1890.] HELODJERMA SUSPKCTUM. 207 



the outer suriace of the mandible, where they entered. Fischer 

 found in his specimen that these ducts branched as they quit the 

 j^land ; this was not the case iu tlie reptile examined by me. Each 

 duct passes obliquely upwards and inwards through tlie lower jaw, 

 and its internal openiu"; within the moutli is found at the base of the 

 tooth it supplies, near the termination of the groove of the tooth. 



These glands resemble each other in size, shape, and position, and 

 they in all probability have the same function. Either one of them 

 lacks something of being rather less than two centimetres for its 

 antero-posterior diameter, and is about a centimetre wide. Sub- 

 elliptical iu outline it will measure at its thickest part, which is at 

 its centre, four or less millimetres,while the organ is held in its position 

 by the firm corniective tissue that surrounds it. Over its surface, 

 superficially, it is easy to discern the ramilicatious of the vein tliat 

 comes away from it and thereafter joins the internal jugular. A 

 tendinous expansion, which arises from the outer surface of the 

 superficial muscles near tlie hinder end of the mandible, is seen to 

 spread out over this organ iu large subjects. It is narrow and rather 

 strong at its commencement, to become very thin and closely adhe- 

 rent to the skin as its fibres diverge anteriorly. There seems to be 

 scarcely any muscular tissue in this tendon, but I am inclined to 

 believe that by its contraction in the living reptile the venom of the 

 giaud can be forcibly jetted through the ducts aud so alon" the 

 grooves of the teeth at the time of its bite. In mv specimen the 

 four ducts serve the anterior moiety of the organ, its hinder half 

 being without these glardular conduits. 



Now, although the upper teeth of Heloderma suspecium are 

 grooved, I fail upon dissection of the parts to find any gland present 

 wherewith they miglit be supplied with poison. Indeed the skin 

 overlying the latero-labial region is quite adherent to the skull along 

 its maigin, while just above it, between the eye and the external 

 nostril, tlie bases of the dermal tubercles aud the underlyiu"- bone 

 often coo^sify. 



There seems to be no reasonable doubt at the present time but 

 that the secretion of these glands in Heloderma is of a poisonous 

 nature, and that the injury caused by its injection into the circu- 

 lation of living animals varies. Still further research is required 

 before we can possess anything like a complete knowledge of its 

 action upon different animals and under varying conditions. It is 

 hoped that experiments tending to make clear such points will be 

 undertaken by the scientitic investigator from time to time. 



VIII. The Olfactory Cavities and the Organ oe Jacobson. 



With the very finest of wire saws I made both a transverse and 

 a longitudinal section through the uarial chamber of one side in a 

 specimen of Heloderma suspecium. The operation brought the 

 structures of the region plainly into view ; liut, so far as I was 

 enabkd to discover, it, revealed nothing that seemed to depart in any 



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