Dr. A. Giintlier on the Anatormj of Hatteria. 129 



ribs with the thoracic 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 

 acromial tuberosity of the scapula ; subvertical 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. la 

 adult examples the iutermaxillaries 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 

 circulation are of the Lacertian type. 



The absence of a copulatory organ is a character by which Hat- 

 teria is distinguished from all other Saurians. Thus Hatteria pre- 

 sents a strange combination of elements of high and low organiza- 

 tion, and must be regarded as the type of a distinct group. Its 

 affinities and systematic position may be indicated in the following 



Synopsis of Recent Reptilia. 



I. SaUAMATA. 



First order. Ophidia. 

 Second order. Lacertilia. 



Suborder A. Aniphisbcenoidea. 



Suborder B. Cionocrania. 



Suborder C. ChamceJeonoidea. 



Suborder D. ^yctisaura. 

 Third order. Rhynchocephalia. 



II. LORICATA. 



Fourth order. Ci-ocodilia. 

 III. Cataphracta. 



Fifth order. Chelonia. 



May 9, 1867. — Lieut.-General Sabine, President, in the Chair. 



" On the Development and Succession of the Teeth in tlie Marsu- 

 pialia." By William Henry Flower, F.R.S., F.R.C.S. 



Although the dentition of adult individuals of all the animals which 

 constitute the remarkable Order or, rather, Subclass Marsupialia 



Ann. ^- Mag. N. Hist. Ser. 3. Vol. xx. 9 



