AMPULLARIA. 421 
nearly closed umbilicus; in the single specimen before me from the Lake of Nicaragua 
a very narrow opening is just visible. The other known Central-American species with 
closed or nearly closed umbilicus, as A. erogata, A. pealeana, and A. conoidea, all differ 
in the general form of the shell. It is also the only American Ampullaria I have seen 
with a distinct thickening behind the outer margin of the aperture, a character often 
found in Indian and African species of the genus ; nevertheless, the operculum is 
corneous, thin, concave, shining brown. 
Tate? gives no description of his Pomus pyrum, but, to judge from the locality, it is 
probably referable to the present species. The true A. pyrum, Philippi (Martini & 
Chemnitz, Syst. Conch.-Cab. ed. 2, Ampullaria, p. 18, t. 5. fig. 2), from Brazil, bears 
some resemblance to A. hondurasensis, but differs from it in being much attenuated 
beneath, as the specific name (pear) indicates, and in having a shorter spire and larger 
aperture. — 
III. HELICIFORMES. 
16. Ampullaria cerasum. (Tab. XXIV. figg. 1-6.) 
Ampullaria cerasum, Hanley, Conch. Misc., Ampullaria, t. 2. figg. 7 (1854-58)'; Reeve, Conch. 
Icon. x., Ampullaria, t. 21. fig. 99°. 
Globose, solid, with somewhat elevated spire and moderately deep sutures; last whorl well rounded in its 
upper half, gradually attenuated in the lower half; surface rather smooth, but closely impressed with 
somewhat broad, unequal, vertical strie, ashy-olive or dull chestnut-brown, with inconspicuons slightly 
darker bands ; umbilicus moderate, cylindrical ; aperture occupying about $ or rather more of the whole 
length, with thick, bright red or orange peristome; outer margin well arcuated ; basal margin broadly 
rounded ; columellar margin nearly vertical, thick, but only at its insertion reflexed, and concealing very 
little of the umbilicus. 
a. Long. 37, diam. 32; apert. long. 274, diam. 17 millim. 
& 5 33, » 31; .» 23, . 16 ,, 
e204, ... 24; 20, 4, #15 ~= 4, 
go 285, 23; = 19, , 12 ~=~,, 
é. ” 203, ” 243 3 ” 17, ” 12 ” 
Bon 2 4 19: 9 163, , ll, 
Hab. S.E. Mexico: Teapa in Tabasco (H. H. Smith). 
The above measurements are taken from full-grown specimens from the same 
locality, all these having a thickened and bright-coloured peristome ; the specimen ¢é 
is much worn above and its length therefore is less than its diameter. The colour of 
the peristome is usually bright red, nearly scarlet, in some specimens orange: in all 
those before me this red or orange colour reaches to the very edge of the aperture. 
whereas in Reeve’s figure the edge is whitish and the orange coloration is only visible 
inside behind it, but in the text he describes the peristome as bright scarlet; Hanley, 
too, terms the species “red-throated.” The interior of the aperture is greyish-violet, 
with distinct darker bands. 
