34 Frederic T. Lewis. 



anterior cardinal vein. Small brandies of the anterior cardinal vein 

 are found ventral to the brachial plexus. In a slightly older embryo 

 (Fig. 2) these ventral branches are continuous with the thoraco- 

 epigastric vein so that the brachial plexus is enclosed in a venous 

 ring. This arrangement of the subclavian veins has been described in 

 the rabbit and man by Hochstetter,-* and the corresponding stage in 

 the rabbit has been figured.^ 



In addition to the subclavian vein, the anterior cardinal has another 

 important branch. This begins as a median vessel in the lingual 

 region (Fig. 1). It turns sharply to the right, receives tributaries 

 from the lateral superficial tissues and descends in front of the vagus 

 nerve. In the lower part of its course it is close to the dorsal portion 

 of the pericardial cavity. It passes on the lateral side of the vagus 

 nerve to enter the anterior cardinal vein. In the older embryo this 

 ling-uo-facial branch (F. ling-fac.) is easily recognized. The median 

 vessel in the sublingual region is present, but it has not been drawn, 

 since in this embryo it is drained by the linguo-facial branch of the 

 left cardinal vein. As seen in the reconstruction, the linguo-facial 

 vein has acquired a new outlet, which is anterior to the place where 

 the hypoglossal ner^^e crosses the cardinal vein. The hypoglossal 

 nerve, which before was lateral to the cardinal vein, is now sur- 

 rounded by it,^ and the venous loop through which it passes is 

 shown near the top of Fig. 2. That part of the linguo-facial vein 

 which descended in front of the vagus nerve has apparently disap- 

 peared, and the vein is no longer in relation with the pericardial 

 cavity. 



It is perhaps worth while to call attention to the scattered data 

 regarding this linguo-facial vein. It was discovered by Grosser in 

 embryo bats and described as follows :''' 



"The veins of the branchial arches consist in young embryos of 

 Rhinolophus of a median longitudinal vein near the ventral surface 



*Hocbstetter, F. Ueber die Entwicklung der Extremitatsvenen bei den 

 Amnioten. Morpb. Jabrb., 1891, Vol. 17, pp. 26-27 and 32-33. 



^Lewis, F. T. Amer. Journ. of Anat., 1905, Vol. 5, p. 98. 



«Tbis accords witb Tandler's observation tbat tbe bypoglossal nerve is lateral 

 to tbe internal jugular vein in buman embryos of 8 and 9 mm. and medial at 

 12.5 mm. Anat. Anz., 1907, Vol. 31, pp. 473-480. 



^Grosser, O. Zur Anatomie und Entwickelungsgescbicbte des Gefasssystems 

 der Cbiropteren. Anat. Hefte, 1901, Heft 55, p. 131. 



