ANOTHER example of a weapon where a large and powerful barb is needful is the Harpoon. As the harpoon is used in capturing the whale, the largest and most powerful of living mammalia, it is evident that a barb which will hold such a prey must be rather peculiarly made. The head and part of the shaft of the harpoon are shown in the right-hand figure of the accompanying illustration. [Illustration: LERNENTOMA.] [Illustration: HARPOON.] The left-hand figure represents a curious parasitic crustacean, popularly called the Sprat-sucker, because it is usually found on sprats. It affixes itself mostly to the eye, the deeply barbed head being introduced between the eye and the socket. In some seasons this remarkable parasite is quite plentiful, while in others scarcely a specimen can be found. Its total length is slightly under an inch, and its scientific name is _Lernentoma Spratti_. The following graphic account of some prototypic weapons belonging to a marine worm is given by Mr. Rymer Jones, and is well worthy of perusal, not only for the vividness of the description, but for its exact accuracy:-- “Here is a Polynoe, a curious genus, very common under stones at low water on our rocky shores. “It is remarkable on several accounts. All down the back we discover a set of oval or kidney-shaped plates, which are called the back-plates (_dorsal elytra_); these are flat, and are planted upon the back by little footstalks, set on near the margin of the under surface: they are arranged in two rows, overlapping each other at the edge. These kidney-shaped shields, which can be detached with slight violence, are studded over with little transparent oval bodies, set on short footstalks, which are, perhaps, delicate organs of touch. The intermediate antennæ, the tentacles, and the cirrhi or filaments of the feet, are similarly fringed with these little appendages, which resemble the glands of certain plants, and have a most singular appearance. “If we remove the shields, we discover, on each side of the body, a row of wart-like feet, from each of which project two bundles of spines of exquisite structure. The bundles, expanding on all sides, resemble so many sheaves of wheat, or you may more appropriately fancy you behold the armoury of some belligerent sea-fairy, with stacks of arms enough to accoutre a numerous host. “But, if you look closely at the weapons themselves, they rather resemble those which we are accustomed to wonder at in missionary museums,--the arms of some ingenious but barbarous people from the South Sea Islands,--than such as are used in civilised warfare. Here are long lances, made like scythe-blades, set on a staff, with a hook on the tip, as if to capture the fleeing foe, and bring him within reach of the blade. Among them are others of similar shape, but with the edge cut into delicate slanting notches, which run along the sides of the blade like those on the edge of our reaping-hooks.