450 J. FRANK DANIEL 
against that of the V above described so that the two V’s roughly 
form an hour-glass. 
Viewed from the ventral side (fig. 2) the cranium is roughly 
flat-iron-shaped, with the apex projecting between the olfactory 
capsules (ol.c.). At the most posterior part of the cranium is 
a niche, the sides of which are produced by the occipital condyles 
(o.cd.). In the mid-ventral line, one-fourth the distance from 
the posterior border to the tip of the nose, is a foramen (or a 
pair of foramina) through which the internal (posterior) carotid 
arteries reach the brain (f.2.c.); laterad of these on each side 
are similar perforations (f.e.c.) through which the external 
(anterior) carotids pass on their way to the orbital region. A 
line through the internal carotid foramina, and at right angles 
to the long axis of the cranium, divides the ventral cartilagi- 
nous mass into two regions, the anterior of which is the embryonic 
trabecular region, the posterior region that of the parachordal 
cartilages. 
Along the lateral margin, in ventral view, from behind forward 
are the post-articular processes (po.hm.) bounding posteriorly 
the deep fossa into which the hyomandibular cartilage fits. An- 
terior to the fossa is a pre-articular process (pr.hm.). In 
front of the latter is a constriction, anterior to which is a wide 
projection—the basal plate (6.p.); considerably in front of 
the basal plate, at the sides, is the palatal fossa (pl.f.) into which 
a projection of the palatoquadrate cartilage fits. At the anterior 
tip of the cranium the basitrabecular cartilage (b.tr.) arches 
upward to be met by two dorsolateral rostral pieces coming down 
from the dorsal part of the cranium. At the sides of the basi- 
trabecular piece are the external openings for the olfactory 
capsules (ol.c.). 
In this view may be described the olfactory capsules and the 
nasal cartilages at their margins. The capsules are thin, carti- 
laginous structures which are formed as the skeletogenous 
protection for the olfactory organ. Dorsally the capsules are 
continuous with the cranium (see also fig. 1); ventrally they 
thin out to delicate lamellae of cartilage which surround the 
nasal aperture, excepting in the postero-medial part, where the 
