274 Bulletin American Museum of Natural History [Vol. LIIl 
The Middle American genus Pachychilus also stands close to Pota- 
doma. It agrees in being oviparous, with smooth mantle margin and 
similar teeth; but it differs by the less evolved, more closely spiral 
operculum. ‘The shells are strikingly similar in some species. 
PSs ’ 
CLL QPF a 
LRN 
{iP ; 4 <a 
SOM LE AOU GN Ee 
wr (7 oF Ei 5 ey NI 
ve 
ange 
wee J mitre 
PA ea x! 
. ED 
= ee) 200 
m0 0, 2H 
600 800 1000 Miles 
! 
4006008 Kilometers 
490 
30 40 SO 60 
Map 3. Distribution of the genus Potadoma. 
The following is a list of the species known at present: 
Potadoma alutacea Pilsbry and Bequaert. See p. 278. 
Potadoma bittikofert (Schepman) = Melania biittikoferi Scumpman, 188°, Notes 
Leyden Mus., X, p. 249, Pl. x, figs. 5a-c. St. Paul’s River, near Bavia, Liberia. 
Potadoma conulus (I. and H. C. Lea) =Melania conulus I. anp H. C. La, 
"1850, Proc. Zool. Soc. London, p. 190. Fernando Po. 
Potadoma. freethit (Gray) = Melania freethit Gray, 1831, ‘Zoolog. Miscellany,’ 
p. Il. M. frethit Gray, in Griffith, ‘Cuvier’s Anim. Kingdom,’ XII, Moll., Pl. 
XIV, fig. 2 (not of Brot, 1874, in Martini and Chemnitz, ‘Syst. Conch. Cao. ft, oa. 
Melaniaceen,’ p. 67, Pl. vir, fig. 7). M. nigritina MOoRELET, 1848, Rev. Zoolog. Soe. 
Cuviér., p. 355; and 1858, “Séries Conchyl.,’ I, p. 31, Pl. 1, fig. 8 (type locality: 
Gaboon). M. nigrita MorELEt, 1851, Journ. de Conchyl., IT, p. 191, Pl. v, fig. 2. 
