1915.] NATURAL SCIENCES OF PHILADELPHIA. 300 
almost every form known by large lots) may be (1) Superior, axial 
and basal, or (2) axial only. In Hachita forms we have also the 
combination (3) axial and basal, which is never found in the Chirica- 
huan series, where it is replaced by the combination (4) swperior 
and axial. Every Hachita species has, therefore, in different speci- 
mens of the same colony, the characters of the supposed subgenera 
or sections Bostrichocentrum, Haplostemma, Distomospira, and Tri- 
stemma, while a Chiricahuan species will belong to Bostrichocentrum, 
Eudistemma, and Tristemma. In external form and sculpture there 
are no differences greater than specific between the Hachita and 
Chiricahua species. 
The Hachita Holospiras belong, if we accept the criterion of 
intergradation, to only one species, for which the prior name is 
H. crossei. Between this species and H. bilamellata there is a perfect 
series of intergrades in size, sculpture and number of whorls. We 
mean by this that some individuals of an H. crossez colony could not 
be distinguished from mearnsi; some mearnsi can be exactly matched 
in a colony of bilamellata, or of media; and certain slender shells of 
bilamellata would pass as longa. The other named forms are more 
distinct, probably because we did not happen to collect where the 
intergrading colonies live. The races are therefore based upon the 
forms dominant in each colony. One might easily define a half 
dozen species, if only a few shells from each place were in hand; 
or if the internal lamelle were taken to be of specific weight, it 
might be thought that there are between two and three times that 
number. é 
There are many colonies, most of which have some special char- 
acters. A thorough exploration of the northern end of the range 
will undoubtedly bring to light very many more forms, so that any 
treatment of the group must now be tentative. For our present 
purpose we consider the smallest form (crossez) and the largest (b7- 
lamellata) as species, ranking the others as subspecies, though in some 
cases they are more distinct than these two are from one another. 
Several thousand shells were collected. 
The colonies at Stations 1, 2, 3, 12, are of very limited extent, 
physical features restricting them. Station 5 is much larger. The 
other Stations, 4, 6, 8, 9, 10, 11, merely represent collecting points 
in large areas where Holospira may be picked up almost anywhere 
over considerable tracts, while at the same time there are large 
areas in the region over which these stations are scattered where 
no shells can be found. 
