THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 37 



GRAMMATOPHORA MARINA (LYNG.) KUETZ. 



Valve linear-elliptical, with smooth apices. Septum with a wide undulation near its 

 origin, thence straight and incrassate at the end. Strise in quincunx, 18-21 in 10 M- 

 Diatoma marinum Lyngbye. 

 Blue clay. Along the coast. 

 PI. 8, Figs. 17 and 18. 



GRAMMATOPHORA MARINA VAR. SUBTILISSIMA (BAIL.) V. H. 



Valve linear, slightly constricted near the smooth apices. Septum undulated near its 

 origin and then straight, incrassate at the end. Puncta in quincunx very subtle, 34-36 in 

 10 it. 



Grammatophora subtilissima Bail. 



Grammatophora oceanica var. subtilissima (Bail.) V. H., according to De Toni. G. 

 marina and G. oceanica are united by some authors; the latter has more subtle striae. 



Along the coast. 



PI. 8, Figs. 13 and 14. 



GRAMMATOPHORA SERPENTINA RALFS 



Valve linear-elliptical, long, measuring to 150 fj. (De Toni) ; smooth at the apices. Sep- 

 tum with numerous undulations and hooked at the apex. Puncta in quincunx, 17 in 10 p.. 

 Along the coast. 

 PL 8, Fig. 21. 



GRAMMATOPHORA ANGULOSA VAR. HAMULIFERA (KUETZ.) GRUN. 



Frustule nearly quadrate; valve with rounded but not smooth apices. Septum bent 

 into a sharp angle near its origin and ending in a broad hook. Puncta in transverse rows, 



14 in 10 ju- 



Along the coast. 



PL 8, Figs. 15 and 16. 



GRAMMATOPHORA ISLANDICA EHR. 



Frustule oblong; valve elliptical-lanceolate. Septum robust with several undulations 

 and hooked at the end. Pseudoraphe distinct; transverse rows of puncta, 10 in 10 /*. 



Reported by Kuetzing in the Atlantic Ocean and by Kain at Belmar, N. J. I have not 

 found it on our coast and I believe, in some cases, it has been confused with G. angulosa 

 var. hamulifera. The figure is drawn from an Iceland form in H. L. Smith T. S., 186. 



PL 8, Figs. 19 and 20. 



STRIATELLA AG. (1832) 

 (dim. of stria, referring to the lines on the frustule) 



Frustules tabulate, adnate in short, stipitate filaments, scarcely siliceous, divided into 

 partitions, septate or partly so at alternate ends. 



