HYOMANDIBULA OF THE GNATHOSTOME FISHES 609 
dibular artery), which is exactly the relation that a mandibular 
ray would normally have to the afferent artery of its arch; and, 
if it be a mandibular ray, the apparently tortuous course of the 
arteria hyoidea would be explained, for, without other apparent 
reason, that artery passes from the internal surface of the so- 
called palatine arcade outward across the ventro-posterior edge 
of the symplectic, crosses the external surface of that element, 
and then runs inward across its dorso-anterior edge to reach the 
pseudobranch. The relations of the rami mandibularis exter- 
nus and internus facialis to the symplectic would also receive 
explanation, for the attachment of the symplectic to the hyo- 
mandibula is always, in all the Teleostei with which I am familar, 
ventral to the point where these two nerves separate from each 
other, and, as one of the two nerves runs outward and the other 
inward, the symplectic, if it be a mandibular branchial ray, 
would naturally lie either between them or internal to them both, 
according to the position of the point of contact of the outer end 
of the ray with the hyomandibula. Furthermore, the symplec- 
tic is said to be found, frequently in the Teleostei, completely and 
indistinguishably fused with the hind end of the quadrate, which 
would be wholly natural for a branchial ray related to that car- 
tilage. The little chain of cartilages which, in Torpedo, con- 
nects the hyomandibula with the symplectic cartilage, would 
then be derived from other rays of the mandibular series, for, 
that these cartilages can represent the symplectic, seems improb- 
able from their relations to the afferent mandibular artery. 
This artery, in the Teleostei, crosses the external surface of the 
symplectic, as just above stated, while in the Batoidei it would 
seem as if it must lie internal to the little chain of cartilages, for 
it is well known that it lies postero-internal to the spiracular 
cartilage (Dohrn ’85). 
As in the Batoidei, and apparently for the same reason, there is, 
in the Teleostei, no inferior postspiracular ligament. That the 
teleostean M. adductor hyomandibularis, which has so markedly 
the position of the selachian inferior postspiracular ligament, can 
be the homologue of that ligament seems improbable because of 
the relation of the one to a pharyngeal and of the other to an 
