322 ME. F, E. BEDDABD ON THE [NoV. 17, 



thyroid gland. On the other hand, in the Cobra the conditions 

 are quite difierent. The right Carotid, although perhaps not 

 nioi-e than one-half of the diameter of the left, is quite as fvilly 

 developed as regards the length of its course, and runs right up 

 to the head and lies closely side by side with its fellow artery. 

 It is rather curious that both arteries plunge into the thickness 

 of the tissues of the head, not on opposite sides as might be 

 expected, but close together on the same (left) side. 



Another difference in the situs viscerum is indicated by the 

 following measurements : — In Ophiophagiis the origin of the 

 superior mesenteric artery is 73 inches from the mandibular 

 symphysis and 21 1 from the cloacal aperture. The corresponding 

 measurements in the Cobia which 1 examined were 35 and 

 15 inches respectively. There is thus in the Hamadryad a 

 shortening of the "aladominal" region of the body as compared 

 with the Cobra, and a consequent crowding of the viscera therein 

 contained. This is also expi-essed by the nearness of the kidney 

 to the testis already referred to. In spite of this the lung of the 

 Hamadryad has a longer vascular, and therefore respiratory, 

 region than the Cobra. The measurements are as follows : — In 

 the Cobra the lung ceases to be vascular 18 inches from the snout, 

 in the Hamadryad 38 inches. Were the proportions the same, the 

 length of the Hamadryad from snout to vent wovild be 107^ inches ; 

 it is, as a matter of fact, 93 inches. It follows, therefore, that the 

 vascular part of the lung in this snake is proportionately longer 

 than in the Cobra. 



It seems to me to be plain that these various characters are, at 

 least, more striking as a means of separating the two snakes than 

 those used by the original describer of " Hamadryas liannali " * 

 or by those who have succeeded him. 



But a more i-emarkable character still distinguishes this snake 

 from its ally, the Indian Cobra. In the latter snake, as is well 

 and has been long known t, the tracheal rings are incomplete 

 dorsally as cartilaginous rings, the interspaces being merely mem- 

 branous. The membrane, however, except at the beginning of the 

 trachea, has a diameter fully as great as that of the cartilaginous 

 tract ; it is, moreover, tough, longitudinally creased, and obviously 

 dilatable. 



In Ophiophagus the tracheal rings are similarly incomplete from 

 the very first, but the membi-anous interval is less tough and 

 strong (though the snake is considerably larger), and very much 

 less in relative and even in actual diameter. So far, therefore, 

 the differences are but slight. A very remarkable difference 

 is illustrated in the accompanying drawings (text-figs. 37, 38, 

 pp. 323, 324). At intervals this dorsal tracheal membrane is 



* Cantor, "Sketch of an undescvibed Hooded Serpent, &c.," Asiat. Researches, 

 vol. six. 1836, p. 87, and also P.Z.S. 1838, p. 73, where it is described as "Hama- 

 dryas opMophaqus," a reference omitted by Mr. iBoulenger in his Catalogue, who 

 quotes onlj', though so far correctly, P. Z. S. 1839, p. 32. 



t Cuvier, ' Le^rons d'Anatomie Comparee red, par Duvernoy,' ed. 2, Paris, vol. Vii. 

 1840, p. 93. '' 



I 



