1890.] HELODERMA SXJSl'ECTUM. 203 



serted into the posterior end of the corresponding arytenoid. The 

 dilator muscle, upon either side, is superficial to the constrictor of 

 the same side. The constrictors by their common contraction close 

 the aperture of the glottis during the acts of respiration and deglu- 

 tition. Dorso-laterally, the cartilaginous wall of the laryngeal box 

 is ample and broad, while ventrally it is narrow ; and its capacity 

 is but slightly increased over that of the end of the trachea, which 

 it surmounts. 



In my female Heloderma the trachea, including the larynx, had 

 a length of seven and a half centimetres, to the bifurcation of the 

 bronchi, being composed of about 57 cartilaginous rings, each and 

 every one of which are incomplete down tiie median dorsal line. 

 Some few of these tracheal rings bifurcate, as we occasionally find 

 them in Man. Either bronchus is unusually long, its rings being 

 incomplete as they are in the trachea, which it lacks but little of 

 having the same calibre. For instance, in this same specimen a 

 bronchus measures three and a half centimetres in length, while its 

 size changes but little from the bifurcation to its terminus, thus 

 being nearly half as long as the trachea. According to Mivart, 

 the bronchi in Lizards are usually "very short" (Encycl. Brit, 

 vol. XX. p. 458), and to this rule Heloderma certainly forms an 

 exception. A pulmonary vessel follows up either bronchus along 

 its anterior aspect, as one does along the opposite side of the tube, 

 each coming from the posterior portion of the lung. 



Either lung is larger anteriorly than it is posteriorly, ending be- 

 hind in a rounded tip (see fig. 3, Plate XVI.), while it is in the fore 

 part only that we find a pulmonic tissue of the finer more spongy 

 sort, as these sacs behind are covered by a serous coat of a denser 

 texture, and are filled in by air-cells of the larger more open kind, as 

 is the case very generally in this class of Vertebrates. These lungs 

 are of about the same shape, size, and length in our present subject, 

 and their extremities within the abdominal cavity take up but little 

 room. 



Now either bronchus curves slightly as it comes through the an- 

 terior moiety of the lung, and its rings are lost posteriorly in that part 

 where the pulmonic tissue begins to become coarse. Bronchial 

 branches are not definite, as communication is made with the lung- 

 tissue by means of short-necked apertures found at a few points 

 along their sides, principally anteriorly. 



VI. Notes upon the Oral Cavity and Associated Parts. 



At the roof of the mouth we have presented us for examination, 

 posteriorly, the Eustachian piis. These are large and deep, espe- 

 cially behind ; they shallow out as we proceed mesiad and towards 

 the front. At the back part of either one of them there is situated 

 the subelliptical aperture that leads into the organ of hearing, and 

 these apertures, in a large specimen of Heloderma, are nearly 3 

 centimetres apart. Anterior to the point where the Eustachian pits 

 cease, the lining membrane of the roof of the mouth is not so deeply 



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