1867.] 



Dr. Giinther on the Anatomy of Hatteria. 



461 



2. Sutural union of the tympanic with the skull ; firm and solid union 

 of the bones of the palate with the tympanic, as shown by the sutural con- 

 nexion of tympanic and pterygoid, broad sutural connexion of the colu- 

 mella with tympanic and pterygoid, immoveable ptery go- sphenoid joint, 

 firm and extensive attachment of pterygoid to ectopterygoid. 



3. This restriction of the mobility of the bones named is compensated 

 by an increased and modified mobility of the lower jaw, the mandibles 

 being united by ligament, and provided with a much elongate articular 

 surface. 



4. Displacement of the palatine bones, which are separated by the pter- 

 ygoids, and replace a palatal portion of the maxillaries. 



.5. Perforation of the tympanic; extremely short postarticular process of 

 the mandible. 



The vertebral column and the remainder of the skeleton show the fol- 

 lowing peculiarities : — 



1. Vertebrae amphicoelian ; caudal vertebrae vertically divided into two 

 equal halves. Points of minor importance are the uniform development 

 of strong neural spines, and the direction of the caudal pleurapophyses 

 which point forwards. 



2. The costal hsemapophyses are modified, first, into a series of ap- 

 pendages identical in position with the uncinate processes of birds ; and 

 secondly, into a double terminal series connecting the ribs with the tho- 

 racic and abdominal sterna, the distal pieces being much dilated and 

 forming the base of a system of muscles (retractors of the abdominal ribs). 



3. The development of a system of abdominal ribs, standing in intimate 

 and functional relation to the ventral integuments. 



4. Continuity of the ossification of the coracoid ; presence of an acro- 

 mial tuberosity of the scapula ; sub vertical direction of the os ilium. 



5. The arrangement of the bones of the limbs and their muscles does 

 not show any deviation from the Lacertian type. 



The dentition of Hatteria is unique. That of young examples differs 

 scarcely from the dentition of other acrodont lizards. In adult examples 

 the intermaxillaries are armed with a pair of large cutting- teeth ; a part of 

 the lateral teeth are lost, and the alveolar edges of the jaws are cutting and 

 highly polished, performing the function of teeth. A series of palatine 

 teeth is in close proximity and parallel to the maxillary series, both series 

 receiving between them in a groove the similarly serrated edge of the 

 mandible. 



As regards the organs of sense, the absence of the pecten of the eye and 

 of the tympanic cavity, the commencement of a spiral turn of the cochlea, 

 and the attachment of the hyoid bone to the terminal cartilage of the 

 stapes — are to be noticed. 



The structure of the heart and of the organs of respiration and circu- 

 lation are of the Lacertian type. 



The absence of a copidatory organ is a character by which Hatteria is 



