414 SCHULTE, SEI WHALE. 



caudad, the plane of its orifice being practically vertical. The blow-hole is then not only dilated 

 during respiration but its rostral extremity is elevated through an arc of 90. To permit the 

 latter movement it is necessary that its wall should be highly elastic or should present some sign 

 of redundancy when closed, in the form of folds which might open out during elevation of the 

 region. The Spritzsack, the oblique diverticulum of the lateral wall, would seem to supply the 

 latter condition, for it is partially opened up by traction upwards on the rostral extremity of 

 the blow-hole even with the limited degree of movement possible in the alcoholic specimen. 

 The direction of the fasciculi of the two layers of the transverse rostral muscles justify the 

 ascription to them of the dilatation of the nares, and in view of the almost total lack of muscular 

 insertion into the mesal wall of the passage it seems clear that this act is accomplished almost 

 entirely by the movement of the lateral parietes. As regards the elevation of the rostral extrem- 

 ity of the blow-hole, the initiation of the act is more difficult of explanation. Once started, 

 and the front end of the nares slightly elevated, the sagittal fasciculi of the frontalis and caudal 

 portion of the deep transverse muscle could well serve to complete their erection, but inasmuch 

 as even in the foetus their origin is but little above the plane of the blow-hole, they would act 

 at great disadvantage if not absolutely at dead center. The difficulty is to account for the 

 initial elevation. If some resiliency of the wall may be assumed, and this in view of Andrews's 

 observation 1 seems warrantable, the action of the oblique muscle below the Spritzsack may 

 supply the required moment. From its oblique position it must draw the caudal end of the 

 blow-hole ventrad and laterad. If the narial wall possesses sufficient rigidity to allow this 

 movement to tilt dorsad the rostral extremity, the preliminary elevation might in this way 

 be secured. The small muscle extending between the midline and the caudal extremity of each 

 blow-hole may correct the lateral component in the pull of the oblique muscle. The return of 

 the nares to the horizontal position is provided by the sagittal premaxillary muscle, and with 

 this fixing its rostral extremity the mesal fasciculi of the frontalis would serve to effect an 

 approximation of the lateral to mesal wall of the narial passage, closure being further provided 

 by the interlocking arrangement of the folds about the Spritzsack, which is such as to secure 

 their tighter coaptation under the influence of external pressure. 



The other facial muscles are poorly developed and of great delicacy in this foetus so that 

 little more than their presence could be ascertained. The orbicularis palpebrarum was thickest 

 at the canthi, where it had attachments to the orbital margin. At the inner canthus a tendo 

 oculi was present. There were no tarsal plates. At the outer canthus a small band of muscular 

 fibres arising from the postorbital process joined the orbicularis. It seems to correspond to 

 the malaris externus of Stannius. In the margin of the lips, mingled with fasciculi of the trans- 

 verse rostral muscle in the case of the upper lip, of the panniculus in the lower, are longitudinal 

 strands. In the floor of the subocular prolongation of the vestibule these unite to form a small 

 sheet, which caudad can be traced to the deep surface of the panniculus. I could not follow 

 it to pharynx. The system would therefore seem representative of the orbicularis oris, the 

 buccinator being reduced in consequence of the failure to develop a cheek by the advance of 

 the angulus oris. 



Extrinsic muscles of the eye. These conform so closely to Weber's 2 descriptions that they 

 require but brief mention here. The four recti with the superior oblique arise from an annulus 



1 Vide Pt. I, Spouting. 2 Weber, M. Studien iiber Saugethiere, II, Jena, 1886. 



