1873.] OWEN — DENTIGEROUS BIRD. 515 



The articular end of each mandibular ramus (PL XVI. figs. 1 & 

 2, 30) is broken away : an impression on the matrix shows the 

 vertical diameter of the ramus (fig. 8, 30), at the joint with the 

 tympanic, to have been 4^ lines (0-009 m.) ; in advance of this the 

 preserved part rapidly gains depth and gives 8 lines (0-017 m.), 

 where it is parallel (figs. 1, 2, 30, 3i) with the fore border of the orbit. 

 Here a fracture or suture runs from below upward and forward to 

 beneath the hind point or end of the upper jaw (fig. 2, 21). If this be 

 a suture, it divides the confluent angular (30), surangular (31), and 

 articular elements from the combined splenial and dentary (fig. 2, 32). 

 The latter element loses depth as it advances ; the fore part is 

 obliquely broken away nearly opposite the broken fore part of the 

 upper jaw. The vertical diameter of the mandibular ramus is here 

 reduced to 5 lines (0-010 m.) ; the portion of ramus preserved on 

 the left side is 2 inches 5 lines (0-060 m.) in length ; on the right 

 side a corresponding portion of the ramus is preserved, 2 inches 

 2 lines in length, but with more of the lower border broken away. 

 The course of what remains of the boundary between the dentary 

 (fig. 1, 32) and hinder part (ib. 31) of the ramus corresponds so 

 closely with that of the left ramus (fig. 2) as to add to the pro- 

 bability that it is a retained suture, or a yielding of the ramus along 

 the line of, perhaps, a partially ossified suture. 



The upper border of the mandible beneath the zygoma is mode- 

 rately convex toward the orbit, but not partially produced as a 

 coronoid process ; the ramus here is thin transversely in proportion 

 to its depth, its thickness not exceeding 2 lines. 



The upper two thirds of the outer surface of this part of the 

 mandible is feebly convex vertically, and is divided by a ridge due 

 to the subsidence of the flat lower third part of the outer surface. 

 The line of this ridge or subsidence slightly ascends to the suture 

 with the dentary. Prom the part of the suture where such line 

 terminates, a groove (PL XVI. fig. 2,/) begins, which traverses the 

 outer surface of the dentary almost parallel with the alveolar border, 

 and at 4 or 5 lines below it ; the part of the outer surface of the 

 dentary above the groove is rather more prominent than that below 

 the groove. 



The outer surface of both upper and lower beak-bones is sculp- 

 tured by fine, irregular, subreticulate, seemingly vascular, linear 

 impressions and foramina. 



The alveolar border of the preserved hind part of the upper jaw- 

 bone, an inch in extent on the right side (PL XVI. fig. 1). is produced 

 into nine tooth-shaped processes, conical, subcompressed, sharp- 

 pointed, slightly inclined forward. A view of this part of the skull, 

 twice the natural size, is given in fig. 5. The hindmost tooth pre- 

 served is but a quarter of a line long, the next is about half a line 

 in length, the third in advance is a little longer, the fourth a little 

 shorter ; the fifth (ib. ib. a) suddenly increases to a cone or triangle, 

 2| lines along its longer (hinder) side, 2 lines along its shorter 

 (fore) side, and nearly as long across the base, which is confluent 

 with the jaw. The alveolar border swells slightly where it forms 



