32 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. XIV. 



the superficial and deep masseters near the mandibular condyle and issu- 

 ing between the masseters to an insertion on the anterior base of the ear. 



Zygomaticus. This is in three divisions all arising on the zygoma. 

 Two of them originate from the lateral surface of the posterior half of 

 the zygoma behind the eye. They are small well-formed fasciculi closely 

 similar to each other and somewhat distinguished from the third division 

 which lies below (entad) them. They run forward to the level of the 

 angle of the mouth where they become tendinous and proceed thus for 

 some distance to insertions in the tissue on the side of the upper jaw at 

 the base of the whiskers. 



The third division, to which some other name may be applicable, 

 is similar in appearance but arises from the side of the lower anterior 

 angle of the zygoma and its slender tendon is inserted into the skin of the 

 inside of the upper lip in the vicinity of the base of the labret. 



Retractor naris. A slender muscle arising from the fascia between 

 the eye and the zygoma. It crosses the outer surface of the anterior root 

 of the zygoma and becomes a very slender threadlike tendon which runs 

 forward to an insertion on the nasal cartilages. 



Digastricus. Arises on the paroccipital process between the condyle 

 and the mastoid bulla and runs down around the ear and thence for- 

 ward to spread over the interramal space and attach along the sides of 

 the mandible from the base of the angular process to the symphysis. 

 Anteriorly it is largely aponeurotic. A tendinous slip diverges at a point 

 ventrad of the masseter and passes dorsad to the caudal median border 

 of the mylohyoid. It is essentially as in Didelphis. 



MUSCLES OF THE NECK. 

 Plates IV, VI. 



Sterno-hyoideus. This is the principal muscle exposed on removing 

 the skin from the lower side of the neck. It arises on the ental surface 

 of the second sternebra and runs directly forward opposite its mate and 

 inserts on the posterior side of the hyoid bone caudad to the insertion of 

 the genio-hyoid. Some of its superficial fibers inosculate with those of 

 the genio-hyoid. Like the other muscles connected with the hyoid and 

 the tongue, it is not peculiar. 



Genio-hyoideus. A flat paired muscle immediately cephalad of the 

 sterno-hyoideus and entad of themylo-hyoideus. It arises on the body of 

 the hyoid bone and inserts on the mandibular symphysis. 



Sterno-thyroideus. A thin, paired muscle lying between the trachea 

 and the sterno-hyoideus- Laterally it is thin and transparent and 

 toward the median line it is somewhat thicker, especially in its caudal 



