CASTLE: NORTH AMERICAN RHYNCHOBDELLIDA. oT 
was observed in one case. The number of eggs in a sac, as well as the total 
number of eggs laid by an individual, is greater in this species than in G. stag- 
nalis. The following figures will indicate the number of eggs borne by four 
good-sized individuals, which laid eggs in the laboratory in June, 1898. The 
vertical line represents the median plane of the body; the positions of the 
numerals show how the sacs were placed with reference to one another and to 
the median plane of the body ; the numerals themselves indicate how many 
eggs were in each sac. Anterior is toward the top of the page, and the right 
side of the body toward the left of the page, the animals having been observed 
in ventral view. 
Inpivipuat I. Inpivipuat IL. 
da. a. 
16 | 17 11 6 
T 16. 20 ye ie ile 13 l. 
22 | 13 1g | 14 
Pp: p- 
Total 54 + 50 = 104 444 33=77 
Inpivipuav IIL. INDIVIDUAL IV. 
a. 
a. 5 
2] 13 16 | 14 
iF 18 20 l. ite 21 “19 ie 
19 | 18 17 | 13 
ie Pp: 
39 + 51 = 90 54 + 51 = 105 
Average number of eggs in a sac in above cases, 15 (as against 4 in G. stag- 
nalis); average number of eggs borne by an individual, 94 (as against about 30 
in the case of G. stagnalis). 
It will be noticed that one of the anterior sacs often contains a relatively 
small number of eggs (as noticed in the case of G. stagnalis also), suggesting 
that it served to finish off the egg-laying, the sacs being arranged in the order 
in which they were formed, from behind forward. 
d. DiGESTIVE TRACT. 
The mouth is situated anterior to the eyes, well forward in the anterior half 
of the oral sucker (Figures 14,15). From here the thin-walled pharyngeal sac 
(sac. phy., Figure 13) leads back to the base of the proboscis in somite XII., just 
behind the male genital pore. When the animal is at rest the proboscis (pr’b., 
Figure 13) usually extends through the four somites between the brain and 
