Blue clay. Not uncommon. Pl. 35, Fig. 7. SURIRELLA CRUCIATA A. S. Valve ovate; pseudoraphe very narrow; costæ, 2 in 10 µ; the outline of several of the median costæ strongly emphasized, while the other costæ are indistinct. L. 54 µ. Blue clay. Pl. 35, Fig. 10. SURIRELLA GRACILIS GRUN. Valve linear, with sub-cuneate ends, slightly constricted in the middle; pseudoraphe very narrow; costæ, 6-7 in 10 µ; transverse striæ about 26 in 10 µ, punctate. L. 75 µ. According to De Toni (p. 598), this form is a Nitzschia. It has, however, a narrow pseudoraphe. Pavonia, N. J., artesian well. Rare. Pl. 35, Fig. 11. SECTION 3 SURIRELLA FASTUOSA EHR. Valve ovate; costæ about 1-2 in 10 µ, dilated at the margin and contracting at about one-fourth the distance toward the middle; area, ovate-lanceolate; pseudoraphe, narrow and indistinct; intercostate striæ more evident near the margin, 19 in 10 µ, becoming again evident in a narrow band about one-half the distance to the pseudoraphe. L. 50-120 µ. Along the coast. More common southward. Pl. 35, Fig. 1. {128}SURIRELLA FEBIGERII LEWIS Valve ovate-lanceolate; costæ about 2½ in 10 µ with punctate interspaces extending half the distance toward the median hyaline area, which is divided longitudinally on each side of the narrow pseudoraphe by two longitudinal bands composed of short, transverse, irregular, punctate lines. Along the coast. Pl. 36, Fig. 3. SECTION 4 (STENOPTEROBIA) SURIRELLA ANCEPS LEWIS Frustule linear, straight or nearly so; valve sigmoid with rounded apices; costæ marginal, nearly obsolete; striæ distinct, about 15 in 10 µ; pseudoraphe wide. L. to 320 µ. Hammonton Pond and Tom's River, N. J. Pl. 34, Fig. 2. SURIRELLA INTERMEDIA LEWIS Frustule linear, straight, widened at the truncate ends; valve linear, sigmoid, tapering to the sub-acute ends; costæ about 5 in 10 µ; striæ about 20 in 10 µ. L. variable. Hammonton Pond, N. J. Pl. 34, Fig. 3; Pl. 39, Fig. 9 (zone view). This, perhaps, is forma sub-acuta Fricke. Fig. 7, Pl. 34, is probably a small form of S. intermedia, from Willistown, Pa. It resembles a Nitzschia. SURIRELLA DELICATISSIMA LEWIS Frustule linear, rounded at the ends; valve linear-lanceolate, sometimes very slightly constricted in the middle, with acute apices; costæ, 5 in 10 µ; striæ about 20 in 10 µ; pseudoraphe well defined, lanceolate. L. to 90 µ. Fresh water. Newtown Square. Pl. 34, Figs. 5 and 6 (small forms). SURIRELLA ARCTISSIMA A. S. Valve linear, tapering to the sub-acute ends; costæ marginal, 5 in 10 µ; striæ, 18 in 10 µ; pseudoraphe not evident. L. 184 µ. May's Landing, N. J. Pl. 34, Fig. 4. Fig. 10, Pl. 39, is a small form from Newtown Square, Pa., in which the length is 86 µ, the costæ 5 and the striæ 16 in 10 µ. PODOCYSTIS KUETZ. (1844) (pous, a foot, and cystis, a bag) Frustules cuneate, similar to Surirella, but attached by short stipes to other algæ; valve obovate. {129}PODOCYSTIS ADRIATICA KUETZ.