382 The Ohio Naturalist. [Vol. Ill, No. 5, 



is a fully formed capsule. It is possible that the diverse habits 

 of the two forms may account for this reversion of development. 

 "Spelerpes, which spends its larval existence for the most part 

 hidden under rocks and in the dark, needs an acuteness of hear- 

 ing and a sensitiveness to vibration for which its cousin compen- 

 sates by an early developed and well protected eye. 



Trabeculae. — (Plate 10.) The trabeculae cranii appear as 

 two longitudinal bars supporting the anterior end of the brain and 

 the nasal sacs. Just behind the superior labial cartilages, they 

 are flattened out into a pair of disk- like, slightly concave projec- 

 tions serving to support and protect the nasal sacs. There 

 is no juncture of the trabecular bars here as is the case in 

 the frog. Just behind the nasal capsule, the trabeculae resume 

 their rod-like form, presentl}- becoming compressed to form a sort 

 of triangle, concave on the outside. This is the optic capsule 

 before mentioned. Back of this point, the trabeculae are pierced 

 by the optic foramena (Plate 8), and again, still further back, by 

 another and larger foramen, which admits some of the larger ves- 

 sels to the brain. Just above this latter foramen, the quadrate 

 separates from the trabecula. This is given off from the upper 

 half of the trabecular bar (Plate 8) and curves down to meet and 

 articulate with the lower jaw (Meckel's cartilage), while the 

 lower half curves in to meet its fellow just in front of the noto- 

 chord (Plate 10. bp.), forming a support for the main part of the 

 brain. The auditory capsule is continuous with the quadrate 

 above and trabeculae below. PVom the point of their juncture, 

 the trabecular bars continue as a pair of flattened rods — the para- 

 chordals (Plate 10), which together with the notochord form the 

 .floor of the brain case. Just behind the auditory capsule, the 

 parachordals show a leaf- like process, which serves as a protective 

 case for the medulla and upper cord. 



Upper IvABiALS. — Plates 8, 9, 10, la.) The.se labials are a 

 pair of rounded caps which fit over the ends of the trabeculae. 

 They are pointed above and blunt below. It seems that these 

 labials should be used, governed by suitable muscles, in sucking, 

 in case the larva uses that means of obtaining food, but a diligent 

 search failed to re\'eal any muscles which might l^e used in that 

 way. The superior labials are, like the traliecular cartilages, 

 entirely separate from one another. They are so freely and 

 loosely articulated, moreover, as to permit of the possibility of 

 considerable movement. 



Lower Labials. — (Plates 8, 9, lb.) The inferior labials, on 

 the other hand, are so fused as to present the aspect of a single, 

 compact cap, which fits over the rounded anterior part of the 

 lower jaw. They are comparable in a general way, to the labials 

 of Rana. The upper and lower labials are apparently among the 

 first cartilages to appear, since at this stage they are very com- 



