MYOLOGY OF FISHES. 



20.: 



the ventral and lateral tracts separate to give passage to the pec- 

 toral fins, as at a, h, fig. 134. 



From this part forward, portions of the myocommas undergo 

 that change, analogous to anchylosis, which justifies their being 

 regarded as distinct longitudinal muscles: here the separated 

 ventral tract, fig. 135, a, derives a firmer origin from the clavicle, 

 and, in consequence of the forward curve of the coracoid, it is 

 not only expanded but lengthened out, in order to be inserted 

 there. But the serial homology of this fasciculus with the more 

 normal ventral portions of the succeeding myocommas, the haema- 

 pophysial attachments of which have not risen above the aponeu- 

 rotic state, is unmistakeable. The lateral portion of the anterior 

 myocomma, fig. 134, h,g, is attached to the upper end of the coracoid 

 and to the scapula ; the dorsal portion, f, to the suprascapula, par- 

 occipital and superoccipital. We recognise the dorsal portion of 

 the posterior cranial myocomma in the fasciculus called ' protractor 

 scapulte,' fig. 134, e, the middle portion in that which is exposed 

 by the removal of the operculum, and which extends from the 

 scapula to the mastoid, fig. 137, 26; the ventral portions in the 

 fasciculi continued from the coracoid forward to the hyoid, c, e, 



131 



Side muscles of head, Perch, xxxm. 



fig. 135 : the corresponding portions of the more anterior cephalic 

 muscular segments may be recognised in d and 27, fig. 135. 



