ZOOLOGY. —{Continued. J 



Art. LX. — On the Venous System of the Skate (Eaja nasuta). 

 By T. Jeffery Parker, B.Sc, Lond., 

 Professor of Biology in the University of Otago. 

 [Read before the Otago Institute, 1st February, 1881.] 

 In making a series of injections of the Skate's vascular system a few months 

 since, I was struck with one or two instances in which the facts, as I made 

 them out, were either directly contradictory of the statements usually made 

 about the vascular system of Elasmobranchs, or showed very interesting 

 deviations from the normal state of things. In bringing forward my obser- 

 vations, I think it will be as well to give a general connected account of the 

 whole venous system in the Skate, since, as far as I know, this has not yet 

 been done. Many of the more important veins are, however, figured by 

 Monro in his classical monograph on " The Anatomy and Physiology of 

 Fishes," and, as I shall have occasion to point out, the veins in connection 

 with the kidneys are described in detail by Jourdain. It may also be as 

 well to mention, for the benefit of any who may be interested in the matter, 

 that the arteries of the Skate are described by Hyrtl,* his paper being illus- 

 trated by a series of very beautiful coloured plates. 



The heart consists, as usual in elasmobranch fishes, of sinus venosus 

 (fig. 1, S.V.), am'icle (mi.), ventricle (v.), and truncus arteriosus (c.a., h.a.). 

 The sinus venosus with which we are especially concerned, as it receives the 

 venous blood from all parts of the body, is a transverse vasiform chamber, 

 situated in the postero-dorsal region of the pericardium, to the walls of which 

 it is attached by a strong sheet of fibrous tissue. At each end, just outside 

 the pericardium, it becomes connected with a chamber {j)c. s.) situated at 

 the anterior end of the abdominal cavity, and in close relation with the 

 coracoid portion of the shoulder-gu'dle. The chamber receives all the 

 chief veins of the body ; it answers evidently to the vessel called Ductus 

 Cuvierii in bony fishes, which again is known to be hormologous with the 

 anterior vena cava, or precaval vein of the higher animals ; it may therefore 

 be called the precaval sinus. 



The precaval sinus is au uTCgularly ovoidal chamber, about two cen- 

 timetres long by a trifle over one centimetre in width ; when laid open from 



• Wien. Sitz. Ber., XXV., 1857 ; and Wien. Denkschr., XV., 1858. 



