No. I.] SKELETAL ANATOMY OF AMPHLUMA. 



31 



the labyrinth the prootic rises so as to overlap the parietal, and 

 at length it alone forms the outer wall of the groove. This pro- 

 cess of the prootic continues thus to its termination at the very- 

 tip of the beak-like process of the parietal, which Wiedersheim 

 has figured on Tafel II, Fig. 17. 



The antorbital is almost entirely cartilaginous, but posteriorly 

 coalesces with the ossification of the orbitosphenoid. 



I find no cartilage strengthening the capsule of the eye. 

 While such a support seems usually to be present in the eye of 

 the Urodela, I find none in that of Spelerpes longica2id7is. The 

 integument passes over the eye of Aviphiuma, and the connec- 

 tive layer is very dense and thick. The animal probably enjoys 

 very limited powers of vision. 



In the lower jaw we find the articular undergoing ossifica- 

 tion ; but this seems to be due rather to an extension of the 

 bone of the angular first around, and then into, the territory of 

 the articular, than to an independent centre. 



As already observed in the case of the larva, the ossification 

 of the hyoid seems to be rather a parostosis than a cartilage bone. 

 The bone lies on the mesial side of the cartilage. At the ante- 

 rior end of the hyoid, the bone seems almost immediately to press, 

 itself through the cartilage, so that there is cartilage on both 

 sides of the bone. Further back, the bone thickens, becomes 

 crescentic in section, and partially encloses the outer and main 

 portion of the cartilage. In Fig. 9 at Cc.k.o. I have represented 

 the section and position of this bony portion of the hyoid. The 

 letters Ce.h.c. point to the portions of the cartilage. These 

 relations continue nearly to the upper end of the hyoid. For 

 the greater distance, the cartilage on the mesial side is a very 

 slender rod, and at one point it disappears entirely, but almost 

 immediately it comes into view again. As there is no trace of 

 this inner rod of cartilage in the larva, it must grow from the 

 extremities of the outer cartilaginous rod. Near the posterior 

 end of the hyoid, the two portions of the cartilage reunite into 

 one mass. 



About the ends of the hypohyal are located several nodules 

 of cartilage, which probably represent the basihyal. Dr. Wieder- 

 sheim has figured these as he has observed them in the adult. 



A large portion of the basibranchial is ossified. The first 

 branchial arch is ossified from end to end. Here, as in the case 



