The Non-Marine Mollusca of Portuguese East Africa. 151 



as Pimctum cryophilum (Mts.), from Abyssinia, of which the radula has been 

 figured by Jickeli.* It is true that Jickeli does not show the three smaller 

 cusps, but these cusps are so minute in Punctum and Laoma that they can 

 only be clearly seen under a yV-in. oil-immersion objective, and have there- 

 fore generally been overlooked until recently. 



Punctum pallidum Conn., 1922. 



(Plate IV, fig. 17.) 



1922. Punctum pallidum Conn., A.M.N.H. x, p. 119. D. 



Hah. L. Marques. Mount Vengo, 5500 ft. (Cressy). 



The jaw (text-fig. 16, A) is horse-shoe shaped, and is composed of about 



B 



Text-fig. 16. — Punctum jyallidum Conn., Vengo Mountain. 



A. Jaw; X300. 



B. Half of a transverse row of teeth from the radula ; X 1600. 



eighteen thin imbricating plates, which appear to have a fibrous structure. 

 The plates are largest laterally, where they overlap one another to the extent 

 of about half their width ; in the middle of the jaw they only overlap very 

 slightly. 



The radula (text-fig. 16, B) measures -32 X -08 mm. when flattened out. 

 The individual teeth are extremely small, with minute cusps. The central 

 teeth are rather narrow, with oblong basal plates. They are tricuspid, but 

 the mesocones are only about one-third the length of the basal plates, and 

 the ectocones about one-third the length of the mesocones. The lateral 

 teeth, which are slightly broader than the central teeth, each have two 

 principal cusps, the mesocone and the ectocone, which are similar to each 

 other and of about the same size as the mesocones of the central teeth. 

 Alternating with these two cusps there are three more, exceedingly minute 



* Nova Acta Acad. Cses. Leop.-Carol., vol. xxxvii, 1874, p. 55, pi. i, fig. 4. 



