Mollusca from Central Africa. 63 



Hab. Karonga, northern end of Lake Nyassa (Mgr. Le- 

 chaptois) . 



I have before me a good series of this shell, the largest 

 specimen measuring 42 - 5 by 97 mm. 



Spatha approximans , sp. n. (Fig. 14.) 



Shell closely allied to S. nyasse?isis, Lea *, but broader 

 posteriorly, more acuminate, and covered with a periostracum 

 much paler in colour ; the interior of the shell is exceedingly 

 finely granulate. 



Long. 64, lat. 100 mm. 



Hab. Shire River, at a point from 3 to 4 kilometres to the 

 south of Lake Nyassa (Mgr. Lechaptois). 



Spatha bertilloniana, sp. n. (Fig. 15.) 



Shell moderately flat, rectangularly ovate, solid, scarcely 

 angled posteriorly, covered with a fine reddish-chestnut peri- 

 ostracum, sculptured with coarse, broad, somewhat distant, 

 concentric growth-lines and very fine, transverse, radiate 

 stria? ; umbones small, not prominent ; dorsal margin nearly 

 straight, somewhat ascending ; ventral margin constricted 

 towards the middle ; anterior side squarely rounded ; poste- 

 rior side broadly produced, bluntly acuminate; anterior 

 adductor scars ovate, well impressed ; posterior adductor scars 

 broadly ovate, moderately impressed ; infra-umbonal visceral 

 scar in right valve broad, in left valve small, short, and deep; 

 palleal margin coarsely defined ; interior of shell nacreous, 

 pinkish white, iridescent, especially towards the posterior side, 

 sculptured with fine, interlacing, irregular, wavy striae con- 

 verging towards the centre of the shell. 



Long. 51 - 5, lat. 97 mm. 



Hab. Karonga, north end of Lake Nyassa. 



A very handsome species, of which the internal sculpture 

 is most curious and may, in a measure, be compared to the 

 markings of finger-prints ; in the single specimen before me 

 this remarkable sculpture is much more apparent in the right 

 than in the left valve. 



EXPLANATION OF THE PLATES. 



Plate IV. 



Fig. I. Helicarion perfragilis, sp. n. 



Fig. 2. Thapsia gereti, sp. n. 



Fig. 3. Subulina maringoensis, sp. n. 



* Proc. Zool. Soc. London, 1877, p. 719. 



