776 MR FRANK J. COLE 
the pharynx, where it soon terminates. As shown in fig. 8, the external boundary of 
the fusion rod may be somewhat irregular and perforated. 
The posterior arch of the dental plate (p. d. p.) is not concerned with the support. 
of the teeth, but serves for the attachment of the tendon of the M. longitudinalis 
linguee, which fans out as it approaches the arch so as to be inserted into practically the 
whole of its posterior border. The actual appearance of the posterior arch is not shown 
in any of the figures, for it must be remembered that all the figures represent the dental 
skeleton flattened out. The floor of the mouth sends down a longitudinal gully-like 
evagination or keel, into which, doubtless, the food drops after being liberated from the 
teeth in order to be passed backwards into the cesophagus. This evagination is very 
compressed from side to side, in the empty mouth, and lies entirely below the level of 
the teeth. In front, its base rests on the anterior arch, which, however, does not support 
its sides (except for a very abbreviated space posteriorly), since the arch, which is not 
bent, has to make too wide a deflection in order to take up a position external to the 
bases of the teeth. Hence the obtuse V. The posterior arch, having no connection 
with the teeth, is not deflected away from the diverticulum, but is sharply bent up on 
each side of it from the middle line so as to form in transverse section an acute V-shaped 
figure. The dorsal extremities of the arms of the V are continued backwards and 
outwards as spherical rods just internal to the inner row of teeth, to fuse with the 
internal process of the anterior arch as above described. In the sections, the posterior 
arch was cleft by a deep fissure behind, but there were no further indications of a 
separation of the arch in the middle line into two halves. The arch consists mostly of 
hard cartilage, but there is a median block of soft cartilage, and more soft cartilage 
where it fuses with the anterior arch. The tendon of the M. longitudinalis lingue, as 
it fans out to be inserted into the arch, exhibits the same soft pseudo-cartilage-like 
appearance in its median portion as in the tendon of the protractor muscle. 
The large space between the anterior and posterior arches is entirely filled in by 
ligamentous tissue containing the same soft pseudo-cartilage-like tissue. It is, in fact, 
the direct continuation of the tendon of the M. longitudinalis lingue, as described by 
J. MtLurR ; and its presence is obviously necessary, or the pull of the tendon would 
break the slender cartilaginous connections between the two arches. 
I am not describing the teeth here, since, as J. MULuer first pointed out, they do 
not belong to the skeleton, but only rest on the skeletal parts of the “tongue.” They 
will be described with the skin in my third part. In the meantime I may point out 
that according to my dissections, and also a reconstruction of the teeth from serial 
sections, there are nine apparent teeth in the outer row (0. 7. ¢.) and ten* in the inner 
row (7. 7. t.). Cp. fig. 9. In both rows, however, the first two teeth are fused at the 
base, and for this and other more important reasons each pair corresponds morpho- 
logically to one tooth only. ence the above numbers should be reduced by one in 
each row. The last tooth in each row is liable in some specimens to be overlooked, 
* PARKER gives for Myaine 7 and 9, and J. Mtxumr 8 and 8-9, which illustrates my point below. 
