166 



represented in pi. 1 . fig. 8 of the ' Ossemens Fossiles." The vacuity in the back part of the 

 ramus of the jaw, between the angular, surangular, and dentary pieces, is relatively longer 

 than in the true Crocodiles. * The number of alveoli in the premaxillary is 5 5 ; in the 

 maxillary, 14 14; in the dentary, 18 18. 



The bifurcation of the rib of the axis is deeper than in the Crocodilus acutus. There are 

 the same number of hatchet-shaped, or anterior floating ribs, and of true ribs, as in the Cr. 

 acutus. The rudimental pleurapophyses are preserved upon the 20th vertebra. There are 

 four lumbar, two sacral, and thirty-nine caudal vertebrae ; the sixteen anterior of which sup- 

 port transverse processes, which are anchylosed pleurapophyses, traces of the suture being 

 still visible in some of the anterior ones. 



Mus. South. 



761. The skull of a young Alligator lucius. 



The number of alveoli is in the premaxillary, 5 5; in the maxillary, 15 15; in the 

 dentary, 19 19. The seven posterior sockets are confluent, and form a partially divided 

 common groove. There is no trace of vomer upon the palate of this or of the preceding 

 specimen. 



Hunterian. 



-\ 



762. The skull of a young Alligator lucius, in vertical longitudinal section : it shows 



the large proportional size of the cranial cavity at this period. The point of 

 the nasals joins the premaxillaries and divides the external nasal aperture. 



Prepared from a specimen presented by the Zoological Society of London. 



763. The disarticulated bones of the skull of a young Alligator lucius, minus the 



hyoid and scapular arches, the right alisphenoid, and the divided anterior por- 

 tions of the vomer. The individual bones are numbered upon coloured labels 

 indicative of their natural arrangement and names, according to the Table of 

 SYNONYMS. Hunterian. 



764. The skull of the black Alligator (Alligator niger). 



The number of alveoli is in the premaxillary, 5 5; in the maxillary, 13 13; in the 

 dentary, 18 18. The vomer is divided at the median line, and the anterior expanded part 

 of each moiety appears upon the bony palate, between the premaxillary and maxillary bones ; 

 the palatine suture between the same bones bending down to the hinder border of the palatal 

 anterior aperture of the nostrils. The fossae for the reception of the crowns of the inferior 

 canines are well developed at the outer end of this suture : the palatine bones are unusually 

 exjwnded anteriorly : the posterior nasal apertures are horizontal, as in the Alligator lucius. 

 The specimen was brought from Guiana. 



Purchased. 



