52 SYSTEMATIC PALEONTOLOGY 



Genus TRETULIAS Cope. 



Dental canal obliterated, and dental groove without osseous roof. 

 Gingival canals and foramina present at one side of the alveolar groove. 



Tketulias buccatus Cope. 

 Plate XXV, Fig. 2. 



Tretulias buccatus Cope, 1895, Proc. Amer. Philos. Soc, vol. xxxiv, p. 143, pi. vi, 

 fig. 2. 



Description. — " This species is represented by parts of the mandibular 

 rami of two individuals. . . One of these measures 607 mm. in length, 

 and is in fairly good preservation; the other is a shorter fragment, 

 and is considerably worn. They agree in all respects, 



" The longer fragment is gently curved both inwards and downwards. 

 It is compressed anteriorly, and more depressed posteriorly, so as to 

 be but little deeper than wide. The external face is very convex, 

 more so posteriorly than anteriorly, so that that part of the superior wall 

 which is developed is horizontal, as in the Siplionocetus priscus Leidy. 

 The internal face is little convex, and is slightly concave on a line near 

 to and parallel to the inferior border. Generally this angle is obtuse, 

 and is a little more than right ; anteriorly, near the extremity it becomes 

 more ridge-like. Posteriorly the section of the ramus represents more 

 than a half-circle, the base being the internal face. The internal basal 

 concavity referred to disappears posteriorly, but its place is occupied 

 by a Meckelian fissure, which extends along the bottom of the groove, 

 disappearing at the end of the terminal two-fifths of the length. 



" The gingival canals are very oblique, extending horizontally for- 

 wards and outwards. The internal foramina issue at spaces of one and 

 two inches, and they are not connected by a superficial groove. The 

 superior (external) series are equally oblique, extending forwards and 

 opening obliquely upwards. Only two of these canals are present on the 

 sijecimen, and these are on the posterior two-fifths of the length. They 

 are not complete on the external side, and are therefore only grooves. 

 The common canal is open external to them, and separates the superior 

 from the external face of the ramus. It has not the form of the section 

 of the ramus as in other species, but is shallow, and with its long axis 



