662 ALETS. [Vou. XII. 
in the second and third arches of Polypterus (van Wijhe); or 
as two independent pieces, as in Acipenser and in the first arch 
of Polypterus (van Wijhe), the two pieces, or two portions, 
where they exist, being always the one anterior and inferior 
and the other posterior and superior. Van Wijhe says 
(No. 129, p. 225) that where but one pharyngobranchial is 
found it always lies below the ‘“‘ Kiemenvene,”’ by which must 
be meant the efferent artery of the arch, and that where two 
are found the anterior of the two always lies below that artery 
and the posterior always above it. He has, accordingly, called 
them the infra- and supra-pharyngobranchials, respectively, and 
has suggested that the latter should be considered as a fifth 
element of a complete and normal arch.! He also states, as a 
general rule, that the epibranchial of an arch always touches or 
articulates with the infrapharyngobranchial of the next follow- 
ing arch, a relation that would naturally arise if the arches are 
primarily Y-shaped at their dorsal ends, and continuous one 
with the other, as Stohr (No. 117, p. 9) gives them in early 
stages of Triton. 
At the point where the epibranchial touches the next follow- 
ing infrapharyngobranchial, in Amia, the two elements are 
always connected by an articular ligament. They are also 
always connected, in Amia, by a second series of ligaments, 
the interarcual ligaments, which connect the epibranchial with 
the next following infrapharyngobranchial or epibranchial, one 
or both. This important series of ligaments seems to have 
escaped van Wijhe’s notice. 
The first branchial arch may articulate with, or be closely 
attached by ligament to the cranium by the anterior of its two 
pharyngeal elements alone, as in Amia, by the posterior element 
alone, as is apparently the case in Polypterus (van Wijhe), or 
by both elements, as in Acipenser (van Wijhe). Where the 
articulation or attachment is by the anterior element it is, in 
1 Attention should here be called to a mistake in the lettering of the pharyngo- 
branchials in van Wijhe’s Fig. 2 (No. 129) which shows the branchial arches of 
Acipenser. If the pharyngobranchials on the first two arches in this figure be 
compared with those in his Fig. No. 3, and with those in Parker’s Fig. No. 5 
(No. 86, Pl. XVIII), it will be evident that the anterior processes in van Wijhe’s 
figure should be the infra- and not the supra-pharyngobranchials, as they are marked. 
