[ 400 ] 
the organ, and become gradually narrower towards 
tail ; however, they are very narrow at their beginnings 
or anterior ends. Thofe neared: to the mufcles of thQ 
back are the broadeft, owing to their curved or ol^ique 
fituation upon tliefe mufcles, and grow gradually nar- 
rower towards the lower part, which is in a great mea- 
fure owing to their becoming more tranfverfe, and alfo 
to the organ becoming thinner at that place o;. They 
have an outer and an inner edge. The outer is attached 
to the fkin of the animal, to the lateral mufcles of the 
fin, and to the membrane which divides the great organ 
from the fmall ; and the whole of their inner edges are 
fixed to the middle partition formerly defcribed, alfo to 
the air-bladder, and three or four terminate on that fur- 
face which inclofe the mufcles of the backr?;. Thefe 
fepta are at the greateft diftance from one another at their 
exterior edges near the fkin, to which they are united; 
and as they pafs from the fkin towards their inner attach- 
ments they approach one another ro. Sometimes we find 
two uniting into one. On that fide next to the mufcles 
of the back, they are hollow from edge to edge, anfwer- 
ing to the fliape of thofe mufcles ; but become lefs and 
lefs fo towards the middle of the organ ; and from that 
towards the lower part of the organ, they become curved 
in the other direction (O, At the anterior part of the 
large organ, where it is nearly of an equal breadth, they 
run pretty parallel to one another, and alfo pretty flreight ; 
• 
(p) PI, IV. where the diiferent breadths are feen in one view. 
(q) PI. IV. (r) PI. IV. (s) Pi. IV. 
A but 
