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The British Leeches 
Family II. HERPOBDELLIDAE. 
Synonym: 
Nephelidae. 
Non-parasitic, carnivorous Arhynchobdellae without denticulate jaws. 
Eyes, when present, generally eight in number, disposed transversely in two 
groups which are separated by one or more rings. Complete somite com¬ 
posed of 5—11 often unequal 7'ings. The nephridial pores open near the 
margins of the body on the ventral surface. Eggs deposited in flattened 
elliptical capsules which are attached to some foreign body. 
This family is represented in the British Islands by two genera, 
Herpobdella and Trocheta. 
In the first genus the rings composing a complete somite are all of 
equal size. This is not the case however in the second of these genera 
where, as we shall see, the complete somite, in its primitive form, consists 
of a number of equal rings together with one ring, the fourth, which is 
only half the size of the others. This odd ring or intercalated ring is 
found in the complete somite of several genera of Herpobdellidae and 
according to its absence or presence Blanchard (1897, pp. 101—103) 
has divided this family into two series:—(1) The Haplodesminae, in 
which the complete somite is composed of a simple (dn-Xov?) chain 
(beagof of equal rings, and (2) the Epactodesminae, in which the somite 
is complicated by the presence of an intercalated (en ra/cro?) ring. The 
intercalated ring is not always the smallest in the series; in Dina 
(R. Blanchard, 1892), a genus closely allied to Herpobdella, and repre¬ 
sented in Europe, it is the largest ring in the somite and divided 
transversely. 
Series 1. Haplodesminae. 
Complete somite without an intercalated ring. 
Genus: Herpobdella, de Blainville, 1818. 
Synonymy: 
Helluo, Oken, 1815 (not Helluo, Bonelli, 1813). Erpobdella, de Blainville, 1818. 
Nephelis, Savigny, 1822. Hirudo (Erpobdella ), de Blainville, 1827. Herpobdella, 
R. Blanchard, 1894. 
With four or three pairs of eyes, the first pair of which always occurs 
in somite II. Complete somite formed of five equal, undivided rings. The 
