1905.] NATURAL SCIENCES OF PHILADELPHIA. 271 



1. Penis long, the distal half strongly twisted, there being two dis- 

 tinct kinks, resulting in convolutions variously disposed, and of course 

 not alwa^^s falling the same in the same species or variety. 0. strigosa, 

 from Pecos, and 0. elrodi (PL XIX, figs. e3 and 2) belong here. 



2. Basal half of the penis swollen and muscular, the distal half 

 smaller, without distinct kinks. 0. s. huachucana and 0. harhata (PI. 

 XIX, figs. 6 and 5) are of this type. 



3. Penis small, short, the basal half not much larger than the distal 

 l^ortion, the latter not kinked. 0. neomcxicana and 0. yavapai (PI. 

 XIX, figs. 7 and 9) have penes of this kind. 



All the above have the penis longer than the epiphallus. In the 

 subgenus Radioccntnim the epiphallus is as long as the penis or 

 longer. 



As yet my observations have covered only about a dozen of the num- 

 erous species and subspecies ; and until more of the forms of the central 

 and northern States are examined, characters of the soft anatomy 

 cannot be fully utilized in classification. 



There are two types of dentition in Oreohelix. The ordinary forms 

 have unicuspid central and inner lateral teeth. Here stand 0. strigosa, 

 cooperi, newcombiana, huachucana, yavapai, neomcxicana. and haydcni. 

 In the second type of teeth ectocones are developed on all of the t^eth, 

 the centrals being thus tricuspid, the lateral and marginal teeth all 

 bicuspid. Of this kind are 0. idahoensis, 0. hemphilli, 0. harhata, 0. 

 chiricahuana and 0. clappi, but in the last species the ectocones are not 

 well developed. 



The series of Huachuca Orcohelices shows that colonies of the same 

 original stock vary greatly and often show parallel variations in differ- 

 ent canyons. 



Those from the greatest altitudes are smallest (PI. XXI\^, figs. 25-27, 

 29-32, Limestone Mountain, 8,000 feet; PL XXIV, fig. 28, Carr Can- 

 yon, 7,000 feet, etc.), though some large shells occur elsewhere at equal 

 elevations. 



Conspicuously banded shells were taken only at high elevations 

 (PL XXIV, figs. 17, 18, Brown Canyon, 7,000 feet), plainer ones occur- 

 ring lower down in the same canyon; but not all the high altitude 

 shells are so marked. 



Gerontic or senile individuals or colonies are common, manifested 

 by deep descent of the last whorl in front, with a tendency to form a 

 free or solute peristome (PL XXV, figs. 33-35, Ida Canyon). 



The carinatc periphery is an ancestral character of 0. strigosa and 

 its allies, present invariably in the noanic stage. It wall be noted that 



