424 MOLLUSCA. 
and of a somewhat reddish-fawn-colour ; in the smaller example the umbilical rim is 
completely closed, in the larger one nearly so. 
A. rufilineata, Reeve (Conch. Icon. x., Ampullaria, t. 2. fig. 7), is somewhat similar, 
but has a more open umbilicus and a shorter spire; it approaches nearer A. figulina, 
Spix. | 
Species of Ampullaria (sensu strict.) erroneously accredited to 
Mexico or Central America. 
A. reflera, Swains.: see note to A. flagellata (anted, p. 409). 
A. columbiensis, Sow. : see A. flagellata, var. tristrami (anted, p. 413). 
A. eximia, Dunker: ascribed in Paetel’s Catalogue, ed. 4, p. 478, and in his collection, 
to Mazatlan ; it is really from the Lake of Maracaibo, in Venezuela, and Paetel’s 
specimen agrees perfectly with typical examples from that locality in Dunker’s 
and Albers’s collections in the Berlin Museum. 
A. pyrum (Phil.): see A. hondurasensis, Reeve (anted, pp. 420, 421). 
A. retusa, Phil.: ‘Mexico, David,” in Dunker’s collection ; probably an erroneous 
locality, as it is only known otherwise from Guiana and Brazil. There is, however, 
a place named David in Chiriqui. 
A. rufilineata, Reeve: see A. pealeana (anted, pp. 423, 424). 
Subgen. CERATODES. 
Ceratodes, Lansdown Guilding, Zool. Journ. iii. p. 540 (1828). 
Marisa (part.), Gray, Philos. Mag. & Journ. Ixiii. p. 276 (1824) *. 
Shell discoidal, the progress of the whorls remaining in the same plane; aperture 
oblique. | 
Externally similar to Planorbis, but distinct, at first sight, by the obliquity of the 
aperture, which is directed towards the right side of the animal (in Planorbis to 
the left), the shell of Ceratodes being really dextral and the under half of the aperture 
projecting more forward than the upper half, as is the case in the other species of 
Ampullaria. Horny operculum, two pairs of feelers, and respiratory siphon as in 
the normal Ampullarie [see the figure of the living animal of J. (Ceratodes) cornu- 
arvetis in dOrbigny’s Voyage Am. mér., Moll. t. 48. figg. 7, 8, which is often copied |. 
* Marisa, Gray, was originally intended for all American Ampullarie, as it is characterized only by the 
horny operculum and simple peristome, not by the form of the shell; and it was not before 1847 (P.Z.8, 
p. 148) that it was limited by the author himself to A, cornu-arvetis, for which at that time the name Ceratodes 
was already available. 
