NO. 1519. 



MOROSAURUS AGILIS REBESCRIBED—GILMORE. 



155 



somewhat roughened ridge is developed, which in Dijjlodoem, Doctor 

 Holland has interpreted as the point of attachment for the nuchal liga- 

 ment. Marsh has represented the suture between supraoccipital and 

 exoccipital as continuing straight across toward the median line, but 

 after removing the pro-atlas it was found to turn upward. (Compare 

 figs. 1 and 3.) The further direction of this suture can not be deter- 

 mined from this specimen. 



The parietals appear as two lateral processes extending from either 

 side of the crest of the skull backward and downward, thus forming 

 the anterior and inner lateral margins of the supratemporal fossa. 

 The parietal suture is not indicated in this specimen. As shown by 

 Professor Osborn in 3L grandi^, the parietals hardly enter into the 

 composition of the roof of the 

 cranium. Anteriorly thej^ 

 unite with the frontals, pos- 

 teriorly with the supraocci- 

 pital which they enclose on 

 three sides. At their poste- 

 rior termination the}' overlap 

 the squamosals. To a lim- 

 ited extent the parietal artic- 

 ulates with the exoccipitals. 

 The great backward and 

 downward extension of the 

 parietals seem peculiar to this 

 species. 



Only a portion of the squa- 

 mosal of the left side is pre- 

 served with this specimen. 

 It forms the posterior bound- 

 ar}^ of the supratemporal 

 fossa. Along its inner mar- 

 gin it articulates with the paraoccipital process of the exoccipital. 

 Anteriorly it is overlapped by the posterior extremity of the parietal 

 and externally it meets the postf rontal. 



Th-Qfrcmtals appear to be united on the median line by an interlac- 

 ing suture. Over the or])ital cavities the bone is thickened and the 

 exterior margins somewhat roughened and rounded. Anteriorly and 

 medially these bones thin out to a sharp edge, A broad process is 

 sent out from the outer anterior margin which probably articulated 

 with the prefrontal while the median part articulated with the nasals. 

 The orbital surface is concave antero-posteriorly. Its inferior surface 

 united by suture with the or])itosphenoid. 



The element here designated hy the writer 2^^ postf rontal is the one 

 Marsh identified as the postorbital bone. (See fig. 1 j;6>. and Plate 



Fig. 3.— Oblique posterior view of the skull of Mo- 



ROSAURUS AGILIS (CAT. No. 5384), \ NAT. SIZE. £.f . OC, 



exoccipitals; F, frontals; F.in, foramen magnum; 

 O.c, occipital condyle; Pa, parietals; Po.J, post 

 frontals; H. o<\ supraoccipital; Sq., squamosal. 

 Right side restored somewhat from the left. 



