1889.] NATURAL HISTORY OF DERO. 443 
Nos. 5, 6, 7. The cells which compose the epidermis of the clitellum 
are much taller than those which constitute the epidermis else- 
where; they are columnar in form and loaded with granules to 
such an extent that the nucleus (in individuals stained with picro- 
carmine) was altogether invisible. In a surface-view of a fully 
developed clitellum the cells often appeared to project as shown in 
fig. 24; the cells of the clitellum are at first only occupied by a 
few highly refractive granules, the cell-outline being very indistinct 
(fig. 2a). In longitudinal sections of the clitellum (fig. 2d) the un- 
stained cuticle could be easily seen ; very frequently the cuticle was 
separated from the outer extremities of the clitellar cells by a space 
containing an amorphous substance, which in individuals coloured 
by picrocarmine solution was stained deep pink. I regard this 
substance as the product of the activity of the clitellar cells, destined 
probably for the formation of the cocoon; its accumulation between 
the cuticle and the epidermal cells seems to be remarkable, even if 
the secretion has been caused by the stimulation of the glandular 
cells by the preservative reagent. 
Spermathece.—There is a single pair of these organs situated in 
Spermatheca of Dero in longitudinal section. sp, spermatozoa. 
the 5th segment. The apertures to the exterior are placed on the 
boundary-line between this segment and the 4th, just in front of the 
ventral setze. These setee were constantly two in number to each 
bundle; I did not observe any variation in this respect in a number 
of individuals. The number of setz in the ventral bundles of the 
three segments anterior to the fifth I found to vary slightly, although 
usually three. Except as regards their apparently fixed number, 
the setee lying behind the apertures of the spermathecee were in no 
way different from those of other segments ; as in the asexual form, 
the dorsal setee of segment 5 and of those preceding it are entirely 
absent. 
The spermathecz were in every case distended with spermatozoa. 
The structure is illustrated in fig. 3, which represents a longitudinal 
section ; the narrow duct of the pouch is lined with an epithelium 
of tall cells, elsewhere the cells of the lining epithelium are much 
smaller. 
All the specimens were so fully mature that it was no longer 
possible to recognize the position of the ¢estes and of the ovaries. 
30* 
