66 REPORT — 1841. 



reference to the Crocodilus hiporcatus, or other existing species of Crocodile 

 or Alligator, are the larger size of the temporal holes as compared with the 

 orbits, the more regular and rapid diminution of the head towards the snout, 

 the straight line of the alveolar tract, and the greater relative length and 

 sienderness of the muzzle, which is evident notwithstanding its imperfect 

 condition. These differential characters are equally manifest in the larger, 

 and in some respects more perfect specimen, of the cranium of this species 

 in the British Museum. 



Amongst existing Crocodiles, the Bornean species, called Crocodilus Schle- 

 (/elii, most resembles the Crocodilus Spenceri. But in the Sheppy Crocodile 

 the posterior smooth surface of the occiput is less concave ; its upper boun- 

 dary line is indented in the middle by the termination of a median longitu- 

 dinal depression upon the upper surface of the skull, which is not present in 

 the existing species, in which the corresponding surface is flat. The de- 

 scending process of the basi-occipital, below the articular tubercle, is smoother 

 in the Crocodilus Speiiceri ; the interorbital space is flatter : the upper tem- 

 poral foramina equal the orbits in size — a character by which the Crocodilus 

 Spenceri manifestly approaches the Gavials. The nasal and superior maxil- 

 lary bones are smoother ; the sloping profile line of the face is straighter, and 

 the lateral converging lines of the upper jaw are straight. These characters 

 are well shown in the British Museum specimen. 



The upper jaw slightly expands about one-third from its termination, then 

 contracts, and again expands at the muzzle. At this anterior part the bones 

 are more pitted than they are nearer the cranium. The alveolar margin 

 seen in the whole skull is slightly undulating. The jugal bone is slender and 

 nearly horizontal. The lower jaw has a large elliptical vacuity at its ex- 

 panded posterior part. Its alveolar risings correspond with the sinkings of 

 the same part in the upper jaw. In all these characters it corresponds with 

 the Crocodilus Schlegelii of S. MUUer. 



Upon the lower surface of the skull the pterygoids in the Crocodilus 

 Spenceri are terminated anteriorly by a broader and straighter transverse 

 line ; from the middle of which the palatines are continued, their posterior 

 extremities not being expanded, as in the Crocodili vulgaris or hiporcatus, 

 but of the samei breadth as the rest of the bone. The anterior and internal 

 curved border of the transverse bones is more regular. The dental series 

 terminates posteriorly nearer the anterior part of the transverse bone. The 

 teeth, If^o = 84, are more uniform in size, and more regularly spaced ; 

 the intervals, however, vary from 1 1 to 2 and 3 lines ; and that between the 

 first tooth in Mr. Spencer's mutilated specimen and the second equals 7 

 lines. The diameter of the base of the crown of the tooth is 3 lines : there 

 are nine of these teeth in the same extent as that which includes eleven teeth 

 in a specimen of the Crocodilus vulgaris, having a skull of similar breadth. 

 The teeth in the Crocodilus Spenceri are subcircular, Avitli an anterior and 

 posterior longitudinal ridge, with intervening fine longitudinal sti'iae. 



The sculpturing of the cranial bones is very similar in the recent and fossil 

 Crocodiles, but the facial bones are smoother in the Crocodilus Spenceri, as 

 they likewise seem to be in the Crocodilus Schlegelii. 



The following dimensions are taken from the skull of the Crocodilus Spen- 

 ceri in the British Museum : — 



Ft. In. Ln, 



Length of cranium from the lower end of the tympanic bone to 



the beginning of the nostril 2 



Breadth of ditto between the articular end of the tympanic bones 10 



From the articular end of the tympanic to the orbit 8 6 



