DISTRIBUTION OF SUBCUTANEOUS VESSELS IN GANOIDS II 7 



adductor muscle and the great lateral trunk muscle, to discharge 

 itself in the occipital sinus. 



Branchial Lymphatic Sinuses (Fig. 8, n and 12, Br.S.). 

 Each of these reservoirs is a cavity of considerable size, which 

 occupies most of the space above the superior pharyngeal region 

 between the auditory capsule and the levator branchial muscles, 

 and is separated from the skull only by the jugular vein. Its 

 posterior depth is double the anterior. This difference in depth 

 is not due to a gradual tapering down of the sinus, but rather 

 to an abrupt rise in the level of the floor a little forward of the 

 center of the sinus ; so that this sinus might almost be said to 

 consist of an anterior and a posterior portion. The anterior 

 division lies directly mesad of the first and second branchial leva- 

 tor muscles (Figs, n and 12, L.Br.A.(i) and (2)). Cephalad 

 it tapers down into a sort of papilla, which curves around these 

 two branchial muscles to unite in front with a papilla from the 

 hyo-opercularis sinus in forming the so-called cephalic sinus 

 (Figs. 8, ii and 12, Ceph.S.), which empties into the jugular. 

 Directly mesad of the first branchial levator muscle there is an 

 orifice in the floor of the anterior portion of the branchial sinus 

 (Figs, ii and 12, D.Br.L.T.(i)O.) through which a trunk 

 formed from the union of the first dorsal branchial lymphatic trunk 

 (Figs. 8 and 9, D.Br.L. ^.(i)) and a fork of the second dorsal 

 branchial lymphatic trunk is discharged. What might be desig- 

 nated as the posterior mesal corner of the left anterior branchial 

 sinus receives the dorsal lymphatic trunk (Figs. 8, ii and 12, 

 D.L.T.). Leaving now the anterior part of the branchial 

 sinus we find that the posterior portion of this sinus extends 

 caudad and ventrad beneath the occipital sinus, and in the 

 neighborhood of the epibranchial of the last branchial arch it 

 communicates above with the occipital sinus (Figs. 8, 9, ii and 

 12, Br.S.O.). In L. osseus there is an opening in the anterior 

 ventro-lateral corner of the posterior part of the branchial sinus 

 (Fig. 12, D.Br.L.T.(2)O.} through which one fork of the sec- 

 ond dorsal branchial lymphatic trunk is discharged. This ori- 

 fice is situated almost opposite the space between the second 

 and third branchial levator muscles. There is still another 

 aperture about opposite the fourth branchial levator muscle 



