1875.] and Development of the Batrachian Skull. 137 



The supposed upper piece was merely the outer edge of the arch in 

 front, the mandibular arch; and therefore all reasonings upon the meta- 

 morphosis, afterwards, of such a coalesced segment fall to the ground. 



Professor Huxley showed me, and my new researches told the same 

 tale, that the hyoid arch does not coalesce at all with the mandibular ; 

 that the "columella," whether answering to the " hyomandibular " of a 

 fish or not, has no existence as cartilage, even in young frogs and toads 

 that have taken to land life ; afterwards, when they are one third larger, 

 this cartilage appears. 



Professor Huxley, and -my own observations agree with his, also 

 showed me that the stapes is not formed by the separation of a plate of 

 already formed cartilage, but chondrifies later than the auditory sac and 

 much earlier than the columella : in the Urodela it is formed by the seg- 

 menting off of a flap of the chondrified capsule. Our mutual researches, 

 after these errors were made evident to me, gradually brought us into 

 greater harmony in our interpretation ; and the working out by Professor 

 Huxley of Menobranchus, and by myself of others of the Urodela, has 

 been of great service in making clear the meaning of the more complex 

 skull of the Anura, 



Being well provided with materials for working at the common 

 toad's skull, and, through the kindness of friends*, for various stages of 

 the two " aglossal" toads, namely Dactyleihra and Pipa, it came to pass 

 that I was in a good position for searching out this subject further, with 

 new light and new material. 



Moreover these are not the only types of the Batrachia that have more 

 recently engaged my attention ; but the great bull-frog and the paradox- 

 ical frog have also had various stages of their skulls laboured at by me. 

 These would have swelled my paper to too great a size ; I hope to offer 

 them when the tree-frogs, Bombinator toads, and other kinds have been 

 studied. 



In this paper I have given, first of all, correcter figures of the nasal 

 labyrinth of the adult frog. Before my former paper was in print I had 

 seen that in the bull-frog the " trabecular cornua" kept their distinctness 

 on the front nasal wall. Professor Huxley has discovered rhinal processes 

 in Rana esculenta and in Rana temporaries He also showed me a distinct 

 nucleus of cartilage in front of the nasal sac. There are two such carti- 

 lages on each side, as I soon found, the modified and subdivided " upper 

 labials ;" these are shown in the new figures. 



By comparison of the skull of the Anura with that of the tailed Am- 

 phibia, a better idea can be had of the relations of the mandibular pier 



* I am indebted to Professor Huxley for adult skulls of Dactylethra and Pipa ; to 

 Dr. Dobson, F.L.S., of Netley, for another adult Dactylethra ; to Mr. T. J. Moore, of the 

 Liverpool Free Library and Museum, for four stages of the larval Dactylethra ; to Dr. 

 Giinther, F.K.S., for embryos of Pipa: and to Professor W. H. Flower, F.K.S., for 

 ripe young of the same. 



YOL. XXIY. L 



