955:607)
occurs in the immediate vicinity of San Josecito today. None of the rami
from the cave differs appreciably from those of the _subnubilus_ group
of _Cratogeomys castanops_, a group of small subspecies including
_planifrons_, _subnubilus_, _rubellus_ and _peridoneus_. All are small
in external measurements and skull and differ markedly in this respect
from the group of large subspecies (the _subsimus_ group) that occurs
farther northward in Coahuila and Nuevo Leon.

#Cratogeomys# sp.

A rostral part of a skull, L.A.C.M. (C.I.T.) No. 2927, is referable to
the genus _Cratogeomys_. This fragment consists of the anterior part of
the skull, including a portion of the frontals, the premaxillae, a small
part of the left maxilla, and the anterior parts of the palatines. The
nasals are missing, but both incisors are in place including most of the
roots. The single median sulcus on the anterior face of each incisor is
typical of the genus _Cratogeomys_. The rostrum is long (25.8), as great
in length as in the largest subspecies of the _subsimus_ group of
_Cratogeomys castanops_ (see previous account for explanation) and as
long as the rostrum of _Cratogeomys perotensis_ which is now known only
from Veracruz, Mexico. The length of the rostrum was measured from the
most anterior median projection of the premaxillary to the most
posterior dorsal projection of the same bone. Actually, and especially
in relation to its length, the rostrum of the fossil is remarkably
narrow. The breadth of the rostrum measures 10.4, which is comparable to
that in the _subnubilus_ group of small subspecies, and less than that
(11.4 in the smaller adult females to 13.7 in the larger adult males) in
the _subsimus_ group of large subspecies. The breadth of rostrum in the
fossil is 40.3 per cent of the length of the rostrum. In living
_Cratogeomys castanops_ (both the large and small subspecies groups, and
including both females and males) the breadth of rostrum amounts to
between 44.0 and 51.4 per cent of its length. The rostrum in
_Cratogeomys perotensis_ (and in other species of the _merriami_ group)
is relatively much broader than in _Cratogeomys castanops_. Even though
the rostrum of the fossil is narrower than in Recent species of
_Cratogeomys_, the ventral border in the area of the palatine slits is
more heavily constructed than in any of the living species, and it is
nearly parallel-sided rather than tapered toward the midline anteriorly.