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                      ejf.Abt OSTRICHES                           233
the Sterx Mm. it proceeded from the middle of one of the grexat Di~phragmes
anA ci c aving on thu forepart to the Tranfverfe Mufclcs of the lower Bielly
and on the hind-part to the Aponeitrofes of the Mufcles of the Lungs,it w
tnt to
faften it fifil tothe other great Dliapbrrme. Underneath it wva garoifhcd
with Fat about the thicknefsof ones Finger.
  The Lmgij-being included between the Ribbs and little Diaphr.agrnsscall
ed bv us the Mufcles of the Lungs, were compof~d of two Red and Spongi-
ous itl<lhy parts, as in other Birds. They were each ten inches long and
three and a lalf broad, being an inch and a half thick. Each of the two
Branches of the Afjera Arteria, entring into the Lungs, was divided into
fe-
veral branches, which were diftributed into its whole Parenchyma, as in Ter-
retlial Animnals, except that all thefe Branches were fimply Membraiious
without any Cartilages. The Airpalfing into thefe branches, went to the
external .Iurfacc of thle Parenchyma which was pierced with an infinite number
of little holes, which were feen through a very thin Coat, %,Wherewitlh the
wholeLungs were covered to inclofl theAirand let it out only thro five holes'
each about five lines Diameter, and ranked according to the length of the
Lungs, tome towards the Back-bone, others towards the Sternum. ThoE
holes which were towards the Sternman, piercing the flefby part of the Muf
cle of the Lungs to penetrate into the Bladders) were oblique; and it feei'd
to be thus formed that the Air might be voluntarily retained in thef&
Blad-
ders by thle AIlon of the Mufcle, which, by contrading it felfe, might
leffen this hole, for Iome ufes which may be conjeEtured, as it fhall be
explain-
ed in the fEquel.
   The four Bladders which were on each fide at the top of the Thorax, were
 included, as has been fiiid, between the Displhragme and the M' ufde of
the
 Lungs wherewith they 'vQre covered over. The Coat of each Bladder was
 fafened by the fidcs of the  iphragme and" Mufcle of the Lungs. At
the
 top and bottom it was joyned to the Coats of the Neighbouring Bladders be-
 tween which it was. 'IThe fifth Bladder, wvhich was a great deal larger
than
 the reLt, was not included between the Di.-phragme and the Mufcle of the
 Lungs, but between the two Diaphrages with the Inteines and other parts
 of the lower Belly; and that they touclht the Mufcle of the Lungs only at
 the place where it was Pierced, to give paffage to the Air that it received
 from the Lungs. In Eagles and fome other Birds, we found thefe Bladders
 faftned by the bottom to a Membrane exceedingly loaded with Fat, which
 incloled as in a Sack the Ventricle and Inteftines, and whichl we have taken
 for an Epiploonr.
    lhe parts of this Strudure could not be fo well obferved in other Birds,
bt
 reafon of the tendcrniets of thle Coats whvlereof thefe Bladders are compofe,
 which in the 0//rich are about the thicknefs of a Hog's Bladder; and we
 found thole of the lower Belly in one of our Subjeds four times thicker,
be-
 ing Scirrhous: But in molt other Birds it is almoft impoffible not to cut
 them in making the Diffetdion, and they can be well viewed only by keep-
 ing them extended by blowing into the Afpera Arteria.  This knowledg
 of this Strudure gave the Society an occarion of making feveral Refledions
 on the manner of Relpiration in general, and on that particular to Birds,
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