ON PHORON1S 0 VALIS, STRETHILL WRIGHT. 133 
For a more detailed description of the growth of the 
regenerating lophophore reference should be made to the 
memoir of Schultz (1903 1 ). 
(6) Direct Evidence of Transverse Fission. 
It has not been very easy to obtain unmistakable evidence 
of the occurrence of this process, but several specimens have 
been found which appear to be demonstrative in this respect. 
PI. 9, fig. 31, represents what may be regarded as the 
commencement of this process. At the extreme distal end of 
the non -muscular part of the body an annular layer of tube- 
substance has been formed, projecting into the cavity of the 
tube, and slightly constricting the body-wall, which does not 
as yet show any indication of transverse division. 
In PI. 9, fig. 29, a similar process of constriction is 
taking place in the non-muscular region, at some distance 
from its distal end. The tube lies in very close contact 
with the body of the animal, but a constricting lamina 
can be seen on the left side of the figure. The body- wall 
now shows evidence of being constricted, and it may be 
noticed in particular that the mass of adipose tissue (ad.) 
which fills up most of the proximal region of the body-cavity 
is being divided into two parts by the constriction. This 
specimen furnishes the most direct evidence which has been 
obtained of the occurrence of the process in question. 
In PI. 9, fig. 32, two individuals lie in the same tube, the 
cavity of which has been divided by a transverse septum. 
The proximal end of the distal individual has a bilobed 
character, differing from the evenly rounded surface which 
characterises the normal ampulla. This lobed appearance of 
the proximal end has been noticed in many of the individuals, 
and may be taken as evidence of the occurrence of fission, 
the rounded form of the ampulla not being yet reconstituted. 
The figure shows that the mesentery of the alimentary canal 
is attached to the emargination between the two lobes. The 
distal end of the individual on the proximal side of the 
