3 8 4 
The Ohio Naturalist. 
[Vol. Ill, No. 5 , 
of a basi-branchial plate, ( b ) the large size and peculiar contour 
of the urohyal, (c) the ceratohyals, which hang free from the 
basihyal, and do not articulate with the quadrate as they do in Raua 
and Cryptobranchus, and (ct) the absence of any “free” branchials, 
that is, any branchials unattached to the basihyal cartilage. 
Basihyal.— (Plates 8, 9, bh.) The basihyal is a rounded and 
slender rod of cartilage projecting well forward into the tongue 
and prolonged posteriorly into the slender urohyal. Just behind 
the rounded anterior extremity is found the articulation of the 
ceratohyals. This articulation is not close, but the ceratohyals 
seem to be rather loosely swung from the front of the basal cart- 
ilages. From the posterior portion of the cartilage, the first and 
second cerato-branchials are given off in close succession, and 
from this point the cartilage continues as the urohyal. In the 
specimen prepared, the basihyal and branchial cartilages were 
probably somewhat distorted, on account of the unnatural posi- 
tion of the tongue, so that in the drawing (Plate 8) they are 
higher in relation to the rest of the skull than they should be ; 
the measurements, however, and relative sizes are accurate. 
Urohyal. — (Plate 9, uh.) The urohyal bar is much longer 
in Spelerpes longicaudus than in the same stage of the frog. It 
is median and basal, and forms simply an elongation of the 
basihyal. The urohyal terminates, however, in a flattened spatula, 
which affords a place of insertion for two heavy muscles. 
Ceratohyals. — (Plates 8, 9, ch.) The ceratohyals are a pair 
of curving bars of cartilage, swinging freely from a loose articu- 
lation with the anterior part of the basihyal. Their direction is 
dorso-caudal, and they terminate freely in the mesoderm a short 
distance behind the quadrate and external to the auditory capsule. 
Branchial Arches. — (Plate 9.) The branchial cartilages at 
the given stage of this specimen are all in junction ; that is, none 
of them hang free at either extremity. They may be classified 
into three pairs of ceratobranchials and four pairs of epibranchials. 
The first ceratobranehial is the largest of all the branchial bars 
(Plate 9, bra.). It is given off from the anterior extremity of 
the basihyal. It curves slightly down and out and shortly gives 
rise to the first epibranchial and joins with the second cerato- 
branchial in originating the second epibranchial arch. The sec- 
ond ceratobranchials (Plate 9, brb.) are at their beginning notice- 
ably smaller than the first ceratobranchials, but soon increase in 
■size. This ceratobranehial gives rise to the second epibranchials 
(in conjunction with the first ceratobranehial bar) and to the 
third ceratobranehial (Plate 9, bre.). The third ceratobranehial 
soon divides into the third and fourth epibranchial cartilages 
(Plate 9, be. , bd.). The four epibranchials run free for some 
distance and at their posterior extremity are again united to one- 
nnother by a curving bar of cartilage. 
