Prof. Bailey on some new Fossil Infusoria. 141 



represents T Wths of a millimetre, magnified equally with the 

 drawings. 



West Point, Oct. 3] , 1843. 



Note. — I take an opportunity afforded while correcting the 

 proof-sheet of the preceding article, to state that since it was 

 written I have examined some sediment which I collected from 

 a small creek, opening into the Atlantic ocean near Rockaway 

 Pavilion, Long Island, and that among many interesting infuso- 

 rial forms I had the pleasure of finding recent specimens of Po- 

 discus Rogersi, having four foot-like processes. I also found 

 that rare and beautiful form, Biddulphia palchella, and was 

 struck with its generic resemblance to the above-mentioned Zy- 

 goceros Tuomeyi. It is possible that the latter should be refer- 

 red to the genus Biddulphia. Large and beautiful specimens of 

 Triceratium favus, Ehr. occurred with the above, and I noticed 

 also Diclyocha fibula and D. speculum, besides numerous spe- 

 cies of Coscinodiscus and Actinocyclus. Small Polythalamia 

 belonging to the genus Rotulia occurred with the above, thus 

 giving upon our sandy sea-coast a mixture of infusorial and Po- 

 lythalamian forms analogous to that which Ehrenberg has ob- 

 served in some of the chalk marls of Europe and Africa. In 

 examining mud from Boston harbor, I have recently detected 

 portions of that truly beautiful infusorial form, Isthmia obli- 

 quata. For full descriptions of it, and of the above-mentioned 

 Biddulphia pulchella, see a paper on British Diatdmaceas, by 

 John Ralfs, Esq., in the Annals and Magazine of Natural His- 

 tory, Vol. XII, p. 271. A translation of Ehrenberg's paper, de- 

 scribing some of the interesting forms detected by him living in 

 sea water, will be found in Taylor's Scientific Memoirs, Vol. Ill, 

 Parts X and XI, accompanied by figures of Podiscus Germani- 

 cus, Zygoceros rhombus, Triceratium favus, and several other 

 forms above referred to. J. W. B. 



West Point, Dec. 5, 1843. 



Extract from a letter by Prof. Wm. B. Rogers, to the Junior 

 Editor, dated Richmond, Dec. 13, 1843. 



Dear Sir — I regret that it is not in my power to furnish an 

 account of the tertiary infusorial formation of Maryland, re- 



