No. 3.] MUSCLES AND NERVES [IN AMIA CALVA. 665 
mandibular does in its arch, the conditions required of a supra- 
pharyngeal element. The anterior process of the metapterygoid 
also fulfils those required of an infrapharyngeal element, for the 
truncus maxillaris trigemini, and the artery accompanying that 
truncus, lie between the two processes, in front of the levator 
of the arch, and that levator, the levator arcus palatini, is 
inserted largely on the inner surface of the median process, 
and lies entirely internal to that process. The anterior process 
is connected by connective tissue with the skull at a low level, 
and the median process by ligamentous tissue and by muscle 
at a high level. If the metapterygoid be the pharyngeal element 
of the arch, the quadrate becomes the epal element, and it fulfils 
in a measure the conditions required of such an element. Its 
distal end lies at the outer angle of the arch, as it should, and 
it is firmly bound to the symplectic, which is the anterior and 
inferior process of, or the infrapharyngeal element itself, of the 
next following or hyoid arch. In the Characinidae (No. 106, 
p. 65) the quadrate is not firmly and rigidly bound to the 
hyomandibular as in Amia. It is loosely bound, so that con- 
siderable movement is possible between the two pieces, as 
between the corresponding pieces in the branchial arches. 
The metapterygoid being the proximal element of the man- 
dibular arch, the palatine would probably be part of a premandib- 
ular arch, and the coronoid process of the mandible possibly 
another. The four divisions of the levator maxillae superioris 
would then be the levator, interbranchial, or interarcual mus- 
cles of this arch. That there are two or more premandibular 
arches has been often asserted ; that parts of one or more of 
these arches are represented in the palato-quadrate, or so-called 
palatine arch is indicated in many ways; by the innervation 
of the levator maxillae superioris by a special branch of the 
trigeminus ; by the general course of the trigeminus and its 
branches, the ramus maxillaris inferior lying always internal to 
the coronoid process where it would not naturally lie if the 
process belonged to the outer, anterior edge of the mandibular 
arch; by the fact that the palatine is found as a wholly 
detached and separate piece in siluroids (Pollard) and possibly 
also in Scymnus lichia (No. 99, p. 232), and that it is jointed 
