RECENT RESEARCHES IN THE DIATOMACE®. 229 
that while the latter is stipitate the former is free. To this Pfitzer 
adds another mark of distinction founded on the character of the 
has i 
endochrome-p chnant wo endochrome-plates, while 
in Achnanthedium lanceolatum there is but , which lies upon the 
conve is peculiarity places Achnanthidium in intimate 
relationship with the ne , Coeconeis. Cocconeis Pediculus at 
least possesses a single endochrome-plate, occupying a position similar 
to that of Achnanthidium lanceolatum, split up on the edge, and with its 
scallops reaching the girdle-band. It exhibits also a strong slit on one 
side, a circumstance which in the author’s opinion shows that the 
Cocconeidee are not decidedly symmetrical in the longitudinal plane. 
This feature - ‘ianee itself in Achnanthidium likewise, in the 
structure of the concave valve, by a stronger development of the 
central nodule on one side than on the other. The endochrome-plate 
so f p 
Cocconeidlea are pom distinct from the Naviculee, and exhibit a 
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Amphoree and Cocconeidee the endochrome-plate stands related to the 
surface of attachment. The former attaches iteelf at one girdle-band, 
been discovered in the act, but Cocconeis has “alge Carter first 
found that two cells secrete a gelatinous envelope, open, 
true act of copulation construct a single spore, which is first globular, 
then becomes ellipsoid, and finally separates into two longitudinal 
portions, each of which is an auxospore. he contrary, Smith 
observations refer to Cocconets Pediculus, Smith are re wha : 
calls the nearly allied species, Cocconeis Placentula. Liiders agrees in 
this point with Carter, and Dr. Pfitzer confirms their position in 
regard to C. Pediculus. The followi wing differences are noticeable. 
One supposes the separation has been completed within the envelope, 
the other not till it has been thrown off. According to Carter the 
firstling-cells turn the concave sides one to the other; according to 
Liiders they are parallel. Dr. Pfitzer observes that the material at 
his command was too young to enable him to degide this questions 
Gomphonemee, 
In this are included three ancge hs Sphenella Gom- 
phonema; 38. See ip oe e dis ge by =O — 
ide 
central nodule. Still ete are De oricelly constructed, as the 
upper end is broader than the lower. As the Achnanthea exhibit a 
