THE LEECHES OF JAPAN. 371 
4th, 5th, and 6th, each by three rings; the 23rd somite in- 
cludes three rings; the 24th and 25th each two rings; and 
the 26th one ring, with an occasional rudiment of a second 
(the 102nd). 
The 5th and 6th rings, designated as the buccal rings, com- 
pletely coalesce on the ventral side; and the same is true of 
the two post-buccals (7th and 8th). This apparent coalescence 
really means the suppression of the ventral half of the non- 
papillate ring. 
The nephridial pores are placed in the posterior edge of the 
last ring of the somite ; the first pair (1st p.) in the 13th ring, 
and the seventeenth pair in the 93rd ring. 
The male orifice lies two rings behind the fourth pair of pores, 
between the 30th and the 3lst ring; the female orifice 
lies five rings behind the male, between the 35th and the 
36th ring. 
The anus lies behind the 101st ring. The post-anal ring 
(102nd) is at best only rudimentary, and can only doubtfully 
be claimed as belonging to the body. 
In the Medicinal Leech found in Sebeto River (Naples), we 
have only a few differences to note. The two buccals are faintly 
demarcated on the ventral side, while the post-buccals are fully 
united. The total number of rings is 102, and the anus lies 
in the 102nd ring, nearly dividing it (fig. 50). 
Except in colour-marking and size, the European Hirudo 
agrees almost perfectly with H. nipponia. 
2. Aulostoma of Leipsic and Naples. Whether the 
Aulostoma of Leipsic is specifically distinct from that of Naples 
or not, is a question that I am not prepared to answer decisively ; 
and I will not therefore prejudge the case by giving them 
different names. My examinations have been made mainly for 
the purpose of ascertaining how far the somites correspond to 
those of Hirudo. 
The total number of rings between the first pair of eyes and 
the anus is 100, one less than in Hirudo; but this difference 
turns out to be of subordinate importance. As shown in 
fig. 52, the anal aperture is very large, completely dividing two 
