542 LOUISE SMITH 



the mucous membrane is removed, is an extremely delicate but 

 definitely marked muscle, peculiar to adult free-tongued sala- 

 manders, which I call the suprapeduncularis (figs. 21 and 23). 

 It is the muscle which Wiedersheim designates by the letter T 

 (75, fig. 134) and describes as arising from the medial border of 

 the ceratohyal (ibid., p. 191). I find that in Spelerpes bislineatus, 

 however, it is quite plainly attached to the anterolateral border 

 of the dorsal surface of the ceratohyal on each side and stretches 

 across within the dorsal fold of mucous membrane, with its 

 anterior edge defining and strengthening the free border of the 

 orifice through which the tongue protrudes (fig. 2, a). 



Of the other larval muscles, most of which were in association 

 with the degenerated epibranchials (constrictors, levators, 

 depressors, etc.), only two are represented. A rather deep-lying 

 stout, muscular band encircles the ventral half of the oesophagus 

 dorsal to the pericardium. The larger part of this is made up 

 by the digastricus-pharyngeus, but a small portion is formed by 

 the dorsolaryngeus. The component parts are not clearly defined 

 however, but tend to form a continuous pharyngeal sheet, as has 

 been pointed out by H. H. Wilder ('96, p. 188). 



METAMORPHIC PHENOMENA 



1. Skeleton 



The metamorphosis of the hyobranchial skeleton of Spelerpes 

 bislineatus shows some very interesting facts which I do not 

 find mentioned in the literature. I have placed these in the 

 form of a normal table which presents the details of develop- 

 ment from the larval apparatus to that of the adult. Cross- 

 sections of the four specimens described in this table are pic- 

 tured in figures 29 to 47, and the condition of the skeleton of a 

 metamorphic animal about like stage III is shown in figure 28. 



Perhaps the newest and most striking of the metamorphic 

 phenomena and that which may give a clue to the whole method 

 of skeletal metamorphosis is shown in the development of the 

 adult epibranchial. This cartilage is not merely the larval first 

 epibranchial with its position slightly changed, as has been 



