1897] NOTES AND COMMENTS 223 
THE SIRENIAN MAMMALS 
THE want of all definite knowledge of the ancestry of the 
Tertiary land-mammals is strange. Our absolute ignorance of the 
origin of the marine mammals like the whales, dolphins, and sea- 
cows is still stranger. Marine deposits of the Cretaceous and early 
Eocene periods are recognised nearly all over the world, but not a 
trace of the Cetacea and Sirenia has been found in them. So far as 
known, these curious types appear fully evolved at the top of the 
Eocene. 
Nor does embryology help us much. It has shed a little light 
upon the nature of the Cetacea; we might therefore expect some 
information from this source concerning the Sirenia. Thus far, how- 
ever, the results are small, and Prof. Willy Kiikenthal’s new memoir 
on the Sirenia (in Semon’s “ Zoologische Forschungsreisen in Aus- 
tralien und dem Malayischen Archipel,” vol. iv., lief. 1), which is 
one of the most important monographs issued during the past month, 
does not contribute much to the solution of the great problem. 
The available material, it is true, is small—only four stages of 
Halwore and six stages of Manatus—and only three chapters 
(external form, integument, and dentition) are published. It is a 
most important contribution to the facts of the case, and for this 
alone we must at present remain grateful. 
THE ORIGIN OF THE IRISH FAUNA 
Not only is it almost impossible as yet to fathom the mysteries 
connected with the dawn of the present order of things in the dis- 
tribution of life on the various land-areas; it is very difficult to 
discover the routes of the migration and distribution of organisms 
even during comparatively modern periods. During the last few 
years, however, much attention has been paid to the relations of the 
existing faunas and progress made in the determination of their 
affinities. Among others, many Irish naturalists have discussed in a 
very interesting manner the relations of the fauna of their island, 
and have arrived at various conclusions, some of which may prove 
to be of permanent value. 
Quite recently Dr R. F. Scharff, Keeper of the Natural History 
Collections in the Dublin Museum, has returned to the subject, and 
published an interesting paper in the Proceedings of the Royal 
Irish Academy (ser. 3, vol. iv., No. 3, 1897, pp. 427-514). The 
contribution is lengthy, and it is written in a somewhat disconnected 
style; and how the author gets from his premises to his conclusions 
is not always apparent. Dr Scharff argues that part of the Irish 
fauna lived in Ireland in pre-glacial times; that the lower con- 
