MYOLOGY OF REPTILES. 231 



There are small modifications of the muscles of the long anterior 

 outstretched ribs of the Cobra, fig. 46, pi, which sustain the 

 peculiar folds of integument forming the conspicuous ' hood ' of 

 that poisonous snake. These ribs are protracted or raised by the 

 levatores breviores, and by two sets of pretrahentes, one passing 

 over two ribs to the third behind, the others passing over one 

 rib to the second, and by the intercostales externi. The muscles 

 passing from the hood-ribs to the skin come off about four lines 

 from the head by a short tendon, the fleshy band extending 

 between one and two inches, outward and backward to its inser- 

 tion into the skin. 



The muscular system of the trunk reaches, in Reptiles, its 

 maximum in Serpents ; it is reduced to a minimum in Tortoises : 

 yet, where it has to act on the only moveable part of the verte- 

 bral column of these slow and heavy house-bearers, it is specially 

 and in some parts largely developed. 



Homology can seldom be determined or discerned, save in a 

 general way, in the fleshy parts of Chelonia ; as, e. g., that the 

 muscles upon or about the trunk-vertebra? answer to those so situ- 

 ated in lower or higher Vertebrates ; and that the primitive seg- 

 mental character of such muscles is still indicated by distinct and 

 successive attachments to a consecutive series of bony segments, as 

 is shown, e. g., in fig. 148, 37, 39, fig. 149, 27. Where a more 

 special determination has been attempted it has usually rested on 

 a similarity of attachment of one end of a muscle, with acknowledged 

 discrepancy at the other end ; as when Cuvier * compares 27, fig. 

 148, to the sacrolumbalis and lonyissimus dor si ; and when Bojanus 2 

 gives the latter name to the portions of myocommas at the opposite 

 side of the back-bone, fig. 148, or calls the muscle, fig. 152, 91, 

 which arises from the pubis, the iliacus internus. It will be 

 understood, therefore, that in applying to the muscles of the Box- 

 tortoise (Emys Europaa), the names assigned to them by the 

 author of the exemplary and beautiful monograph 3 from which 

 the illustrations, figs. 148 159, have been copied, they are to be 

 taken more or less in an arbitrary sense, and that the characters 

 of the muscles mainly exemplify the greater degree in which the 

 adaptive principle prevails over the archetypal one in the soft than 

 in the hard parts of the frame. 



On the dorsal aspect of the vertebra? of the back, the muscular 

 system is restricted to the ( spinalis dorsi,' fig. 148, 39 ; it rises 

 from the neural and beginning of the costal plates, neural arch 



1 xiii. i. p. 292. 2 xxxviii. 3 Ib. 



