82 UPPER CRETACEOUS TELEOSTS 
tooth is the longest tooth in the upper jaw and forms the continuation, anteriorly, of 
the tooth row on the ectopterygoid. The base of the tooth merges imperceptibly 
into the main body of the bone and is arranged at go° to it. The tooth is, in all 
respects, identical to the pterygoid teeth, being laterally compressed to produce 
cutting edges. From its extreme anterior position and the fact that there is no other 
tooth base or any indication of a second tooth, it is assumed that this tooth is not 
replaceable and remained fully functional throughout life. On the dorso-medial 
region of the anterior end of the palatine there is a facet which housed the lateral 
wing of the mesethmoid and vomer. Posteriorly the palatine fits into the dorsal 
groove of the ectopterygoid and dorsally is extended to produce a facet for the 
reception of the ventral region of the lateral ethmoid. The lateral face of the 
palatine has a shallow, oblique, ill-defined groove in which the most anterior region 
of the maxilla was contained. 
Dermal upper jaw. The dermal upper jaw consists of two bones, the maxilla and 
the premaxilla (Woodward, 1903, fig. 13). The premaxilla is particularly prominent 
with an anterior and a lateral region arranged at practically go° to each other. 
There is an enlarged premaxillary pedicel anteriorly which contacts its opposite 
partner in the mid-line. The pedicels lie in the same plane as the anterior region of 
the skull-roof, and each pedicel contains a large oval foramen within it. The pre- 
maxillary pedicels articulate with the anterior edge of the mesethmoid. The lateral 
face of the bone is relatively smooth although grooves are present. One groove runs 
parallel with the pedicel at the anterior end of the lateral face, and a second very 
shallow groove runs along the oral border of the bone. The oral border itself bears a 
single row of marginal, acutely pointed teeth, approximately 20 in number. 
The maxilla is long and slender, the head being unexpanded and incurved. The 
head of the maxilla rests in the groove on the lateral and dorso-lateral surfaces of 
the palatine. The maxilla slopes posteriorly and ventrally and was presumably 
attached to the premaxilla ligamentously. The maxilla is straight, of uniform shape, 
entering the gape of the mouth at the posterior end of the premaxilla. The maxilla 
shows no signs of having been provided with teeth. 
Mandible. The mandible is shown in medial view in Text-figure 36. It is very 
long and deep, with the symphysial region much constricted and irregular in shape. 
The whole upper margin of the mandible is formed of dentary as well as the anterior 
two-thirds of the lower edge. The dentary is a large V-shaped bone with the apex 
toward the symphysis. The symphysis is deepened slightly by the presence of 2 or 
3 small, finger-like ventral processes. Ventrally the bone is much thickened. The 
oral edge of the dentary gives rise to an internal tooth bearing flange. Anteriorly 
this flange contacts the lower thickened region demarcating an internal V-shaped 
space. This space presumably housed the remains of Meckel’s cartilage. Teeth are 
present in two rows, a marginal row of minute, acutely pointed teeth approximately 
30 in number ; and an inner row of enormous teeth. These latter teeth are very 
similar to those found on the palato-pterygoid. The row consists of about 8 func- 
tional teeth. The anterior tooth of the series arises just behind the symphysis and is 
