230 LLOYDS NATURAL HISTORY. 
found abundantly in the Secondary rocks of South Africa, and 
which are known as Anomodonts; the Reptiles in question 
being the only known Vertebrates having a shoulder-girdle of 
the type characterising the Monotremes. Assuming these 
Anomodonts to be more or less nearly related to the ancestors 
of the latter, we are, however, still quite in the dark as to the 
intermediate links ; as we are also in regard to the genetic 
relationship of the Monotremes to what we may term the 
True Mammals. There occur, however, in the Secondary and 
Tertiary rocks of many parts of the world certain very remark- 
able extinct Mammals which from the peculiar characters of — 
their molar teeth are termed Multituberculata. Now these 
teeth present a certain distant resemblance to those of the 
Duck-bill among the Monotremes, and this, together with 
certain other evidence, may be indicative of some relationship 
between the two groups. The relationship must, however, at 
best, be but distant, and since the majority even of these } 
ancient Multituberculates appear to have been comparatively | 
specialised animals, it will be evident that we are still a very 
long way off the discovery of the true phylogeny of the Mono- | 
tremes. ! 
It may be added that in the Duck-bill the temperature of | 
the blood is some 20% F. lower than in ordinary Mammals. 
THE DUCK-BILLS. FAMILY ORNITHO- 
RHYNCHID. 
Aquatic fluviatile Monotremes, in which the sexes differ | 
markedly in size, presenting the following characters : 
Muzzle in the shape of a broad, flattened beak, covered with | 
delicate and sensitive skin, assuming in the dried state a horny | 
consistence ; tongue not extensile; fur without spines; tail | 
well-developed, broad and flattened ; feet modified into swim- 
ming organs, with the toes broadly webbed, and the soles. 
