Nos. IAND2.] AXATOMY OF SCOMBER SCOMBER. 225 



septum, just before it becomes attached to the hind end of the 

 exoccipitale, there is a slight indication of a dorso-posterior 

 pocket. The first septum joins at this point, and becomes fused 

 with, the second septum, the first septum lying, apparently, ven- 

 tral to the antero-mesial process of the suprascapular and the 

 second septum dorsal to that process. 



On the dorsal surface of the dorso-median pocket of the first 

 septum, that is, morphologically, on its anterior surface, there are 

 two fibrous ridg^es which project upward and come to the outer 

 surface of the muscle mass that fills the temporal groove. The 

 outer edges, so exposed, of these ridges, form two slightly curved 

 lines, parallel in general direction but with the hollows of their 

 respective curves presented toward each other. The posterior 

 halves of these lines lie dorsal to the two splint-like anterior proc- 

 esses of the suprascapular. Between them there is a third longi- 

 tudinal fibrous line. The anterior half of this third line is at- 

 tached, along its deeper edgQ, to the bottom of the temporal 

 groove, the line of attachment extending backward to the point 

 where the bottom of the groove changes abruptly from a higher 

 to a lower level. Posterior to that point the fibrous band pro- 

 jects backward into the muscle fibers of the first muscle segment, 

 giving insertion to that part of those fibers that lie between the 

 two fibrous ridges of the first intermuscular septum. This middle 

 fibrous line thus represents a part of the anterior fibrous covering 

 of the trunk muscles, and, in the nomenclature used by me, would 

 have to be designated as septum zero. Another part of this same 

 formation is attached to the hind edge of the posterior process 

 of the squamosal, and, extending backward, covers the outer sur- 

 face of a part of the anterior end of the trunk muscles. 



The pedicle of the suprascapular is thus seen to lie in the first 

 intermuscular septum ; the two slender, pointed anterior processes 

 of the bone to lie in the lines of the two fibrous ridges on the 

 antero-dorsal surface of the same septum; and the antero-mesial 

 process of the bone to lie between the first and second septa. In 

 Amia the pedicle of the suprascapular lies immediately in front of 

 the first septum. The septa in Scomber thus agree, in this respect, 

 as well as in their apparent relations to the clavicle and to the 

 occipital and spinal nerves, with the corresponding septa in Amia. 



