Valve hyaline at the ends, with transverse rows of puncta producing the appearance of costæ between the rows; pseudoraphe distinct; foramen single. _Diatoma arcuatum_ Lyngbye. Common along the coast. Pl. 8, Figs. 1, 2, and 3; Pl. 40, Fig. 10. {36}According to T. H. Buffham (Jour. Quek. M. C., Series 2, Vol. 2, p. 131), the frustules are of two kinds, those in which the length and breadth are the same and those which are much lengthened, with a wide hyaline girdle frequently in the middle. At the time of fructification the smaller frustules are attached to a larger one which produces a sporangium at the end of the girdle from which the other end of the frustule has disappeared, or, if the two halves of the frustule remain, two sporangia are formed. RHABDONEMA MINUTUM KUETZ. Frustules small; valve not smooth at the ends, elliptical or lanceolate-elliptical, with transverse rows of puncta; pseudoraphe distinct. Foramen single, alternating above and below in adjoining partitions. Common in the blue clay and along the coast. Pl. 8, Fig. 7 and Pl. 38, Fig. 11. RHABDONEMA ADRIATICUM KUETZ. Valve linear-lanceolate, with smooth angles; rows of puncta transverse, the intervals appearing as costæ, as in arcuatum. Foramina, three. Blue clay in the Pensauken and Pavonia deposits and along the coast. Pl. 8, Figs. 4, 5 and 6. TABELLARIA EHR. (1839) (tabella, a tablet) Frustules quadrangular, adnate in filaments, frequently found in zig-zag chains, united by a gelatinous isthmus, at length separating. Valve linear, inflated in the middle and at the ends; striæ transverse. Chromatophores numerous, small, along the zones. TABELLARIA FENESTRATA (LYNG.) KUETZ. Valve elongated; pseudoraphe narrow; transverse striæ faint. In the zone view a straight septum is shown at each end of a valve. Common, especially in the cedar swamps and ponds of the Pine Barren region, N. J. Pl. 8, Figs. 11 and 12. TABELLARIA FLOCCULOSA (ROTH) KUETZ. Valve linear, with median inflation larger than the terminal; pseudoraphe rather broad in the middle; transverse striæ subtly punctate. In zone view the frustules are quadrangular, or nearly so, with about six sometimes curved septa at one end alternating with those on the other end. _Conferva flocculosa_ Roth. Common especially in the Pine Barrens of New Jersey. Pl. 8, Figs. 8, 9 and 10. GRAMMATOPHORA EHR. (1840) (from gramma, a letter, and phoreo, I bear) Frustules quadrangular, adnate, in zig-zag, united by an isthmus, or, usually, found free; divided by two sinuate and perforate curved septa. Valve linear or oblong, sometimes with sinuate sides, and with a pseudoraphe and transverse punctate lines. Chromatophores granular. {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. Striæ in quincunx, 18-21 in 10 µ. _Diatoma marinum_ Lyngbye. Blue clay. Along the coast.