INO Ze GRAMMICOLEPIS BRACHIUSCULUS. 281 
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the two elements being completely united. Below, it is convex 
from side to side, correspondingly concave above, where it 
forms the floor of the interfronto-ethmoidal chamber, already 
alluded to above. I have previously described how now the 
ethmoid is deflexed, and becomes concaved in front to form 
the lower limits of that excavation on the anterior aspect of the 
cranium. 
This, as we have already seen, terminates in a conical point, 
and even beyond this the bone is carried forwards as a median 
Figure 4.— Under side of the cranium of Grammicolepis brachiusculus ; life size; 
reference letters the same as in former figures, with 2/, hyomandibular facet, and gf, 
foramen for the exit of the glossopharyngeal nerve in the opisthotic (O/.0O.). 
triangular process, the apex of which rests upon the parasphe- 
mold (Figs 3) “i. PFS.). 
Upon either side of the ethmoid, the flat anterior aspect of 
this cranium is completed by a broad prefrontal (P7f). The 
form assumed by one of these elements can best be appreciated 
by referring to Fig. 5, which represents the cranium of Gram- 
micolepis seen from behind, while the anterior face is in the 
horizontal plane. In this position the posterior aspects of the 
prefrontals come into view. 
Each one essentially consists of a thicker and vertical outer 
