SPECIAL WORK. 
Mamm. 59 
Osborn, H. F. The Structure and Affinities of the Mesozoic Mammalia. 
J. Ac. Philad. ix, pp. 186-265, pis. viii & ix, 30 woodcuts, 
This elaborate memoir, after some introductory matter, commences 
with a description of 'the British forms, which is followed by a long 
section devoted to the classification and zoological relationships of all the 
known forms ; and a third describing the origin and succession of the 
teeth. The following is the classification adopted : — 
A . — First Group. 
Subord. Multituberculata. 
Fam. Plagiaulacidae. 
Microlcstes, Plagiaulax, Ctenacodon , Ptilodus, Neoplagiaulax , 
Meniscoessusj and perhaps Thylacoleo. 
Fam. Bolodontidae. 
Bolodon , Allodon , and perhaps Chirox. 
Fam. Tritylodontidae. 
Tritylodon , Triglyphus. 
Fam. POLYMASTODONTIDAE. 
Poly mastodon. 
Incertgs Sedis — Stereognathus. 
B. — Second Group. 
Order. Protodonta. 
Fam. Dromotiieriid^e. 
Dromotherium , Microconodon. 
Subord. Prodidelpjiia. 
Fam. Triconodontidae. 
AmphilesteSy Amphitylus , Tricojtodon, Priacodon. 
Phascolotherium , Tinodon. 
Spalacotheriurn, M enacodon. 
Fam. Amphitheriidae. 
Amphitherium , Dicrocynodon , Docodon f Enneodon. 
Peramus. 
Fam. Peralestidae. 
Peralestes, Peraspalax , Paurodon. 
Fam. Kurtodontidas. 
Kurtodon. 
Subord. Insectivora Primitiya. 
Fam. Amblotheriidae. 
Amblotherium , Achyrodon. 
Fam. Stylacodontidae. 
Stylacodon , Phascolestes, Dryolestcs , Asthenodon. 
Incertaa Sedis — Laodon. 
The relationship of the Multituberculata to the modern Diprotodontia is 
discussed, and also their alleged affinity to the Monotremata ; and it is 
considered uncertain whether they are to be regarded as a branch of the 
Monotreme or of the Marsupial stock. In Group B, the Triconodontidce 
are regarded as certainly Marsupials, the Amphitheriidcc probably, and the 
Kui'todontidcc possibly so, but their characters are considered sufficiently 
