1905.] ' WNATURAL SCIENCES OF PHILADELPHIA. 253 
upper part. The spermatheca is long and narrow, its duct rather 
short. The epiphallus and flagellum measure 22 mm.; flagellum 2 
mm.; spermatheca and duct 20 mm. The specimens had been placed 
in alcohol without drowning. 
The jaw (Pl. XXIII, fig. 16) has seven ribs, grouped in the median 
half, the ends smooth. 
The radula (Pl. XXII, fig. 8) has about 38.1.38 teeth. The ecto- 
cones are developed on central and lateral teeth. From the twenty- 
fourth or twenty-fifth teeth outward from the middle the inner cusp 
is bifid. The ectocones are unsplit. A central and two lateral teeth 
are shown. 
This snail, so far as the shell is concerned, would be referred without 
hesitation to A. chiricahuana; the differences being less than the ordi- 
nary range of individual variation in Ashmunella or Polygyra; but the 
genitalia are so utterly unlike in the two forms that it is obvious that 
they are not even nearly related. From the granulation and the weak 
traces of teeth it seems that A. metamorphosa is probably a toothless 
derivative of the A. levettei stock; I regret that I have no alcoholic 
specimens of A. levetter or A. l. heterodonta for comparison. A. esuritor 
differs from metamorphosa by its angular or distinctly subangular 
periphery, rougher surface when perfectly fresh, and perhaps somewhat 
wider umbilicus; but it must be admitted that the two forms are so 
similar that their distinction may be difficult without an examination 
of the soft parts. The genitalia, however, are so very different that 
the two species cannot even be closely related. They must be inde- 
pendent derivatives from toothed ancestral forms. 
I dissected two of the three specimens received. They could be 
extracted only by breaking into the shell. Having been preserved in 
alcohol without drowning the specimens were much more contracted 
than the A. chiricahuana and A. esuritor I examined. A somewhat 
extensive experience with snails in all conditions of preservation has 
shown that beyond a moderate diminution of the absolute size, the 
characters of the genitalia are not altered by preservation of the animal 
in strong alcohol. 
Genus SONORELLA Pilsbry. 
Pilsbry, Proc. Acad. Nat. Sci. Phila., 1900, p. 556 (definition, anatomy); 
Bartsch, Smiths. Misc. Coll., Vol. 47, p. 187, 1904 (monograph). 
The soft anatomy of this genus has hitherto been known in a single 
gpecies. The study of numerous specimens of several species enables 
me to extend the generic characterization. 
The shells in these Helices, while interminably modified locally in 
