Shells from Lake Tanganyika. 95 



canaliculation ; the outer lip is faintly effuse and prominent, 

 and the coluraellar folds are similar and in the same position 

 in each. 



Turbonillal terebriformis. 



Testa subulata, nitida, albo-grisea, superne pallide lilacea, oblique 

 costata et striata ; anfractus circiter 18, lente acci'escentes, api- 

 cales — ?, sequentes 3-4 convexi, longitudinaliter teiniiter striati, 

 circa medium biangulati, caeteri convexi (superioribus quam infe- 

 rioribus couvexioribus, fortissimo costatis), costis obliquis, sub- 

 acutis, distantibus, instructi, lineis incrementi tenuissimis oblique 

 flexuosis striati ; anfr. ultimiis ad peripheriam rotunde subangu- 

 latus, costis inferne obsoletis ; apertura longit. totius i adaequans ; 

 columella rectiuscula, superne obsolete uniplicata. 



Longit. 12 millim., diam. 2-|. 



The costae (about eight in number) on the upper wliorls are 

 stronger and further apart than on the lower ones, and are 

 more convex in outline ; on the last volution they number 

 about twelve or thirteen. The aperture is somewhat broken 

 away anteriorly, so that the generic position of this interesting 

 species is not quite certain. The texture and costation some- 

 what recall the appearance of some species of Terehra. 



Streptostele Horei. 



Testa parva, elongata, anguste rimata, cerea ; anfractus 7|, apicales 

 laeves, caeteri convexiusculi, sutura profunda leviter obliqua se- 

 juncti, costoUis confertis, erectis, superne ad suturam denticulatis 

 instructi, inter costellas nitidi ; apertura mediocris, longitudiuis 

 totius I subasquans ; perist. incrassatum, album, anguste retiexura, 

 margine externo prope suturam intus sinuate, columellari dilatato, 

 rimam semiobtegente ; columella indistincte contorta ; paries 

 anfr. ultimi prope extremitatem labri tuberculis duobis parvis 

 munitus. 



Longit. 6.^ millim., diam. 2 ; apertura 1 1 longa et lata. 



This species is well distinguished by the fine longitudinal 

 riblels, which at the upper extremities give a finely denticu- 

 late appearance to the deep suture. The single specimen 

 under examination exhibits two denticles at the upper part of 

 the aperture upon the wall of the body-whorl — one near the 

 upper end of the upper lip, the other near it but further 

 within the mouth. The labrum is conspicuously sinuated 

 above near the suture and has a tubercular thickening within 

 below the sinus. 



