4 
ZOOLOGICAL LITERATURE. 
a memoir on this animal under the title Symbolae Sirenolo- 
gicae.^^ At a somewhat later period he received additional and 
more perfect materials, so that he was enabled in the year 1861 
to lay before the Academy of Sciences of St. Petersburg a con- 
tinuation of the ^ Symbolai/ forming Fasciculus II. However, 
being desirous of rendering these researches as complete as pos- 
sible, especially with regard to the comparison of the osteology 
of living and fossil Pachyderms and Cetaceans, he delayed the 
final publication until now, when to the second fascicle a third 
could be added. Thus the author’s researches extend far beyond 
the Sirenia ; and therefore the Recorder thinks it better to insert 
this notice here, instead of under the heading of that group. 
The SECOND fascicle is divided into five books. Book First 
treats in detail of the osteology of Rhytina, of the masticatory 
organs, and the size to which the animal attained ; Books Second 
and Third of the osteological characters of Manatus, Rhytinay 
Helicorcy and Halitherium) in Book Fourth the relations of 
those genera to one another with regard to osteological cha- 
racters are considered. Book Fifth is devoted to the osteologi- 
cal relations between the Sirenia and Pachydermata, the author 
entering into an examination of the skeletons of Tapir, Rhinoce- 
ros, Hippopotamus, Elephas, Mastodon, Dinotherium, Palceothe- 
rium, Suid(e, Equus, Anoplotherium, Toxodon, and llyrax. In 
the same manner the osteological characters of the principal 
divisions of tlie Cetacea are sketched out, and their affinities to, 
or differences from, the Sirenia considered. 
The THIRD fascicle contains additions and matter supplementary 
to the subjects treated in the two preceding. It is divided into 
seven books: — 1. On the literature, anatomical and zoological 
chameters, geographical distribution, and mode of life of the Si- 
renians generally ; 2. of the Manatus, and 3. of Halicore espe- 
cially. 4. This book contains chiefly supplementary matter 
referring to the literature of Rhytina, to the representations (a 
new ideal figure is added) , to various parts of its anatomy, to its 
geographical distribution and extinction. Some remarks on the 
extinction of Halitherium are added. 5. A very extensive re- 
view of the opinions of the various authors on the affinities and 
classification of the Sirenia. 6. All the essential characters of 
the Sirenians, Ungulates, Cetaceans, and Zeuglodonts are com- 
pared. The Sirenians are considered to be a distinct order of 
Mammals, allied to the phytophagous Pachyderms, and divided 
into two families, viz. Manatidae and Halicoridai, the latter com- 
prising Hatitherium, Halicore, and Rhytina. 7. In conclusion 
the author treats of the relations of the genera of Sirenians to 
one another with regard to their geographical distribution and 
geological age. He enters into an examination of tlie evidence 
offered by these animals in support of the evolutional theory, and 
comes to the conclusion that the generic Sirenian type existed 
