AMPULLARIA.—VIVIPARA. 425 
A. geveana, Desh., A. glauca, L. (effusa, Miill.), and A. luteostoma, Swains., constitute 
a gradual passage from Ceratodes to the ordinary form of Ampullaria. 
All the species of this subgenus, like most of the true Ampullariw, have dark spiral 
bands, whereas no known Planorbis is distinctly banded. 
Geographical distribution: Costa Rica and the southernmost Caribbean islands 
(Tobago, Trinidad) to Southern Brazil and Argentina. 
21. Ampullaria rotula. (Tab. XXV. figg. 1, 1a, b.) 
Ampullaria rotula, Mousson, in Malak. Blatt. xvi. p- 183 (1869) °. 
Ceratodes rotula, Mousson, ibid. xxi. p. 19 (1873)?; Pfr. Novit. Conch. iv. p- 138, t. 1381. 
fige. 4-7 °. 
Rather inflated, greatest height (breadth) of the shell at the aperture distinctly more than half the greatest 
diameter ; upper face (the right in the creeping animal) slightly inserted, the first whorls even, the last 
two somewhat elevated above the centre, the last at this point obtusely angulated; lower face (left) 
deeply and broadly excavated, the whorls being on this side also obtusely angulated and falling off steeply 
towards the centre ; each whorl is thus distinctly seen as a spiral prominence in this excavation. Colour 
greenish-yellow or pale greenish-brown on the upper (right) face, darker on the lower (left) face; dark 
blackish-brown well-defined spiral bands, one or few narrow ones on the upper half, more on the under 
half of the periphery, none on the uppermost part ; in one specimen the broad periphery and the lower 
face are of dark colour, with scarcely perceptible darker bands, contrasting with the pale upper face. 
a. Diam. maj. 40, min. 29, alt. prope apert. 22; apert. diam. 15 millim. 
b. 9 34, ” 28, ” 18 5 ” 14 ” 
C. 29 28, ” 22, ” 14; ” 11 ” 
d. oe) 23, ” 17, 9 11 : 39 9 99 
a. Mousson’s measurements ; 6, c. Seebach’s specimens ; d. Van Patten’s specimen. 
Hab. Costa Rica (Van Patten & von Seebach, in Mus. Berol.). 
CotomBiA: Lower part of the Magdalena River (Wallis 1~*); Ocafia, east of this 
river (coll. Dunker); Rio Hacha (Sievers, Mus. Berol.). 
It is strange that neither H. Pittier nor P. Biolley has sent a specimen of this 
remarkable shell from Costa Rica; but as the Berlin Museum has received examples of 
it from that country from two different travellers, there cannot be any doubt as to its 
Central-American habitat. 
VIVIPARA. 
Vivipare, Cuvier, 1808 ; Lamarck, 1809. . ; 
Viviparus, Montfort, 1810; Frauenfeld, Verh. zool.-bot. Ges. Wien, xii. p. 1161 (1862). 
Vivipara, Sowerby, 1813. . . = 
Paludina, Lamarck, 1812 (part.), auct.; Fischer & Crosse, Miss. Scient. Mex., Mollusca, ii. p. 280 
(full description and historical account). 
Shell of moderate size, oval or conoidal, rather thin, brownish or horn-coloured, often 
with spiral sculpture or spiral bands; aperture oval, angulated above. Operculum 
horny, concentric. fe , 2 
A single pair of stout feelers, the right one in the male thickened and shortened. 
Viviparous. 
BIOL. CENTR.-AMER., Terr. and Flnviat. Mollusca, September 1899. 54 
