BLOOD-VESSELS OF MUSTELUS ANTARCTICUS. 
731 
Fig. 20. 
Fig. 21. 
Fig. 22. 
Fig. 23. 
Fig. 24. 
Fig. 25. 
Anterior face of the next section, showing the apex of the ventricle and the 
ventral moiety of the pericardio-peritoneal septum. 
The anterior end of the liver (Lr.) is cut through, showing the hepatic 
sinus with its vertical partition (P.). In the cardinal sinus is seen the 
aperture of the subscapular sinus (S. sccip. S'.), and the lateral vein is cut 
through close to the entrance of the brachial vein (Brack. V .); Cor., 
coracoid ; Ovd., oviduct. 
Posterior face of the same section, showing the cardinal sinuses at their 
widest. Letters as before. 
Through the first dorsal fin, showing the principal abdominal viscera and 
their blood-vessels ; posterior face of section. 
Card, st., cardiac division of stomach ; Fyl. st., pyloric division ; Intest., 
intestine showing spiral valve ; Lr., liver; Spl. , spleen ; Ov., ovary ; Ovd., 
oviducts, the left abnormally situated to the right of the stomach and 
intestine ; Kd., kidne} r s. 
Portion of section through the posterior abdominal region (4 cms. cephalad of 
pubes), showing the median position of the right cardinal. 
Through the symphysis pubis, showing the diminished size of the cardinal, 
the increased size of the renal portal, and the anastomosis of the lateral 
veins ; anterior face of section. 
Beet., rectum ; Ovd., oviducts. 
Posterior face of part of the same section, showing the caudal vein bifurcating 
to form the renal portals. 
Scyrnnus kick in. 
Transverse sections of embryo, Stage O” (Balfour) ; all fifteen times nat. size. 
Fig. 26, Through the posterior branchial region. Various segments of the branchial 
arches, not yet chondrified, are indicated by dark shading. 
Br. 2, Br. 3, the second and third holobranchs ; Pin., the pharynx. 
Fig. 27. Through the cardiac region. The section is slightly oblique, the right side 
being caudad of the left, and showing the entrance of the jugular into the 
precaval sinus; on the left side the jugular and inferior jugular are still 
separate. 
CEs., oesophagus. 
Fig. 28. Taken a .short distance (eight sections) caudad of the preceding, which it 
resembles in being slightly oblique. On the left side the entrance of the 
cardinal into the precaval sinus is shown ; on the right the cardinal is 
separate, and the entrance of the lateral vein is shown. The ventricle is 
5 a 2 
