SKATES. 
81 
It f Common Skate, 
wtl] be seen to possess a fimbriated border, and is coloured 
bl 'I altliongb all besides within the chamber is 
sio' f u >«ay >36 influenced by the appetites or pas- 
of d* -ii although it is not subject to the influence 
^ te will. It is too near the lens to be brought into its focus, 
It IS the nature of a fringe like this to hinder the defi- 
vis''^'| ^°’'i^^ation of a border to the picture painted on the 
isual nerve; thus producing an eifect similar to that caused by 
an instrument lately invented by photographers, and placed by 
wh object-glass or lens of the camera, to give 
look 1 ^ ^ vignette appearance to their pictures. An object 
be becomes by this structure better defined, 
attention is not permitted to be limited by any 
rgm that would ai>pear from a border shaped by a more 
An able anatomist might not encounter insuperable difficulty 
^hi pointing out in the principal bones of the pectoral fins of 
^^is class of fishes, what bears an analogy to the arm and 
th ° 1 tliat portion answering to 
ran extended forward to find support in a protube- 
mubVi of the head. From these bones proceed a 
exon ' ^ flexible and jointed rays, which constitute the 
for pectoral fin, and at the same time provide 
as tl/ of action. These rays divide and sub- divide 
ainonm fPvoad out, and in the Common Thornback Ray 
of in’ °i number, having in them twenty rows 
the r ’ f made like 
their ° classes termed osseous fishes, in which instance 
minute structure appeared beautifullv radiated. 
arranid '' '’^"tral fins 
VOL I ^ ^ continuation of the pecto- 
N 
