BY W J. McKAY. 945 



In dissecting a dog at the time of writing this paper, we were 

 struck by the similarity of the constitution of the sacro-lumbalis 

 and accessorius in that animal with these muscles in the snake, 

 the position of the nerves being also similar. 



The external portions of the posterior primary division of the 

 spinal nerves run up internal to the external aponeurosis of the 

 longissimus, and giving off a branch to supply this muscle and the 

 inter-transversarii, pierce the aponeurosis and supply the sacro- 

 lumbalis and accessorius. 



M. ACCESSORIUS AD SACRO-LUMBALEM. 



Mm. praezygapoi^hyses - costales, Hoffmann ; Gelenhfortsat- 

 ri}ypenmuskeln oder lange Uippenhehev^ D' Alton ; Stratum 

 quartum, Hiibner. 



The accessorius is made up of a number of small muscles, each 

 of which springs from the junction of the inner with the outer 

 third of the ribs, and runs forwards and inwards to be inserted 

 into the head of the third rib from the origin. These muscles are 

 hidden from view by the sacro-lumbalis which lies above. They 

 are not attached to the zygapophyses, as stated by Hoffmann and 

 D'Alton. 



Cranio-vertehral ryiuscles. 



M. SPINALIS CAPITIS. 



M. capito-vertehralis^ Hoffmann; Z)er aufsteigende Muskel zwis- 

 chen den Born- und Gele7ik/ortsdtzen, D'Alton; M. spinalis, Hiib- 

 ner; Dorn-und Halhdornmttskel, Meckel. 



The spinalis dorsi is continued forward towards the head, where 

 it is inserted on the supra- and exoccipital bones close to the middle 

 line. The only change that is noticeable is that the muscle becomes 

 more fleshy, the tendons of insertion into the spinous process being 

 much smaller. Its insertion in the skull is tendinous. The con- 

 tinuation of the spinalis in Diemenia is not so well marked as in 

 the other forms. If we follow the muscle forward we find at 

 about the tenth dorsal vertebra, that the bundles begin to end in 



