LEECHES. 
59 
In the leech, which is the type of the first and lower 
order, the body is somewhat flattened and divided into 
numerous short, indistinctly marked segments, not bear- 
ing any bristles or appendages. The head is small, with no 
appendages, bearing five pairs of simple eyes, while each 
end of the body terminates in a sucker. The mouth is 
armed internally with three teeth arranged in a triradial 
manner (Fig, 65, i^'),'so that the wound made in the flesh of 
persons to whom the leech is applied consists of three short, 
deep gashes radiating from a common centre. Our com- 
mon pond leech {Macroidella decora^ Figs. 64, 65) is of a 
Fig. 63.— Common fish-leech, a, 
natural size; 6, head with two 
eyes; c, teeth. Gissler, del. 
Fig. 64.— Young Macrobdella de 
CO I a. Body unnaturally flat 
tened. Gissler, del. 
rich deep olive color above, and orange red on the und^^r 
side. It is four inches in length. Another common pond 
leech is Neplielis, of which we have several species. 
The eggs of leeches are laid in sacs, or, as in Clepsine 
(Fig. 63), the fish-leech, are covered with a transparent 
fluid substance, which hardens and envelops the eggs. The 
Clepsine remains over the eggs to protect them until they 
hatch; and the young fix themselves to the under side of 
the parent, and are thus borne about until they are fully 
developed and able to provide for themselves. 
