280 FEESH-WATEE AQTJAEIA. 



live, wten at liberty, in ponds and small lakes. The eggs 

 are enveloped in cocoons, which are deposited upon the weeds 

 or hanks of the water! These Leeches are said to be five 

 years arriving at maturity, but before this age they may be 

 used for medicinal purposes. Leeches have no branchise : 

 they respire by means of their skin. The mouth of a Leech 

 is curious and interesting. It has three teeth, somewhat 

 like circular saws, which make three small cuts, all inclining 

 towards the same point. A Leech is both gluttonous and 

 abstemious ; that is, it will either make such a meal as to 

 swell to more than double its ordinary size, or it will live for 

 months, or even years, with no other food than that which it 

 can obtain through a constant change of river or pond water. 

 The number of eyes which a Leech has varies according to 

 its genus : some have as many as ten. As these creatures 

 frequently rise or sink in the water, according to the state of 

 the atmosphere, they are regarded by some people as useful 

 " weather prophets." The Medicinal Leech is from 4ui. to 

 7in. in length, and is able to take at one meal from Idr. to 

 4oz. of blood. 



The Horse Leech (Hseinopsis sanguisuga) is about 4in. long 

 and jin. broad. Its body becomes rather wider towards the 

 tail end, and its mouth is large and protruding above. It is 

 greenish-black upon the back, and yellowiah-gi-een under- 

 neath. This Leech is a graceful swimmer, and lives very well 

 in an aquarium. It is found in ponds and lakes, where it 

 may be seen occasionally swimming near the surface, when 

 it can easily be taken in a hand-net. 



The Glutton Aulostome [Aulostnma gulo) is not a suctorial 

 animal : its teeth are not strong enough to make the necessary 

 wound for the extraction of blood. It is, however, an exceed- 

 ingly greedy creature, as its name implies. It feeds readily 

 upon garden-worms, snails, fish, leeches, and other aquatic 

 animals. This Leech is common in ponds and lakes, and as 

 it is bold and active, it is rather an interesting inmate of an 

 aquarium, of which it should be the only occupant. 



The Eight-eyed Leech {Nephelis ootoculata) is an active 

 and hardy little animal, and quite ready to adapt itself to 



