3 BAUR. [Vol. VII. 



the whole posterior part is typically Lacertilian. He shows 

 that the nasal region " most nearly resembles that of the Vara- 

 nus and Monitor amongst existing Reptilia." But the true 

 nature of the nasal bones is not recognized. The pterygoids, 

 palatines, vomers, are correctly determined. At the end Profes- 

 sor Owen says : " The fossil evidences of the Mosasaurians 

 hitherto made known do not yield a single character peculiar to 

 and characteristic of the Ophidian order." According to Owen, 

 the Mosasauridse are aquatic Lacertilia, like the Pinnipedia, 

 aquatic carnivora. 



Professor Cope in his reply admits his mistake in the deter- 

 mination of the pterygoid and palate. He still considers the 

 squamosal (mastoid Owen) as the paroccipital (opisthotic), and 

 does not admit that this element is confluent with the exoccipi- 

 tal. The order Pythonomorpha is retained, with the following 

 characters of the skull. 



1. "The parietal bones are decurved on the sides of the 

 cranium, and are continuous with the alisphenoid and pro-otic 

 elements. 



2. " The opisthotic is largely developed, and extends upward 

 and forward to the walls of the brain case. 



3. " A distinct element connects the squamosal with the pari- 

 etal bone above the opisthotic." 



We shall see later on how far these characters are correct. 



Marsh, 1880. 



Professor Marsh's ^ latest contribution to the subject was 

 given in 1880. 



A peculiar bone is described and figured as a hyoid ; some 

 sclerotic plates are figured. The transverse bone is described : 

 " It is an L-shaped bone, thin and somewhat twisted. One 

 ramus unites by suture with the corresponding process of the 

 pterygoid, and the other extends forward, nearly at a right angle, 

 to join the posterior end of the maxillary." The true nature of 

 the pterygoid, already known since Cuvier and Goldfuss, and 

 again tested by Owen, is expressed again. " Cope has called 

 these dentigerous bones 'palatines,' ^ and stated that they were 



1 Marsh, O. C, New Characters of Mosasauroid Reptiles, Am. Journ. Sci., Vol. 

 XIX, January, 1880, pp. 83-87. 



2 The fact is, that Marsh was the one who made this mistake for the first time. 



