507 
BousFIELD (°85) has described for Slavina, and Miss RANDOLPH (93) 
for Embocephalus. 
General. 
Epidermal glands have been observed in the limicolous 
Oligochaetes by the following writers: BucHHoLz (62), LeyYpIG (°65), 
NasseE (°82), REIGHARD (’84), VEJDOVSKY (84), and more recently, by 
RANDOLPH (’93), and BRoDE (’98). 
Without attempting to review these observations in detail, I may 
point out that the foregoing account of these cells besides containing 
details not hitherto recorded, differs from the accounts of previous 
observers chiefly in two particulars. In the first place, I have been 
unable to find any arrangement of gland cells into girdles upon each 
segment; as described by Leypic in Pheorcytes, VEJDOVSKY in Enchy- 
traeus and Tubifex, and BRODE in Dero. In the second place, I have 
no evidence to show that the gland cells are produced by the modi- 
fication of ordinary supporting cells; as described by VEJDovVskY in 
Tubifex, Enchytraeus, and Aulosoma. I have not found transition 
stages between the supporting cells and the gland cells. On the other 
hand, I have found numerous instances, near the caudal end, of 
transition stages between basal, or reserve cells, and gland cells; and 
I believe that the gland cells are developed solely from these basal 
cells. I have not, however, been able to determine the whole life 
history of the gland cell. Having performed its function, it may 
degenerate and be absorbed, to be replaced by a new cell developed 
from another cell of the epidermis; or it may merely enter upon a 
period of rest, after which it again becomes functionally active. In 
the latter case, gland cells once developed, would persist throughout 
the life of the worm. As may be seen from my descriptions, the 
evidence I have been able to collect upon this point, favors the latter 
view. This evidence, while positive in character, is incomplete; and 
the whole subject needs further investigation. 
Both isolated sense cells, and sense organs have been ob- 
served hitherto in the limicolous Oligochaetes; the first, by Lrypi1e (’65), 
in Pheorcytes Menkeanus; and Nasse (’82), in Tubifex rivulorum; the 
second by Tımm (’83), in P. Menkeanus, and Nais; Vespovsky (’84), 
in Chaetogaster diaphanas; BousrIELD (’85), in Slavina appendiculata, 
S. serpentina, and S. lurida; RAnDoLPH (’93), in Embocephalus volutans, 
and E. plicatus; and both together by BropE (’98), in Dero vaga. 
Again I shall not attempt to review these observations in detail. 
The use of the silver stain has enabled me to give a precise de- 
scription of the sensory epidermal structures of Tubifex rivulorum, and 
