68 The Microscope. 



I have also found what is thought to be^a new Auliscus, which 

 has been named Auliscus spinosus, n. s. from] the two spines on its 

 disk. Disk with strongly marked'lines radiating inward, which join 

 a well defined inner rim, enclosing a center with interrupted striae, 



giving it the appearance of points. 

 I have mounted one slide with six- 

 teen Kaphidodiscus. I have some 

 iilteen other forms of diatoms which 

 [ have not yet placed or named, and 

 -ome may be new, as I cannot place 

 them, or the correspondents who have 

 seen them, for study. One noticeable 

 fc^atare is that there are to be seen 

 specimens of well-known forms which 

 vary from the standard types just a 

 Auiii.ub, X. s. little. This deposit has as yet been 



only partially examined, and yet we have over one hundred forms 

 from the following genera : Actinocylus, Actinoptychus, Aidiscus, 

 Amphitetras, Asterolampra, Asteromphalus, Euodia, Chsetoceros, 

 Biddulphia, Aulacodiscus, Coscinodiscus, Pleurosigma, Eupodiscus, 

 Heliopelta, Hyalodiscus, Melosira, Raphoneis, Navicula, Podosira, 

 Triceratium, Sceptroneis, Pyxilla, Grammatophora, Rhizosolenia, 

 Stephanogonia, Mastigonia, Stephanopyxis, Kaphidodiscus, new 

 genus, Encampia, Craspedodiscus, and several which I have not yet 

 been able to place. I have mounted a few of the rare forms, as 

 well as general slides from this deposit. 



I have from a country well some forty miles from Richmond a 

 new deposit which as yet I have only partially examined, but I find 

 it entirely new and distinct from any Maryland or Virginia deposits 

 I have ever seen, the one predominant form being Craspedodiscus, 

 of which there are six new species, with from three rows of cells in 

 the rims up to ten or twelve rows, and all different from those 

 figured in Schmidt's Atlis Plate 66. 



KAPHIDODISCUS N. G. 



Frustules disciform, with more or less of a well marked (cellu- 

 late) marginal rim, center naviculoid, with interrupted meridian 

 line and radiate (moniliform) stria3, which are prolonged to the 

 margin of the disk. 



Raphidodiscus Marylandica, N. G.^^Thos. Christian. 



Raphidodiscus Febigerii, N. G. — Thos. Christian. 



Raphidodiscus Christianii, N. G. — W. J. Gascoyne. 



