585 



forward first by the dorsal commissure that connects the anterior 

 glossopharyngeus and posterior hyoidean efferent arteries and then 

 by the epibranchial portion of the latter artery, this latter epibranchial 

 artery falling into the hind end of the prehyoidean section of the lateral 

 dorsal aorta to form the continuous common carotid artery of Hyrtl's 

 descriptions. 



In Eaja clavata Hyrtl shows the circulus cephalicus formed 

 exactly as above set forth, excepting that the hyoideo-glossopharyn- 

 geus dorsal commissure is shown as double in its posterior portion 

 instead of being single, as in Eaja radiata. In Raja nasuta Parker, 

 in a lateral view of the arteries of the fish, shows the lateral dorsal 



acer 



-aaJS 



ilh aal ra elh cor 



Fig. 2. Diagrammatic representation of tlie arteries in Raja. 



aorta as a definitely continuous vessel, the hyoideo-glossopharyngeus 

 section of the lateral dorsal aorta being shown in its proper place and 

 no hyoideo-glossopharyngeus dorsal commissure being shown. In a 

 ventral view of the arteries of the same fish, a bend, or depression, 

 in the lateral dorsal aorta is shown immediately above the first gill 

 cleft and into this bend a short and stout efferent artery falls, this 

 artery arising from the dorsal commissure that lies above the first 

 gill cleft. This short efferent artery must accordingly either be formed 



