38 ILLINOIS BIOLOGICAL MONOGRAPHS [38 
lamina externa bears a short posterior process from its ventral margin, a 
remnant of resorption now going on, so that the choanal gap in this stage 
is incomplete. 
Just in front of the connection of the lower margin of the lamina externa 
to the cornu trabeculae, the lamina continues forward as two cartilage 
bars, the upper more cylindrical, the lower somewhat flattened, between 
which the organ of Jacobson is included. By the fusion of these parallel 
rods with the alary process above described, an elongate naris is formed 
which extends over one-half the entire length of the capsule; and at the 
same time these cartilages all unite to form the tip of the capsule, a flat- 
tened plate which covers the end of the nasal sac (Figs. 67, 68). 
The nasal capsule of Epicrium is considerably different from that of 
any other Amphibian and can hardly be said to be Urodelan. In a very 
few points, resemblances can be drawn between the Caecilian and Urodelan 
structures; but these are so few, and the modification of the parts in the 
Caecilian is so great, that few close relationships can be established. The 
independence of alisphenoid cartilage and trabecula in Epicrium, find no 
parallel among the Urodela where these parts are continuous and form the 
wall of the cavum cranii; while in no other capsule do we find the deep 
and narrow external naris, as is present in my older stage. 
The floor of the capsule is formed by a cartilage called by Peter (1898) 
the solum nasale, which can be none other than a modified cornu trabeculae 
which has developed laterally and has united to the lamina externa, just 
anterior to its fusion with the antorbital process. So that in this relation 
of cornu trabeculae, lamina externa and processus antorbitalis, there is a 
condition quite similar to the other capsules, such as Triton and Ambly- 
stoma, although superficial resemblances are lost. That the solum nasale 
was a cornu could not be derived from a study of the later stage where 
the greater development has taken place anteriorly, placing the solum in 
line with the planum basale; but the resemblance between the cornu 
trabeculae of my two weeks Cryptobranchus larva and this structure in 
my younger Epicrium seems to indicate the identity of these parts. 
Superficially, the capsule of Epicrium resembles that of Amphiuma 
more than any other Urodele. In both the sensory parts are but poorly 
protected, wide gaps occurring in all sides of the skeleton. The presence 
of a six-sided planum basale, with its anterior prolongations, the planum 
verticale with its antero-lateral alary processes are structural resemblances 
between these animals. On the other hand Epicrium lacks the circum- 
narial ring of Amphiuma, and in its place has developed a partial cupola, 
possibly in correlation with the burrowing habit of this Amphibian. 
In the origin of the planum verticale from the basale, as well as in the 
similarity of their cornua, Epicrium recalls Cryptobranchus; and it does 
not violate probability to assume that the small process ‘developed 
