86 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 



I can find neither description nor figure of any species to which I can ascribe this form. 

 It approaches D. elliptica. The alveoli are quite distinct and distant from each other. 

 Brackish water. Very abundant in a gathering from Squan River, N. J. 

 PI. 20, Fig. 10. 



DIPLONEIS OCTJLATA (BREB.) CL. 



Valve elliptical; striae radiate at the ends, about 20 in 10 n, coarsely punctate. L. 23 n. 



Fresh water. 



PL 26, Fig. 7. 



The figure is drawn from Bre"bisson's original material in H. L. Smith's Type Slide 

 No. 299. 



Navicula oculata Br4b. 



Reported from New Jersey. I have not seen this species in this locality. Navicula 

 oculata, referred to by Kain as occurring in Shark River, is not this form. 



DIPLONEIS GEMMATA (GREV.) CL. 



Valve oblong-linear, with cuneate ends and parallel or slightly concave sides; central 

 nodule large; horns parallel; furrows about one-third the width of the valve. Costse about 

 5 in 10 n, alternating with double rows of fine puncta; short costse occur along the borders 

 of the horns. 



Port Penn, Delaware River. 



PL 20, Fig. 16. 



DIPLONEIS CAMPYLODISCUS (GRUN.) CL. 



Valve suborbicular; central nodule quadrate; horns divergent; costse, 6 in 10 n, alterna- 

 ting with double rows of alveoli; furrows broad, costate near the horns. 



Differs from Cleve's description in having 6, instead of 4, costse in 10 p. 

 Pensauken, N. J. (artesian well). Rare. 

 PL 20, Fig. 6. 



MASTOGLOIA THWAITES (1856) 



(mastos, a breast, and gloios, gelatinous, referring to the "mamillate cushion" in which 



the frustules are often immersed) 



Frustule rectangular. Valves similar, naviculoid. Central and axial areas usually 

 narrow or indistinct; striae punctate, parallel in the middle. On each side, between the 

 valve and the zone, is a septate plate. 



ANALYSIS OP SPECIES 



Striae interrupted by a hyaline furrow on each side of the median 



line kinsmanii 



Strise not interrupted : 



Loculi, five, or less exigua 



more than five, equal, ending at distance from the ends smithii 



ending near the ends, distinct lanceolata 



indistinct elegans 



very numerous apiculata 



unequal angulata 



