The Non-Marine Mollusca of Portuguese East Africa. 



175 



long as it still shows trace of keel ; suture simple, well defined. Aperture 

 subovate, peristome simple, acute ; outer lip nearly straight in profile, 

 receding slightly to the base ; columella nearly white, concave in the type, 

 with margin extremely narrowly and shortly reftexed, forming a minute 

 rima, but very variable, as in other specimens it may be either straight or 

 concave, and slightly truncate at the base, without marginal reflection. 



Long. 22-0, lat. 8-7 ; apert. alt. 7-7, lat. 4-8 ; last whorl 12-1 mm. 



Hab. L. Marques. District north of Macequece (Cressy). 



Text-fig. 20. — Pseitdoglessula {Pseudocerastus) cre.%syi, Conn. 

 Apical sculpture ; x 32. 



The largest specimen seen measures 26-3 X 9-75 mm. 



The distant apical sculpture (text-fig. 22) distinguishes this fine species 

 from all of its allies except conradti Mts. and subcarinifera Smith, both of 

 which are smaller forms. 



The fact of its live animal being available for examination renders it 

 advisable to select as type a shell which is slightly abnormal, since the 

 undue inflation of the outer lip causes the aperture to appear out of line 

 with the axis, a character which, although not unusual, is not general in 

 this species. The rimation, which in this case is of no specific value, is to 

 some extent dependent on this inflation, as when the columella is straight 



