SCHULTE, SEI WHALE. 411 



attached to the squamosal at its junction with the zygoma. Its rostral prolongation divides 

 into three slightly diverging strands, of which the lateral reaches the zygoma in its rostral third, 

 the middle is attached to the junction of the zygoma with the maxilla, and the mesal inserts 

 upon the orbital border of the maxilla. Beauregard describes this tendinous complex as being 

 placed ventral to the orbital aponeurosis, but in this specimen it seemed to be incorporated in 

 it and capable of pulling it ventrad on the contraction of the muscle. From the tendon the mus- 

 cular fasciculi diverge fan-wise, having a general ventro-caudal direction and forming a belly 

 large in proportion to the tendon. They are inserted into the lateral surface of the mandible 

 between the deep portion of the masseter and the depressor mandibulse, the latter preventing 

 them from extending to the border of the body or of the ramus except at the extreme caudal 

 angle of this insertion. From its size and position this portion of the masseter would seem to 

 find its chief function as a tensor of the orbital aponeurosis. The orbit on its ventral aspect 

 bulges into the roof of the vestibulum oris, and the protection to its contents, attained by keeping 

 the aponeurosis taut, may serve as compensation for the deficiency of its osseous encasement. 



The deep portion of the masseter can be resolved into two parts. The rostral arises from 

 the junction of zygoma and squamosal, from the postorbital process of the squamosal and from 

 the tendon of the dorsal muscles which is there attached. Its fasciculi are directed ventrad and 

 rostrad and are inserted into the lateral surface of the mandible, from the concavity at the side 

 of the coronoid process to the border of the mandible rostral to the superficial portion of the 

 masseter. The fasciculi of more rostral insertion correspond in position to the intermediate 

 layer of Beauregard, but I could not follow them to a tendon or to an origin distinct from the 

 remainder of the layer. The caudal portion of the deep layer arises from the tendon of the 

 dorsal muscles and from the middle root of the zygomatic process of the squamosal, and is 

 inserted into the margin of the sigmoid notch and adjacent lateral surface of the mandible. 

 It has a triangular form with the base at the origin, and is in part under cover of the rostral 

 portion of the deep layer, from which it can not be wholly separated, as the two portions exchange 

 fasciculi to a considerable degree; these pass chiefly from the origin of the caudal to the belly 

 of the rostral portion. 



The temporal muscle is the largest of the quintal muscles but, as is usual in young animals, 

 fails to fill the temporal fossa, occupying with its rather thin sheet of bundles only the lower 

 and deeper portion of the fossa and being covered by a thick and compact layer of fat. The 

 limit of its origin is an arched line coinciding rostrad with the anterior temporal ridge and then 

 falling off obliquely to the mastoid region. The fasciculi converge upon a tendon, which appears 

 at the rostral border of the muscle and is inserted into the summit and rostral border of the 

 coronoid process. Many of the caudal fasciculi continue to the mandible and are inserted 

 fleshy into both surfaces, chiefly the ental, and into the caudal margin of the process. 



The internal pterygoid is of moderate size. It arises from the caudal margin of the 

 palate and the adjacent surface of the internal pterygoid plate. It is directed as a flat 

 band laterad and caudad towards the mandible; here assuming a more sagittal direction it 

 passes between the mandible and the auditory bulla, to the fibrous covering of which it adheres 

 firmly and from which it receives an increment to its bundles. It now broadens into a thin 

 sheet and turning laterad it is inserted into the mesal surface of the mandible in a depression 

 between Meckel's cartilage and the angular process, into the angular process itself and the caudal 

 margin of the ramus, and behind this into the dense fibrous tissue surrounding the temporo- 



