1910. | J. STEPHENSON: On Bothrioneurum iris. 243 
appear to be sometimes absent in the following segment also ; thus 
in a specimen with no ventral sete in xi, there was on one side 
in xii one seta only, and on the other side none ; while in another 
case none could be distinguished in either xi or xii. 
The spermatophores characteristic of the genus are present on 
some, not all, sexual individuals. They have the general form 
described by Beddard; when empty, many, indeed nearly all, 
exhibit a characteristic deformation (fig. 1). Such spermatophores 
appear at first sight to have a large pear-shaped opening on one 
side, the broad end of pear being towards the attached end of the 
spermatophore ; the margins of this apparent opening seem to be 
raised and rounded. The appearance is however probably due to 
shrinkage, since the margin of the apparent opening may not be 
complete at the narrow end of the pear ; moreover, one empty 
spermatophore had no such appearance of a lateral rent ; and in 
one case an open mouth was distinctly seen at the distal end of 
the spermatophore. “The spermatozoa therefore probably escape 
from the free end of the spermatophore, and, as Beddard pre- 
viously concluded, arguing from the solid nature of the stalk, 
hypodermic impregnation is improbable. 
The spermatophores may occur singly, or may be present in 
larger numbers; I counted as many as five in one specimen, and 
two on several occasions. ‘They are found on the clitellar seg- 
ments, often in or near the intersegmental groove behind the male 
aperture. I have never seen any on the ventral surface, 1.e., 
within the ventrolateral ridges which give this part of the body a 
triangular appearance in transverse section ; they are, for example, 
all dorsal or dorso-lateral in the specimen with five spermatophores 
already referred to. With one exception, all spermatophores seen 
were empty. 
The female apertures are small openings in the interseg- 
mental furrow behind the male aperture. 
Reproductive organs. ‘The testes spring from tne junction of 
the septum and the ventral body-wall. The sperm funnels are 
small. The first part of the conducting apparatus is contained in 
a forward bulging of the septum on each side, so that this part of 
the tube is at the same actual level in the animal’s body as the 
testis in the preceding segment, and the testis may appear wedged 
in between the winding vas deferens on the outer and the intestine 
on its inner side. The vas deferens is divisible into two regions, 
of which the characters and relations are as described by Beddard. 
The atrium (spermiducal gland) differs a little from the pre- 
vious description of B. ivis. The typical condition, as illustrated 
by several series of sections, appears to be as follows :—the first 
part is a well defined tube, without the thick investment of peri- 
toneal cells which clothes the vas deferens ; it is circular in trans- 
verse section and gradually widens, having on the whole a some- 
what fusiform shape; its epithelium consists of numerous layers 
of close-set cells, the inner ones being columnar; the cells are 
very finely granular, and the cytoplasm stains equally. Thenext 
