380 C. O. WHITMAN. 
Ne phridia.~—Seventeen pairs,' located in the same rings as 
in Hirudo. 
Segmental Papille.—Beginning with the 5th annulus, 
which bears the fourth pair of eyes, the papillate annuli are,— 
5th, 8th, llth, 14th, 19th, 24th, 29th, 34th, 39th, 44th, 49th, 
54th, 59th, 64th, 69th, 74th, 79th, 84th, 89th, 94th, 98th and 
100th. Occasionally we find traces of pappille on the 102nd. 
Thus the number of papillate annuli is the same as in 
Hirudo; but the order is the same only as far as the 94th, 
which shows a difference in the annular composition of the 
posterior abbreviated somites. 
Fach of these annuli, except a few at either end of the body, 
bears fourteen minute segmental papille, eight on the dorsal 
and six on the ventral half. On the dorsal side (figs. 57, 59, 
Pl. XX) there are two median (m.), four lateral (il. ol.), 
and two marginal (my.); on the ventral side (fig. 58) two 
median, two lateral, and two marginal. 
The median dorsal papille, which are smaller and _ less 
distinct than the others, can be traced as far forward as the 
2nd annulus, being replaced on the Ist by the first pair of eyes. 
The two inner lateral papillz (2.) are the most strongly 
developed, and exhibit very plainly a serial relationship with 
the eyes. The outer lateral papillz could not be traced 
farther forward than the 5th annulus. Both the inner and 
outer lateral papille are whitish, and easily seen with naked 
eye. The marginal papille lie in the very edge of the olive 
green of this side, and are quite conspicuous from having the 
bright colour of the ventral side. No distinct traces of these 
were found anterior to the 11th annulus. 
The median papille of the ventral side are oéxtnewiely 
minute, and much farther apart than those of the dorsal side 
(fig. 58). The lateral papillz lie directly behind the nephridial 
pores, and are almost as conspicuous as the pores themselves. 
Their distance from the margin is about one fourth of the 
1 Brooks states that there are eighteen pairs in the Macrobdella he ex- 
amined, 
