Lake Tanganyika and East Africa. 429 



liquis leviter flexuosis sculpti. Sutura simplex, aliquanto obli- 

 qua, profundiuscula. Apertura parva, longitudinis totius i haud 

 sequans. Columella perarcuata, inferne abrupte truncata. 



Hob. Near Lake Tanganyika (Thomson), 



Streptaxis Craveni. 



Testa anguste umbilicata, oblique distorta, laevis, nitida, sordido 

 lactea. Anfr. 7, leviter convexi, infra suturam confertim costu- 

 latim striati ; anfr. ult. antice subito descendens, inde supra anfr. 

 penultimum aliquanto ascendens, peroblique excentricus. Aper- 

 tura obliqua, haud denticulata. Labrum ad suturam sinuatum, 

 in medio prominulum, arcuatum, inferne obliquum, leviter in- 

 crassatum et reflexum. Columella incrassata, anguste reflexa, 

 parum areuata. 



Long. 29 millim., diam. 22 ; aperturas long. 15 millim., lat. 12i. 

 Hab. On hills between the mouth of the river Dana and 



Mombasa, E. Africa (Dr. J. Kirk). 



Streptaxis gigas. 

 Testa maxima, alba, late umbilicata. Anfr. 6, regulariter accre- 

 sceutes, convexiusculi, costulis perarcuatis, validis, confertis in- 

 structi; anfr. ult. infra peripberiam nitidus, lineis incrementi 

 tenuibus sculptus. Apertura magna, sublunata. Labrum obli- 

 quum, superne arcuatum et productum, inferne late sinuatum, 

 tenue. Columella aliquanto supra expansa. 

 Alt. 30 millim., diam. 33 ; apertura? long. 17| millim., lat. 15. 

 Hob. Between Lake Nyassa and the east coast (Thomson) . 

 Streptaxis mozambicensis. 

 Testa parva, rimata, albida, laevis, nitida. Anfr. 6, convexi, infra 

 suturam profundam crenulati ; anfr. ultimus obliquus, antice 

 descendens, prope labrum breviter ascendens, supra aperturam 

 paulo complanatus. Apertura circulariter lunata, parva, haud 

 denticulata. Labrum leviter arcuatum, obliquum, anguste ex- 

 pansum. Margo columellaris latius expansus. 

 Alt. 7| millim., diam. anfr. ult. 4^ ; aperturoelong. 3 millim., lat. 2-1.. 

 Hab. Between Lake Nyassa and the east coast (Thomson) . 

 Unio Horei. 

 Testa oblonga, subrhomboidalis, postice leviter latior, insequilateralis, 

 tenuiuscula, margaritacea, epidermide tenui flavo-olivacea induta, 

 concentrice striata, supra umbones corrugata, utrinque prope mar- 

 ginem dorsalcm radiatim plicata. Margo dorsalis rectiusculus ; 

 margo anterior late curvatus, posterior obliquus parum arcuatus, 

 ventralis leviter curvatus. Facies interna alba, margaritacea. 

 Dentes anteriores et posteriores lamellrcforines. Cicatrices parum 

 profunda;, anterior profundior, subquadrata. 

 Long. 161 millim., lat. 25 ; diam. 9^ millim. 



Hab. Lake Tanganyika (Thomson). 



