1882. } WHALES OF THE GENUS HYPEROODON. 723 
bidens, butskopf, dalei, borealis, &e.'; and, though allied to Berardius, 
Mesoplodon, and Ziphius, and also, though less closely, to Physeter, 
its strongly marked differential characters have, since the early part 
of the century, thoroughly established its generic isolation. 
It is well known to pass the summer months in the Arctic Seas 
which lie to the north of the Atlantic, and to migrate southward 
in the autumn, although its actual winter quarters do not seem 
to have been ascertained. Scarcely a year passes without one or 
more specimens having been taken or stranded on some part of 
the coasts of the British Isles, usually in the months of September 
and October. Similar captures have also been recorded upon other 
parts of the coasts of Eastern Europe, such as Norway, North Germany, 
Holland, and the north of France. From this point they seem to 
leave the shore; for no authentic instances are recorded of their 
occurrence on the west coast of France, or of Spain, or in the Medi- 
terranean. Most of the specimens thus seen, or at all events taken, 
are solitary individuals, generally young; but not unfrequently two 
are met with together, an adult female accompanied by her young, 
the former often falling a victim to her maternal solicitude for the 
welfare of the latter. 
Of the external characters of this common form of Hyperoodon, 
which usually attains a length of from 20 to 25 feet, many descrip- 
tions and drawings have been published ; and there are few osteo- 
logical museums of any importance which do not possess a skeleton 
of it. The earliest figure, made with really scientific accuracy, is 
that published by John Hunter in the ‘ Philosophical Transactions’ 
for 1787, from the individual (a female 21 feet long) taken in the 
Thames in 1783, the skeleton of which is still preserved in. the 
Museum of the Royal College of Surgeons. 
Hunter, in his classical memoir on the Cetacea, says, speaking of 
this specimen:—‘“ The one which I examined must have been young 
[as is proved by the condition of the skeleton] ; for I have a skull of 
the same kind nearly three times as large, which must have belonged 
to an animal thirty or forty feet long.”’ This skull has unfortunately 
not been preserved; but portions, evidently belonging to the same 
individual, are still in the Museum. Of these the anterior part of 
the lower jaw, of great density and containing the two teeth, the 
great age of which is attested by the solid condition of their bases, 
was catalogued by Professor Owen as that of an “immature” animal’. 
No notice appears ever to have been taken of Hunter’s reference to 
this large specimen, or of the existence of any form of Hyperoodon 
different from that commonly known, and of which more detailed 
descriptions were given by Vrolik *, Wesmael ‘, Eschricht °, Thomp- 
' Balena rostrata, Chemniz, Beschiift. der Berlin. Gesellschaft Naturforscher, 
iv. p. 183 (1779); Delphinus bidentatus and Delphinus butskopf, Bonnaterre, 
‘Cétologie, p. 25 (1789); Delphinus diodon, Lacépéde, ‘Hist. nat. des 
Cétacés,” p. 809 ; and Hyperoodon butskopf, idem, ibid. p. 319 (1804). 
* Descriptive Catalogue of Osteological Series, vol. ii. no. 2480 (1853). 
5 Nat. Verhand. Maatsch. Haarlem, 2. Verz., D. 5 (1849). 
Nouv. Mém. de I’Acad. Roy. de Bruxelles. xiii. 4. p. 1 (1841). 
Untersuchungen iiber die nordische Wallthiere, 1849, 
