ANNIVERSARY ADDRESS OF THE PRESIDENT. xlvil 
From the time when Cuvier’s wonderful researches upon the 
extinct Mammals of the Paris gypsum first made intercalary types 
known, and caused them to be recognized as such, the number of 
such forms has steadily increased among the higher Mammalia. 
Not only do we now know numerous intercalary forms of Ungulata, 
but M. Gaudry’s great monograph upon the fossils of Pikermi 
(which strikes me as one of the most perfect pieces of paleontological 
work I have seen for a long time) shows us, among the Primates, 
Mesopithecus as an intercalary form between the Semnopitheci and 
the Macaci; and among the Carnivora, Hycnictis and Ictitherrum 
as intercalary, or, perhaps, linear types between the Viverride and 
the Hyenide. 
Hardly any order of the higher Mammalia stands so apparently 
separate and isolated from the rest as that of the Cetacea; though a 
careful consideration of the structure of the pinnipede Carnivora, or 
Seals, shows, in them, many an approximation towards the still 
more completely marine mammals. The extinct Zeuwglodon, however, 
presents us with an intercalary form between the type of the Seals 
and that of the Whales. The skull of this great Eocene sea- 
monster, in fact, shows—by the narrow and prolonged interorbital 
region; the extensive union of the parietal bones in a sagittal 
suture; the well-developed nasal bones; the distinct and large 
incisors implanted in premaxillary bones, which take a full share 
in bounding the fore part of the gape; the two-fanged molar teeth 
with triangular and serrated crowns, not exceeding five on each 
side in each jaw; and the existence of a deciduous dentition—its 
close relation with the Seals. While, on the other hand, the pro- 
duced rostral form of the snout, the long symphysis, and the low 
coronary process of the mandible are approximations to the ceta- 
cean form of those parts. 
The scapula resembles that of the cetacean Hyperoodon, but the 
supraspinous fossa is larger and more seal-like; as is the humerus, 
which differs from that of the Cetacea in presenting true articular 
surfaces for the free jointing of the bones of the forearm. In the 
apparently complete absence of hinder limbs, and in the cha- 
racters of the vertebral column, the Zeuglodon lies on the cetacean 
side of the boundary line ; so that, upon the whole, the Zeuglodonts, 
transitional as they are, are conveniently retained in the cetacean 
order. And the publication, in 1864, of M. Van Beneden’s memoir 
on the Miocene and Pliocene Squalodon, furnished much better means 
than anatomists previously possessed of fitting in another link of 
the chain which connects the existing Cetacea with Zeuglodon. The 
teeth are much more numerous, although the molars exhibit the 
zeuglodont double fang; the nasal bones are very short, and the 
upper surface of the rostrum presents the groove, filled up during 
life by the prolongation of the ethmoidal cartilage, which is so cha- 
racteristic of the majority of the Cetacea. 
It appears to me that, just as among the existing Carnivora, the 
walruses and the eared seals are intercalary forms between the 
fissipede Carnivora and the ordinary seals, so the Zeuglodons are 
