THE ANATOMY OF POLYPTERUS. 3338 
thick-walled, deeply-pigmented, coronary vein, which runs free in the pericardial 
chamber from the ventricle to the ductus Cuvieri. 
From the dorsal side of the dorsal aorta just behind the junction with it of the 
second efferent branchial artery there passes outwards on either side a small vertebral 
artery, which curving dorsally round the spinal column appears to enter the spinal 
canal. 
Fig. 7. 
The arterial system of Polypterus. 
br., brachial ; br.’, branch of subclavian to shoulder-girdle; br.'’, branch of subclayian which becomes the 
coronary artery; 6r. I. [J. III. IV.aff., branchial afferent I., I1., III., 1V.; br. . 17. IU. IV. eff., 
branchial efferent I., IL., IIL, IV.; ca., carotid; cal., coeliac; ev.g., external gill; hy.aff., hyoidean 
afferent; hy.eff., hhyoidean efferent; /y.eff.’, hyoidean efferent branch; p.a., pulmonary; s.cl. 
subclavian ; sp., spermatic, d 
Pollard has pointed out the extremely primitive condition of the dorsal arterial 
system in Polypterus. ‘The single efferent vessel from each gill-arch uniting with a 
median dorsal aorta, resembles most the condition found in Chlamydoselachus and the 
embryos of other Selachians, 
3a 2 
