694 REPORT OF NATIONAL MUSEUM, 1898. 



The ophthalmic artery is divided from the facial, according to Eathke^ 

 excepting in the Peropoda and Angiostomata, where it rises from the 

 arteria cerebralis. The latter is the primitive fcetal connection in all 

 snakes. 



The cardinal veins are unimportant in the Serpentes, the posterior 

 vena cava having taken their place. This vessel originates at the 

 kidneys, being formed by the successive union of numerous venw renales 

 revehcntes, and extends to the liver. It runs in a groove of the superior 

 side of this organ, and receives veme hepaticw along its course, and then 

 passing above the heart enters the sinus venosus on the right side of 

 the right auricle. Authors differ in their accounts of the origin of the 

 vena cava. Schlemm states that it is formed by the union of two 

 branches, one from each kidney, while Stannius states that it is derived 

 from the right kidney only. In an anaconda {Eunectes murinus) 1 traced 

 it easily from the right kidney, but was not successful in following the 

 left renalis revehens to a junction with the right, though I can not 

 assert that none exists. I found the junction to be near the left testis 

 in a Coluber quadrivittatus. The kidneys receive each a vein which cor- 

 responds to the vena iliaca of the Sauria, which are derived from a 

 single vena caudalis. In Chersydrus there is a second large vessel run- 

 ning from the liver to the heart, which may be a vena hepatica. 



The anterior caudal diapophyses of the Serpentes are bifurcate in a 

 vertical plane. Between these branches are placed the lymphatics, 

 which empty by a small vein into the vena iliaca. The thymus gland is a 

 small elongate body lying near each carotid on each side, and near the 

 heart. The thyroid gland is near the auricles of the heart on the middle 

 line. Suprarenal bodies are present near the testis or ovaries, lying 

 along the venw renales revehentes. 



THE RESPIRATORY SYSTEM. 



This system includes the larynx, trachea, and lungs. The characters 

 of the larynx in the various groups of snakes have not yet been worked 

 out. A small tubercle may be observed at the anterior canthus of the 

 glottis in many snakes. In two genera of Colubriuai it is developed 

 into a compressed vertical epiglottis, which by its rapid vibrations on 

 the expulsion of air from the lungs produces a considerable noise 

 {Upiglottophis, Pityophls). The trachea in the Serpentes is not divided 

 into bronchial tubes, but where there are two lungs it is discontinued 

 at the bifurcation, except in the case of the presence of a rudimental 

 right lung. In this case the wall of the trachea is ])erforated by a 

 foramen which communicates (rarely by a tube) directly with the rudi- 

 mental lung. In such a case the tracheal cartilages may be continued 

 for a long distance as a band on the left lung (genera HalsopMSy 

 Pityophls). 



The lungs are sacs surrounded by a layer of reticulate bars or 

 lamime of greater or less thickness. The bars are most robust at the 

 anterior part of the lung, and become more attenuated and inclose 



