270 PROCEEDINGS OF THE ACADEMY OF [Mch., 
altitudes. To attain a true idea of the relationships of any given alti- 
colous dwarf it is essential to know the forms of the lower canyons of 
the same region. 
The first step toward a fundamental knowledge of the races and 
species of Oreohelix must be the study and definition of races in the 
broad sense above indicated. In my opinion, the minor modifications 
can be so overnamed that the wider distinctions become altogether lost, 
as in the Utah series. The field is vast, and for many years to come 
there will be plenty of room for work. Anybody who secures a good 
series of the forms of any district can materially help the cause by 
working them up. 
The sculpture of the embryonic shells and the genitalia seem to afford 
the most important characters for specific classification. It would 
take us too far afield to discuss the entire mass of data at hand. This 
must be reserved for another occasion. Only forms from central and 
southern Arizona and New Mexico are dealt with below.? The meas- 
urements of the genitalia in millimeters follow: 
Species Penis phi he Vagina tec and Gf aoe 
O. strigosa, Pecos 16.3 6.3 5 21 18.5 85,100 
O. elrodi 17 6 8 19 22.5 79,475 
O. s. huachucana 14 6:52, 4 5 22 21 83,370 
O. barbata 6 SN TAY Bae. 13 13.5 87,011 
O. yavapai ee 2 a | 15-16 | 79,415 
O. y. neomexicana | 4 pai || ta | res 15 80,700 
The species thus far dissected show considerable differences in the 
genitalia, chiefly in the proportions and shape of the penis, the forms 
falling into three groups, as follows: 
7 For comparison with the southern forms I have, however, figured the anatomy 
of O. elrodi (Pils.), from Montana, Pl. XIX, fig. 2. The penis is like that of O. 
strigosa, from Pecos, the lower third having thick walls, densely plicate within; 
above that the walls are thinner, densely lined with long papillz, and in the upper 
third there are several low fleshy ridges, also papillose. There is an extremely 
short, conic penis-papilla in the apex. The vas deferens enters the epiphallus 
centrally. The vagina is much dilated and muscular above. The uterus is pro- 
vided with muscular strands forming an incoherent protractor muscle (fig. 2, 
r.u.). The embryos were packed in like coins except the two lower ones. The 
dimensions are given in the table. 
