22 PKOCEEDINGS OF THE NATIONAL MUSEUM VOL. 70 



The insertional portion is, however, divisible into two parts. The 

 pars posticus consists of those fibers originating caudad to an 

 imaginary transverse line passing through the blowhole. .Insertion 

 is upon the caudal margin of the latter and for some distance deep to 

 the orifice. The pars anticus arises rostrad of the imaginary line 

 mentioned above and is inserted not upon the dorsal membrane 

 covering the superficial respiratory sac (see p. 39) but upon the 

 lateral and ventral portion of this sac, and upon the dorsal mem- 

 brane of the deeper sac. 



Deep to the anterior part of the dilator is a small layer of fibers, 

 which may or may not constitute an entirely separate muscle. It 

 arises along the ridge situated just laterad of the most anterior of 

 the maxillar}^ foramina, and is inserted lightly upon the ventral 

 membrane of the deeper respiratory sac and into the cartilagenous 

 tissue cranio-ventrad to it. Surrounding the deeper j)ortion of the 

 bloAvhole, especially rostrad, is fibro-muscular tissue of very fine 

 texture. Because of its situation this must have some mobile func- 

 tion, which one might be inclined to doubt merely from an examina- 

 tion of the tissue. 



The facial musculature of Kogia and Balaenoptera seems to be so 

 radically different from that of Neomeris that without loiowing the 

 innervation of all or making direct comparisons, an attempt to 

 homologize the muscles would be useless, Murie's figures, but not 

 his text, for GlobiocepJiala show an occipito-frontalis and levator 

 labii superior alaeque naris, which evidently correspond with what 

 are herein termed the two divisions of the dilator naris ; and Murie's 

 nasolabialis corresponds in situation to the muscle of Neomeris to 

 which the same term is given ; but for Glohiocephala the insertion is 

 stated as deep, while in Neomeris it is superficial. 



The huccinatorius is quite thin and weak. It originates from be- 

 tween fibers of the nasorostralis and is inserted upon the membrane 

 of the mandible. 



Neomeris has a small muscle tentatively termed, because of its posi- 

 tion, the tympano-zygomaticus^ which stretches from the more ven- 

 tral portion of the zygomatic process of the squamosal to the tissue 

 investing the ear bone, with fibers running cranio-dorsad. Whatever 

 may be its chief function, it adds strength to the weak articulation of 

 the mandible with the skull. This may possibly be homologous with 

 the depressor mandibulae as described for Kogia and Balaenoptera^ 

 but this is considered to be extremely doubtful, as the fibers are 

 directed differently and the function can not be the same. 



MDSCLES OF MASTICATION 



The masticatory musculature of this animal is very poorly devel- 

 oped and is clearly degenerate. 



