Ls 
Lg & Proceedings—Geological Society of London. 187 
i 1899), H. Kynaston (el. 1894), W. G. Adams (el. 1865), 
R. Assheton (el. 1886), Hon. Robert Marsham-Townshend (el. 1859), 
Sir Sandford Fleming (el. 1877), F. W. Millet (el. 1900), A. Dunlop 
(el. 1874) G. H. Hollingsworth (el. 1879), B. Holgate (el. 1877), 
W. Simpson (el. 1893), J. T. Hotblack (el. 1900), H. ‘Rote (el. 1890), 
D. A. Louis (el. 1909), H. S. Bion (el. 1911), W. J. Clunies Ross 
(el. 1882), and others. He also referred to the death of William 
Rupert Jones, late Assistant Librarian. 
The President then discussed the use of fossil remains of the higher 
vertebrates in stratigraphical geology. ‘The study of fossil fishes, to 
which he had referred in his Address of 1915, raised the question as 
to whether animals of apparently the same family, genus, or species 
might not originate more than once from separate series of ancestors. 
The higher vertebrates, which inhabited the land, might most 
profitably be examined to throw light on the subject; for the land 
has always been subdivided into well-defined areas, isolated by seas, 
mountains, and deserts, so that animals in these several areas must 
often have developed independently for long periods. Students of 
shells are unanimous in recognizing what they term homcomorphy, 
and trace immature, mature, and senile stages in the course of every 
race that can be followed through successive geological formations. 
Vertebrate skeletons, which have much more numerous and tangible 
characters, and approach senility in more varied ways, should afford 
a clearer view of general principles. 
Even among vertebrates the evidence that most concerns the 
geologist is not always easily interpreted. For instance, the 
Sparassodonta and horned tortoises of the Argentine Tertiary are 
‘so closely similar to the existing Thylacines and the fossil Miolania 
of Australia, that they are still sometimes quoted as proving the 
former existence of an Antarctic Continent uniting the South 
American and Australian regions. On the other hand, they may be 
‘merely survivors of cosmopolitan races at the two extremes of their 
former range, with certain inevitable (but not altogether similar) 
marks of senility. In making comparisons, indeed, it is no longer 
enough to distinguish the fundamental and merely adaptive characters 
of animals; it is also essential to note separately those characters 
which depend on the early, mature, or senile position of the particular 
animals in the evolving series to which they belong. 
Hitherto there seems to be only one case in which we have enough 
materials for forming a judgment as to whether a fundamental 
advance may occur more than once. Mammal-like reptiles are 
abundant in the Permian of North America and in the Permian and 
Trias of South Africa and other parts of the Old World. Recent 
studies have shown that all specializations in the North American 
forms are in the direction of higher reptiles, while all those in the 
South African forms are in the direction of mammals. Hence, 
although there is evidence of two possible sources of mammals, only 
one appears to have produced them. 
Among advances of lower degree, the origin of the monkeys or 
lower Anthropoidea may be considered. It is agreed that they arose 
from the Lemuroidea which were almost universally distributed over 
