~I 
bo 
_S. W. Williston. 
of but little moment as having no bearing upon questions of morpho- 
logical interest. 
The two larger skulls, very clearly belonging to the typical species 
L. hamatus, those which have furnished most of the information given 
in the present paper, are somewhat obliquely compressed, as is often 
the case with the Permian fossils of Texas; one of them toward the 
right, the other toward the left. They are of precisely the same size, 
and the correction of their distortions in the figures is a matter of 
little difficulty (Plate I and Plate IL). The skull, it is seen, is remark- 
able for its attentuated facial region, and for the beak-like extension 
of the premaxillaries, terminating in the long, rake-like teeth. The 
nares, situated nearly at the extremity of the rostrum, are semioval 
in shape, directed outward. The face in front of the orbits is nar- 
row, gently convex from side to side, with nearly vertical sides and 
a gentle longitudinal convexity in the middle. The orbits are a 
little longer than wide, their diameter a trifle greater than the inter- 
orbital width. Posteriorly the skull is flattened in the middle above, 
and greatly expanded in width, the expansion beginning near the 
back part of the orbits, the lateral margins curving inward at the 
extreme posterior part. The large pineal foramen is situated near 
the front part of the parietal bone, about midway between a line 
drawn through the hind margins of the orbits and the hind margin 
of the skull in the middle line. There is a pronounced emargination 
of the hind margin of the skull, extending the width of the parietal 
bones. In well-preserved specimens the markings of the surface of 
the skull are very distinct, consisting, for the most part, of round or 
oval pits forming a reticulation, but not distinctly arranged in rows. 
In other specimens these pits are less conspicuous, and the surface 
in some appears almost smooth. 
The relations of the bones of the upper surface of the skull have 
been figured by Case and myself in the papers cited, but I am con- 
vineed, from a careful study of the material at my command, that 
we were both more or less in error in the supposed recognition of 
elements which we took for granted must have been present. The 
premaxillee are separated in several of the specimens in the museum. 
They unite broadly above with the nasals, by a rounded border in 
