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RECENT RESEARCHES IN THE DIATOMACEA, 291 
RECENT RESEARCHES IN THE DIATOMACEZ. 
By Rev. E. O’Meana, A.M. 
Via. 
Tux forms embraced in the four groups to be now considered are 
placed by Dr. Pfitzer, in reference to themselves and to other groups, 
in a relationship Mati different from that assigned to them by most 
writers of authority on the subject. The groups referred to are 
Amphipleurea, Plgitropitea, Amphitropidea, and Nitzschiee. Hei- 
berg indeed places the genus Amphipleura “under that of Witzschia, 
and that because ae pede of the former family, which a ha 
specially examined, was that named by ‘Smith’ A. sigm 
a ideas group, in which he included Borkleya. Pfitzer agrees with 
Amphi pleura, according to ae is between the Nitzschiee and 
Surirellee. Rabenhorst placed it under the Naviculacee in his Siissw. 
iat., but subsequently, in Fl. : é 
Synedria and Mitzschiee. According to Kiitzing, Wm. Smith, and 
Prof. H. L. Smith, Amphipleura is ar ig to a position more or less 
Pome associated with the Wavicu 
next groups, Piaptroitie and Hoe gs roa are 
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intimately + sndetete wi nus Amphipro as 
been regarded as ne ye the Naviculacea, but the allied 
forms ar Pfitzer asodated Bho: the Nitzschiee. The character 
which these fou in com consequence of 
which they are so intimately ‘associated ay that author, is the develop- 
ment of certain longitudinal li ore or less bas minent keels. 
Whether this ‘Nnradtellatte hod "hed Genel as reason to 
e val 
namely, ee ocivaite (Ehr.) Kiitz.—possesses two endo- 
chrome-plates lying on the girdle-bands. A central plasm-mass 1s also 
bservable. In the process of constructing auxospores, only Berkleya 
Dillwynii, (Ag.) Grun, has been observed by Lii nage a this 
