The Non-Marine Mollusca of Portuguese East Africa. 



161 



RhacMs catenata (von Martens), 1860. 

 1860. Bulimus {Rhachis) catenatus Mts., Mai. Blatt. vi, p. 212, pi. 2, 



fig. 7. D.F. 



Hah. Mozambique. Querimba I. (Peters). 



Text-fig. 17, F represents a paratype in the British Museum. 



A 



% 



Text-fig. 17, F.— Rhachis catenata (Mts.), paratype, X 1. 



Genus Khachidina Thiele, 1911. 

 Shell usually perforate, comparatively globose, of moderate size and 

 frail texture, with a tendency to expansion of the peristome when fully 

 developed. The radula has been figured by Thiele.* 



Rhachidina melanacme (Pfr.), 1855. 

 1855. Bulimus melanacme Pfr., P.Z.S., p. 96, pi. 31, fig. 8. D.F. 

 1889. Pachnodus sesamorum. Ancey, Bgt., Moll. Afr. equat., p. 66, pi. 3, 



figs. 2-3. D.F. 



Hah. Mozambique, ex sacks of sesame {sesamorum, Ancey). Querimba 1. 



(Peters). 



L. Marques. Tette (Peters). 



The type of this species in the British Museum appears to be a slightly 

 distorted example, the last whorl being unduly swollen in relation to the 

 earlier ones, which are slightly less in diameter than in R. usagarica (Smith). 

 The shell also is a little thicker in texture, white, with a very black apex 

 and one thin dark brown peripheral band ; a few small dark brown spots 

 are irregularly grouped on all the whorls. Sesamorum, which I have not 

 seen, is certainly a synonym of this or the next species. 



Rhachidina usagarica (Smith), 1890. 

 1890. Rhachis usagarica Smith, A.M.N.H. vi, p. 152. pi. 5, fig. 5. D.F. 

 1897. Buliminus {Rhachis) melanacme Pfr.. var. usagaricus Smith, Mts. 

 D.-O.-A. iv, p. 76. N. 



* Arch. f. Moll.-k. liii, 1921, pi. 4, fig. 2. 



