Amiiom]! of Ili/la aurea. 



353 



loopinir of the veins, especially seen in the mandibular, external 

 jupular. and femoral veins, has been much more conspicuous in 

 the fnitrs this year (1908) than previously. The chief variations 

 found are as follow : — 



Anterior Vena Cava. — There is usually not only one linj^ual 

 vein, but a number of smaller ones coming from the floor of the 

 mouth and entering the mandibular vein, chiefly in front of the 

 entrance of the main lingual vessel. Earely, the lingual itself 

 arises by several large branches which unite close to the external 

 juirular vein. The mandibular vein receives generally a, large 

 branch fri m the skin just as it turns inwardsi at the angle of the 

 ja.w. Occasionally a connection was found between the two 

 external jugular veins across the ventral surface of the body. 



The second main vein of this system, the so-called innominate 

 of the Amphibia, and its branches, are the most variable in the 

 body. The innominate vein may be comparatively long, i.e., 

 up to 5-6 mm. At other times, it isi entirely absent, its two 

 component branches entering the anterior vena cava side by 

 side (see Text figure 5). Rarely, the internal jugular, subs- 

 capular, and main subclavian veins all enter a short, wide 

 vessel, which joins the external jugular vein to form the 

 anterior vena cava (see Text figure 6). As an exaggeration along 



A\/C 



Abnormal precaval venous system of Hyla aurea. 

 (Reference letters as in Text-figure 5). 



this same line of variation, the whole innominate vein, Avith a 

 length of 1 mm., has been seen to empty into the subclavian 

 vein, at about one-half of the length of the latter (see Text 

 figure 7). A further development of the condition in which 



/ivc 



Abnormal precaval venous system of Hyla aurea. 

 (Reference letters as in Text-figure 5). 



r/o 7 



