No. 4()!)J 



IllOLOCY OF rill. 1)1 <,()\i 



Mammalia; further we sliould not fori^et that tlieir terrestrial 

 type, with its adaptations of the IkkIv to i)r('sMnv an.l wrinht. 

 is greatly modified by adaptations to an a(|iiatic hfe. Thus as we 

 trace the evolution of the Sireiiia, their nieehanieal a(hiptations 

 to terrestrial lif<- u ill he h-^ and le.. n<.tieed u hile tho.e for a.,uati. 

 existenee ^^ill in.-reaMno-h force theinsehe^ upon onr attention 

 In like manner the anatomical chanuv. hrouoht about 1a these 

 adaptations show the same progression. Such convergent ana- 

 tomical changes in animals of the same biological environment 

 are due to the influence of identical causes. In the case of these 



were acting on different objects ic. </.. ('<Ma<ca an<l Mr(Miiai and 

 therefore it is conceivable that the same cau>es may brin^ abont 

 different results. 



'rhe dugong is the host of great numbers .^f parasius. both 



onol)ia. Internally, at the opening- of the inner iiares, on ihe 

 dorsal surface of the velum palatimmi. but parui iilarlx in the 

 Eustachian tubes of botli sides, were found minieroiis leaf-shaped 



with the Opi.sfhohriixi mrldrarr .lescribed in I SS 1 l,v I'lscher. 

 He had received them from Semper .of Wmv.Un^^' u ho collect.Ml 

 them in the Philipj)ines from the tvmj)anic cavity of the .lno-.)ng. 

 Leuckart also, in ISTo, described a trematodt> from the l-aista- 

 ehian tube of the dugong tmder the name of Mntii>^i<ninit<i •htjmn.s 

 Von Linstow (78) considers both forms as prob:ibl\ identical. 

 The favorite habitats of these trematodes give, we belie \e, an indi- 

 cation of the path by which the infection has spread m c ase of 

 the dugong, namely, from the nose, to pharynx, Mustaehian tubes, 

 and tympanic cavity. To be sure, Boenninghaiis i : 1 , j). :!.">'.» has 

 controverted the idea that inca.se of the parasites of the uhale's 

 <':ir the path of infection has been through the i)harvii\ and the 



