1909.] NATURAL SCIENCES OF PHILADELPHIA, 507 
Cave Creek Canyon, for one-eighth of a mile at the head. 
This is another modification of the levette: stock, differing from 
heterodonta and varicifera by its wider umbilicus and less closely coiled 
whorls, from the former by deficient lip teeth, and from the latter by 
the usual presence of a minute parietal tooth. In genitalia it does not 
differ from typical levettev. While not conspicuously differentiated, 
we have thought it well to give the form specific rank. 
Ashmunella levettei heterodonta Pils. Fig. 6. 
Proc. A. N. S. Phila., 1905, 241, pl. 15, figs. 81-91: Nautilus, XVIII, 
Deol. 
This form has the shape of A. levette:, and typically has a low, 
straight-topped tooth within the outer lip, a small tubercular tooth 
at junction of outer and basal margins, and a faint prominence in the 
position of an inner basal tooth. The parietal tooth is minute or 
wanting. There are barely over 6 whorls, which therefore are a little 
wider than in A. levettez. 
We have elsewhere noted the extreme variability of the teeth im 
heterodonta. They may be much more developed than described above, 
or so degenerate that only faint traces of teeth are discernible. A 
form-chain connecting levettei and varicifera exists. | Whether hybrid- 
ism plays a part here remains uncertain. 
Fig. 6. Ashmunella levettei heterodonta. Cotype. 
This form occurs in the heads of Ida and Cave Canyons. In one 
place heterodonta goes over the divide two or three hundred feet, but in 
no other case do these species cross to the other side of the range. 
A. levetter or heterodonta are not found in varicijera territory. There is 
no mingling of Ashmunellas except large and small forms of levette?. 
The peculiarities of habit, variation, etc., of the Ashmunellas, Oreo- 
helices, etc., is worthy of a year’s study in the Huachucas. The area 
