48 PROCEEDINGS OF THE NATIONAL MUSEUM vol.73 



likely. From Murie's text I am unable to judge of the precise degree 

 of resemblance ^Yitll Eumetopias and Odohenus. 



M. cleidomastoideus (figs. 2, 4, 18) was found in the otariids only. 

 In two it was slender and had origin by fasciculi from the cranial 

 border of the broad or posterior division of the cephalohumeral — 

 this representing the clavicle. Insertion was chiefly tendinous upon 

 the mastoid process adjoining that of the trachelomastoid. No men- 

 tion of this muscle in Eumetopias was made, but Murie found it in 

 Odohe7ius. 



Supra- and infra-hyoid. group. — M. omohyoideus (fig. 18) was 

 fairly well developed in the Zalophus. Its origin was inseparable 

 from the deep half of the cleidomastoid, thus arising from the border 

 of the cephalonumeral, this representing the clavicle. It passed be- 

 neath the sternomastoid and was inserted upon the basihyal. I do 

 not consider that it was present in the PJioca, but Miller says that in 

 P. vltulina it was a part of the sterno-thyro-hyoid ; and in Arctoceph- 

 dlus the outer margin of the sternomastoid, which latter is not to be 

 considered seriously. 



M. sternohyoideus et sternothyroideus. (Figs. 18, 19.) In the Zalo- 

 phits the former had almost disappeared. There was a single thin 

 muscle arising from the manubrium deep to the presternum with 

 insertion chiefly upon the thyroid cartilage but a separate slip ex- 

 tended also to the hyoid superficial to the thyreohyoid. This was 

 separable from the main muscle no farther caudad than the thyroid 

 cartilage. In the Phoca these two muscles were inseparable at their 

 origin from the lateral two thirds of the first costal cartilage. A 

 single thin muscle band then extended rostrad separable into two 

 parts, a superficial slip inserting upon the thyro- and basi-hyals, and 

 a deeper to the thyroid cartilage. Miller said that in Arctocephalus 

 the common origin was from the tip of the presternum. 



M. thyreohyoideus (figs, 18, 19) was normal, stretching from the 

 thyroid cartilage to the thyrohyal. 



M. geniohyoideus (figs. 18, 19) in the Zalophus arose from a re- 

 stricted area near the symphysis menti, and broadened to an inser- 

 tion upon the entire basihyal. In the Phoca this was just reversed, 

 for the origin was broader than the insertion, which latter extended 

 but a few millimeters from the midventral line. 



Deep lateral and subvertebral group.— M. scaltnus (figs. 18, 19). 

 I regard the homology of the different divisions of the scalenus in the 

 pinnipeds as too uncertain to render wise any attempt at present to 

 call them anticus, medius, and posticus, and prefer to refer to them 

 by number. In the Zalophus there were two divisions that were 

 almost vestigeal. (i) arose from the third rib partly deep to the 

 serratus magnus. It extended as a slender wisp of muscle to a weak 



