BLOOD-VASCULAR SYSTEM OF THE LORICATI ii 
terior mesenteric artery was not observed; possibly, however, it 
was not injected. The posterior spermatic proper breaks up 
into numerous branches, which run along the posterior surface 
of the ovaries or penetrate the testes. The most posterior branch 
of the third spermatic artery is destined to supply the common 
oviduct or spermduct and sends off the antertor urinary 
bladder artery to the bladder. The postertor urinary bladder 
artery (Pl. I, figs. 1 and 10; Ur.B.A.) or the urinary bladder 
artery proper arises from the aorta directly behind the kidney, 
and in the specimen from which fig. 10 was drawn, a renal 
artery was given off to the kidney. In addition to supplying 
the urinary bladder this vessel usually sends off a branch to the 
great lateral muscle. It is probably a modified hzemal artery. 
(c) Comparisons of Hexagrammos, Scorpentchthys and Sebas- 
todes. — In these 3 different genera there is not nearly as much 
variation in the distribution of the dorsal aorta as there is in the 
distribution of the cardinal veins. Hexagrammos is identical 
with Ophiodon. In Scorpenichthys there are only 2 spermatic 
arteries, but what has been designated as the urznary bladder 
artery (P1. IV, fig. 29; Ur.Bl].A.) arises much farther cephalad 
than the corresponding vessel in Ophzodon, and may in part be 
homologous to the posterior spermatic artery of Ophodon, 
except that it does not supply the reproductive organs; running 
along the dorso-caudal surface of the kidney it passes between 
the suprarenal bodies and sends off a branch to each of them. 
(It will be noticed that the suprarenal glands are located much 
further dorsad on the kidney than they are in Ofhzodon.). 
Then passing ventrad the urinary bladder artery passes behind 
the posterior mesenteric vein to supply the posterior part of the 
urinary bladder, and usually it is continued still farther ventrad 
to supply the rectum. In Sedastodes several changes are intro- 
duced, which are caused by the presence of the air-bladder and 
anterior spermatic arteries. Where the anterior spermatic artery 
is given off in Ophiodon, Hexagrammos and Scorpenichthys a 
similar vessel arises from the aorta in Sedastodes; this vessel, 
however, is destined to supply the air-bladder and is designated 
as the posterior atr-bladder artery (P1\. IV, fig. 31; P.A.BI.A.). 
In passing over the left side of the kidney it gives off several 
