1893.] SHELLS FROM BRITISH CENTRAL APEICA. 641 



interna ptdcTierrime margaritacea, iriclescens, mterdnm pallide 

 rosacea; dens cardinalis anticus valvce sinistrce elongatus, leviter 

 corrvr/atus, v. de.vtrce dujde.r, dens iiosticus vnicns v. de.rtrce 

 ehnijahis, rectus, tenuis, prominens, v. sinistrce duplex. 

 Lonrjii. 53 millim., alt. 30, diam. 9|. 

 Hai). Lake M^-erii {11. Crawsliaii). 



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 Unto d.elj^hims, 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 Ili/ria elongata, Swainsou, from British Guiana (Exotic 

 Conch, p. 29, pi. xxiv.). 



31. Pliodon spekei (Woodward). 



Hah. 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 the " species " from the Central African lakes 

 described by'that author, they are of little or no value. 



32. Mtjtela (Spatha) kyassaeksis, Lea. 



Hah. Nyasa (A. Whyte). 



The specimens in the present collection are considerably larger 

 than Lea's type, being 3| inches long, 2| high, and 1| in diameter. 

 Besides being more oval than S. rubens, as pointed out by Lea, 

 this species is more inreqiiilateral, the beaks being situated mucli 

 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 jolinstoni, p. 633. 



2. karongana, p. 633. 



3, 4. HelLv {Fella) whytei, p. 634. 

 n, 6. Vivipanis mweruensis, p. 636. 



7. , var. ■pagodiformis, p. 630. 



8. crawshayi, p. 637. 



9. Cleopatra johistoni, p. 637. 



10. mweruensis, p. 637. 



11. Melania woodwardi, p. 638. 



12. mweruensis, p. 639. 



13. imitatrix, p. 639. 



14. crawshayi, p. 639. 



15. Physa karongensis, p. 640. 

 16, 17. Unio nyassaensis, p. 640. 



18, 19, 20. johistoni, p. 640. 



1 Nouveautes Malacol., I. TJnionidse et Iridinidse du lac Tanganika, 1886, 

 pp. 66-93; Iconogr. Malacol. Tanganika, 1888, pis. xxsi.-xxxv. 



