496 Bulletin American Museum of Natural History [Vol. LIII 
Nile divide in 1869-71! and others were collected by the American Mu- 
seum Congo Expedition in the region of Niangara and Faradje. Many of 
the snails brought back by these travelers were undoubtedly obtained in 
the forest galleries which fringe most of the rivers of the Northeastern 
Congo savanna and which possess essentially the same molluscan fauna 
as the rain forest belt farther south, though the number of species is 
much smaller. In this category would come Achatina schweinfurthi E. v. 
Martens, originally discovered by Schweinfurth at Mt. Baginze on the 
Congo-Nile divide, and the slug Atoxon faradjense Pilsbry found by Lang 
and Chapin at Faradje. 
Whether the Ubangi Savanna District possesses typical, fragile 
grass-land Achatine, such as those that are known from the Upper 
Katanga, appears uncertain. On the other hand, Burtoa nilotica schwein- 
furtht E. v. Martens and Limicolaria festiva (v. Martens) seem to inhabit 
the savanna proper; during the dry season these snails bury themselves 
deep in the ground and close their aperture with a calcareous epiphragm. 
The manner in which large numbers of Ledoulxia mozambicensis (Pfeiffer) 
were estivating in the leaf-sheaths of wild bananas near Faradje has been 
described by H. Lang.2 He also found other typical savanna snails in 
the same locality: Rachis braunsit (v. Martens), R. béhmi delicatus Pils- 
bry, and Pachnadus herbigradus Pilsbry. The last-named species estivated 
in colonies within hollow twigs, five feet or more from the ground. 
3. Southern Congo Savanna District 
This district comprises the region south of the continuous belt of 
Guinea rain forest, between 4° and 8° to 9° 8. In the west it extends far 
beyond the borders of the Belgian Congo into Angola and includes most 
of the Portuguese Enclave of Kahinda. East of the Kasai it is bordered 
by the highlands of Marungu, Upper Katanga, and the Kasai-Zambesi 
watershed. From the mouth of the Congo to Lake Tanganyika it extends 
in longitude over some 1,800 kilometers, while from north to south it is 
about 300 kilometers wide. 
Topographical and geological conditions are rather varied over this 
large area, but the altitude is rarely over 1,300 m. and most of the coun- 
try is much below 500 m. to 800 m. Along the coast of the Atlantic one 
may distinguish a maritime zone forming a narrow strip, scarcely over 80 
1H. v. Martens. 1870. ‘Conchylien aus dem obern Nilgebiet.’ Malakoz. Blatter, XVII, pp. 32-36; 
18738.. Zusammenstellung der von Dr. Georg Schweinfurth in Afrika gesammelten Land und Siiss- 
wasser-Conchylien.’ Op. cit., X XI, pp. 37-46. 
71919, Bull. American Mus. Nat. Hist., XL, pp. 247-248, Pl. x; figs. 2 and 3: 
