2 20 ALUS. [Vol. XVIII. 



the clavicle, external to the pharyngo-clavictilaris externus, and 

 the other internal to that nniscle, either from the anterior edge or 

 the inner surface of the clavicle. Both bundles fuse anteriorly with 

 certain tendinous portions of the main body of the muscle which 

 have their insertion near the dorsal edge of the lateral surface of 

 the sternum. When these two bundles are removed a third bundle 

 is exposed, lying on the dorsal portion of the lateral surface of the 

 main muscle and crossed by a broad tendinous line. When it also 

 is removed the main portion of the muscle is exposed. This latter 

 part of the muscle is limited, both anteriorly and posteriorly, by 

 broad tendinous bands or ends, and is crossed at fairly equal inter- 

 vals by two tendinous lines, the lines beginning near the ventral 

 edge of the muscle and running upward and backward about two 

 thirds across it. These tendinous lines do not extend entirely 

 through the muscle, but they are nevertheless, in all probability, 

 the homologues of the two muscle septa that in Amia separate the 

 muscle completely into three segments. 



On the mesial surface of the muscle there are four somewhat 

 separate bundles, two superficial ones and two deeper ones, the 

 superficial bundles naturally lying mesial to the deeper ones. One 

 of the two superficial bundles is crossed by a tendinous line, and 

 is directly continuous with parts of the trunk muscles. The other 

 arises from a large tendinous sheet that has its attachment to 

 parts of the ventral fin. The two deeper bundles are inserted on 

 the mesial surface of the clavicle, on' a membranous formation that 

 is continuous with the one that gives insertion to the muscle fibers 

 on the lateral surface of the same bone. 



The sternohyoideus is innervated by a nerve that arises from 

 the trunk formed by the fusion of the three occipital nerves of the 

 fish. This nerve enters the dorsal surface of the muscle and there 

 breaks up into several branches. 



The Anterior Muscle Segments of the Trunk of Scomber 

 are much more distorted than those of Amia. If one of the first 

 full segments be examined, the outer edge of each of the inter- 

 muscular septa bounding it is seen to run at first, for a short dis- 

 tance, forward and laterally from the mid-dorsal line. It then 

 turns backward and laterally, at a sharp angle, and after coursing 

 in a nearly straight line for a considerable distance turns again 



