Prof. Bailey on some new Fossil Infusoria. 137 



Art. XVI. — Account of some new Infusorial Forms discovered 

 in the Fossil Infusoria from Petersburg, Va., and Piscata- 

 way, Md. ; by Prof. J. W. Bailey, — (with a plate.) 



The results of a hasty examination of specimens of fossil in- 

 fusoria from Petersburg, Virginia, were given by me at the meet- 

 ing of the Association of American Geologists and Naturalists in 

 Albany, but more careful observations have led to the discovery 

 of several new and interesting forms, and have made me better 

 acquainted with the nature of others which had then been seen 

 only in the fragmentary state. Many of these forms are, I be- 

 lieve, entirely unknown to naturalists, and as additional interest 

 has been given to them, by the fact that several of them occur 

 at the new locality just discovered by Prof. W. B. Rogers at Pis- 

 cataway, Maryland, as well as at Petersburg, Virginia, I am in- 

 duced to publish the following account, accompanied by sketch- 

 es, which although they purport to be mere outlines, will yet 

 serve to give a tolerably correct idea of these very curious and 

 anomalous bodies. Among the most interesting of these bodies 

 are the following. 



1. Podiscus Rogersi, nob. (figs. 1 and 2, Plate III.) This is 

 the most beautiful fossil animalcule which has ever been discov- 

 ered. It undoubtedly belongs to the same genus as the curious 

 living forms discovered by Ehrenberg in sea water, and very natu- 

 rally named by him Tripodiscus Germanicus, as his specimens 

 had but three foot-like projections. But as our species shows that 

 the number of feet may vary from three to seven, I have ven- 

 tured to change the generic name to Podiscus, and I trust that 

 Ehrenberg will be willing to adopt so slight a modification of 

 the name of this genus, the honor of the discovery of which be- 

 longs to him alone. As our species is the largest and most beau- 

 tiful of the fossil infusoria occurring in the infusorial strata, of 

 which Professor William B. Rogers of the University of Virginia 

 made the truly splendid discovery, I have selected it as pecu- 

 liarly appropriate to bear the name Podiscus Rogersi. The char- 

 acters of this genus, as given by Ehrenberg, are as follows : " It 

 belongs to the Bacillaria, section Naviculacege. Its members are 

 free and possess a round bivalved siliceous lorica, having three 

 [or more] appendiculated processes, and dividing by longitudinal 



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