viii.] THE MUSCLES. 323 



ment, as in Emys^ where it runs between the transverse and 

 neural processes and the carapace. 



The cervicalis ascendens. This anterior continuation of the 

 sacro-lumbalis is of great constancy, appearing even in 

 Reptiles, e.g. Iguana and Chameleo. 



Transversalis cervicis. This muscle, which is the anterior 

 prolongation of the longissimus dorsi, is less constant, as in 

 at least some Reptiles, e.g. Iguana and Chameleo (Fig. 284), it 

 does not seem to have any distinct existence. 



The complexus is a muscle of great constancy, as it is 

 found in Reptiles, e.g. Iguana and Chameleo (Fig. 284), while 

 even in Batrachians and 'Fishes it must be considered as 

 included in that part of the dorsal extensor mass which 

 adjoins the head. 



The rectus capitis posticiis major is relatively much smaller in 

 man than in many Mammals, compared with the rectus capitis 

 posticus minor; while man's obliqui capitis are also relatively 

 smaller than in very many. Thus in the Horse the posterior 

 oblique hasten times the bulk of the more normally developed 

 rectiis posticus minor. 



A whole series of muscles may be developed which in man 

 are entirely absent. These are the numerous muscles which 

 move the tail, and which may obtain a vast bulk, as in the 

 Cetacea and in Fishes. 



To describe these muscles in detail would rather come 

 within the scope of a treatise on the Comparative Anatomy of 



i 



4 3 



FIG. 291. DIAGRAM OF CAUDAL MUSCLES OF RIGHT SIDE OF TAIL OF Iguana, 

 showing how the ventral mass resembles the dorsal part, and how the ten- 

 dinous intersections of the muscular fibres are drawn out into cones. 

 N, neural spine ; H, hypapophysial spire : z, zygapophysis ; t, transverse process ; 

 i, dorsal series of cones ; 2, upper lateral series of cones ; 3, lower series of 

 cones ; 4, ventral series of cones. 



animals than within that of the present work. Here, however, 

 it may be stated that the enormous coccyx of the Porpoise is 

 provided not only with dorsal muscles which continue on 

 backwards the erector spinas (with its main divisions) from 



Y 2 



