96 THE SALAMANDER 



which have their insertion in the inscription next anterior, this 

 muscle is scarcely to be distinguished from the remainder of the M. 

 rectus abdominis superficialis, from which it is derived. 



Innervation: By the terminal branches of N. spinalis 14. 



Function: It is the elevator of the cartilago ypsiloidea. 



M, ypsiloideus posterior (m.y.p.). Whipple (i 906). 



M. pyramidalis .... Most other authors. 



This is a larger, more powerful, and better defined muscle, although 

 its derivation from the rectus abdominis is still apparent. It arises 

 from the antero-dorsal edge of the pubis deep to the M. rect. abd. 

 prof, and spreads in a more or less fan-like manner to be inserted on 

 the ypsiloid cartilage — on the lateral edges of the shaft, and the 

 posterior edges of the lateral processes. The muscle is thicker at its 

 lateral edges than mesially, and has considerable power. 



Innervation: By twigs from the combined nerve formed from 

 NN. spinales 14 and 15 (.f* N. ileo-hypogastricus). 



Function : It is the depressor of the ypsiloid cartilage (see also p. 45). 



The M. ohliquus externus forms the most superficial layer of the 

 lateral body-wall muscles. Like the rectus muscle it is divisible into 

 superficial and deep strata. With regard to synonyms. Funk (1827) 

 refers to the muscles of the lateral body-wall collectively as MM. 

 intercostales, and while later authors dealing with the body muscles 

 of Urodeles (mainly Cryptobranchus), e.g. Humphry, Mivart, 

 Hoffmann, &c., make some distinction between the several layers, 

 their views are not always identical, and there is also consider- 

 able variation in the relative development of the various strata in 

 different genera. It is therefore better that the reader should refer 

 to Maurer's paper for a comparative discussion, than to attempt to 

 correlate these authors' synonyms here. 



M. ohliquus externus superficialis (m.o.s.'). Maurer (i 892). 

 The fibres of this portion arise dorsally from the ribs immediately 

 ventral to the sulcus lateralis^ and also from the several inscriptiones 

 tendineae which are continuous with their lateral extremities. The 

 insertion is mainly on the ensuing inscription, but the most ventral 

 fibres terminate along a line joining the shoulder-joint with the hip, 

 and are inserted into a tendinous sheet which passes over the rectus 

 muscles, ventrally, to the opposite side. This tendon, as well as the 

 intermuscular inscription, is closely applied to the skin, and is very 

 difficult to separate therefrom. The muscle extends from the rib of 



