126 THE SPERM WHALES, GIANT AND PYGMY. 
in the order are two great groups, which, we may at once 
add, are suborders; and that these groups are distinguished 
from each other by numerous characteristics: the most ap- 
parent of these are, in one group, (the MvsrrcETE,) the de- 
velopment of whalebone on the roof of the mouth, and the 
entire want of teeth,* — they being reabsorbed into the gums 
before birth, —the development of an olfactory organ, and of 
nasal bones free at their distal ends ; and in the other group, 
(the DENrICETI,) the absence of the whalebone, and the 
development of teeth after birth generally persistent in one 
or both jaws during life, but in some forms more or less 
early deciduous; the olfactory organ is atrophied, and the 
nasal bones are appressed to the frontals and overlapped 
by the vomer. 
It is not in one alone of these groups that we find associ- 
ated together, in a natural morphological combination, giants 
and dwarfs, although only in one do we find the contrast in 
the present age of our globe. It is the family of Physeter- 
ide (the sperm-whales) which furnishes us with the con- 
trast in living forms; only giants are now living to repre- 
sent the Balenide (the right-whales), and Balenopteride 
(the fin-back whales), but in the miocene age, a species of 
a fin-back whale lived that when adult was not even as large 
as the new born young of the fin-backs now living. + It is, 
however, only with the pygmy sperm-whales, equally small 
or even smaller, compared with their gigantic relatives, ł that . 
we will now concern ourselves. And we will commence our 
study with the enquiry as to what are the essential charac- 
ters of the family to which they belong. Our task is ren- 
* Teeth are present, however, in the foetus, but are not functionally developed. 
‘ope in Proceedings of the Academy of Natural Sciences of Philadelphia. 
rÀ 
. D. Benne 
size authentically recorded of the sperm-whale is seventy-six feet in length, by thirty- 
n dd a | H MTS f e 
MAGS vinu Þ 
largest examples they commonly obtain.” Professor Flower, after a critical study, 
concluded tt length might be about sixty feet, and * ventures to question whether 
the cachalot frequently, if ever, exceeds that length, when ed in a. straight line." 
The Kogiina attain a length of from seven to eleven feet. 
