VOL. I. | Variation in Shells. 331 
Color, ashen buff or grayish, with a broad or narrow band, fre- 
quently bandless. 
Helix Ayresiana, var. Santa Cruz Island. 
Largest specimen: greatest diameter, 30 mm.; altitude, 17 mm. 
Smallest spécimen: greatest diameter, 17 mm.; altitude, 1o mm. 
This variety is of a uniform light chestnut color, with closer and 
finer sculpturing then the typical or San Miguel Island specimens. 
The form is generally more depressed and approaches Hf. Traskit. 
Helix Tryonii Newc. Santa Barbara Island. 
By its sculpturing, as well as its general form, this shell is closely 
connected to J. intercisa, but is quite different in its pattern of 
coloring, and is generally a coarser and heavier shell. The re- 
volving lines so prominent in /. intercisa and H. Ayresiana are 
nearly obsolete in H. Zryonii, but they can be easily traced bya 
common pocket lens. By its coloring the shell is divided into two 
zones, the upper one being variously clouded with blotches of 
chestnut on a ground of dirty white. Below it is generally uniform 
in its dirty white color, but uniform cream and milk white individ- 
uals also occur. The young are more acutely carinated at the peri- 
 phery than the young of either H. intercisa or H. Ayresiana, but 
the angle dies out on the body whorl as it approaches maturity. 
The columella portion of the peristone in fully adult specimens 
very often has an obtuse tooth-like callosity, which also occurs in 
adult specimens of . zztercisa. 
Largest specimen. greatest diameter, 26 mm. ; altitude, 25 mm.; 
Smallest elevated specimen: greatest diameter, 20 mm. ; altitude, 
18 mm. 
Smallest depressed specimen: greatest diameter, 20 mm.; alti- 
tude, 15 mm. 
The following varieties indicate its different patterns of coloring 
and are arranged to show a connected series from the darkest col- 
ored to the milk-white albinos. 
Var. varius. The upper or dark zone is of a lighter shade of 
bluish brown or chestnut than the preceding, and is flecked and 
sprinkled with ashen white; band at the periphery, dirty white be- 
neath. 
Var. nebulosa. Lighter colored above than var. varius, marbled 
and clouded with various patterns of dark brown and dirty white ; 
dirty white beneath. & 
