50 
be more closely related to T. allobrogum than to the other species, it is 
recorded under that name, with a query indicating the uncertainty of its 
position. 
TRICHODRILUS ALLOBROGUM Claparéde (?) 
EXTERNAL CHARACTERS 
The natural color of the worm seems not to have been noted, but 
the body wall was presumably unpigmented. It is 45 mm. long and its 
diameter in 10 is 0.54 mm. Anterior to 10, the body tapers gradually to 
a diameter of 0.33 mm. The prostomium appears to be elongate, but as 
it was doubled upon itself, it could not be measured. There are 116 
somites in the specimen, which has evidently lost several somites from 
the posterior end. Each somite has an annulation dividing it into a nar- 
rower anterior part and a wider posterior one, the latter bearing the 
setae. The setae are slender, elongate, nodulated, and sigmoid. A dorsal 
seta from 10 is 0.175 mm. long, 0.003 mm. in diameter at the base, and 
0.007 mm. in diameter at the nodule, which is at a distance of 0.061 mm. 
from the tip. The clitellum is indistinct, although the worm was in a 
sexually active condition at the time of fixation. 
The spermiducal pores are borne at the distal ends of a pair of 
genital papillae which are on the ventral surface of 10, just posterior to 
the ventral setae. The oviducal pores are in the intersegmental groove 
11/12, in line with the ventral setae. There are two pairs of spermathecal 
pores, one of which is on 11, between the ventral setae and the oviducal 
pores, and the other in 12/13, in line with the ventral setae. 
INTERNAL CHARACTERS 
The pharynx is thick-walled and extends into 6. In 4 it is 0.043 mm. 
in diameter, while the diameter of its lumen is 0.017 mm. It is covered 
with large deeply staining glandular cells, the septal gland cells, from 4 to 
6. There is no distinct line of division between the esophagus and 
pharynx. The chloragogue cells begin in 7. The structure and relations 
of the circulatory system and of the nephridia are not sufficiently clear 
to be of value in comparisons. 
There are two pairs of spermaries attached to the septa 8/9 and 9/10 
respectively, and projecting freely into 9 and 10. These two somites are 
filled with developing spermatozoa unenclosed in sperm sacs, but there is 
a small median sperm-sac projecting anteriorly into 8, and either one or 
two sacs filling up most of 11 and 12. The spermatozoa in these somites 
are distinctly enclosed in walls which are somewhat twisted and do not 
permit of a satisfactory determination as to the number of sperm sacs. 
Only one pair of spermiducal funnels could be located, and these are 
on the anterior face of 9/10. The presence or absence of a posterior 
pair can not be ascertained because of the folding of the sections in the 
region where they would be most likely to occur, but they are probably 
present. On each side a narrow sperm-duct, measuring 0.014 mm. in 
diameter with a lumen 0.003 mm. in diameter, extends posteriorly from 
