60 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 20,. 



The lower canine (figs. 1 & 2 c') is subcompressed, very slightly 

 recurved, 9 lines in length, 2 lines in breadth. The projecting crown 

 is 5-i- lines long ; the implanted base is 3|- lines long : this extends 

 very close to the lower margin of the mandible and becomes a little 

 contracted there, but shows a short conical pulp -cavity, without any 

 trace of the germ of a successor. It closely resembles the completely 

 formed canine of a mammalian carnivore, in shape, structure, im- 

 plantation, and direction. 



The upper canine (ib. c) is larger; two-thirds of the tooth are 

 preserved on the right side (fig. 2) ; the inner wall of the socket is 

 shown on the left side (fig. 1 c). In shape this tooth resembles the 

 lower canine : its greatest breadth is nearly 3 lines, its length seems 

 not to have been less than 11 lines : it crossed the lower canines 

 obliquely, its socket being more backward and outward in position ; 

 and while the points of the lower canines a little diverged from each 

 other, those of the upper ones slightly converged. The socket of 

 the upper canine extends close to the upper surface of the skull, and 

 even causes a slight prominence on that part of the maxillary, close 

 to its suture with the nasal. The depth of the implanted part of 

 the upper canine is 7 lines. There is no trace of a recess for a suc- 

 cessional tooth at the base of the inner wall of the socket (c, fig. 1). 



Twelve close-set, conical, subcompressed teeth succeed the lower 

 canine, their protruded crowns becoming shorter, and their implanted 

 bases longer, as they recede in position. A thin layer of bone imme- 

 diately surrounding the simple base of each molar tooth has a brick- 

 red colour, as if retaining a stain from the hematosine of the vascular 

 alveolar fining membrane ; the exposed socket of the upper canine 

 presents the same colour ; the other parts of the fossil bone are grey. 



The upper molars passed external to the lower ones when the mouth 

 was shut. The "symphysis mandibulae " is very short. The rami 

 diverge from the linear trace of junction, at an acute angle, straight 

 to the articular end. The length of each ramus from the lower and 

 back part of the symphysis is 2 inches 8 lines. The receding 

 " mentum " is 6 lines long : the depth of the ramus below the first 

 molar is 4| fines ; it gradually increases to 6 lines below the last 

 molar. 



There is a series of small vascular foramina above the alveolar 

 border of the upper jaw; and indications of the same saurian character 

 are discernible in parts of the lower jaw. 



The reptilian nature of the above-described skull is shown by its 

 single occipital condyle, and by the complex " frontal bone " ; its 

 crocodilian affinities by its terminal single nostril. The more gene- 

 ralized saurian character is exemplified by the large temporal fossae 

 and the " foramen parietale" ; whilst a most singular and suggestive 

 approach to the mammalian class is made in the above-described 

 characters of the dentition. 



The predominance of the canines, their seeming want of successors — 

 the certain absence, at least, of such evidence as would have appeared 

 had the canines been subject to the ordinary law of saurian dentition — 

 point to at least an analogical relationship with the Dicynodonts ; 



