600 
DR. GUNTHER ON THE ANATOMY OF HATTERIA. 
by a low, sharp ridge, the two ridges converging behind. The process for the attachment 
of the ectopterygoid ( t ) is unusually long, rectangular at the base ; two of the branches 
of the ectopterygoid receive this angular process between them. 
Before I pass to the description of the remaining part of the skull, the mandible, I 
maybe allowed to notice the appearance of th e palate whilst covered with the soft parts 
and the mucous membrane. Corresponding to the interpterygoid vacuity in the skull, 
there is a longitudinal arrow-shaped deep depression in the median line of the palate, com- 
mencing on a level with the hinder end of the palatine teeth. This depression is gene- 
rally widened behind in Lizards, or at least continuous with the plane of the base of the 
skull ; but in Hatteria it is entirely closed behind, in consequence of the proximity of 
the hypapophyses of the basisphenoid. Another, small but very deep, recess exists 
immediately behind the palatine series of teeth, in front of the long styliform process 
of the pterygoid and ectopterygoid. The boundary between palatine and pterygoid is 
marked by a slight ridge of the mucous membrane, nearly corresponding to the suture 
between those two bones ; this ridge runs forward to the inner hinder angle of the 
choana ; and posteriorly it is arched outwards, to form the gingival fold of the palatine 
series of teeth ; it is split into two folds in front of this series, one to accompany the 
alveolar edge of the maxillary, whilst the other runs along the outer margin of the 
choana, which can be nearly entirely covered or closed by it. The choanse are rather 
narrow slits not extending backwards to the palatine teeth. The auditory recess is 
rather shallow, eustachian tubes being absent with the tympanic cavity. 
The symphysis of the mandibles is formed by a fibrous ligament allowing of some 
mobility ; the persistent cartilage of Meckel is entirely replaced by fibrous tissue near 
the symphysis*. A part of the sutures between the bones of which the lower jaw of 
Lizards is generally composed have entirely disappeared (if they ever existed), so that 
the following bones only can be distinguished. The dentary ( u ) forms nearly entirely 
the outer surface of the mandible, a comparatively small articular portion and the top 
of the coronoid process excepted. The foramina mentalia vary in number from two to 
four, and are small. There is a very distinct foramen between the dentary and articu- 
lar, penetrating to the inner surface of the mandible; it is identical with the large 
vacuity of the lower jaw of the Crocodile, and very indistinct or entirely closed on the outer 
surface in the Lizards. The splenial ( v ) is narrow elongate, behind twisted downwards 
to the lower side of the mandible and terminating about 3 millims. from its extremity. 
The coronoid (sc) is triangular, covering with one angle the cartilage of Meckel, and forming 
with another the coronoid process. The articular bone (tv) is very peculiar : if an angular 
bone was present at an early age, it has now entirely coalesced with the splenial, there 
being scarcely any osseous projection behind the articulary surfacef. The articular 
* Indeed Heloclerma appears to be the only Lizard in which, this cartilage forms the symphysis (Troschul, 
Wiegm. Archiy, 1853, p. 301). 
t In Grammatojohora, Monitor, and in a great number of Lizards the angular bone projects far beyond the 
articulary surface, frequently turned upwards in an oblique direction. Two muscles arise from this projection, 
