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Show 1877.] MR. E. A. SMITH ON SHELLS FROM LAKE NYASSA. 719 23. UNIO NYASSAENSIS, Lea. Unio nyassaensis, Lea, Proc. Acad. Nat. Sci. Philad. 1864, p. 108 ; Journ. Acad. Nat. Sci. Philad. (1866), vol. vi. p. 33, pl. 12. f. 32. U. nyassee, Sowerby, Conch. Icon. sp. 224, f. 224, a, b. U. nyassensis, Lea, Sowerb. op. cit. Errata and Index. Var.= £7. kirkii, Lea, I. c. p. 108 ; Journal, p. 32, pl. 12. f. 30. Var. = U". aferula, Lea, I. c. p. 109 ; Journal, p. 34, pl. 13. f. 34. Hab. Lake Nyassa (Dr. Kirk). This species, like many others of this genus, is subject to considerable variation in form and sculpture. The three forms described by Lea are evidently nothing more than mere varieties of one and the same shell. 24. SPATHA ALATA, Lea. Spatha alata, Lea, Proc. Acad. Nat. Sci. Philad. 1864, p. 109 ; Journ. Acad. Nat. Sci. (1866) vol. vi. p. 35, pl. 12. f. 31. Hab. Lake Nyassa (Dr. Kirk). 25. SPATHA NYASSAENSIS, Lea. Spatha nyassaensis, Lea, I. c. p. 109 ; Journal Acad. Nat. Sci. Philad. p. 36, pl. 13. f. 33. Hab. Same as the preceding. II. MARINE SPECIES. 1. B U L L I A MOZAMBICENSIS, sp. nov. (Plate LXXV. fig. 18.) Shell elongate, acuminately spired, more or less livid in colour ; whorls nine, the two apical ones smooth and shining, the rest but slightly convex, separated by an oblique suture, sculptured with oblique, somewhat flexuous, fine and close-set plicae, which extend from suture to suture in the upper whorls, and gradually become obsolete about the middle of the last volution; these riblets or plications, which are about equal in thickness to the spaces between them, give the upper margins of the whorls a finely crenulated appearance, and are subgranulous, through being intersected by spiral striae, which gradually become wider apart as the shell increases ; they are about nine in number on the penultimate whorl; the last is encircled by about 13; and the keel which winds around its base is of a brown colour, and the portion of the whorl below it whitish ; mouth ovate-acuminate above, occupying a little more than § of the entire length of the shell, olive-brown or purplish-brown margined with white within the labrum and at the base; labrum thickened, acute at the edge, and inconspicuously sinuated above; columella arcuate in the middle, thinly coated with a white enamel, which, extending above the lip and winding along the suture, gradually vanishes as it proceeds up the spire. Length 32 millims.; diam. of last whorl 11 ; length of mouth \2\, width nearly 6. Operculum unguiculate, concentrically and transversely striated. Hab. Mouth of the Macusi River, Quilimane, E. Africa. 47* |