436 E. A. ANDREWS. 
and also prove of value in the understanding of some fun- 
damental problems of regeneration, two additional cases of 
doubling of the posterior end in earthworms are here pub- 
lished, together with eight cases in a marine Annelid. 
ALLOLOBOPHORA FETIDA. 
The two abnormal specimens of the “ Brandling” here de- 
scribed were taken at Bryn Mawr, Penn.,in April, 1892, at the 
period when the conjugation process seems to be at its maxi- 
mum. Some conception of the probable frequency of such dupli- 
cations in this animal may be got from the facts that the first 
abnormal individual, which we will call A, was found amongst 
480 preserved specimens collected at one time by Dr. T. H. 
Morgan (to whom I am indebted for much of the following), 
while the second individual, B, was found amongst 560 collected 
at different times : a third collection of 220 specimens carefully 
examined when alive contained no bifurcated individuals. 
The first specimen, A, as seen in fig. 1, is perfectly normal 
down to and including the 73rd somite, where a marked bi- 
furcation occurs. An examination of the anterior region proved 
that the sexual organs were normal and mature, and that the 
sperm receptacle contained ripe sperm, indicating that con- 
jugation had taken place. 
Posterior to the 73rd somite there are two large abneenal 
rings marked, like the normal somites, by dark brown bands on 
the dorsal surface, as seen even in this alcoholic specimen. 
From the second of these spring the two tails or terminals ; 
one having 18 somites and an anal piece; the other, on the 
right, only 7 somites and an anal piece. There are thus 
73 +2 + 18 = 93 somites in what seems the main axis of the 
animal and seven in what appears as a lateral outgrowth from 
the second abnormal ring. This lateral terminal springs from 
the right side and lies in the same plane as the main trunk, as 
is evident from the enlarged views, figs. 2 and 3. 
In the dorsal view, fig. 2, we see that the dorsal pores are 
everywhere present in the normal positions, except that there 
are none visible at the base of the right terminal, between its 
