100 ALLEN 



red, the ratio being 28 to 2. Fig. 26 represents the corpuscles 

 as also being very scarce in the vein, but here the red predomi- 

 nate, the ratio being 9 to 2 ; while in the artery the corpuscles 

 are abundant, the ratio of red to white being as 36 is to 8, 

 which, however, is a striking number of white corpuscles for 

 an artery. In the artery the three tunics are very thick and 

 well differentiated. 



Facial Lymphatic Trunks. In Polyodon there are two 

 such canals, on either side of the body, which for convenience 

 sake have been designated as the facial lymphatic trunks and 

 the anterior facial lymphatic trunks. 



The latter trunks (Fig. i, F.L.T.(i)) take their origin from 

 the adipose tissue of the paddle, in front of the nasal sac. 

 They are distinctly subdermal vessels, being situated some 

 little distance above the orbito-nasal arteries and veins. When 

 the level of the posterior border of the nasal sac is reached, 

 each trunk bends outward and downward, to pass backward, 

 superficially, along the surface of the adductor mandibulae 

 muscles. In the region of the spiracle it lies immediately in 

 front of the facialis artery, and receives a rich network from 

 above (Fig. I, L.N.(2}), that passes over the facialis artery, 

 nerve, and vein, to communicate above with the principal 

 facialis trunk. Frequently vessels are received, which collect 

 the network arising from the connective tissue that envelops 

 the adductor mandibulae muscles ; these branches ordinarily 

 accompany and often nearly encircle corresponding blood ves- 

 sels. As previously stated in the neighborhood of the posterior 

 extremity of the premaxilla, branches are received, that have 

 their source from a rich network above (Fig. i, L,.JV.(^ )), 

 which passes over the hyomandibular and its retractor muscle 

 to communicate with similar branches that end in the hyo- 

 opercularis lymphatic trunk. 



In connection with the anterior facial lymphatic trunk it was 

 just noted that the main facial lymphatic trunk (Figs. 1,2, and 

 3, F.L. T.) gathered a rich network in the region of the spiracle 

 that came from the facialis vein, nerve, and artery, and was 

 also in communication with the anterior facial trunk. The 

 lymphatic canal thus formed follows up along the dorsal surface 



