(Hendey, in litt., does not consider this a pseudo-raphe), and marginal, more or less elevated, keels produced into wings (alae) containing the raphes on each side. Distinct canal pores usually visible.

278. Surirella fastuosa (Ehr.) Kütz. (Pl. 8, Fig. 121a.)

Kütz., 1844, 62, 28, 19.

Boyer, 1916, 127, 35, 1.

Hend, 1951, 75, 9, 7.

Navicula fastuosa Ehr., 1841, 19.

Cells solitary; frustule in valve view ovate or broadly elliptic; valves with costae inflated at margins, tapering to central area which is broadly lanceolate and hyaline or very faintly striate; striae more evident at margins, and toward centre where they are well defined and parallel to the margins. Length, 65μ.

Distribution. Estuarine-neritic, marine; benthic and epontic, on weeds and fouling test plates. Australia: Heron Island, Moreton Bay, Lake Macquarie, Botany Bay, Port Hacking. New Zealand Hauraki Gulf, Lyall Bay (Petit, 1877). Frequent but never abundant. var.? (Pl. 8, Fig. 121b.)

Differs from type in narrower central area, and in having the ratio of the septa in the central area to those of margin of three to one.

Distribution. Brackish water; Port Hacking.

279. Surirella gemma (Ehr.) Kütz., 1844. (Pl. 8, Fig. 122.)

Kütz., 1844, 62, 7, 11.

Boyer, 1916, 125, 36, 4, 1927, 540.

Hend., 1951, 76, 8, 10.

Navicula gemma Ehr., 1840, 76, 4, 5.

Cells solitary; frustule in girdle view narrow-cuneate, valves ovate to elliptic-ovate; alae very reduced; axial area very narrow; surface faintly striate between unequally distant costae, which reach median line. Length, 75–80μ.

Distribution. Estuarine; benthic, mesohaline, epiphytic, infrequent. Australia: Lake Macquarie, Port Hacking, Botany Bay. New Zealand: Hauraki Gulf.

280. Surirella tenera Greg. (Pl. 8, Fig. 123a, b; Pl. 9, Fig. 123c.)

Greg., 1856, 4, 11.

Boyer, 1927b, 540.

Valves ovate, rounded at one end, acute at other; central space narrow, well defined; costae indistinct, striae punctate, evident near margin. Length, 100–150μ.

Distribution. Australia: Port Hacking, Lake Dobson.

var. ? (Pl. 8, Fig. 123b.)

Distribution. Australia: Lake Dobson.

281. Surirella javanica A.S. (Pl. 8, Fig. 124a, b.)

A.S., 1875, 4, 13.

Valves with rounded ends, slightly constricted in middle, girdle straight; central space lanceolate, well-defined; costae distinct, about 17 on each side; costae of central area alternating. Length, 70μ.

Distribution. Australia: Heron Island, Port Denison (Grun.).

282. Surirella ovalis Breb. (Pl. 8, Fig. 125.)

In Kütz., 1844, 61.

Boyer, 1916, 39, 11; 1927b, 541.

Valves ovate; costae short, marginal, radiate, often unequal; central space ovate, indistinctly costate; striae scarcely visible. Length, 40–80μ.

Distribution. Fresh later. Australia: Lake Dobson.