24 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
The oral sucker (suc. or., Figure 7) lies on the ventral side of the head, within 
the limits of rings 1-3 (somites I.-Iv.). 
The mouth (or., Figure 7) opens anterior to the middle of the oral sucker as 
well as anterior to the eyes. 
The posterior sucker (act., Figures 1, 4), also ventral in position, is slightly 
longer than broad. Average dimensions for the largest individuals are :— 
length, 1.31 mm. ; width, 1.24 mm. 
d. REPRODUCTIVE ORGANS. 
The male genital pore (po. @, Figure 4) lies in a mid-ventral position between 
rings 24 and 25; that is, between the anterior and middle rings of somite x11. 
The female genital pore (po. 9, Figure 4), which is a broad transverse slit, . 
lies just one ring behind the male pore, between rings 25 and 26, the middle 
and posterior rings of somite x11.) 
XIII. XVIII. 
Testes (Figure 4, te.), six pairs, placed intersegmentally in somites er = 
The size and appearance of the testes vary considerably with the seasons. In 
the fall and early spring they are generally large and their outlines more or 
less irregular, for they adapt themselves to the spaces left them among the 
dorso-ventral muscles and other deep-lying organs. The testis wall is quite 
thick on its dorsal, ventral, and lateral aspects, but somewhat thinner on its 
median aspect. It is lined with a loose germinal epithelium of spindle-shaped 
cells, except at its dorso-median angle, where there is a small patch of ciliated 
epithelium continuous with that of the vas efferens. 
Male genital ducts. — The vas efferens is a short, delicate tube, which leads 
dorsad and cephalad to join a longitudinal duct similar in structure to itself 
and only slightly larger, the proximal or collecting part of the vas deferens 
(Figure 4, va. df.). Anterior to the first pair of testes, that is, about on the border 
between somites x11. and x11., the collecting portion of the vas deferens bends 
sharply toward the median plane of the body and passes between the strong 
dorso-ventral muscles, which, like a row of pillars, mark off on each side the 
1 I am unable to find in any published account an explicit statement as to the 
position of the genital pores in this species. Budge (’49) figures the male pore in 
the posterior third of ring 25 and says, “ Gegen den 25 Ring findet sich die sehr 
feine miannliche Geschlechtséffnung.”” He does not figure the female pore, but 
says (p. 100), ‘‘Ungefahr am 27. Leibesringe die 4ussere [female] Geschlechtsoff- 
nung liegt.” This would make the genital pores distant from each other about two 
rings, which, however, is incorrect. 
Ludwig (’86) incorrectly describes the position of the genital pores for the 
entire genus ‘‘Clepsine” as follows (p. 781) ‘“‘mannliche Geschlechtséffnung 
zwischen dem 25. und 26., weibliche zwischen dem 27. und 28. Ringel.” This state- 
ment rests upon two erroneous assumptions, first, that the number of distinct rings 
is the same in the head region of all species, and, secondly, that the genital pores 
are always two rings apart. In only two of the six species described in this paper 
are the genital pores separated by two rings. 
