704 
PROFESSOR T. J. PARKER ON THE 
veins from the tissues of the tail, and, on leaving the hcemal canal, divides, at 
the level of the posterior extremity of the kidneys, into the symmetrical (right 
and left) renal portal veins. 
2. The renal portal vein. 
Veine porte renale, Veine de Jacobson, Jourdain (12). 
Renal portal vein, Rolleston (24), Parker (21, 23). 
It is somewhat remarkable, considering that the elaborate researches of Jourdain 
(12) appear in so well-known a journal as the “ Annales des Sciences Naturelles,” 
that the existence of a true renal portal vein in Elasmobranchs is either ignored 
or expressly denied by the writers of all the more important zoological text-hooks 
with the single exception of Rolleston (24). Stannius (25), Milne Edwards (14), 
on the authority of Hyrtl, Huxley (10), Gegenbaur (7), Macalister (13), and 
Claus (4) all state explicitly that in Elasmobranchs, as in Cyclostomes, the caudal 
vein opens directly into the cardinals. Macalister certainly states that branches 
from the cardinal veins enter the kidneys, forming a reno-portal capillary plexus, 
and Gegenbaur mentions the existence of similar vence renales advehentes as branches 
of the caudal. But neither author gives a sufficiently detailed account to enable 
the reader to understand what the exact relations of the renal portal system are 
supposed to he. 
As a matter of fact Jourdain, following up the earlier researches of Jacobson, 
Robin, Steenstra Toussaint, and others," has clearly proved the existence of a 
renal portal system in Raja, Squatina, Squctlus, and Spinax, in all of which he 
shows there to be no direct passage for blood between the caudal and the cardinal 
veins in the adult. I have confirmed Jourdain’s results in Raja nasuta (21, 23), 
and now find that they hold good also for Mustelus antcircticus. 
The renal portal veins (Plate 34, figs. 1 and 3 ; Plate 37, figs. 22, 23, 24, Ren. 
port. V.) formed, as stated above, by the bifurcation of the caudal vein, pass forwards 
each along a groove on the dorsal aspect of the corresponding kidney, sending off 
numerous afferent renal veins (vense renales advehentes) into the substance of the 
gland, and gradually diminishing in calibre towards its anterior end (cf, figs. 24, 23, 
and 22, Ren. port. V.). 
The spinal (segmental) veins from the posterior abdominal region of the vertebral 
column and the posterior oviducal veins from the hinder moiety of the oviduct 
* Jacobson, ‘Meckel’s Arcliiv,’ vol. 3, 1817, p. 147; and “ De systemate venoso peculiari in permultis 
animalibus observato,” Hafnise, 1821. Steenstka Toussaint, “Comment, de syst. uropoet. piscium,” 
‘Ann. A.cad. Lugd.-Batav.,’ 1834-35; and “ De syst. nropoet.. Squali glauci,” ‘ Hoeven en Triese, 
Tijdscbrift,’ vol. 6, 1839, p. 199. Robin, “Note sur quelques portions dn systeme veineux des Raies,” 
‘Revne Zool.,’ vol. 9, 1846, p. 5. Owen, “Lectures on the comparative Anatomy and Physiology of the 
Vertebrate Animals,” I., 1846, p. 284. (Quoted by Joukdain in 12.) 
