No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 579 
tance below the surface of the muscle, and then comes to its 
outer surface ; in Galeus it comes immediately to the outer 
surface of the muscle and in its further course lies on that sur- 
face. In both fishes it is joined near the front end of the 
muscle by a branch of the facialis, apparently the r. mandibu- 
laris externus facialis of Amia. 
The tendon above described gives insertion at the corner of 
the mouth to the tendon of Add8. From its lower, inner sur- 
face the fibres of the superficial portion of the mandibular part 
of the adductor arise. It seems, therefore, to represent the 
tendon Az Ao! of Amia, and the muscle fibres arising from it 
to represent Az and Aa’, the deeper portions of the adductor 
muscle corresponding to A; and do’. At the point where 
the r. maxillaris inferior trigemini pierces or meets the tendon 
several branches are sent into the adductor muscle, supplying 
its deeper as well as its outer portions. These branches run 
backward between the two portions of the muscle, thus corre- 
sponding in position to the branches that, in Amia, run down- 
ward and backward between Az and A3, innervating those 
muscles. That part of the muscle that arises from the upper 
surface of the tendon, and hence lies directly superficial to the 
main inferior maxillary nerve, therefore, corresponds to the 
superficial layer Az! of Amia. The rest of the superficial por- 
tion, or possibly the tendon alone, represents the deeper layers 
A." and Az!" of Amia, which, if they are represented by the 
tendon alone, must have acquired their relative importance 
later. 
With the several portions of the adductor found in rays 
and described by Tiesing I am unable to make any satisfactory 
comparison whatever. 
In teleosts the adductor presents markedly different arrange- 
ments in different species. The innervation of the different 
parts of the muscle not being definitely known, a definite com- 
parison with the muscles found in Amiais not possible. Certain 
probabilities can, however, be arrived at. 
The third and fourth divisions of the levator maxillae supe- 
rioris of Amia are, as already stated, probably found as special 
insertions of the adductor in teleosts, or as aberrant bundles 
