Cope.] 44 O [Nov. 



anteroposterior. The proportions of the premaxillaries and of the inter- 

 nal and external rows of those of the jaws are as in the P. isolormis. 



The protrusion of the muzzle, and position of the nostrils ; also the size 

 of the orbits and interorbital width are as in P. isolomus. The length of 

 the largest specimen is 90 mm., of the smallest 70 mm. 



The vomers are decurved anteriorly. The posterior border of the pos- 

 teiior nares is opposite the anterior border of the orbits. The point of 

 divergence of the posterior or ectcpterygoid wings of the palatines is 

 opposite the posterior border of the orbit. I count fifteen teeth on each 

 internal palatine border, and five on the external palatine series. The 

 posterior or (?) ectopterygoid patch contains about twenty teeth. All the 

 palatal teeth have circular cross sections. 



The clavicles do not meet on the middle line, but show a portion of the 

 sternum between them. The sternum posterior to the clavicles is quite 

 narrow. The distal extremity of the humerus is in a plane which has 

 an angle of nearly 90° to that of the head. The plane of its narrow 

 inner face is nearly at right angles with the general plane, and it projects 

 beyond the latter distad. Condylar border concave ; entepicondylar ala 

 large. 



Measurements. mm. 



Length of sixth cervical centrum • 5.5 



Elevation of neural spine of cervical centrum 10.2 



Length of clavicle, vertical portion 15 



" " horizontal portion 13 



Width of sternum, at clavicles 24 



" " posteriorly 5 



Length of humerus 33 



Width of head of humerus 13 



" of distal extremity of humerus 16 



Diameter of shaft of humerus 3.5 



Partotichu.s hamatus, sp. nov., PI. viii. Figs, 1, 2. 



Represented by a cranium with lower jaw in pretty good preservation, 

 and a second smaller cranium with lower jaw, from which the end of the 

 muzzle is wanting. Besides exceeding in size the other species, this one 

 is characterized by the elongation and compression of the muzzle, and by 

 the extent of the projection of the premaxillary region beyond and below 

 the mandibular rami. 



The length of the skull a little exceeds its posterior width. The lateral 

 outlines expand rapidly from the anterior borders of the orbits, posteriorly, 

 while from this point anteriorly the lateral oullinesof the muzzle converge 

 very gradually. The transverse section of the muzzle is subrectangular, 

 and not a segment of a circle as in other species, the superior fiice being 

 nearly flat, and the maxillary borders soniewhat contracted. This form 

 may however be due to pressure. Opposite the posterior border of the 

 nostril the premaxillary border is steeply decurved, forming a concavity 



