

THE DIATOMACE^E OF PHILADELPHIA AND VICINITY 31 



(6) BIDDULPHIIN^E 



BIDDULPHIA GRAY (1831) em. VAN HEURCK (1885) 



(a genus, constituted from Conferva biddulphiana of the English Botany, named after 

 a Miss Biddulph) 



Frustule prismatic or subcylindrical, concatenate, filamentous, or in zig-zag, or, as 

 usually found, free. Zone well developed. Valve triangular, polygonal, elliptic or subcir- 

 cular, convex, more or less elevated at the angles into processes or horns. Markings cellu- 

 lar or punctate. Chromatophores, small plates of various forms. 



KEY TO THE SPECIES 



Valves costate biddulphiana 



Valves not costate: 



Markings cellular, angles elevated into horns favus 



angles not elevated antediluviana 



Markings punctate, angles with subconical processes 



and long spines granulata 



spines short rhombus 



spines minute smithii 



processes truncate, valve elliptical turgida 



valve orbicular laevis 



processes absent, valve divided by irregular lines alternans 



not so divided reticulum 



BIDDULPHIA BIDDULPHIANA (SMITH) 



Frustule quadrangular with convex ends and rounded angles. Valve elliptical with 

 undulated sides, divided by septa into three or more sections. Processes large, rounded, 

 globular or subconical. Zone varying in width. Surface with rounded reticulations hi lon- 

 gitudinal and transverse rows, except at the centre where they are concentric and smaller. 



Conferva biddulphiana Smith (English Botany, 1807, PL 1762, upper figures). 



Diatoma biddulphianum Ag. 



Biddulphia pulchella Gray. 



Blue clay. Hoboken Tunnel. Along the coast. 



PL 7, Figs. 1, 2, 3, and 4. 



Quite variable in size and number of septate divisions. Fig. 3 is an unusual form with 

 narrow zone, having but one row of large reticulations, evidently a young frustule. 



BIDDULPHIA FAVUS (EHR.) V. H. 



Frustule quadrangular, elevated at the angles into subconical processes oblique to the 

 longitudinal axis. Valve triangular or quadrangular, plane, of two layers, the outer layer 

 composed of large hexagonal cells in rows parallel to the sides, the inner of small puncta 

 radiating from the centre. Zone punctate in quincunx, never found open. 



Triceratium favus Ehr. 



Blue clay. Common along the coast. 



The quadrangular form occurs only southward. 



PL 6, Fig. 6. At "a" a cell showing the lower punctate layer. PL 40, Fig. 16, a trans- 

 verse section of a portion of the valve showing the cellular structure and the punctated 

 lower stratum. 



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