MOUTH AND NOSE 



and was at least a quarter the size of the adult tongue, although the 

 whole head was perhaps but one-hundredth of the bulk. Transection 

 of the adult tongue shows but few muscle fibers and these are partly 

 disassociated. Connective tissue is soft and flabby with much soft fat 

 of oozy consistency, so that when a large piece of the tongue is turned 

 over on the ground by means of an iron hook it is strongly reminiscent 

 of a large bladder partly filled with mercury. In a freshly killed speci- 

 men the tongue lays flabbily at the base of the oral cavity, appears 

 shrunken and almost shapeless and, as said, is clearly almost nonfunc- 

 tional. So there is ontogenetic reduction of the tongue in this group, 

 indicating definite lessening of function. Incidentally it is hardly likely 

 that just this change in the character of the tongue could take place 

 without a corresponding reduction in the size of the esophagus, and 

 hence, in the function of deglutition. 



Now the integument of the throat in these whales has an intricate 

 system of longitudinal plicae, grooves, or folds, extending from the chin 

 to the mid-ventral line for half its length or more, and from the angle 

 of the mouth to the base of the fore limb (see figure 9) . Their pres- 

 ence has given rise to fanciful theories, as that the grooves are highly 

 vascular and so in this manner oxygen is secured from the sea water, 

 but anatomical facts clearly illustrate the reason for their being. After 

 death the gular musculature is often relaxed, allowing the throat to 

 bulge, but occasionally it is more tensed, as in life. Unfortunately I did 

 not dissect the fetus which I examined so my acquaintance with the 

 gular musculature of this group is limited to what I could learn by hasty 

 observation while numerous finbacks were being cut up. It is evident 

 however, that neither Schulte (1916) nor Carte and MacAlister (1869) 

 properly interpreted all of the conditions which they encountered in 

 this group of whales. That Schulte' s designation of his mylohyoid as 

 a part of the three-sheeted gular musculature is erroneous is shown by 

 its innervation as well as by its position in relation to adjacent muscles. 

 Furthermore it seems that the muscle which he called a geniohyoglossus 

 was in reality the mylohyoid, his hyoglossus the geniohyoid, and his 

 sternomandibularis probably the specialized digastric at least this 

 seems, from its position, the most logical interpretation; but lack of 

 precise statements as to the innervation of all muscles prevents incon- 

 trovertible interpretations. At any rate it seems fairly certain that the 

 three main sheets of the gular musculature comprise a specialization 

 of at least two sheets of a primitive sphincter colli, now occurring as 

 a sphincter colli superficialis, a sphincter colli profundus, and a re- 



[81] 



