PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 397 



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horizontal. They terminate by quadrate plates that tend to approach 

 the median plane, these horizontal plates i^rotruding in the articulated 

 skull back of the articular facets and the quadrate bones. Broadly 

 oblong", and raised above the general level of the bone, the articular 

 facets look upwards and a little backwards and ontwards. The coro- 

 noid hones are placed, one on either side, slightly posterior to the middle 

 l^oint of the ramus; they project upwards and back- 

 wards as laterally-compressed processes that show ex- 

 ternally still fairly-developed traces of their original 

 sutures ; upon this aspect, also, we observe the irregular 

 sutural line, indicating the point of ending of the dentary 

 portion of the maxilla. 



Each ramus is perfectly smooth beneath, being gently 

 convex from side to side, broadly so longitudinally. 

 The external curve about the symphysis is parabolic in 

 outline, the inner bein g sharply acute, and , passing back- ^^- -J- 

 wards as tbe inferior ramal border, maintains a more or less parallel 

 position with the external or alveolar border. Anchylosis is never 

 thoroughly established between the dentary elements at the symphysis, 

 this joint having an articnlation very similar to the symphysis pubis 

 of anthropotomy, the interested bones coming apart npon very slight 

 provocation in the dried skeleton, showing each articular fiice to be 

 roughened for an amphiarthrosial joint. 



In the specimens that I have examined, the teeth in the upper jaw 

 seem to invariably pass completely round the alveolar process, while in 

 the lower jaw a few always seem to be lacking on either side of the 

 symphysis; this is also the case in \ 

 Gerrhonotus, but not so in a specimen 

 of Eumeces sldltonianus. These teeth 

 are of the pleurodont tj'pe; in other 

 words, they are anchylosed to an outer 

 alveolar plate, as in many of the Iguani- _^ _ , ,, ,, 

 d(e. Above their points of union to the '^^^'^ ^ 

 alveolar process they are conical in form, ,' yi\, ( 

 pearly white, and glistening, being ar- ^^. j 

 ranged in a row of some seventeen to 

 -f^?- ^- twenty in each ramus, the largest being 



found in the middle and the smallest at either end. The ^■^- -^ 

 hyoidcan arch seems to be largely cartilaginous in structure, though a 

 good deal of bone tissue does exist in it, i)articularly about the center. 

 In form it resembles the capital letter X, the upper limbs being directed 

 forwards and outwards, the hinder ones backwards and outwards; the 

 body of the hyoid occupying the intersection as an equilateral triangle, 

 with one of the angles placed anteriorly in the middle line, ard from 

 which is produced a delicate "glosso-hyal"; the posterior limbs spring- 

 ing from its outer angles, and the anterior ones, apparently by articu- 



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