894 THE AMERICAN NATURALIST. [Vor. XXXIV. 
median testis. .A nerve bundle passes off from each end as 
from a normal brain. 
There are eight buds arising from three budding zones. 
The two lateral of these zones bear each three buds, the un- 
paired zone having but two. These latter have the normal 
relation to the right-hand cesophagus and lophophore, and are 
unrelated to those of the other side. I have not succeeded in 
making out the relations of the excretory organs in this case. 
It should perhaps be noted that in each of the adult double 
monsters (in which the gonads are developed) the paired indi- 
viduals are of the same sex (Figs. 1 and 49, and Fig. 54). 
None of the buds developed upon any of the double mon- 
sters is double or in any way abnormal. The condition there- 
fore appears to be not heritable. 
Two hypotheses may be offered in explanation of the facts 
given. According to one, the conditions found represent three 
different stages in a process of longitudinal fission. Accord- 
ing to the other hypothesis, which I believe to be the correct 
one, they have resulted from the incomplete separation of two 
masses of germinal tissue, destined under normal conditions to 
give rise to two distinct buds. Each individual of the pair 
represents the resultant of the tendency toward normal devel- 
opment modified. by the hampering influence of the adhering 
mass of tissue. Each double monster is therefore the result 
of a compromise between the two conflicting bud Anlagen. 
There seems to be no good ground for comparing the double 
monsters of Loxosoma and the double embryos normally pro- 
duced sexually in the phylactolaematous Bryozoa. 
In opposition to the first hypothesis is the fact that the 
union between the paired young buds (Figs. 2 and 3) is no 
more intimate than that between the adults shown in Fig. 1, 
and is less intimate than that between those shown in Fig. 5. 
If fission were taking place we should expect the older indi 
viduals to show the later stages of the process. 
Two facts tend to support the second hypothesis : (1) the 
position of the individuals of the pair with respect to each 
other is side to side, as would naturally result from the union 
of adjacent bud Anlagen ; (2) in all the cases (four) in which 
