1899.] Oy LAND-SHELLS FBOM BBITISH CENTRAL AFRICA. 579 



3. On a Collection of Land- Shells from British Central 

 Africa. By Edgar A. Smith, F.Z.S. 



[Received April 13, 1899.] 

 (Plates XXXIII.-XXXV.) 



The collection about to be described was presented to the 

 British Museum by Sir Harry Johnston in 1896 and 1897, and a 

 brief notice of a portion of it has already appeared in his book 

 on ' British Central Africa ' (pp. 363, 364). It is of special 

 interest, as very little is known respecting the terrestrial IMollusca 

 of this particular region. The country to the north and east, in 

 German East Africa, has been conchologically explored by many 

 collectors, and a very valuable report upon the fauna has been 

 given by Dr. E. von Martens, in 1897, in a work entitled ' Be- 

 schalte Weichthiere Deutsch-Ost-Af rikas.' Only a very few species, 

 however, had previously been collected in Nyasaland, and reference 

 to these has already been made by the writer in the Societj^'s 

 ' Proceedings ' for 1891, p. 309. Although the present collection 

 contains examples of as many as twenty-tive new species out of a 

 total of forty-four enumerated, none of them are representatives 

 of new generic types, and the forecast given in the paper referred 

 to has, judging by the present collection, proved to be correct in 

 every respect \ The "interesting intermediate links connecting 

 some of the large species of Achatina " have been met with, and 

 a number of new species of other groups of Helicidse " have 

 been found." In working out this collection much difficulty was 

 experienced in determining the AcJiatince. The species appear to 

 grade one into the other, and the more examples we have, the 

 greater the trouble becomes. The genus is spread over the 

 greater part of Central and West Africa, as far north as Sene- 

 gambia, and each district seems to produce its special race, a 

 modification of some neighbouring form ; so that the separation of 

 species becomes more and more difficult through the discovery 

 of intermediate links from every fresh locality. The same may be 

 said of the Ennece, and indeed of most of the other groups. 



The specimens were obtained by Mr. Alexander Whyte, or 

 under his direction, at the following localities : — 



(1) Nyika Plateau, 7000 feet, towards the north end of Lake 

 Nyasa, on the west side ; (2) Mount Zomba, 6000 feet ; (3) Zomba 

 Plateau, 5000 feet; (4) Mount Chiradzulu, 5000 feet; and (5) 

 Malpsa, 6000 feet, all to the south of the lake. The Masuku 

 Plateau 6000-7000 feet, where several of the specimens were 

 obtained, is also probably in the same region. 



' The collection also contained a few slugs, including Atoxon tenhittun 

 Siinroth '?) and a species of Veroiiicclla. 



