Proceedings. Ixxxv. 



further remarkable characteristic, which distinguishes them 

 from all other Mammals, viz., that they have no Placenta. 



The Monotremes, of which there are but two species known 

 to science, form the lowest order of Mammals, and are 

 distinguished by many singular structural peculiarities which 

 are found in no other animals except birds. The one 

 great peculiarity, from which the name of their order is 

 derived, is essentiallly bird-like, the word Monotrema being 

 made up of two Greek words, signifying a single hole or orifice, 

 both the species of Monotremes having only one external orifice 

 for the evacuation of their urine, and the discharge of the excreta 

 from the intestine. This arrangement is found in all birds, but 

 it is not found in any Mammals except Monotremes. In fact, 

 the chacteristics of Birds and Mammals are so singularly 

 blended in the Monotremes that they can best be described as 

 connecting links between the animals of those two great 

 classes. 



Mr Flower next proceeded to explain what a connecting 

 link is, as understood since the general acceptance of the 

 doctrine of evolution ; and, after sketching briefly the general 

 principles of the theory of evolution as now generally received, 

 he pointed out that the effect of it was to show that the relation 

 of all vertebrate animals, and probably of all animals to one 

 another, can best be expressed in the form of a genealogical 

 tree: all existing forms of vertebrates having been derived by 

 the ordinary process of generation, and by an infinite series of 

 successive minute variations, accumulated through countless 

 genei'ations, from a common ancestor. The new and superior 

 forms would naturally supersede the older ones, so that 

 existing animals would, for the most part, be represented 

 only by the extreme ends of the boughs of the tree ; all the 

 intermediate forms having, with rare exceptions, died out, and 

 having ceased to exist, except in some cases, as extinct animals 

 known only to the geologist. It is these intermediate forms 

 that are commonly known as connecting links. The}' seem to 

 be left for us as guide posts, as it were, to indicate to us the 

 way in which the animal creation has been travelling ever 

 since the world was made. 



Referring to the many connecting links which are known to 

 science, Mr. Flower described in detail the Mud Fish (Lepido- 

 siren) now found in the Nile and other African rivers, and which 

 forms a conecting link between the Fish and the Reptiles, and 

 the Archeopteryx, long since extinct, which is a connecting 

 link between the birds and reptiles, and then proceeded to 

 describe in detail the Ornithorhynchus, as a connecting 

 Imk between the Birds and Mammals. After calling atten- 

 tion to the peculiar shape of the head and the very 



