1890.] HELODERMA SUSPECTUM. 219 



iiiijiortaiit structures which are ou their way to the rhiual spaces. 

 That is, duriug life such is the case. Passing uext to a cousider- 

 atiou of the naaals, they are seen to be fused together iu a manner 

 quite similar to that which has just been described for the iVoutals, 

 aud it is only upon the roof of the rhinal spaces that the sutural traces 

 can be made out at all. Laterally, a nasal articulates with the 

 corresponding maxillary and prefrontal ; anteriorly the two unite 

 to send forward a process that articulates with the preniaxiilary iu 

 the middle line ; posteriorly the uaso-froutal suture is seen to be 

 re|)reseuted by a deeply zigzagged line ; and, finally, these fused 

 nasals at their autero-inferior surface, mesially, meet the hinder 

 ends of the sejjtoniaxillaries. Tliey assist in the formation of the 

 peripheries and upper ])arts of the external uarial apertures. 



Articulating with the nasals, the vomers, the maxillaries, aud the 

 septomaxillaries, the premawilla presents a strong mid-process ia 

 front which is carried backwards as the nasal process. Its alveolar 

 portion is rather broad aud comuiouly bears upon either side four 

 teeth. Behind these, and in the middle liue upon tlie ventral 

 aspect, are seen two small processes placed side by side. The united 

 anterior apex of the vomers just reaches to them. A similar character 

 to this is seen in a skull of lijuuna tubcrculatu at baud, only iu 

 it the apices of these two little apophyses have fused together, thus 

 forming a foramen between them. 



Again viewing the tore part of the skull upon its externo-lateral 

 aspect, we observe that the thickly set, fused osseous dermal 

 tubercles are carried down over the maxillary and jugal bones upon 

 either side. They do not, however, entirely cover the nuixillunj, 

 for a narrow strip of its externo-alveolar portion is free from them, 

 and this exteuds from the jugal all the way round to the uarial 

 aperture of the same side. As iu so many other forms of Lizards, 

 this smooth aud narrow surface of the maxillary seen u|)0ii its 

 external asjiect, bounded below by its free alveolar margin, is 

 characterized by a longitudinal row of some six or seven miuute 

 foramina ; they pierce the bone opposite the teeth, or iu some 

 instances even between them. 



Either one of the maxillaries articulates with a good many bones ; 

 it articulates with an os transversum, with a palatine, with a jugal, 

 lacrymal, and prefrontal, with a septomaxillary aud a premaxillary, 

 with a nasal, and finally it may even come iu contact with one of 

 the vomers of the corresponduig side. A maxillary forms the outer 

 lateral wall of the nasal fossa, and also a part of the roof of the 

 same cavity. It also, in Heloderma, contributes largely to the 

 formation of the bony part of the roof of the mouth : and here upon 

 its ventral asjject it is somewhat concaved, while along its alveolar 

 edge the row of teeth are found. These latter are grooved in a 

 manner similar to the teeth found iu the mandible, notwithstanding 

 the fact that they do not now seem to be intended to conduct a 

 poisonous fluid at the time the reptile inflicts its bite. 



Septomaxillnries are large and thoroughly ossified. They are iu 

 contact wit!) the maxillaries, the premaxillary, the nasals, and the 



