302 H. H. WILDER, 



If we turn now to the figures of Urodeles given in the plates, 

 we may compare them as follows. 



b) Extrinsic system. 

 As original elements we have here F^, augmented by Dg in cases 

 of suppression of the 4'^ branchial arch, and D,. As these elements 

 become so variously modified in both form and function, it seems 

 impossible to suggest terms which may be used throughout. I pro- 

 pose, therefore, to employ so far as possible the terms already in use, 

 relying for suggestions of homology upon the symbols employed in 

 the diagrams. These will be used as letters of reference attached to 

 the figures, and will be appended in parenthesis to the names of 

 muscles whenever ambiguity is possible. For the extrinsic muscles of 

 Urodeles, I shall employ the following terms: 



Name Authority Equivalent Sj^nonyms 



Hyo-pharyngeus Göppert V^- Hyo-trachealis 



Digastricuspha- Göppert F^ +J)g Hyo-trachealis 



ryngis 



Dorso-trachealis Henle D^ Dorso-pharyngeus 



Dorso-laryngeus Henle \ i r -r\ Dilatator laryngis 



Of the above terms the only one likely to cause confusion is 

 Hyo-pharyngeus. It must be borne in mind that it is not the com- 

 plete equivalent of the broad pharyngeal sheet of the Proteidae 

 (F5 + Fg), but of its posterior portion only (Fg). If confined in its 

 use to the other Urodeles, it can cause no confusion, as in these only 

 one of the Pharyngo-branchiales comes to development (Fg). 



Hyo-pharyngeus ( Fg). As pointed out by Göppert, this 

 muscle in its normal relationship is i)haryngeal and not resi)iratory, 

 its connection with the larynx and trachea being occasional and then 

 mainly one of contact alone. Its usual i)osition is that seen in Nec- 

 turus (Fig. 8 Fg), where it spreads out as a sheet on the cardiac 

 side of the larynx, appearing as a supi)orting back-ground to that 

 organ when viewed from the pharyngeal aspect. This tyi)ical position 

 is seen in Menopoma (Fig. 23) and in Amphiuma (Fig. 15), where it 

 is, however, reduced to a narrow strip. In Siredon it is wider and 

 more i)rimitive and covers the larynx in a ventral view (Fig. 22). Its 

 position in Siren (Fig. 13) is unique, lying here pharyngeal to the 



