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The PseudobrancMal and Carotid Arteries 

 in the Gnathostome Fishes. 



By 



Edward Phelps AUis jr., Menton. 



With Plates 9. 



Anyone who has had occasion to consult the literature relating- 

 to the pseudobranchial and carotid arteries of fishes will well know 

 how confusing are the frequently conflicting statements regarding 

 these vessels, and also the frequent changes not only in the nomen- 

 clature relating to them, but also in the homologies that are implied 

 in, or actually affirmed b}", that nomenclature. Having recently had 

 occasion to reconsult this literature, and wishing to summarize it 

 in some convenient form for future reference, I decided to make a 

 series of diagrams of the arteries and related vessels as they are 

 shown or described in the several monographs and text books at 

 my disposal. But these diagrams, to be of any use or value, would 

 necessarily all have to be constructed according to some common 

 plan. So I decided to adopt the type of diagram given in mj 

 work on Amia (Allis, 1900), where the internal and common carotids 

 and the corresponding lateral dorsal aorta are shown as parts of 

 a single straight and continuous vessel. And the diagrams so con- 

 structed, after a number of unsuccessful trials, have not only made 

 plainly evident certain well-known homologies, but have also, and 

 quite unexpectedly, established certain other homologies that are 

 usually overlooked or insufficiently alluded to, and suggested still 

 other homologies that may be of importance. 



That the internal carotid and lateral dorsal aorta of vertebrates 

 are primarily parts of a single continuous vessel is said by Ayees 



