PLATE LXXXIV. 



Figures magnified 500 diameters. 



Fig. 1. RAPHIDODISCTTS MARYLANDICA, T. C. Microscope, May, 1889. 



" 2. CHRISTIANII, Gascoigne. Microscope, May, 



1889. 

 Figs. 3, 4. FEBIERII, T. O. Microscope, May, 1889. 



These three described species must be reduced to a single one. The 

 impression conveyed by the examination of a photograph of R. Ma- 

 ri/Jandtca, is that of two different diatoms accidentally wedged to- 

 gether; the markings of MILOSIRA can be plainly made out when 

 those of Raphidodiscus are out of focus ; and R. Christianii is simply 

 Marylandifa without the enveloping MILOSIRA ; or more correctly, 

 Marylandica and (~'hri.?t,in>iii lodged in a Milosira. R. Febigerii is 

 simply Christianii with its marginal rim broken away. C. M. Vorce, 

 Cleveland, Ct. The Microscope, May, 1889. 

 Fig. 5. STEPHANOPYXIS SPINOSISSIMA, Grun. ; Schrn. At., 123, f. 18. 



St. Monica. 



" 6. PSEUDOAULISOUS RADIATUS, Schru. At., 32, f. 28. 



" 7. ODONTODISCUS SUBTILIS, Grun. Do not see why this should 



be called Odontodiscus without any evi- 

 dence of teeth, (Odontos.) 

 Figs. 8,9. STEPHANOPYXIS SUPERBA, Schm. At., 123, f. 4, 5. Large and 



small forms. 

 Fig. 10. XANTHIOPSIS UMBONATTJS, Grev., T. M. S., 1866, p. 2, 1, f. 5. 



