154 W. A. KIDD, ESQ:, M.D., Bes: M.R.C.S., F755, ON 
experiment of cutting off the fins of one side, or of the two 
pectoral fins. ‘The tail fin has this double purpose in a 
special manner, as if a steamer were propelled and steered 
at the same time by screw or rudder. The teeth of fishes 
are of great variety as to number, size, and arrangement, and 
contribute of course very largely to the protection and supply 
ot food to the animal, especially the latter, and can be 
renewed indefinitely as a rule. We may notice the terrible 
armature of the sharks with their interlocking formation, 
and numerous rows of reserve-teeth which lie folded back 
behind those in use, also the great basking shark, sometimes 
28 feet long (e.g., one caught at Shanklin), shows a remarkable 
development of denticles on the surface of its body, con- 
stituting very efficient mail armour, and otherwise rather 
devoid of protective structures. 
Other more rare methods of protection among fishes can 
only be enumerated, e.g., the electric organs near the tail 
of the electric eel, found in the river sand lagoons of Brazil; 
the series of galvanic plates along the back of the torpedo, 
or electric ray; the strange modification into spines of the 
skin of the globe-fishes, capable of immense distension by 
means of air taken in through the gullet. When well filled 
with air it becomes nearly circular, the spines stick out at 
right angles to the surface, and the inflated globular creature 
floats along the surface of the water, and can afford to 
laugh at almost any hungry enemy; it is appropriately 
called the sea-hedgehog. 
Again, some small fishes frequenting the coral reefs of the 
Pacific, called Scorpenoids, possess appendages of the skin 
causing them to resemble seaweeds, so that they are easily 
hidden. Some of these are justly feared because of their 
poisonous dorsal spines. The class of swordfishes forms a 
remarkable group of specialized animals, the well-known 
offensive weapon being a prolongation of the upper jaw. 
This well-armed warrior of the deep not being otherwise well pro- 
tected, and having neither scales nor teeth—its active structures 
of offence or defence are sufficient to allow it to dispense 
with passive ones. Its great weapon can transfix a codfish 
or tunny, and even, by repeated stabs, a whale, and will even 
penetrate the strong timber of a ship. At the College of 
Surgeons Museum one may see a portion of the bow of a South 
Sea whaler with the end of a sword trom one of these fishes 
embedded in it. At one blow the fish had lunged his sword 
through and transfixed 134 inches of solid timber. Another 
