110 ANOSTOMA. 



judging by the growth-lines, carried with the equatorial plane nearly 

 vertical ; but at that period it falls or tilts to the right, not to the 

 left as in Helices, and the subsequent growth of the whorl across the 

 base necessarily follows. The " teeth " of the aperture are entirely 

 homologous with those of Odontostomus. See page 27, fig. 3. 



Unlike the shell, the soft anatomy is not especially peculiar, being, 

 so far as known by Dr. Paul Fischer's account of A. rinyens, essen- 

 tially similar as regards the genitalia to that of Odontostomus, while 

 the jaw and teeth are like Macrodontes. The elongation of the 

 whole genital system is greater than in Helicoid snails generally, and 

 doubtless correlated with the unusual length of the last whorl. The 

 cerebral ganglia are more separated than usual in the Holopoda. 



Key to Species. 



1. Angular lamella and upper suprapalatal fold concrescent, forming 



a perforation in the lip at its upper end, ringens, carinatum. 



2. No perforation in the lip. 



a. Typically 8-toothed. 



b. A columellar lamella but no basal fold developed ; 



two suprapalatal folds ; lip white, broadly reflexed ; 



shell angular at the periphery. octodentatum. 



b. 1 A columellar lamella and a basal fold developed ; 



shell more globose, not keeled. deshayesianum. 



a} Having 5-7 teeth ; lip comparatively narrow, tinted ; shell 



angular at the periphery. depressum. 



1. Group of A. octodentatum. 

 A. OCTODENTATUM F. de Waldheim. PI. 6, figs. 40-44. 



Shell biconvex, the alt. half or nearly half the greatest diameter, 

 solid, obtusely angular at the periphery. Brown-tinted whitish, the 

 base copiously dappled with oblong spots and more or less spirally 

 clouded with dull reddish-brown ; upper surface having a broad 

 reddish-brown band above the periphery, often mottled, and fading 

 at its upper edge, and a narrow dark spiral band bordering the suture 

 below, fading on the two earlier whorls. Surface slightly striate 

 above, and on the first half of the base, the last half whorl regularly 

 latticed or malleate in diamond pattern. Whorls 5, the first one 

 flattened, the last half-whorl straightened, running to the periphery 

 and up-turned, with three long and one short groove behind the lip. 



