2^2 MEMOIRS?/' the 
coitrivance of nature is admirable in forming and adapting this 
part lb ibitably to that end 5 for there are two remarkable ilrong 
bones, not to be met with in any other fl;e]eton, which from their 
office \)rrfyfon calls OJJ'a Marfupialia^ or Janitor es Marfupii'^ 
thefe bones are fo fiiftencd to the upper and internal edge of the 
OJJa fJiibis^ that at their bails here they touched each, jaft at the 
coalition of the bones, that form the Offa 'Pubis ; the other extre- 
mities of thefe bones were 16 diftant from one another, as to mea- 
fure 2 T inches; tlic bails of thefe bones, where joined to the 
OJJa 'Pubis, was half an inch broad, having two heads, the larger 
lying near the coalition of the OjJaPubis^ and the leiTer towards 
the Os CoscMciicis, having in the middle a Sinus-, into which was 
received a protuberance of the OJfa Pubis:, by this contrivance it 
appears, that there can be no motion of thele bones, nearer or 
farther from each other, but that they mufi: Hand always at an 
equal diftance, but they were obierved capable of a I'mall motion 
inwards, towards the fpine, and outwards from it ; thele bones, 
as they alcended from the Os 'Pubis grew more (lender, being 
about the middle but a quarter of an inch l>road, and each two 
inches long 5 thele bones were furniraed with four pair of muf- 
cles, and another pair run over them, to which they performed 
the office of a Trochlea, or pulley : The firft pair of mulcles, 
that is, which came firft to be diilecSled, upon the pronation of 
the animal, and which from their figure Dr. Tyfon calls trian- 
gulariSy ariles flefny from the whole length of the internal fide 
of thefe bones, and mlerted their oppofitc tendons on each fide of 
the Ririia, or aperture of the Marfupium j under part of thefe 
mulcles lay another, or a iecond pair, flat and thin, liaving their 
origin from the upper part of the internal fide of the OJJa Mar- 
fupialia., and inferting their oppofire tendons a little abo\e the ten- 
dons of the former mulcles 5 the tendency or dire6lion of the mul- 
cular fibres of this pair, in refpedl of the firft, made a decuflation • 
the third pair of mulcles had their rile from the fore-part of the 
bafis of thefe bones, where they were joined to the Os Pubis, and 
were afterwards inlerted into the Linca ajpcra of the thigh- 
bone ^ the iburth pair arofe from the external fide of thcfc 
bones near the bafis, and were inferted into the fore part of the 
thigh-bone near the middle 5 the laft pair of nuifcles arilc 
more immediately from the Marfupiuvt, or poueh itfelf- for 
fpreadmg their mufcular fibres all over this bag, as they ilTue 
from It, by joining their fibres together, they more remarkably 
form a folid mufcle, which paiTing on each fide over the 
middle of thefe bones, that is in the prone pofture of difle^ling 
the 
