16 ARKIV FÖR ZOOLOGI. BAND 7. NIO 25. 



chial arteries. I have followed the course of this artery only 

 in Spheroides, but as I have not had any injected specimens 

 at my disposal, only the main branches will be mentioned. 

 When the artery has run for some distance in the abdominal 

 cavity it gives off two large branches, one of which supplies 

 the airbladder (Fig. 10, 1), the spleen (Fig. 10, 2) and parts 

 of the intestines (Fig. 10, 3), the other the stomach (Fig. 

 10, 4), the liver (Fig. 10, 5) and parts of the intestines (Fig. 

 10, 6). The main trunk of the artery continues caudally, 

 sending branches to the intestines (Fig. 10, 7—9) and the 

 gonads (Fig. 10, 10). 



Aorta. I have followed this vessel in Spheroides. After 

 a short run the aorta gives off a pair of renal arteries (Fig. 

 10, r), then tiirns dorsally and enters a canal formed by the 

 third and following vertebrae. This canal will be described 

 in the part dealing with the skeleton. 



3. Yeiiis. 



Except a few^ remarks abont Diodon and Balistes, I am 

 able to give an account of the venous system only in Sphe- 

 roides (Fig. 1, Pl. I and II). All the venous blood is collec- 

 ted in sinus venosus (sv). Into this chamber a number of 

 vessels enter. The largest are the two Cuvierian ducts, one 

 on each side (d. C). They form the united trunk of the 

 anterior and posterior cardinal veins (v. c. a. d., v. c. p. d.). 

 On each side there is also a suhclavian vein [v. s.) and a 

 vein which I regard as homologous to the lateral vein (v. 1.) 

 of the Selachians entering the sinus. The inferior jugnlar 

 rei7i (v. j. i.) is unpaired and present only on the right side. 



The mos t interesting of all the veins in Spheroides are 

 the laterad veins (Pl. I and II, v. lat.). These vessels have 

 been hitherto found only in the Elasmobranchs amongst the 

 fishes. In Spheroides the lateral vein on each side takes its 

 origin in the cloacal region from a vessel coming from the 

 under side of the tail. Through a large branch, which recei- 

 ves several small veins from the muscles (11—13, Pl. I and II) 

 it communicates with the unpaired posterior cardinal vein. 

 The lateral veins run along the latero-ventral sides of the 

 body immediately external to the peritoneum more or less 



