No. 469] 



BIOLOGY OF THE DUGONG 



59 



duced by dylw^ animals only, for Steller likewise stated that the 

 uninjured rhytinas never uttered a sound, while the wounded 

 ones gave a sort of hollow moan. Also in the case of mana- 

 tee no trace of a voice lias been observed ( Muri<\ 'Ml, ]>. 22- thoiiuh 

 Murie believes that this may be ditlVrcnt under other circum- 

 stances. Ne\(-rtliele->. it is to iu- rcnu^nduMv.! ihal th.< "-irenia 

 have no vocal conU and that theretoiv .ouu.U ..r noi.c niav jht- 



thus presmnablv take their comvse out through the nose. 



As regards the activitv of the sense organs the dugong as well 

 as the manatee has reached a considerable degree of develop- 

 ment. To many sense organs we are unable to assign a very 

 definite function! 'rhi.s is true of the senses iuHuenced l)y chemi- 

 cal stinuilation, particularly the organ of taste, although as Gmelin 

 ('92, p. IS) has shown, a taste organ is found in the matuitee in 

 the form of a so called j)apilla foliata. The care shown in the 

 selection of food likewise points to a certain tast(> function. It is 

 still more difficult to demonstrate the function of the oigan of smell 

 since the olfactory region is a nasal tract that is h(>rmeticallN closed 

 when under water. .\nd yet ( liapinan claims that in conformity 

 with the \\<-ll de\clo|)c<l l.nlhi olt'actorii, the sense of smell must 



to become aware of food thrown in the water throuo-h its sense of 



the same. relVrrin- to Cliapniaii. 



seek their food in the water, can make no use of their sense of 

 smell in obtaining it because the nose is tiululy closed in diving. 

 Even if this were not the case, he contiinies, luaiunials would 

 still be unable to smell under water since the necessary stimulus 

 for their olfactory nerves consists of sctMit particles uhich are 

 held in suspension in the air and not. as with fishes, those that 

 are .suspended in the water. 'Idie <lisuse ,,f th.vse ori^aus in tlie 

 cas<- u\- ^^U.lU'. has led to their partial atrophy or total di^appcar- 

 aiue. Thu-^ in llu^ toothe.l whales the olfa- f.n i,.r\e i^ lacking. 

 an<l correlated ^^hh this is the reducti.m of the excthn.oid hone^. 

 In the Sirenia, however, in .sj)ite of a reduction in this hone, an 

 olfactory nerve and bulbus are well developeil, and This. too. not- 



