— 37 — 



descriptions of the Cyprinidae, but, as described immediately below, it does not coirespond with that 

 fossa in the muscles to which it gives origin. The anterior corner of the depression is connected by 

 a shallow groove with the facialis opening of the trigemino-facialis chamber, this groove lodging 

 the nervus sympatheticus and the rarnus anterior of the nervus glossopharyngeus. In the postero- 

 ventral corner of the depression is the vagus foramen, and slightly anterior to that foramen, near 

 the ventral edge of the depression, is the glossopharyngeus foramen, both of these foramina per- 

 forating the exoccipital. 



Dorsal to the subtriangular depression above described, the posterior half or three-nfths of 

 the dorsal half of the lateral surface of the skull is markedly flat. Anterior to this flat portion, there 

 is a large and deep fossa, on the proötic and pterotic bones, the fossa lying immediately antero- 

 ventral to the elongated facet for the posterior articular head of the hyomandibular, and antero- 

 dorsal to the arch of the external semicircular canal. The anterior border of this fossa is formed by 

 a strong flat process of the proötic, this process lying directly dorsal to the facialis opening of the 

 trigemino-facialis Chamber and immediately posterior to the rounded oval and relatively deep facet 

 for the anterior articular head of the hyomandibular. Partly in the dorsal portion of this fossa and 

 partly on the process that forms its anterior border, the two internal levators of the branchial arches 

 and the external levators of the first three branchial arches have their origins. The external levator 

 of the first arch was little more than a band of membrane on one side of the head of the single 

 specimen examined in this respect; and on this same side of the head of this one specimen the external 

 levator of the third arch was wholly wanting, while on the other side it was a slender muscle much 

 smaller than any of the others. The several muscles all arise together, as a group, the internal levators 

 arising in a line that lies immediately postero-ventral to the line of origin of the external muscles. 

 The levator internus anterior lies internal to the other muscles, and is a stout one which bellies 

 considerably immediately beyond its origin, the belly of the muscle completely Alling that large 

 part of the fossa that lies ventral to the surface of origin of the muscles. This large part of the 

 fossa thus seems to have been formed by the compressive action of this muscle, and not in relation 

 to the points of origin of the several muscles of the group. 



On the flat surface of the skull posterior to this fossa, and also partly in the subtriangular 

 depression, the adductor hyomandibularis and adductor operculi have a large surface of origin. These 

 two muscles are not contiguous at their origins, the surface of origin of the adductor operculi lying 

 slightly posterior to and being slightly larger than that of the adductor hyomandibularis. Dorsal 

 to these two muscles, in a long and narrow line along the dorso-lateral edge of the skull, the levator 

 operculi has its origin. Immediately posterior to the surface of origin of the adductor operculi, in a 

 narrow line near the hind edge of the skull, the external levator of the fourth arch has its origin, 

 this fourth levator, in the one specimen examined, having its insertion on the fourth arch and not 

 on the inferior pharyngeal bone. Posterior to this fourth levator, and in contact with it, a flat muscle 

 has its origin, and running posteriorly has its insertion on the dorsal portion of the clavicle, thus 

 corresponding to the fifth levator of my descriptions of Scomber. This fifth levator would seem to 

 be the homologue of the muscle that Herrick considers ('99, p. 117), in Menidia, as the trapezius 

 muscle. It would seem as if it must also be the homologue of the muscle described by Sagemehl 

 ('84 b, p. 49), in the Characinidae, as the Attractor of the Shoulder girdle, that muscle being said to 

 arise from the skull and to have its insertion on the supraclavicular. Vetter concluded that 

 a trapezius muscle is wanting in Teleosts, as Herrick himself states. 



