HELIX-ISOMERIA. 147 



H. cymatodes PFR. Monographia, iii, p. 208 ; Zeitschr. f. Mai. 

 1852, p. 92. HIDALGO, Viage al Pacifico, Mol., p. 11, t. 2, f. 1, 2, 

 3. MILLER, Malak. Blatter, 1878, p. 169. 



This species is dark colored, very strongly indented or malleated 

 above and below the periphery. The lower surface sometimes has 

 a few golden-greenish flecks or irregular obscure maculations in its 

 substance. The reflection of the columellar lip does not wholly 

 cover the umbilicus, but from behind it a thinner membrane-like 

 callous grows, which in fully adult specimens conceals the perfora- 

 tion. 



Two smaller specimens of this species before me measure alt. 20, 

 cliam. maj. 45, min. 37 mill. ; they are decidedly cariuated, with 4J 

 whorls, and the outer superior part of the lip becomes brown. One 

 of these small shells is closely speckled with golden dots beneath. 



H. PARIETIDENTATA Miller. PI. 61, figs. 11-13. 



Nearly covered umbilicate, lenticular, solid, acutely cariuated, 

 striatulate, very minutely granulate, spirally malleate above and 

 beneath the carina; chestnut, irregularly dotted with whitish and 

 ferruginous ; spire very short, convex, apex brownish, obtuse ; 

 whorls 4|, nearly flat, the first two punctate, the following striatulate, 

 separated by scarcely impressed sutures ; the last turgid on the latter 

 part of the base, abruptly, deeply, angularly deflexed at the aper- 

 ture, a little constricted beneath ; aperture very oblique, retrorse at 

 the cariiia, rhomboidal ; peristome white, right margin above arid 

 beneath the carina brownish, at the carina white, expanded and 

 reflexed, margins joined by a thin callous ; outer lip with an obsolete 

 tooth below the termination of the carina, another lamellar acute 

 white one in the aperture on the penultimate whorl. (Miller.} 



Alt. 20, diam. maj. 46, min. 37 mill. 



Pilaton Valley, Ecuador. 



Isomeria parietidentata MILLER, Malak. Blatter, 1878, p. 169; I. 

 c. 1879, t. 5, f. 3a, b, c. COUSIN, Faune Mai. Rep. Equateur, p. 72. 



This species is like H. cymatodes in being malleate above and 

 below the periphery, and in the general appearance. Typical 

 shells differ from cymatodes in being less constricted behind the 

 superior part of the peristome, in having the denticle of the outer lip 

 further below the termination of the carina, and in having a more 

 deflexed whorl at the aperture. The only specimen I have seen is 

 different from the type in being larger, and so densely dotted with 



