ART. 18 AXATOMY OF CHINESE FINLESS PORPOISE HOWEUL. 39 



OTHER SOFT PARTS 



Blowhole. — The bloAvhole was investigated by cutting thin, hori- 

 zontal sections from this portion of the head. As the thin, integu- 

 mentary blubber layer is removed, one encounters upon either side 

 and cranio-laterad to the blowhole proper, a superficial narial dila- 

 tion or respiratory sac, measuring sojne 40 mm. in a transverse and 

 30 in a sagittal direction. It is lined with sooty mucous membrane, 

 the more dorsal portion of which is but slightly wrinkled, while the 

 ventral surface, more especially mediad, is thrown into heavy folds. 

 It is separated from a similar sac upon the opposite side by a thin, 

 membranous partition. In this plane it is not continuous w^ith the 

 blowhole, access to the latter being by a deeper passage situated be- 

 tween two of the rugose folds and extending caudo-ventrad (fig. 14) . 



Deep to this, on either side, is a second but smaller respiratory sac 

 separated from the more superficial one by a thin layer of fibers of the 

 dilator naris. It is lined with delicate, pink, mucous membrane 

 which becomes sooty toward the passage with which it communicates 

 with the blowhole. The remainder of the accessory air passages 

 and sacs seem to have much individual variation. In the second 

 specimen dissected the deeper respiratory sac communicated, by a 

 passage running caudad, with the extreme lateral portion of the 

 blowhole, and this was continuous with a communication with an 

 accessory sac located caudad to the blowhole. In addition there was 

 a second accessory sac caudad of the first, with passage to the caudal 

 part of the blowhole deep to the first accessory sac, as shown by the 

 dotted line in Figure 14. Whereas the superficial and deep respira- 

 tory sacs are flattened horizontally when collapsed (or rather not 

 dilated), the two accessory sacs upon either side are flattened ver- 

 tically in a somewhat sagittal direction. 



In the first specimen dissected the deeper respiratory sac com- 

 municated directly with the more rostral accessory sac laterad to, 

 but separate from, the blowhole, while access to the latter was had by 

 a passage upon its caudal wall. There was no second accessory sac 

 whatever. 



Finally, there is a lateral dilation of the blowhole upon either side 

 tis indicated by the fossa encroaching upon the maxilla laterad of 

 the anterior narial openings of the skull. In both animals the fleshy 

 septum between the nares persisted for only a few millimeters beyond 

 the bone, the remainder of the blowiiole consisting of a single air 

 passage without valves or other complications, save as there may be 

 valvular action of the respiratory sacs. In the first specimen dis- 

 sected the right narial opening of the skull was about 50 per cent 

 larger than the left ; in the second specimen the left was some 50 per 

 cent larger than the right. It was naturally presumed that this 



