4 BAUR. [Vol. VII. 



a combination of the characters of serpents with those of 

 Lacertilia, and some others of Sauropterygia." 



The characters relating to the skull are the following : — 



a. "The opisthotic bone projects free from the cranium, and 

 is the suspensorium of the os quadratum." 



b. " There is no columella." 



c. "There is no symphysis mandibuli." 



d. "The parietal is decurved posteriorly, and extends to the 

 sphenoid (!'), forming the cranial wall in front of the prootic." 



e. " The sub-articular and splenial elements of the mandible 

 are connected by articular faces." 



/. "The pterygoids are elongate and bear numerous teeth, 

 and in one type are free except at the extremities." 



£■. "The brain case is not fully ossified anteriorly." 



/i. "The squamosal bone is present." 



t. "The angular bone is distinct." 



k. " The OS quadratum is movably articulated to the opis- 

 thotic." 



/. " The OS quadratum embraces and encloses the meatus 

 auditorius externus." 



m. "The opisthotic is supported by a pedestal projecting 

 from the cranial walls, composed of the prolonged prootic in 

 front, and the exoccipital behind, which embraces the suspen- 

 sorium for much of its length." 



Of the above characters, a-e, it is said, are those of serpents ; 

 f-i are lacertilian ; while m is expressed as peculiar and not 

 found in any existing order of reptiles. 



How far Professor Cope is correct will be seen from the 

 description of the skull of Platecarpus. 



Marsh, 1 869-1 872. 



In a paper published in November, 1869, Professor Marsh ^ 

 speaks about the suspensorium of the quadrate in Mosasmiriis 

 princeps. Marsh, "The suspensorium of the quadrate bone is 

 clasped by the pro-otic above and the exoccipital below, and the 

 squamosal forms the greater part of the glenoid cavity." The 

 element called exoccipital is the paroccipital, Owen (opisthotic, 



1 Marsh, O. C, Notice of Some New Mosasaiiroid Reptiles from the Green Sand of 

 New Jersey, Am. Journ. Sci., Vol. XLVIII, November, 1869. 



