ON THE CIRCULATORY SYSTEM OF ELASMOBRANCHS. 435 
30. Notes on the Circulatory System of Elasmobranchs. 
I. The Venous System of the Dogfish (Seyllium 
canicula). By Cuas. H. O’Donocuus, D.Sce., F.Z.S., 
Senior Assistant in the Zoological Department, Uni- 
versity College, London. 
[Received April 2, 1914: Read May 19, 1914.1] 
(Plates I., II. * & Text-figures 1-4.) 
INDEX. Page 
Ve JUMAROCIHG BOM ois dcdcesccscsc ess pecadadpseosenocen eat) 
ee Developmenti eerste eee LOO 
III. The Pre-Cardiac Vessels ..................... 488 
IV. The Post-Cardinal Vessels .. ..... ......... 443 
Vere lateral vieinsteees ess ee errr ee eee a> 
VI. The Sub-Intestinal Vessels .................. 447 
A. The Hepatic Portal Vein ............ 448 
B. The Renal Portal Veins ............... 452 
Walle her CoronanyaVierise eer cette eee) 402 
WIII. The Ductus Cuvieri ........................... 452 
IX. List of References.............................. 453 
I, InrRODUCTION. 
The foundation of our modern knowledge of the circulatory 
ystem of Hlasmobranchs was laid by T. J. Parker in his 
work on the venous system of the skate (Raia nasuta, 9), and 
extended by his masterly description of the blood-vessels of 
Mustelus antarcticus, in 1886 (10). This latter provides a full 
account of the researches prior to that date, and also a full 
bibliography. 
Since that date only two papers have dealt with the subject. 
Rand and Ulrich have discussed the posterior connections of the 
lateral vein in the skate in 1905 (14), and Diamare the splanchnic 
arteries and veins in Scylliwm catulus and Torpedo marmorata (2). 
Since Balfour’s account (1) the general development of the 
venous system in Elasmobranchs has been referred to by a number 
of authors, including Hoffmann (5), Rabl (11 & 12), and Hoch- 
stetter (3 & 4), and the development of the head veins by Grosser 
(2 a), so that it is only necessary here to refer quite briefly to the 
stage in a late embryo so as to indicate the order in which the 
veins in the adult are described. 
Although many dogfish have been dissected, there is no com- 
plete account of the venous system. The descriptions given in 
the text-books for the most part appear to be based upon 
T. J. Parker’s work already referred to, and are not altogether 
* For explanation of the Plates see pp. 454, 4565. 
Proc. Zoou. Soc.—1914, No. X XIX. 29 
