LIASSIC PTERODACTYLES. 471 



displaced beneath the mutilated fore part of the mandible, I take to be the foremost of 

 the mandibular series and suppose that its point would naturally project across the interval 

 between the first and second of the upper teeth. The fourth laniary appears to be more 

 displaced: its base or root, with a lateral depression, is shown behind the fifth tooth of 

 the minute serial teeth, and the crown passes obliquely backward on the inner side of 

 that of the sixth upper laniary, by which it is concealed. Of the serial teeth, with pointed 

 crowns from half a line to a line in length, about thirty may be reckoned occupying an 

 alveolar extent of 2 inches, 9 lines. 



At the hind part of the left mandibular ramus, here exposed, three longitudinal 

 ridges define two vacuities, of which tlie inferior may be natural. The upper one seems 

 more plainly due to loss of the thin outer plate of bone extended between the upper 

 two ridges. The proportions of the ramus closely accord with those of the first- 

 described specimen. The fore part of the mandible is too much mutilated for useful 

 comparison. 



The dentition of Dimorpliodon, as displayed by the second specimen of skull, consists, 

 in the upper jaw, of laniaries with wide intervals, eleven in number on each side ; in the 

 lower jaw, of four, if not five, laniaries implanted at the fore part of each ramus of the 

 mandible at intervals corresponding with three of the four anterior laniaries above ; 

 then follows the long series of close- set and minute pointed teeth. The difference of 

 dentition as compared with the first specimen (PI. 15) is, in the upper jaw, in 

 the additional small laniary or cuspidate tooth at the back part of the series in that 

 specimen. In the lower jaw there does not seem to be any noteworthy difference in 

 the number, kinds, and position of the teeth. The longest laniaries are included between 

 the second and fifth in both jaws : the upper laniaries after the fourth become small and 

 straight. 



At the first view of the framework of the huge head of our Liassic dragon one is 

 struck with the economy of bony material and the purposive skill with which it has 

 been applied or disposed, so as to give strength where resisting power was most 

 required. 



The lodgment of the poorly developed brain enUsts a miserably small proportion of the 

 skidl : the cranium proper, or brain-case, is relegated to an out-of-the-way corner, so to 

 speak, and there it is almost concealed by the projections for joints or muscular 

 attachments. The orbits accord with the large eyes given to this volant and swift-moving 

 Reptile. 



One can conceive no necessary interdependent relation between the wide external 

 bony nostril (") and the organ of smell, nor be led to conjecture that the tegumentary 

 inlets to the nasal chamber were.ilarger than is usual in Reptiles. 



The main pm-pose of the head is for prehension of prey. The jaws are produced far 

 forward to form a wide-gaping mouth, and are formidably armed. We n)ay conceive, 

 therefore, that the dragon may have occasionally seized an animal of such size as to 



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