51 
the spermiducal funnel of 9 to the atrium. It is unconvoluted in its 
passage along the floor of 10 and curves dorsally to enter the atrium in 
this somite. Columnar cells like those which make up the wall of the 
sperm duct line the lumen of the atrium, which is about three times as 
great in diameter as the lumen of the sperm duct. In addition to the 
epithelium of the lumen, the wall of the atrium of either side has a 
layer of muscle which is in turn surrounded by a mass of small glandular 
cells. A layer of circular muscle-fibres, continuous with the layer beneath 
the epidermis of the genital papilla, is present around the distal end of 
the atrium between the epithelial and longitudinal muscle-layers. This 
layer is folded in such a manner as to suggest that this part of the repro- 
ductive apparatus may be an eversible penial organ. 
The ovaries are on the posterior face of 10/11 and project freely 
into 11. The oviducal funnels are on the anterior face of 11/12. There 
are two pairs of spermathecae, one pair each in 11 and 12. These are 
very large and not exactly uniform in shape, although this lack of uni- 
formity is presumably due to their treatment after fixation. The one on 
the right side of 11 is almost spherical and is 0.142 mm. in diameter, the 
wall being composed of flattened squamous epithelium, 0.007 mm. thick. 
The duct leads directly to the exterior from the posterior surface of the 
ampulla, and its cells are more columnar in character than those in the 
wall of the latter. The length of the duct is 0.170 mm.; the diameter, 
0.038 mm.; and the diameter of its lumen, 0.011 mm. There is no sign | 
of the degeneration or disappearance of these organs. The other three 
spermathecae are more ovoid than the one described, but all are approx- 
imately of the same size, and their ducts have the same general relations 
to the ampullae. 
The following brief diagnoses of the three European species of 
Trichodrilus have been appended for the benefit of readers who may be 
interested in the identification of these aquatic worms but do not have 
access to the scattered literature concerning them. 
TRICHODRILUS ALLOBROGUM Claparede 
Length, 20-25 mm. Somites, about 70. Color, yellow. Prostomium 
conical, about twice as long as diameter of base. Clitellum indistinct. 
Nephridiopores in line with ventral setae. Spermiducal pores on 10, on 
pair of genital papillae, posterior to ventral setae. Oviducal pores in 
11/12. Spermathecal pores: one pair on 11 between oviducal pores and 
ventral setae; one pair on 12 in line with ventral setae. Setae simple- 
pointed, sigmoid, nodulated, two per bundle. Five or six pairs of trans- 
verse vessels per somite (one pair blind and contractile). Nephridia in 7 
and 8; lacking in 9-12. Spermiducal funnels: a pair on the anterior 
faces of 9/10 and 10/11 respectively. Sperm ducts from these open into 
a pair of common atria in 10. Atrium pear-shaped, covered with 
glandular cells, with eversible penis at distal end. Spermaries—? Ovaries 
in 11. Oviducts and funnels on 11/12. Spermathecae ovoid; long nar- 
row duct to exterior; a pair in 11 and 12 respectively. 
