Osteology of Loxomma Allmanni. 47 



merely pierce tlie nasal cavity. They are not in connexion 

 with the anterior nares. In Leindosteus^ a short way behind 

 the snout, there is, on each side of the median line, a com- 

 plete perforation of the maxilla for the reception of a man- 

 dibular tooth during closure of the mouth. Perhaps the 

 apertures in Loxomma have the same use ; they are of about 

 the same size as the depressions in front of them, and are 

 bounded internally and in front by the vomers, externally by 

 the alveolar borders of the maxillee, and posteriorly by the 

 anterior ends of the palate-plates of the same bones. 



The maxillaries are the longest bones of the skull, and con- 

 sist of alveolar borders and palate-plates. On the right side 

 the alveolar border of the bone is very nearly perfect, whilst 

 that on the left side is nearly all wanting. The palate-plates 

 are perfect on both sides. 



The alveolar border is a narrow tract of bone, 8| inches long, 

 extending from the premaxillary to the quadrate jugal, with 

 which latter it articulates at about 3^ inches in front of the 

 posterior end of the lateral part of the cranium. The border 

 which remains bears thirteen small teeth irregularly disposed, 

 and has four gaps from which both bone and teeth have dis- 

 appeared. It is highly probable that the teeth had originally 

 been more numerous ; for in another specimen, in Mr. Atthey's 

 collection, of the skull of Loxomma, in which the maxilla 

 measured in length very neaidy the same as that of the speci- 

 men before us, there were twenty-four teeth easily counted. 



The inner edge of the alveolar border towards the front is 

 depressed for the space of 1| inch below the level of the outer. 



The palate-plates of the maxillaries are about 6^ inches in 

 length, with an average width of 1 inch, and extend from the 

 aperture in the jaw and the vomerine plates backwards to 

 articulate with the malars and ectopterygoids. Each is trans- 

 versely divided into two, if not three, pieces, there being an 

 undoubted suture at the distance of 2 inches from the anterior 

 end of the bone, and a doubtful one at nearly the same distance 

 further back ; the supposed third piece bears no tooth. 



The first piece of the palate-plate, a little broader than the 

 others, lies between the alveolar border externally and the 

 vomers and palate-bones internally ; in front it forms the pos- 

 terior margin of the aperture in the jaw ; and immediately 

 behind this edge occurs a large round depression, behind 

 which again is a tusk, but one of smaller diameter than the 

 depression ; the tusk is only | inch in diameter, and its outline 

 is more circular than that of the vomerine tusk. 



The second piece is bounded laterally by the alveolar border 

 and by the palate-bones, and bears, at a distance of 1| inch 



