Mr. E. A. Smith on African Mollusca. 317 



Neuquen, Patagonia*. Mr. Mawson's discovery of the 

 Pterodactyl seems to be the first of the kind in the Southern 

 Hemispliere ; that of the Plesiosaur adds another important 

 locality to the known distribution of an order that has an 

 equally wide geographical range in both Hemispheres. 



XLII. — Notes on African Mollusca. By Edgar A. Smith. 



I. Unionib^ of South Africa. 



At present nine species of this family have been described from 

 the southern extremity of the African continent, namely seven 

 so-called species of the genus Unio and two species of Mutela. 

 Five, if not six, of the forms of Unio really belong, I believe, 

 to one and the same species. They have been separated on 

 account of slight differences of form and sculpture, which, 

 when a large series of specimens is examined, prove to be 

 very unreliable and inconstant. Intermediate forms both in 

 respect of outline and sculpture are met with, showing that 

 the separation of these various forms cannot be maintained. 

 The synonymy is as follows : — 



1. Unio caffer^ Krauss. 



1848. TJnio cafer, Krauss, Siiclafr. MoU. p. 18, pi. i. fig. 14. 



1856. U7iio cc^er, Kiister, Couch.-Cab. p. 143, pi. xlii. figs. 2, 3. 



1866. Unio caffer, Sowerby, Concb. Icon. pi. xli. fig. 226. 



1850. Unio Verreauxianus, Lea, Proc. Acad. Nat. Sci. Philad. vol. viii. 



p. 94. 

 1858. Unio Verreauxianus, id. Journ. Acad. Nat. Sci. Pbilad. vol. iii. 



p. 301, pi. xxvii. fig. 16. 

 1868. Unio Verreauxianus, Sowerby, I. c. pi. Ixix. fig. 352. 

 1850. Unio africatius, Lea, Proc. Acad. Nat. Sci. Philad. vol. viii. 



p. 94. 

 1858. Unio africanus, id. Journal, vol. iii. p. 300, pi. xxvii. fig. 15. 



1865. Unio africanus, Sowerby, I. c, pi. xxii. fig. 100 (wrong locality 

 given). 



1864. Uiio natalensis, Lea, Proc. Ac. N. Sci. Phil. vol. xxii. p. 113. 



1866. Unio natalensis, id. journal, vol. vi. p. 59, pi. xx. fig. 57. 

 1868. Unio natalensis, Sowerby, I. c, pi. ixxi. fig. 362. 



1885. Unio vaalensis, Chaper, Bull. See. Zool. France, vol. x, p 480, 

 pi, xi. figs. 1-3. 



Hah. Rivers of Natal and Cape Colony. 



This species has the surface ornamented with concentric 



* F. P. Moreno, '' Le Mus^e de La Plata " (in ' Revista de Museo de 

 la Plata,' vol. i., 1890), p. 18. 



