Fort Washington, N. Y. , and growing with the Schi- 

 zone7nas^ in the same tube, is the Ho77iceocladias as I have designa- 

 ted. Now what can we say is a species in the /^/a/o^y/actJrt?.'' The 

 species cannot exist, and the genus breaks down, when we come 

 to apply the same mode of reasoning to that. In fact the whole 

 family oi Daito77iace(x will break down, I think, when we come 

 to apply it to that also. 



Kadiolaria : Their Life-History and Their Chissificatioii. 



By Rev. FRED'K B. CARTER, 



MONTCLAIR, N. J. 



\_Continued from page i8o.'\ 



Finally if your form is iijlat disk and the surface of the disk on 

 the flat slides is covered by a porous sieve plate and the chambers 

 of the rings are imperfectly divided by the radial beams it is 

 either Porodt'scus { = Flust7-ella) ^ Perichlamydium^ Stylodic- 



