WEALDEN FORMATIONS 



Species — Brachydectes minor. Plate I, fig. 3. 



This species first indicated the genus in the exploratory operations ; it is represented 

 by the left mandibular ramus (Plate I, fig. 3), which is remarkable, as in the larger 

 species, for the small proportion which the alveolar tract bears to the entire length of the 

 bone, and for the entireness of the outer wall. The alveolar tract is undulated, showing 

 an incisive and a laniary convexity with intervening and hinder concavities. 



The incisive convexity holds five teeth, close set, the two hindmost rather larger than 

 the rest ; but no single tooth is so much larger as to suggest the name of ' canine.' 

 The laniary convexity shows one large canine with a broad, straight, laterally compressed 

 crown. It is preceded by a smaller tooth, rather less than the hindmost incisor, and 

 separated therefrom by a space which may have held two or three small teeth. The 

 alveolar tract behind the canine seems to have lodged three or four teeth, the crowns of 

 which are lost. 



The whole length of the alveolar tract is 23 mm. (1 inch) ; that of the entire ramus 

 is 85 mm. (3 inches 2 lines). The dentary element bifurcates behind as usual; the 

 upper prong joining the surangular, the lower and longer one the angular, but without 

 defining or leaving any vacuity ; the union where such vacuity would have been left in 

 ordinary Crocodiles is situated well within the anterior half of the ramus. The posterior 

 elements are correspondingly of unusual length; their breadth is also proportionally 

 greater than in previously known Crocodilian mandibles. The length of the surangular 

 element (29') is 48 mm. (1 inch 10 lines) ; its depth (vertical breadth) is 13 mm. 

 (6 lines). The upper border describes a feeble convexity ; beneath the articular surface of 

 29 the surangular curves downward and backward, meeting the lower border at a point 

 wedged between the articular and angular elements. 



The articular exposes the outer antero-posterior concave border of the joint. From 

 this it descends obliquely backward and joins the angular in forming the process (30'), 

 which here projects directly backward, its termination being much below the joint, and 

 nearly on the level of the lowest part of the lower border of the jaw. The angular 

 element extends forward from the angle, with its lower border at first straight or 

 feebly concave, and then moderately convex to its junction with the dentary ; a ridge 

 projects along the greater part of this course a little way above the lower border. A 

 portion of the splenial element shows above the fore part of the surangular, and supple- 

 ments the inner alveolar wall at the hind part of the dentary. 



From the lower jaw of Theriosuchits (Plate III, figs. 5, 14, 16) the present differs 

 in the shortness of the dentary element and alveolar series, in the greater depth and 

 verticality of the outer surface of the ramus, and the narrower inferior border. It also 

 offers a generic distinction in the number and shape of the teeth. 



The proportional length and slenderness of the dentary and the absence of any 



