18/7.J MR. E. A. SMITH ON SHELLS FROM LAKE NYASSA. 721 



ing's collection, said to have been from the Red Sea. The shell from 

 Mozambique agrees perfectly with the type, except that the poste- 

 rior end IS rather less produced. I should add that the figure in 

 the Conch. Icon.' considerably exaggerates the beaked appearance of 

 this portion of the type shell. The lunule is elongate, narrow, and 

 detined by a simple striation on each valve. 



5. DONAX MADAGASCARIENSIS, Wood. 



Donax madagascariensis, Wood, Index Testaceolog. SuppI p 5 

 pi. 2. f. 3; Sowerby, Thesaurus, iii. pi. 280. f. 16; Reeve, Conch! 

 Icon. viu. sp. 50. 



D. Keyii, A. Adams, P. Z. S. 185^, p. 87. 



Hab. Macusi River, near Quilimane, East Africa. 



The radiating striae and the ridges between them are much more 

 strongly developed on the posterior cordiform area than on the an- 

 terior surface. On the other hand the oblique ridges on the latter 

 portion of the shell are much stronger than on the former, where 

 they become thin lamellae. The lines of growth are curiously pre- 

 sent on the obhque costae, near the anterior ventral margin of the 

 valves, but not visible in the interstices between them. 



• 6. DoNAx ^MULTJS. (Plate LXXV. figs. 23-25.) 



Shell small, triangular, somewhat elongate, very inequilateral 

 produced anteriorly, compressed and narrowly rounded, posterior 

 area cordiform, not very acute at the margins, slightly sinuated at 

 the middle ; radiately striate, except for a narrow spac'e at the ante- 

 rior dorsal slope ; the striae are very fine, equidistant, those on the 

 posterior area deeper and wider, with distinct intermediate lirulse 

 which are decussated by still more prominent obliquely ascending 

 ones, which do not pass beyond the rounded carina; umbones 

 acute, but little incurved ; interior dorsal slope rectilinearly slopin- 

 posterior very suddenly inclined ; ventral margin straightish ; lunu?e 

 hnear ; ligament small, prominent. 



Colour yellow, purplish, or cinereous, generally varied with darker 

 concentric bands and purplish radiating rays, most distinct within 

 the valves, which are more or less purple, generally white at the 

 crenulated margins. 



Length 9^ millims., height (i, thickness 4. 



Hab. Mouth of the Macusi River, near Quilimane. 



This pretty species reminds one very much of the West-African 

 I), elongatvs. However, it is a trifle shorter, has not the ru«^ose 

 line on the posterior area, nor the flatness in the centre of that p° rt. 



EXPLANATION OP PLATES LXXIV. & LXXV. 

 Plate LXXIV. 



Fig. 1, 2. Paludina jeffreysi, p. 716. 



3, 4. ccrpiUata, p. 717. 



5, 6. rv/irr/so?ii, p. 717. 



Fig. 7. Lanistcs affinis, p. 716. 



8, 9. nyassanus, p. 7ir>. 



10, 11. solidiis. p. 716. 



