wo Edward Phelps Allis jr., 



the posterior instead of from tlie anterior carotid, and this being- said 

 to be unique in all Squalidae studied up to tliat time. If, however, 

 Cakazzi's description of the anterior carotid (my efferent mandibular 

 arteryj of Selaclie be considered, it will be seen that that artery 

 separates, in the orbit, into two parts, one of which forms a glomus 

 in the orbit while the other penetrates the cartilage of the skull 

 to join, at the point c in Caeazzi's figure, not only its fellow of the 

 opposite side, but also the so-called smaller branches of the posterior 

 carotids of opposite sides. From some point on this latter branch 

 of the anterior carotid it is evident that a cerebral artery must have 

 its origin. Caeazzi does not show this latter artery, and it may 

 take its origin from the point marked c in his figures. But, whatever 

 its point of origin, the anterior carotid (my efferent mandibular 

 artery) must there fall into the dorsal aorta (internal carotid), as it 

 does in other selachians. The arrangement is then strictly comparable 

 to that shown in my Figs. 2 and 3; and that part of the anterior 

 carotid (efferent mandibular artery) on which the g-lomus is said 

 to form becomes the ophthalmica magna, the glomus itself I'epresenting 

 the choroid gland. The glomus on the external carotid is therefore 

 some other glandular structure. 



In Clilamydoselachus anguineus (Fig. 4) the vessels, as given by 

 Atees (1889), differ in some respects from those in the fishes so far 

 considered. Aïeus' two figures of the vessels in this fish do not 

 strictly agree, but it is evident that the dorsal end of the efferent 

 hyoidean artery, and that section of the dorsal aorta that lies 

 betw^een the hyoidean and glossopharyngeal arches, are exactly as 

 in Mustelits and Selache. Ayers considers the dorsal part of the 

 efferent hyoidean artery to be represented in what I show as the 

 dorsal hyoideo-glossopharj^ngeal commissure. And the dorsal part 

 of the efferent hyoidean artery, as shown by me, is represented in 

 Ayers' common carotid and a part of his internal carotid, and is 

 considered by Ayees as a dorsal hyoideo-mandibular commissure: 

 the common and internal carotids being considered by Ayees, as 

 already stated, as a vessel resulting from the fusion of a line of 

 dorsal commissures that primarily connected a series of prehyoidean 

 efferent arteries one with another. 



The efferent mandibular artery of Chlamydoselachus differs from 

 that in Mustelus and Selache in that there is no ophthalmica magna 

 shown arising from it; and the external carotid differs from that in 

 the same two fishes in that it is shown arising from the efferent hyoidean 



