602 
DR. GUNTHER ON THE ANATOMY OE HATTERIA. 
first palatine tooth is much stronger than, and separated by a short interspace from, the 
succeeding. Each mandible is armed in front by two incisors and a canine tooth, more 
or less confluent at the base, so that the three teeth together, when ground down by the 
action of the upper incisor, present an uninterrupted oblique edge, most deeply chiselled 
out towards the symphysis (figs. 6 & 7). The alveolar edge of the mandible is polished, 
bearing about sixteen teeth as long as the number is complete ; but (as in the maxil- 
lary) the teeth are gradually lost from the front backwards, and there is, corresponding 
to the remaining anterior maxillary tooth, a very shallow and long concavity scooped out 
by the vertical and horizontal action of this tooth. The toothed, or rather serrated 
hinder portion of the dentary fits closely between the maxillary and palatine series. 
Dentition of young examples. — I have mentioned above that the upper incisors of a 
full-grown example are notched ; this is explained by the remarkable circumstance that 
each is, in fact, composed of two teeth, which are conical and perfectly distinct in young 
examples about 7 inches long (figs. 10 & 11). Also the incisors of the lower jaw are 
separate to their base, and the lateral canine tooth is somewhat removed from them. 
The other mandibulary, maxillary, and palatine teeth do not differ peculiarly from those 
of older- examples. No polished surface can be distinguished on the alveolar edges*. 
Although the peculiarities mentioned render the dentition of Hatteria unique, I find 
on examining a number of acrodont Lizards, that a recent and a fossil genus approach it 
closely in this respect. Uromastyx , an Agamoid genus inhabiting sandy plains of 
Northern Africa and Hindostan, has a very narrow, strong, single intermaxillary, arched 
downwards and more or less overlapping the symphysis of the lower jaw, more so in 
adult examples than in immature (figs. 12, 13, 15). In a half-grown Uromastyx hard - 
wickii (fig. 14) the intermaxillary does not project below the level of the maxillary, and 
is armed with four small, closely set, incisor-like teeth. The maxillary and mandibulary 
teeth are similar, and occupy in an uninterrupted series the alveolar edges of the jaws. 
This dentition is in timeworn away : in the adult of the same species (figs. 12 & 13) the 
intermaxillary and the fore part of the maxillaries and mandibles are edentulous, the 
sharpened alveolar edges performing the function of teeth ; the intermaxillary and the 
upper anterior angle of each mandible project, and these projections have their surfaces 
polished and bevelled as true teeth. In an old specimen of Uromastyx spinipes (fig. 15) 
I find the teeth complete in both jaws, but the intermaxillary projects considerably 
below the level of the maxillary, overlapping the mandibulary symphysis. The osteolo- 
gical characters of Uromastyx do not indicate a further affinity with Hatteria. It fs 
worthy of notice that Uromastyx hardwicJcii is strictly herbivorous; I am not acquainted 
with the food of U. spinipes. 
The fossil genus which I would compare with these recent forms is Bhynchosaurus 
(Owen), from the New Red Sandstone of Shropshire. In this Lizard the premaxillaries 
are paired, and bent downwards over the symphysis of the lower jaw; are these produced 
* I cannot speak quite positively on this point, on account of the specimen having lain for some time in some 
fluid which affected the bones. 
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