1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 111 
(EK. v. Martens) because it was based upon shells from within our terri- 
tory agreeing fully with those prevalent in the regions covered by our 
Congo collections. 
Lymnea (Radix) natalensis exserta (E. v. Martens) 
Limneus natalensis Krauss var. exsertus E. von Marrens, 1866, Malakoz. 
Blatter, XITI, p. 101, Pl. 111, figs. 8 and 9 (var. erectus on Plate). (Type locality: 
Ain Zaba near Zazega, 6,000 ft., Eritrea). 
Limnxa (Radix) exserta E. v. Martens. Bourcurenat, 1883, Ann. Se. Nat. 
Zool., (6) XV, pp. 90 and 125. E. v. Martens, 1897, ‘Deutsch Ost Afr., IV, Be- 
schalte Weichth.,’ p. 136, Pl. v1, fig. 7. DauTzENBERG AND GERMAIN, 1914, Rev. 
Zool. Afric., IV, 1, p. 40. 
Limnexa (Radix) natalensis var. exserta E. v. Martens. GErmatn, 1919, Bull. 
Mus. Nat. Hist. Paris, p. 185; 1920, ‘Voyage dans |’Afrique Orientale Anglaise 
(1912-1913) par G. Babault, Moll. Terr. Fluv.,’ pp. 181 and 185. 
Limneza exerta E. v. Martens. PottonerRa, 1898, Boll. Mus. Zool. Anat. Comp. 
Torino, XIII, No. 313, p. 10. 
Dautzenberg and Germain record this form from Lukonzolwa (in 
Lake Moero), the Lubumbashi River, and the Luvua River (J. Bequaert 
Coll.). We have examined a specimen from the lot of the Lubumbashi 
River and cannot separate it from the other Katanga specimens which 
are recorded below as L. n. undussume (E. v. Martens). 
Lymneza (Radix) natalensis undussume (I. v. Martens) 
Plate XI, Figures 1-1f, 2-2c, 4, and 5-5b 
Limnea (Radix) undussume E. v. Mart ENs, 1897 ‘Deutsch Ost Afr., IV, Be- 
schalte Weichth., p. 135, Pl. 1, fig. 18 and Pl. v1, figs. land 5. J. Tureis, 1911, 
‘Wiss. Ergebn. D. Z. Afr. Exp. (1907-1908),’ ITI, p. 208. DauTzENBERG AND GERMAIN, 
1914, Rev. Zool. Afric., IV, 1, p. 39. Gurmatn, 1916, Bull. Mus. Hist. Nat. Paris, 
p. 194. 
Undussuma, in a brook beyond the Tararo (type locality); smaller specimens from 
Rumande on the western shore of Lake Edward; somewhat different specimens from 
Kigogo (district of the chief Karungo), east of the Semliki, in 0° 20’ N. (all Stuhlmann 
Coll.); Lake Edward (Gromier Coll.); Kisantu; Bukama; Lualaba River at Kibon- 
do (between Kikondja and Bukama) (J. Bequaert Coll.). Lake Mohasi in Ruanda 
(Schubotz Coll.). 
Irumu, in a brook of the savanna! (J. Bequaert Coll.). Faradje 
(Lang and Chapin Coll.). Tshikapa; Lukungu River at Kidada and 
between Kidada and Kitobola; Luebo (H. Schouteden Coll.). Ipamu 
(Vanderijst Coll.). Hemptinne-St.-Benoit (Callewaert Coll). Lubum- 
bashi River near Elisabethville (Michael Bequaert Coll.). We have also 
1These specimens come practically from the type locality of undussume as may be seen from the 
map Eublished in the ‘Report on Congo Land Mollusks’ (1919, Bull. American Mus. Nat. Hist., XL, 
p. 17) 
