Dr. H. Woochvard — On the Fossil Sirenia. 



423 



the Cetacea, in which we have many edentulous species (Bal^nid^) ; 

 others with only two teeth present (Ziphioid Whales) ; others again 

 with very numerous teeth (Delphinidge). 



All the earlier voyagers confounded the Southern Sirenia with the 

 Seals, and the Bliytina with the Morse or Walrus. In 1811, Illiger 

 separated the three genera — Manatns, Halicore, and Rhytina, under 

 the name Sirenia, and placed them between the Seals and the 

 Cetacea. They are now placed by Prof. Flower and other naturalists 

 between the Ungulata and the Cetacea. 



The following conclusions in reference to the Geographical Dis- 

 tribution of the order Sirenia appear to be worthy of the special 

 attention of geologists and palaeontologists. 



l60 120 So 40 



Fig. 3. — Map illustrating the Geographical Distribution of the order Sirenia. 

 AA. Line of extreme Northern distribution of the Sirenia in Tertiary times. 

 £B. to GO. Limits of distribution of existing species of Sirenia. 



If we take the belt of the tropics, that is, 231° N. and 23 i° S. of 

 the equator (or, better still, say 30° N. and S. of the equator), we 

 shall embrace the geographical area of all the living Sirenians. 



If we take another belt of 30° North beyond the tropic of Cancer, 

 we shall embrace the whole geographical area in which fossil remains 

 of Sirenians have been met with. 



Assuming, as T think we may, that the Sirenia at the present day 

 belong exclusively to the tropical regions of the earth, and that Rhytina, 

 in its boreal home, was simply a surviving relic from the past (a 

 sort of geological "outlier,'' as of a stratum elsewhere entirely denuded 

 away), we must conclude that the presence of about 12 genera and 

 27 species of fossil Sirenia, as widely distributed then as the recent 

 forms are at the present day, but with a range from the tropic of 

 Cancer up to 60° of north latitude, affords a most valuable piece of 

 evidence (if such were needed), attesting the former northern 



