; THE LEECHES OF JAPAN. 383 
Cephalic lobe, as in Hirudo, except much smaller pro- 
portionally. 
Acetabulum 8 mm. in diameter, relatively smaller than 
in Hirudo. 
Annuli 106. 
Buccal annuli=5th and 6th. The coalescence is quite 
complete in the middle of the ventral side, but towards the 
margins they are distinct. 
Post-buccal annuli=7th and 8th. Generally distinct 
on the ventral side, but not so deeply separated as the succeed- 
ing annuli. 
Genital Apertures.—Male orifice between the 32nd 
and 35rd annuli, two annuli behind the fourth pair of nephri- 
dial pores. Female orifice between the 37th and 38th 
annul. 
Clitellum embraces the 9th (except 1st annulus), 10th, 
and 11th somites, and one annulus of the 12th somite, making 
fifteen annuli (twenty-seven to forty-one inclusive). 
Anus in the last annulus (106th). 
Ocelli, five pairs, arranged as in Hirudo. First pair the 
largest. 
Csophagus relatively long; with six folds, one dorsal, 
one ventral, two dorso-lateral, two ventro-lateral. The dorsal 
and ventro-lateral terminate in the maxillz. The dorso-lateral 
folds small at the level of the maxillee, but larger posteriorly. 
Maxille three, small, on alternate folds, destitute of proper 
denticles, but provided with two series of irregular, thin, 
denticular plates, which are more or less united, especially at 
the outer and inner angle (e andi, fig. 62, Pl. XXI), where 
the two series bend into each other, thus completing the circuit 
of the outer edge of the jaw. These two series of brownish- 
yellow chitinous plates correspond to the double roots of the 
denticles in Hirudo; they rest on a thick muscular welt 
(w., fig. 61), and are very feebly developed at the two angles 
of the jaw. In the elongated area, inclosed by the plates, 
numerous small fragmentary pieces of the same colour and 
texture are seen (fig. 62), : 
