18 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



AMPHORA ALTERNATA, new species 



Plate 3, fig. 3 



Dorsal side of valve convex in an even arc; ventral slightly bicon- 

 vex, constricted in the center; ends broad and rounded, not flexed; 

 rhaphe double bow-shaped with a strong central nodule, the ends 

 slightly reflexed ; no hyaline area ; beading in closely set transverse 

 rows of oval or rectangular beads, the spacing of each row alternat- 

 ing with that of the rows on either side, thus producing a basket- 

 work or brick pattern. A robust, massive diatom. 



Length 0.141; width 0.034; 6 lines in 0.01 mm. 



Type— Cat. No. 43568, U.S.N.M. 



AMPHORA ANCEPS, new species 



Plate 3, fig. 4 



Valve broad, the breadth one-half the length; the dorsal side with 

 a deep central indentation, resulting in two pronounced peaks; the 

 apices of the valve produced into two short extensions, contiguous 

 with the ventral side and slightly reflexed at the tips; ventral side 

 nearly straight, barely indented at the center; rhaphe close to and 

 parallel with the ventral side; markings rows of elongated beads, the 

 interspaces the same width as the rows, transverse at the center of 

 the valve and increasingly curved outward toward the apices. 



Length 0.068-0.090; width 0.024-0.040; 7 lines in 0.01 mm., 

 measured along the ventral side. 



There is a general resemblance between this diatom and A. cor- 

 pulenta Cleve and Grove, both in its breadth and in the arrangement 

 of its beading. 



Type.— Cut. No. 43569, U.S.N.M. 



AMPHORA ANGUSTA Gregory 



(Schmidt, Atlas, pi. 25, figs. 8, 14, according to Cleve, Nav. Diat., vol. 2, pp. 

 135-6.) 



I have two specimens which correspond with the above two figures 

 in Schmidt's Atlas. But Cleve has made a painstaking study of A. 

 angusta Gregory and A.cymbelloides Grunow and writes that Schmidt's 

 two figures represent, not, as there stated, A. cymbelloides, but A. 

 angusta, which latter, he says, is much more delicately marked. He 

 gives for A. angusta, 7 to 17 lines in 0.01 mm. and for A. cymbelloides 

 at least 29 lines in 0.01 mm. My specimens have 8.3 and 12.5 lines 

 in 0.01 mm. 



AMPHORA ARCUATA A. Schmidt 



(Schmidt, Atlas, pi. 25, figs. 27-29.) 



This is not to be confused with the form bearing the same name 

 in Pantocsek (Hung. Diat., vol. 2, 1888, pi. 4, fig. 70). Schmidt's 

 identification has priority, 1875. 



