EDWARDS; ON AMERICAN DIATOMACK.E. 12!) 



ends slightly rounded." Bailey. I have as yet only found 

 this species in small quantities, and have been unable to 

 make its measurements. There can be no doubt that these 

 two species should be placed in the genus Navicula, as the 

 seeming stauros in the first, the presence of which would 

 seem to rank it in that of Stauroneis, is only a blank space, 

 such as is seen in many species of Navicula, as N. elegans, 

 &c. The presence of moniliform strife in the second species 

 removes it from Pinnularia, which is characterised by its 

 markings being costae, not resolvable into dots. Of N. 

 maculata, I have specimens from Duval's Creek, near Enter- 

 prise, Florida, for which I am indebted to Dr. Christopher 

 Johnston, of Baltimore, Md. 



I here mention a fact that has come within my notice 

 while examining this gathering. Smith's Eupodiscus radiatus, 

 as described and figured in the first volume of his ' Synopsis/ is 

 not the same as the form described under that name by 

 Bailey in 1850. Roper has remarked this same fact ('Trans. 

 Mic. Soc.,' London, vol. vii, p. 19), but was in some doubt 

 until I had the pleasure of forwarding him authentic 

 specimens of it from Bailey's cabinet, when he wrote to me 

 that the examination of them confirmed his opinion that 

 Smith was in error in referring the Thames diatom to that 

 species. It is perfectly distinct, and a true Eupodiscus. 



Since the above article was written, I have been lead, by 

 the advice of Dr. Arnott, to reconsider the subject of the 

 species, which I, in my paper on American Diatoms, called 

 Coscinodiscus actinoptychus. This belongs to Ehrenberg's 

 genus Actinocyclus, the species of which are characterised by 

 the number of rays, — a loose character. It should therefore 

 be placed in that genus for the present, the specific name 

 being left blank until more is known of its natural history. 



