xiv CLASSIFICATION 407 



still protected by the parent, returning to its body for shelter. 

 The type genus Glossiphonia ( = Clepsine) is common in Europe, 

 and has many species. The Mexican and Amazonian Haemen- 

 teria contains a number of species, of which the Mexican H. 

 officinalis is used in medicine ; but according to Miguel Jimenez, 

 its use is apt to be attended with unpleasant symptoms. Drowsi- 

 ness, a buzzing in the ears, and the development of a painful 

 rash are some of the effects produced by its bite. It is disputed 

 whether the animal's saliva or foreign matter introduced by it 

 into the wound are the cause of the symptoms. 



Mesoldella of Blanchard * is said to be intermediate between 

 this family and the next. Each segment has three annuli, as in 

 this family, but the leech has three jaws, as in Hirudo. 



Sub-Order 2. Gnathobdellae. Hirudinea without a proboscis, 

 generally with jaws ; the blood is red ; the eggs are invariably 

 deposited in cocoons. 



FAM. 1. Gnathobdellidae. Pharynx with three denticulate 

 jaws. 



This family as well as the next is terrestrial or fresh-water in 

 habit. It contains a number of generic types, including the 

 medicinal leech, Hirudo medicinalis, and the horseleech, Haemopis 

 (Aulastomum) gulo. The former can be distinguished from the 

 latter by its power of contracting itself into an oval olive-shaped 

 form, which power is not possessed by the horseleech ; the latter 

 has, moreover, only two caeca, while the common leech has ten pairs 

 of these appendages of the intestine. The genus Limnatis is 

 called after the Greek word \i/j,vf)Ti<;, which Theocritus applied to 

 the leech. It is found in the Nile, and caused serious incon- 

 venience to the army of Napoleon. His soldiers in drinking at 

 pools sucked up the small leeches not thicker than a horse's 

 hair, whose presence in the hinder part of the mouth cavity 

 produced divers objectionable results, such as spitting of blood 

 and hindered respiration. 



FAM. 2. Herpobdellidae. Pharynx without denticulate jaws, 

 with three unarmed chitinous plates. 



A characteristic genus of this family is Trocheta, which is so 

 common at the Zoological Society's Gardens and in the Regent's 

 Park, and which has been met with in other places near London ; 

 it is in this country an introduced species, but is found in many 



1 Ann. Mag. Nat. Hist. (6) xii. 1893, p. 75. 



