THE NAUTILUS. 



75 



Fig. 2, T. dioscoricola (C. B. Ad.) X 16.6, alt. 1.38, diam. 

 1.27 mm. 



Fig. 3, T. caeca (Guppy) X 16.6, alt. 1.67, diam. 1.73 mm. 

 Fig. 4, C. e. floridanum Clapp X 21, alt. 1.73, diam. 0.78 mm. 

 Fig. 5, C. e. floridanum Clapp X 21, alt. 1.64, diam. 0.72 mm. 

 Fig. 6, C. e. floridanum Clapp X 20, alt. 1.73, diam. 0.66 mm. 



THE ANATOMY OF TWO AFRICAN NAYADES, UNIO CAFFER AND 

 SPATHA WAHLBERGI. 



BY A. E. ORTMANN. 



Unio caffer Krauss, Sued Afr. Moll. 1848. 



Nodularia caffer Simpson, Synopsis, 1900, p. 825. 



Unio caffer Simpson, Descript. Catal. 1914, p. 574. 



When Simpson placed this species in Nodularia, the anatomy 

 of only two species of this genus was known, and these had the 

 inner gills marsupial. We know now, that Simpson's Nodularia 

 is altogether a conglomerate of entirely heterogeneous forms. 

 The present species was placed by Simpson (in 1914) in Unio, 

 since he had seen gravid specimens. But he does not give any 

 particulars as to the structure of the soft parts, and thus it is 

 desirable to give an account of them. 



I am indebted to B. Walker for the soft parts of a number of 

 specimens of this species, collected at two localities; Lindague 

 Spruit, Natal (trib. to Little Tugela River, coll. in July 1913); 

 and Premier Mine Pumping Station, junction of Elands and 

 Wilge River, near Pretoria, Transvaal (coll. April 1914). 



The gravid females collected in July had mostly eggs, but 

 one of them had glochidia; of those collected in April only one 

 female was gravid, and also had glochidia. It is hardly possible 

 to draw from these dates a conclusion as to the breeding season, 

 except that it might begin in July, provided that there is at all 

 a definite season. 



Anatomy: Anal opening separated from the supraanal opening 

 by a moderate mantle connection, slightly shorter than the 

 anal. Supraanal about as long as or slightly longer than the 

 anal. The latter with the inner edge almost smooth. Branchial 



