Dr. A. Giinther on the Anatomy 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 
eel tuberosity of the scapula; subvertical direction of the os 
um. 
__ 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 
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. SQUAMATA. _—s.. 
First order. Ophidia. 
Second order. Lacertilia. 
Suborder A. Amphisbenoidea. 
Suborder B. Cionocrania. 
Suborder C. Chameleonoidea, 
Suborder D. Nyctisaura. 
Third order. Rhynchocephalia. 
II. LoricatTa. 
Fourth order. Crocodilia. 
III. CaTraApHRACTA. 
Fifth order. Chelonia. 
May 9, 1867.—Lieut.-General Sabine, President, in the Chair. 
“On the Development and Succession of the Teeth in the Marsu- 
pialia.”’ By Witt1am Henry Frower, 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 
