142 HELIX-ISOMERIA. 



the umbilicus ; the ends of the lip are joined by a narrow cord of 

 white callous across the parietal wall. 



Alt. 19, diam. maj. 40, min. 342 mill. 



Alt. 18, diam. maj. 882, min. 32* mill. 



Aperture, breadth, 222, alt. 17 mill. (Meas. outside peristome.) 



Mar mat o, Colombia. 



This species may be known by its thick lens-like form, rapidly 

 widening penultimate whorl, very oblique aperture, deep deflection 

 and constriction of the whorl behind the peristome, etc. The young 

 are acutely keeled, the carina in adults filling the suture ; some 

 variation may be expected in the width of the umbilicus, as in other 

 Isomerise, and imperforate individuals probably occur, although 

 those before me are not so. 



It gives me great pleasure to dedicate this species, one of the 

 most attractive in its regular, graceful contour of the group Isomeria, 

 to JOHN FORD, ESQ., of Philadelphia, a gentlemen whose cabinet and 

 heart are ever open to the needs of fellow conchologists. 



H. CALOMORPHA Jonas. PI. 47, figs. 31, 32. 



Imperforate, orbicular, rather thin, convex above, chestnut colored ; 

 turgid beneath, whitish; spire obtuse; W'horls 6, flat, delicately 

 obliquely striate, the strise very elegantly granulose ; last whorl 

 obtusely angular, the angle encircled by a white band ; aperture 

 effuse, subquadrangular ; lip chestnut colored, broadly expanded, 

 reflexed, thickened toward the axis, with a white tooth below. 

 (Jonas.} 



Habitat unknown. 



Helix calomorpha JONAS, in Wiegm., Archiv f. Naturg. 1839, 

 p. 341, t. 10, f. 3, 4. PFEIFFER, Monographia i, p. 315. 



Known only by the original description and figures. 



H. JLQUATORIANA Hidalgo. PI. 47, fig. 39. 



Covered subrimate, depressed, orbicular, rather solid, convex above 

 and beneath, all over minutely granulate; purplish-brown; spire 

 little elevated, apex obtuse; whorls 5s, slightly convex, regularly 

 widening, the last subangular at the periphery, deflexed anteriorly, 

 turgid, subcompressed laterally and subconstricted at the aperture ; 

 aperture very oblique, quadrangular, pale fuscous inside ; peristome 

 broadly expanded, reflexed, slightly thickened, fleshy-fuscous colored, 

 the right margin unidentate ; margins connected by a thin callous, 



