976 MR. F. A. POTTS ON 
table. The figures in the columns A, B, and C indicate through- 
out the numbers of segments in the regions referred to. 
In this tube (Table I.) from Departure Bay Nos. 2 and 3 appear 
to be complementary, and represent an individual broken in two 
in the median region. While, however, the median segments of 
No. 3 have already regenerated a short and undifferentiated 
region, those of No. 2 have not yet attempted to form a posterior 
region. The regenerating end of No. 3 is figured in Pl. V. 
fig. 12, and it will be seen that a number of segments have 
been marked off by furrows, but that parapodia and sete have 
not yet developed. The peristomium is indicated by the rudi- 
mentary tentacles. It will be noticed that almost the full number 
of segments is established at once, and apparently development 
proceeds simultaneously in each of them. 
TABLE II. 
| 
A. Length of A*. Bb. C. Total length. 
| 
| 
| 
| —— 
| | 
LeNow ics: 11 5°5 mm. (4) 10 12 | 20mm. 
pate a ee) ees 
| No. 2)... 9 4. nm. (+) 8 22 | 15mm. 
INOHoIEE: 12 2mm. (3) 8 40 175 mm. 
| 28 
| No. 4...| 12 | 4mm. (4) 4 (+number of very 19mm. | 
| small segments) | 
| sos ake 
| No. 5 ...| 12 | 65 mm. (3) 14 | 20 21mm. | 
Non Ghee: 12 we 3 20 16 mm. 
| t 
Another tube from Friday Harbour (Table II.) contained six 
individuals, all of which with one exception were well-developed 
and complete specimens. It will be seen that while the number 
of segments is more constant in the anterior region than in the 
other two, its length varies very considerably and bears no 
definite relation to the total length of the body, In No. 3 
(Plate V. fig. 13) it is extremely short, although it possesses the 
usual number of segments, which are of normal width and have 
the full development of setze. There is, however, no strengthened 
seta in the fourth segment, and the peristomial tentacles are 
about half-grown. 
In the other individuals the length of this region varies from 
4-6°5 mm. 
* 
he fraction in this column represents the proportion borne by the length 
of A to the total length. 
