BLOOD-\'ASCULAR SYSTEM OF THE LORICATI 67 



Qiiite an important vessel arises from the right side of the 

 coeliac artery shortly before it separates to form the pyloric caica 

 arteries, or sometimes it may arise from the right pyloric caica 

 artery; it is the vessel designated as /w/t-sZ/V/^/ «r/(?ry(2) (PI- I, 

 figs. I, 6 and ii; Int.A.;,^), which strikes the intestine about 

 mid-way between the pylorus and the rectum. For a short 

 distance it runs along, inclosed in adipose tissue, just dorsad of 

 the intestine, and crossing over to the ventral side of the intes- 

 tine, exchanges places with intestinal artery^). This vessel is 

 distinctly a posterior intestinal artery and usually extends to 

 the rectum. Throughout its entire course it sends off branches 

 to the muscular walls of the intestine, which break up into a 

 capillary network in the connective tissue layer of the crypts. 

 In the region of the liver several small branches from the coe- 

 liac are given off to the anterior part of the intestine. 



{b) Mesenteric Artery (PL I, fig. i ; Mes.A.). — This vessel 

 is destined to supply the spleen, the greater part of the stomach, 

 and intestine. Soon after leaving the coeliaco-mesenteric trunk 

 the mesenteric artery gives off \\\.^ left gastric artery (PI. I, figs. 

 I and 6 ; L.Gas.A.) to the left and ventral side of the stomach. 

 This vessel, which lies above the corresponding vein and left 

 gastric ramus of the vagus nerve, crosses the stomach at right 

 angles, then passing along the left side of the stomach, gives 

 off branches to either side, which soon penetrate the muscular 

 walls and break up into a capillary network in the connective 

 tissue layer of the crypts. The main mesenteric trunk after 

 following the stomach for a short distance bifurcates into the 

 right gastric, and intestinal artery^,. The right gastric artery 

 (fig. I ; R.Gas.A.), which is considerably larger than the left, 

 continues between the right gastric ramus of the vagus nerve 

 and the right gastric vein to the posterior or cardiac portion of 

 the stomach, giving off branches from either side to the mus- 

 cular walls of the stomach. Close to its origin it sends off a 

 branch to the right (see fig. i), which crosses the coeliac artery 

 and the right portal vein to a gland-like body (G. fig. i) situ- 

 ated at the junction of the right gastric and the intestinal veins 

 (in structure this gland is very much like the suprarenal bodies). 

 The Intestinal artery^""^ (PI. I, figs, i and 6; Int.A.(ij) pur- 



