Surirella TURPIN (1828)
(named after Dr. Suriray, a physician of Havre)
Valve linear, elliptical or ovate; pseudoraphe linear or lanceolate; a marginal keel forming wings or alæ seen in zone view; costæ short or reaching the pseudoraphe, frequently with intercostal striæ more or less evident.
The genus is divided by Grunow according to the length and form of the costæ. I include Stenopterobia.
Section 1.—Costæ of nearly equal width throughout, reaching the pseudoraphe.
Section 2.—Costæ short or marginal.
Section 3.—Costæ dilated at the margin, attenuated toward the pseudoraphe.
Section 4.—Valve having the appearance of Nitzschia, with inconspicuous alæ (Stenopterobia).
The endochrome consists of two laminate chromatophores, one on each valve.
The auxospores are single, originating from the union of two frustules (H. L. Smith).