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Annals of the Smith African Museut 



truncatum, but Messrs. West (l<>c. cit., p. 148) consider that the 

 character is so variable that it is not enough to warrant a special 

 variety; in sample 3, however, all the specimens seen possessed this 

 character to a very pronounced extent. G. S. West has already 

 recorded C acerosum from other parts of South Africa. 



6. Closterium libellula, Pocke, Physiol. Stud., 1847, p. 58, Tab. Ill, 

 fig. 29. (Syn. : Penium libellula (Focke), Nordst. ; W. & G. S. West, 

 op. cit., i. 1904, p. 71. PI. VII, figs. 6, 7). 



Fig. 23. — Closterium pritchardianum, Arch., forma, minor, n. form. 

 a. Entire cell, showing the general shape. b. Apex of a semi-cell, 

 more strongly enfarged. a :< 220: b x (ioo. 



Sample 26. 



Long, cell., 220-375 /x ; lat., 39-51 ^; lat. apic, 6-9 ^. Some of 

 the individuals had unequally convex sides. 



7. Closterium pritchardianum, Arch.; W. & CI. S. West, op. cit.. i, 

 1904, p. 172, Pi. XXII, figs. 6-14. 



Samples 5, 26. 



Forma minor, nov. form. Long, cell., 264-285 /a; hit., 36-40 /x. 

 Margine ventrali fere recta, polis vix recurvis (Fig. 23). 



Samples 5, 26. 



I have been in some doubts about the reference of these specimens 

 to C. pritchardianum, but seeing that the general form of the cell and 



