VOL. XXIII.3 PHILOSOPHICAL TRANSACTIONS. 69I 



c c their lesser branches, where they pass from each others and are united at 

 their extremities. 



Fig. 5, the hke appearance in the mesentery of a dog when living ; d d the 

 areae, that are here viewed with the microscope, as they appear to the naked 

 eye. 



Fig. 6 represents the trunks of the vena cava, with their branches dissected 

 from an adult human body. A A the orifice of the vena cava, as it appears when 

 cut from the right auricle of the heart ; a the orifice of the coronary vein of the 

 heart ; b a the superior or descending trunk of the vena cava ; c c A the inferior 

 or ascending trunk, so distinguished from the motion of the blood in these 

 trunks, which is contrary to their position ; d d the subclavian veins ; -j- that 

 part of the left subclavian vein, where the thoracic duct enters it, and dis- 

 charges itself of its chyle and lympha : b the vena azygos with its branches 

 going to the ribs e e ; c the superior intercostal veins ; d d the internal mam- 

 mary veins ; e e the right and left iliac branches ; f p the internal jugular veins; 

 G G the external jugulars ; h h the veins which bring blood from the lower jaw 

 and its muscles ; i i the trunks of the internal jugulars cut off at the basis of 

 the skull; f the veins of the thymus and mediastinum ; gg the veins of the 

 thyroid glands ; h the vena sacra ; i the internal iliac branch ; k the external 

 ditto ; K K the occipital veins ; l the right axillary vein ; m the cephalic ; n the 

 basilic ; o the median vein ; p the trunk of the veins of the liver ; a the phre- 

 nic vein of the left side ; k the right phrenic vein ; r a large vein from the left 

 glandula renalis and parts adjacent ; s the left emulgent vein ; t the right emul- 

 gent, in this subject very much lower than the left, which is not usual ; v v the 

 two spermatic veins ; x x two communicant branches between the ascending 

 trunk of the vena cava and vena azygos, by which the wind passes into the 

 descending trunk of the cava when we blow into the ascending at a p c, though 

 the trunk at a, p, and c, is firmly tied on the blow-pipe ; * an uncommon branch 

 between the lower trunk of the vena cava and the left emulgent vein ; y a vein 

 which brings blood from the muscles of the abdomen into the external iliac 

 branch ; z the epigastric vein of the right side ; 1 the vena saphena. 



The rest of the branches here displayed commonly diflrer so much in various 

 subjects, that the particular descriptions of them, which none but the operator 

 who dissected them could pretend to be master of, would be perhaps as useless 

 as tedious to repeat ; wherefore I pass to those considerable venous trunks which 

 Ate wanting in this scheme. 



Fig. 7 represents some of the large trunks of the veins and their sinuses 

 within the skull, with the beginnings of the internal jugular veins, filled with 

 wax and dried together with the falx, &c. a the extremity of the falx cut 



4 T 2 



