( 119 ) 
thefe Bones are a Fulciment or Bafis ; their Articufarion 
will not admit of a Cootradlion inwards or nearer ro one 
.another; wherefore, when the- 'i^/r/? and 5^^«??^^ Pair of 
Mofcles mcontraU^, they muft oeceiUinly ^^^^-^ or di- 
late the Mouth of the Marfupmn or Tomh The 7'fo>^ 
and Fourth Pair of theft Mufcles m^y kx^^ to extend 
thefe Bones outwards; fo that when this Aoimal hangs 
hj its Xuil ( as it does frequently ) the Weight of th^. 
F(Btm in this Vouch by this means will not prels fo much 
upon the inward nfcera.Tht Fifth and Lafi Pair, as they 
may ferve tO' dilate the Capacity of the PoUch it fclf, fo 
likewife may ferve the better to fufpeod its Weight, when 
the Animal is prom Capite, and if it gravitates too much, 
they may retraft it upland the eafier.becaufe palling over 
rhele Bones like a PuJJy , their force is more aug- 
mented. 
The Antagonid to thefe Mufcles is, the SphinUer Mar^ 
fufii; an oval Series of ftrong, flefliy Fibres, which ferve 
to conflringeznd clofe the Orifice of the Vouch; which it 
does fo perfedrly (zs I have already obferved), that one 
would chink the Skin here not to be Jlit ,^ nor can the 
Orifice be obferved ti!I you have dilated it with your 
Fingers. 
Nature's Contrivance therefore in placing this Touch 
here, io this Hinder Part of the Body, is very great ; 
her Mechanifme in forming thefe tm Bones^ the Janitores 
Marfupii^ which no Seek ton befides has, and fo artfully 
furnifbing them with thefe Mufcles, is moft admirable,- 
that with the Philqfopher, there is none but muftowii 
The Pouch or Marfupium it felf, was a Membranous 
Body, not very thick, tho' confifting of feveral Coats, 
and is to be reciuced into the Clafs of the Veficulous Parts 
of the Body ; which according to my Notion, are part 
Mufcles^ part Glands^ and do perform the Office of both, 
" Motion 
