[ 396 ] 
than would be fufiicient for what may be called its pro- 
greffive motion. For the real body, or that part where 
the vifcera and parts of generation lye, is fituated, with 
refped to the head', as in other fhli, and is extremely 
jhort ; fo that, according to the ordinary proportions, 
this fliould be a very flioit fhli. Its great length, there- 
fore, feems chiefly intended to afford a fiirface for the 
fupport of the peculiar organ : however, the tail-part is 
Jikewife adapted to the progreflive motion of the whole, 
and to preferve the fpecific gravity ; for the fpine, mc^ 
dulla fpinalis^ mufcles, fin, and air-bladder, are continin^d 
through its whole length. Befides which parts, there 
is a membrane palling from the fpine to that fin which 
runs along the belly or lower edge of the animal. This 
membrane is broad at the end next to the head, termi- 
nating in a point at the tail. It is a fupport for the ab- 
dominal fin, gives a greater fur face of fupport for the 
nrgan, and makes a partition between the organs of the 
jtwo oppofite fides. 
.T H E O R G A N S. 
The orgaFxS which .produce the peculiar effedlof this 
-fifh, conftitute nearly one-half of that part of the flefh 
in which they are placed, and perhaps make more than 
one-third of the whole animal. There are two pair of 
thefe organs, a larger, and a fmaller ; one being placed 
.on each fide. The large pair occupy the whole lower 
or anterior, and alfo the lateral part of the body, making 
the , thicknefs of the fore or lower parts of the animal, 
and run alipoft through its whole length ; viz. from the 
idbdomen to near the end of the tail It is broadefl on 
(a) Vide pi." II. fig. i. kkk; 
IB 
the 
