444 
are deposited, and which extends on the ventral surface of the genital 
region only so far as to embrace the orifices of the spermathecae and 
the oviducts. Note that this is about 5 segments, and that the mean 
size of the cocoon corresponds roughly to the length of these 5 seg- 
ments. The sheet, adhering at its edges, is then made bulge out by 
the contraction of the body, and the ova and spermatophores are de- 
posited through the orifices of the oviducts and spermathecae respecti- 
vely. Another sheet is then secreted, and cemented to the edges of the 
first and the cocoon thus formed set free by the contraction of the longi- 
tudinal and transverse muscles of the integument. ‘This simple process, 
or one similar to it, as seems to me, is what we must expect to find, 
but whatever is found, it is to be hoped that a provokingly compli- 
cated problem will soon be cleared up. 
The following description of the histology of the clitellum applies 
to L. herculeus. 
The glands are very largely developed dorsally and dorso-laterally, 
and only slightly — sometimes not at all — ventrally. They are first 
formed in bunches, and this gives externally a peculiar convoluted 
appearance to the organ. A transverse section shows that the body 
wall is surrounded by a delicate cuticle, iridescent by virtue of the fine 
striae dividing it into little squares, which have a decomposing effect 
upon light. Dr. Hurst doubts this cause of the iridescence, assigning 
it to the thinness of the cuticle; but I doubt whether the cuticle is 
not too thick to produce iridescence, and it certainly is in Allolobo- 
phora. Next the cuticle are situated the glandular layers, which will 
probably be found represented in the ventral region. In connection 
with this, it would be noticed that the longitudinal muscular layer has 
an increase proportionate with the decrease in the clitellum. This 
curious fact, which was first noticed by Claparède!, I endeavoured 
to explain by the conjecture that the longitudinal muscles atrophied 
dorsally in order that the secretion of the glands might not be affected 
by any violent expansion or contraction of the body wall in this region. 
The surmise, however, was not altogether justified by the movements 
of the living animal. It now appears to me probable that this ventral 
muscular development is in connection with what Vogt and Yung? 
call les soies copulatrices, or the setae acting as claspers that were first 
observed be Hering. Perhaps the irregularity may more accurately be 
described as normal ventrally and degenerate dorsally. The normal 
1 Histologische Untersuchungen über den Regenwurm. Zeitschr. f. wiss. Zool. 
t. XIX, 1869. 
2 P. 476. 
