4 MR. E. T. NEWTON ON EEMAINS OF [Feb. 1 899, 



and part of the hinder end is broken away. The length of this 

 bone, measured round the outer curve, is 130 mm., and it may have 

 been 140 mm. when perfect ; its greatest depth, 28 mm., is at the 

 hinder end. The anterior part shows the smooth surface overlapped 

 by the premaxilla, and then a depression of the upper margin, which 

 probably received the lachrymal bone. Parther back the upper 

 margin has two prominences : the posterior prominence marks the 

 position of the front of the supplementary maxilla, and behind it 

 is a pit and groove for the reception of the last-named bone ; the 

 anterior process, if we may judge by the arrangement of the facial 

 bones of Amia calva, marks the division between the lachrymal 

 bone and the first of the suborbital series, but there is nothing in 

 Amia ccdva, nor in any of the maxillae figured by Cope, corresponding 

 with this anterior process ; the posterior process, however, has its 

 counterpart in both those forms. 



The outer surface of the maxilla becomes somewhat rugose below 

 the anterior process, and these rugosities become longitudinal streaks 

 towards the thin hinder part of the bone. The oral margin is 

 slightly concave, and shows the bases of a single row of 45 or more 

 teeth ; these are large in front (4 in 19 mm.) and smaller at the 

 back (15 or 16 in the same length), where they become crowded 

 together and tend to form two rows. The supplementary maxilla is 

 represented by about 35 mm. of its anterior part, which fits into the 

 shallow groove on the upper border of the maxilla ; its outer surface 

 is rugose above, and longitudinally streaked below (PI. I, fig. 3 6). 



Mandible. — About 50 mm. of a left dentary bone is preserved 

 (fig. 4), but both ends are imperfect; its greatest depth is 27 mm. 

 The outer surface is streaked with sharp thin ridges above and, 

 though somewhat less so, below ; while the median part is roughened 

 by short, irregular, and oblique grooves, with projecting edges, which 

 communicate with openings that penetrate the bone, very much the 

 same as in Amia calva. The upper or dentary surface is 14 mm. 

 wide in the middle, and a little less towards the front ; its outer two 

 thirds are occupied by the bases of a single row of seven large teeth, 

 while the inner third forms a flattened margin. In Amia calva this 

 inner margin supports a row of ossicles (supplementary splenials) 

 which carry two or three rows of small teeth ; and a specimen from 

 King's Quay, in Mr. Colenutt's collection, retains one such tooth- 

 bearing ossicle still in position (PI. I, fig. 17*) : this shows that the 

 dentition of the mandible in these fossil forms was essentially the 

 same as in the living species. The hinder teeth of this dentary bone 

 were the largest, three of their bases measuring 24 mm. The inner 

 margin of the dental surface turns abruptly downward to form the 

 inner plate, below which is a large cavity, doubtless covered during 

 life by a broad splenial bone ; this cavity is continued anteriorly 

 into a groove, such as Cope describes in the American forms. The 

 lower margin is sharp and knife-like. Unfortunately this dentary 

 bone is too imperfect to show its proper form, but Mr. Colenutt has 

 several smaller specimens from both Bembridge and Osborne Beds, 

 doubtless belonging to this species, which to some extent supply the 



