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Show 1891.] ON THE ANATOMY OF HELODERMA. 1 19 6. On some Points in the Anatomy of Heloderma. By Prof. C. STEWART. [Eeceived January 20, 1891.] (Plate XI.) Having had an opportunity of examining the more or less entire viscera of three specimens of Heloderma, viz. a male and female of H. suspectum, and one female of H. horridum, I have thought that a comparison between them might be of interest, and also that it was desirable to call attention to some features in which m y specimens appeared to differ from the recorded observations of others, and to give a brief description of the male urogenital system of H. suspectum. Dr. J. G. Fischer, in a paper published in 1878, has given figures and a full account of the poison-apparatus, hyoideau muscles, &c. of H. horridum. In the 'Proceedings ' of this Society for 1890 is a very complete description of the anatomy of a female specimen of H. suspectum by Dr. R. W . Shufeldt. Thyroid Gland.-The thyroid of H. suspectum is figured aud described by Dr. Shufeldt as a bilobed structure, the lobes united by a transverse isthmus, and situated in front of the trachea at the base of the heart, but in a footnote (op. cit. p. 206) he states that he may have mistaken blood-stained tissue for the thyroid, but that he failed to find anything else which resembled that organ. In all m y specimens it was readily found, as a paired organ, the lobes placed one on each side of the trachea and totally unconnected by an isthmus. They were surrounded by a well-defined capsule, to which they were attached by trabecular, the capsule apparently forming the walls of a lymph-sinus. In H. horridum the lower border of the thyroid is 47 m m . from the base of the heart, and 73 m m . from the laryngeal opening. The right lobe is 9 m m . long, 5 m m . broad, and 1| m m . thick. The left lobe is 7 m m . long, with width and thickness the same as the right. The lower border of the thyroid in the male H. suspectum is 46 m m . from the glottis, each lobe was 11 m m . long and 3 | broad; the extremity of the left lobe nearest the trachea was pointed, and from the corresponding end of the right lobe there was a delicate prolongation extending forwards, in length equal to that of the main body of the lobe. In the female H. suspectum the thyroid was similar in shape, but somewhat smaller than in H. horridum. Trachea, Larynx, and Lungs.-The length of trachea and larynx from the glottis to bifurcation of bronchi was 110 m m . in H. horridum; from bifurcation to point of entrance into lung 13 m m . There were seven large openings from the continuation of the bronchus into the lung-tissue, in front of its posterior termination. They are situated on the ventral surface. Each of the posterior three shows more or less a division into two, a condition more marked in other Lacertilia, |