242 ' PROCEEDINGS OF THE ACADEMY OF {Mch., 
So far as I know, such variability in a land snail among individuals 
living under the same conditions in one spot is elsewhere absolutely 
unknown. 
Most of the specimens measure from 15 to 18 mm. diam., but there 
is one pygmy of 12 mm. (fig. 88). In the general shape, etc., the race 
does not differ from A. levettei. There is no trace whatever of patho- 
logic or abnormal growth. The forms with well developed teeth and 
those with none were found much less numerous than the intermediate 
stages. The most abundant forms (figs. 84, 85) may be considered the 
types of the variety. 
The toothless examples have the lip slightly wider than that of A. 
chiricahuana. They constitute a race parallel to that, rather than iden- 
tical with it. 
The colonies of Cave and Ida Canyons are evidently undergoing rapid 
degeneration of the teeth, the parent form having been typical A. 
levetter such as occurs in the adjacent canyon westward, and that over 
the ridge. Examples of such degeneration are common enough at any 
stage of progress; but the unique feature about it in this particular 
colony is that the individuals have been so unequally affected that all 
stages of the process are present at one time and place. It does not 
seem to be a case of hybridism between A. levettei and A. chiricahuana, 
as I at one time suspected. The results are unlike hybrid colonies in 
the predominance of intermediate individuals. 
Figs. 80 to 87 of Pl. XV are a series from Ida Canyon, showing stages 
of tooth development. Figs. 89, 90, 91 are from the Cave Creek Canyon 
series. All of these figures are photographed from fully mature shells. 
Two specimens before me from Miller Canyon, or extreme head of 
Cave Creek Canyon, Huachucas, figured on Pl. XV, figs. 94, 95, may 
be toothless heterodonta, as Mr. Ferriss suggests to me; though from the 
narrower lip I had provisionally called them A. chiricahuana, to which 
they seem absolutely similar. If the latter be correct, these are the 
only specimens of that species I have seen from the Huachuca range. 
They,;measure 18.3 and 16 mm. in diameter. The smaller shell is an 
albino. 
Ashmunella levettei proxima n. subsp. Pl. XIV, figs. 65, 66, 70. 71. 
The shell is depressed, biconvex, strongly angular at the periphery, 
pale corneous-brown. Whorls 64, none with punctate sculpture, Aper- 
ture like that of A. angulata, except that the two basal teeth are nearer 
together, the space between them being smaller than that between the outer 
basal and the upper lip-tooth; though tthe two basal teeth are not united 
basally as in A. fissidens. 
