716 The BOOX 
filled with duckweed: and have with this foft 
matter, only a little water. This contrivance 
an{wered fo well, that I received all the Frogs 
in good condition. The {malleft fpecies of 
them was of the fize exhibited in the the thir- 
teenth figure, Tab. XLVIII. Fig. x11. and 
thefe were the Frogs I now took under my 
confideration, as I had fet out by confidering 
thofe of the {malleft kind. This pot contained 
a good many Frogs of twice the fize of the 
former, but they were the offspring of a larger 
fpecies ; fo that I only made ufe of them to ob- 
tain better notions concerning fuch parts of the 
animal, as I had before difcovered them in the 
{maller fpecies. It is now time to defcribe the 
many curious things that occurred in the courfe 
of my fuperficial furvey and anatomical in- 
uiry. 
The firft thing that appeared worth notice, 
without diffection, was the wonderful contri- 
vance and conftruction of the mouth, Fig. 
xiit.g. But as thefe parts of the young Frog 
are too {mall to be properly reprefented in 
figures of their natural fize, I fhall rather ex- 
hibit them as they appear thro’ the microfcope, 
on laying the creature upon its back, with its 
vifcera feparated one from another. The ex- 
ternal opening of young Frogs mouths, is by 
no means placed in the anterior extremity of 
the head, as it is in moft Fifhes, and even in 
grown up Frogs, but opens in the thorax a 
little deeper under the head, as in the Shark, 
fo that the young animal is obliged to turn 
itfelf on its back, in order to feize any thing 
that floats upon the furface of the water ; and 
J have often feen it throw itfelf into this pof- 
ture, either when it happened to be very hun- 
ery, or intended to difcharge the air from its 
lungs: upon thefe occafions, it turned fo nimbly, 
that my eye could fcarce follow it, 
The aperture of its mouth confifts of an un- 
der jaw aa, Tab. XLIX. Fig.1. and a upper 
one 4, both moveable, of an extreme black- 
nefs, and armed with very {mall teeth like a 
faw, with which, confidering its ftrength and 
fize, the little animal is able to bite exceeding 
hard. Thefe parts feem to be made of a flen- 
der, horny, and pretty flexible bone. There 
are, moreover, both above and below the open- 
ing, a great many little horny bones of the 
fame kind, furnifhed with a multitude of little 
black teeth. All thefe little bones are placed 
upon fome mufcular and very white: plaits, 
which ferve the animal like fo many lips, and 
fhut its mouth, or keep it fhut; they firft feize 
the prey it aims at, and then help it to draw 
gradually into its mouth the food it has taken 
hold of : for this reafon the young Frog can 
move open and clofe all thefe mutcular parts 
in a great variety of ways. The {kin lying on 
each fide beneath the mouth, confifts of a 
great number of white papille cc; fo that it 
affords in the Frog itfelf a very beautiful ap- 
pearance. A little lower down are the protu- 
berant eyesdd. ‘The fkin that covers thefe and 
every other part of the body are moft neatly 
coloured like variegated marble with gold ftars 
3 
o NAD VU REY os, 
and {pots as it were upon a black ground. This 
animal, when turned fo as to lic.on its back, 
fhews on the forepart above the eyes, its noftrils, 
thro’ which it breathes, lifting the head for that 
purpofe, a little above the furface of the water ; 
and on this occafion it moves thofe parts, which 
it alternately expands and contracts, in a very 
elegant manner. 
On opening at this time the littl animal's 
thorax, there appear yery diftinGly in this ‘part, 
and a little below the place where the bone of 
the breaft grows, the branchie, or gills, di+ 
vided on each fide into four primary orders, 
or rather ranges ee. We may even fee how 
each of thefe orders is again, as it were, fub- 
divided into a great many globular prominent 
parts, along which the blood-veffels run in vaft 
numbers, and in an uncommon and very beau- 
tiful manner. At the fame time the lungs are 
alfo feen lower down in the abdomen /f, and 
they are almoft always found {welled with air, 
in the manner I have reprefented the right por- 
tion of them; where I have likewife taken oc- 
‘ cafion to exhibit the blood-veffels difpofed over 
this organ. The left portion is reprefented as 
it appears when collapfed; for then there re- 
mains in it but a yery inconfiderable portion of 
air, which, on account of the extreme delicacy 
and tranfparency of the membranes confti- 
tuting the pulmonary lobes, appears no other- 
wife than as a naked bubble of air, lying ex- 
ternally on the part whofe continuation really 
enclofes it. 
This is a moft curious obfervation, as it in- 
forms us there is an animal, which, at one and 
the fame time, has both gills and lungs, both 
ferving to circulate, cool, alter, and purify the 
blood. It is probable the air, in this creature, . 
mixes with the blood in its paffage through the 
lungs; and that afterwards, in company with 
this fluid, it vifits every part of the body; whilf# 
the water, by paffing thro’ the mouth at the 
gills, has at the fame time the very fame 
effect. 
Thefe gills are no other than the little fim- 
briated appendages, which I reprefented bigger 
than the life, in Tab. XLVIII. Fig. xu. as 
hanging on the outfide of the body; and 
which, on being taken in by the creature in its 
growth, are now advanced to the important 
office of gills. It is in this manner exadtly, 
that the vitellus of the Chicken, which at firft 
lies without the abdomen, comes afterwards 
by degrees to be fhut up in the belly, as Dr. 
Steno firft defcribed this natural procefs, which 
he likewife illuftrates with an accurate figure ; 
and immediately after him, that curious Eng~ 
lifhman, Walter Needham: for thefe two 
gentlemen, who were quite unacquainted with 
each other, made this difcovery at the fame 
timé, in different countries. ‘Thefe borders or 
edgings are very difcernible on the little Frog's 
firft appearance from within its albumen, and 
while they continue on the outfide of the body. 
The learned Oligerus Jacobeus was acquainted 
with thefe particles, as appears by his being 
the firft who gave a figure of them, with a 
, fhort 
