SOME NEW AND RAKE DIATOMS. 



This Diatom is figured in Schmidt's Atlas, Plate 75, Fig. 6. 7; also in Van H. Synopsis: 

 from being- at lirst denominated Tn'ceraiiunh it has been transferred to the Genus Pseudo-jSUciodis- 

 cus, created for its reception, together with another, noted in the description of St. Grevilleanus ; 

 it is undoubtedly a Sticlodiscus, and as such we will so call it. 



This splitting of well established genera to accommodate one or two species that happen to 

 vary slightly in size, locality or outline, is to be seriously deprecated, and can but result in con- 

 fusing students and in bringing certain discredit upon those who make it their business to create 

 new genera and species from insufficient material. In the present case the proper place for these 

 three species is in the Genus Stictodiscus. 



Actiiioptvcliii* andulatus, var. verrucosa. H.H.Chase. Valves small ; .0017 



to .0030 inch in diameter: divided into tf compartments ; strongly undulate : umbilicus smooth, 

 hexagonal: outer plate (surface) finely reticulate: the inner surface presenting strong, heavy, 

 meshed markings that are well expressed by " verrucose." and whose character -ire shown in 

 Fig. 8, Plate 2. Habitat. West coast of the U. S. H. H. Chase. 



Xavicula Sillimanoruiii. Ehr. In our plate 2. Fig. 2. is given a figure of this 

 Diatom, which, from being quite rare, has recently been found in rather large numbers, in a de- 

 posit from Crane Pond, Mass. : first figured by Ehrenberg in his Microgeologie, Plate 2. II. f. 13, 

 it was afterward noted by Lewis, in Whjte Mountain Diatoms, page 11, plate 2. fig. 8. Length 

 .0062 inch : striae 20 in .001 in. 



