THE SKATE. 61 



135. The three or four minute apertures on each side of the dorsal 

 wall of the bladder, by which the ureters open. 



136. The adrenals, inter-renals, dorsal aorta, and cardinal 

 veins, which have the same relations as in the male ( 129- 



In both sexes. 



XXXIII. Carefully dissect away the muscular tissue 

 immediately anterior to the heart and between the 

 two sets of gills, and make out 



137. The synangium or bulbus arteriosus (Figs. 20 

 and 21, b.a), a white dilatation, connected with the anterior 

 end of the conus arteriosus or pylangium (c.a, 82), and 

 giving off three vessels, one anteriorly, the ventral aorta 

 (v.ao\ and one on each side, the posterior innominate 

 arteries (p.in). The ventral aorta passes forwards to the 

 level of the anterior gill cavity, and there divides into two 

 vessels, the anterior innominate arteries (a.m) which 

 are given off at right angles to the ventral aorta, one on 

 either side. Each anterior innominate artery soon divides 

 into two trunks, each posterior innominate into three ; these 

 five vessels are 



138. The afferent branchial vessels (Figs. 20 and 21, 

 a.br. i 5), each of which goes to one of .the plates by 

 which the gill cavities are separated from one another, passes 

 from the ventral to the dorsal extremity of the plate, external 

 to the branchial arch (see 166), and gives off branches to 

 the gill filaments. 



139. The hypobranchial artery (Figs. 20 and 21, hy.br), running 

 antero-posteriorly, just internal to the gills, and crossing the afferent 

 branchial arteries : it springs from the brachial artery ( 157), anastomoses 

 with the efferent branchial arteries ( 156), and, besides supplying the 

 tissue of the gills, sends off an anterior coronary artery (Figs. 20 and 

 21, a.co) to the conus arteriosus and ventricle, and a posterior 

 coronary (/.>), to the sinus venosus. 



