980 MR. F. A. POTTS ON 
are incomplete, it seems probable that the phenomenon here runs 
a very different course. The three regions of the Chetopterid 
have no probable connection with those of the Sabellid, nor is 
there any reason that they should behave in a physiologically 
similar manner. In Phyllochetopterus it seems fairly certain, as 
I have pointed out above, that regeneration takes place most 
often from fragments containing median as well as posterior 
(abdominal) segments, and in all cases the full number of 
segments in the anterior region is budded off. But, while in 
both Cheetopterids and Sabellids the anterior region is restored 
by regeneration, in the former family the median region is not 
completely re-formed as is the case in the latter. The number of 
segments in the median region is so variable in number that for 
this and other reasons I am inclined to suppose that regeneration 
does not take place here, or only very slowly. ‘There is certamly 
not the slightest evidence, in any regenerating individuals which 
I have examined, of a transformation of the posterior (abdominal) 
segments into median segments, such as characterises the 
Sabellids. 
Tuer Possrpitiry oF ASEXUAL GENERATION IN P. pictus. 
The case of Phyllochetopterus pictus described by Crossland has 
already been mentioned. It will be interesting here to quote 
some figures which Crossland gives to show the variability in the 
numbers of segments in the anterior (A) and median (B) regions. 
Hight individuals were examined. They are indicated by the 
Roman numerals running across the page :— 
I. II, ite Nye Vie Vie VU) Sve 
AP gia 16 as 13 15 12 15 13 
Bee’ 9 D 7 5 o 8 
Here, too, it will be seen that the median region is much more 
variable than the anterior, the numbers ranging from 3—9 for a 
very small sample of individuals. In view of this and the fact 
that the annelid inhabits clusters of tubes, the relations of which 
are difficult to make out, I think it is possible that asexual 
generation occurs here too. 
MISCELLANEOUS OBSERVATIONS ON THE Habits oF 
Phyllocheiopterus prolifica. 
Owing to the transparency of the tube, in the younger colonies 
at least, it is possible to see something of the movements of the 
worm within. It shifts its position in the tube by the alternate 
relaxation and contraction of the body; when contraction occurs, 
the sete of that part of the body affected are braced against the 
sides of the tube. The sete of the abdomen can be definitely 
