| OCR Text |
Show 1893.] SHELLS FROM BRITISH CENTRAL AFRICA. 641 interna pulcherrime margaritacea, iridescens, interdum pallide rosacea; dens cardinalis anticus valvce sinistrce elongatus, corrugatus, v. dextrce duplex, dens posticus unicus v. dextrce. elongatus, rectus, tenuis, prominens, v. sinistrce duplex. Longit. 53 millim., alt. 30, diam. 9|. Hab. Lake Mweru (R. Graiushay). The shells here described are probably only small representatives of this species. The species is quite unlike any other known form from Africa. It recalls the Unio delphinus, Gruner, from Malacca, on account of the dorsal wing, and agrees with it also exactly in the hinge-dentition and the ligament. In form it even more closely resembles Hyria elongata, Swainson, from British Guiana (Exotic Conch, p. 29, pi. xxiv.). 31. PLIODON SPEKEI (Woodward). Hab. Sumbu, S.E. Tanganyika (R. Crawshay). Only one species of this genus from Lake Tanganyika has come under the writer's observation, although as many as twenty-six so-called species are enumerated by Bourguignat \ Like many of tbe " species" from the Central African lakes described by that author, they are of little or no value. 32. MUTELA (SPATHA) NYASSAENSIS, Lea. Hab. Nyasa (A. Whyte). The specimens in the present collection are considerably larger than Lea's type, being 3f inches long, 2\ high, and \\ in diameter. Besides being more oval than S. rubens, as pointed out by Lea, this species is more inaequilateral, the beaks being situated much more anteriorly and less prominent. The impression of the visceral-sac attachment near the anterior adductor scar is smaller also. EXPLANATION OF PLATE LIX. Fig. 1. Ennea johnstoni, p. 633. 2. karongana, p. 633. 3, 4. Helix (Pella) whytei, p. 634. 5, 6. Viviparus mweruensis, p. 636. 7. , var. pagodiformis, p. 636. 8. crawshayi, p. 637. 9. Cleopatra johnstoni, p. 637. 10. mweruensis, p. 637. 11. Melania woodwardi, p. 638. 12. mweruensis, p. 639. 13. imitatrix, p. 639. 14, crawshayi, p. 639. 15. Phys'a karongensis, p. 640. 16, 17. Unio nyassaensis, p. 640. 18, 19, 20. johnstoni, p. 640. 1 Nouveautes Malacol., I. Unionidas et Iridmidas du lac Tanganika, 1886, >. 66-93 : Iconogr. Malacol. Tanganika, 1888, pis. xxxi.-xxxv. |
