242 PROCEEDINGS OF THE ACADEMY OF [Mch., 



So far as I know, such variability in a land snail among individuals 

 living luider 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 Avith it. 



. The colonies of Cave and Ida Canyons are evidently undergoing rapid 

 degeneration of the teeth, the parent form having been typical A. 

 levettei 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 

 colon}^ 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 PI. 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 X^^, 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 

 the}^ 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. PI. XIV, figs. 65, 66, 70. 71. 



The shell is depressed, biconvex, strongly angular at the periphery, 

 pale corneous-brown. Whorls 6^, none with punctate sculpture. Aper- 

 ture like that of A. angulata, except that Ulc two basal teeth are nearer 

 together, the space between them being smaller than that betwee^i the outer 

 basal and the upper lip-tooth; though the two basal teeth are not united 

 basally as in A, fissidens. 



