.182 



THE EXTINCT BATRACHIA, REPTILIA 



another species of Mosasaurus, and from one of Clidastes, as entirely confirmatory of it. 

 On the other hand, I am unable to assign hind limbs to any of the species of the order. 

 'The anterior limbs combine the characters of Testudinata and Sauropterygia. The ulna 

 and radius, and all more distal portions of the limbs, are those of the latter order. The 

 large ovoid flat carpals, and flat, medially contracted phalanges, with fixed articulations, 

 are of that type. Three of such phalanges have been figured by Leidy, ('ret. Kept. VIII, 

 figs. (! and 7, where they are regarded as radii, and at fig. 13, PL XVII. Ulna and ra- 

 dius are figured PI. VII 1, figs. 9 and 10. 



From the preceding* evidence, we may look upon the Mosasauroids and their allies as 

 a race of gigantic marine serpent-like Reptiles, with powers of swimming and running 

 like the modern Ophidia. Adding a, pair of short anterior paddles, they are not badly 

 represented by old Pon'toppidan's figure of his sea, serpent. 



That their habit was to devour whole is evident, and though the articulation of the 

 lower jaw will not admit of as much extension as that of the Ophidia, it exceeds other 

 reptiles in this capacity, allowing by its lateral flexure, of the passage of large objects be- 

 tween the rami. The carnivorous Dinosaur on the other hand, tore his prey to pieces, as 

 do Mammals of the present day. 



Thus in the Mosasauroids we almost realize the fictions of snake-like dragons and sea 

 serpents, in which men have been ever prone to indulge. On account of the Ophidian 

 part of their affinities, I have called this order the l'ythonoinorpha. 



The families embraced are two, the Mosasauridse and Clidastidee, which differ as 

 follows : 



Vertebrae with zygosphenal articulation wanting- or rudimonfal ; humerus free in life. 



MOSASAURID.K. 



Vertebrae with zygosphenal articulation developed ; humerus probably included in 



life. CLIDASTIMI. 



In time they immediately preceded the Eocene Palaeophides, and probably will find 

 in them distant structural allies. 



I think it highly probable that the genus Saurospondylus of tteeloy, from the lower 

 chalk of England, belongs to this order. If so it is the type of a peculiar family, to be 

 known by the absence of neural spine and low position of the zygapophyses, which have 

 horizontal articular faces. The S. dissimilis, Seeley, is a. much smaller animal than any 

 here enumerated, and is known by a single vertebra,.* 



(ioldliiss states that Mosasaurus possesses a, malax arch. This is absent, in Clidastes, 

 and I am inclined to doubt whether (ioldliiss has demonstrated his point; if present, it 

 must be as he states, very slender. 

 •See Ann. Magaz. Nat. Hist,., L885, Sep*. 



