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SIDNEY E. HAIiMER. 
effecting* their metamorphosis in the neighbourhood of the 
shell. 
Further evidence of the correctness of the interpretation of 
PI. 8, fig. 15, suggested above, is furnished by PL 8, figs. 9, 
28, and PL 9, figs. 34, 37, which show individuals, in varying 
conditions of regeneration, in which the distal part of the tube 
arises laterally from another tube, and, usually, immediately 
on the proximal side of a tube-septum which appears to 
indicate the position of the zone of fission. 
( d ) Size of regenerating individuals as indirect 
evidence of fission. 
The variation in length of the regenerating individuals is a 
very striking fact. The individual shown in PL 7, fig. 2, is 
about 6 mm. long, while that represented in PL 7, fig. 7, is 
only ’3 mm. long. If what is here described as regeneration 
were really explainable as the various stages by which a 
metamorphosed larva reaches its adult condition, there would 
be some definite relation between the size of the specimen 
and the stage of development of the body and lophophore. 
Nothing of the kind can be made out. The earliest stages in 
the development of the lophophore may be found in very long 
individuals, as in PL 9, fig. 36 ; and, conversely, very small 
specimens (PL 7, fig. 5) may have a well- grown lophophore. 
The only legitimate explanation of the facts seems to be that 
regeneration of the lophophore may occur indifferently in 
large and in small specimens; and from the evidence which 
has already been brought forward it appears to be fair to 
conclude that this process is commonly the result of fission. 
In cases where no tube-septum can be discovered on the 
distal side of a regenerating specimen, the process appears 
to be the consequence of the spontaneous loss of the lopho- 
phore, as has been described in other species of Phoronis. 
But in cases like PL 9, figs. 32, 33, the new lophophore is 
clearly being developed as the direct result of the formation 
of a fission-zone. PL 9, fig. 35, represents what appears to 
