92 THE SALAMANDER 



They are attached to the metacarpals, and, although it is difficult to 

 distinguish between 'origin' and 'insertion', nevertheless, since they 

 occupy rather less of the radial side of a given metacarpal, they may 

 perhaps be correctly regarded as arising from this side, and as being 

 inserted on the whole of the ulnar side of the metacarpal of the 

 adjoining digit. 



Innervation: From NN. ulnaris and interossei. 



Function; They are the adductors of the fingers, and serve to 

 draw the digits towards one another. 



MUSCLES OF THE TRUNK AND TAIL 



(PL XVI, %. 6z and PI. XIX, fig. 71) 



1. Historical. 



The muscles of the trunk and tail regions have not been the 

 recipients of much attention ; in fact it is only necessary to cite two 

 authors in order to cover the special literature relevant to the sub- 

 ject. The first of these is Maurer (1892), who made a careful study 

 of the ventral body muscles of Urodeles and compared them with 

 the corresponding muscles of fish. His work is quite well known. 

 The dorsal trunk muscles of Urodeles have been investigated by 

 Nishi (19 1 6), who deals with Cryptobranchus and Necturus. The 

 contributions of other workers are incidental rather than specific 

 additions to our knowledge of these muscles. 



2. Dorsal Trunk Muscles. 



The dorsal body musculature remains very primitive and fish-like, 

 and by most authors is treated generally as the dorsal muscle mass 

 extending from the head to the tip of the tail. Nishi, however, dis- 

 tinguishes three portions. 



M. dorsalis trunci (m.d.tr.). Nishi (19 16). 



Lateralis magnus (5) ...... Carus (1828). 



Gemeinschaftlicher Riickgrats- und Kopfstrecker . Meckel (1828). 



Dorsal muscle mass ...... Most authors. 



The muscle forms the bulk of the dorsal muscle mass. It is com- 

 pletely segmented, being interrupted at each vertebra by a myo- 

 septum which is attached to the neural spine and transverse processes 

 of the vertebra. The myoseptum is not directly transverse but has 

 a strong convexity caudalwards. Its edge is attached mesially to the 

 strong connective tissue surrounding the median dorsal venom 

 glands. Dorso-laterally it is attached to the skin. The dorsal edge of 



