TRANSACTIONS OF SECTION D. 513 
fact that the fat gradually disappears when a race of the Afghan type is removed 
from the arid deserts of Central Asia to Western Europe, where green food is 
available throughout the year. Apart from its coat and its long tail, a Norfolk 
ram with large spiral horns differs in no essential point from a wild Ovis poli ram 
or from a male Siberian Argali (Ovis ammon). 
3. The Life-history of a Water-beetle. 
By F. Batrour Browne, M.A., F.R.S.E. 
WEDNESDAY, SEPTEMBER 11. 
The following Papers were read :— 
1. The Habits of Phyllochetopterus. By F. A. Ports, M.A. 
The worm whose life-history and habits furnish the subject of these notes is 
a new species of Phyllochetopterus which is found living in shallow water off 
the coast of Vancouver Island. It lives in long creeping tubes of a translucent 
horny material, which generally possess several openings, each situated at the 
end of a short branch of the main tube. In nearly all tubes there is more than 
one individual, and sometimes as many as six, but the number of openings to 
the tube does not correspond to the number of the worms. They can change their 
position in the narrow tubes fairly rapidly, and can turn round and pass each 
other. Circulation is maintained by the movement of cilia on the median seg- 
ments and the undulatory movements of the abdomen. Those worms which 
occupy a favourable position protrude their long tentacles from one of the 
openings, doubtless to assist in the collection of food. 
_ The body, as in most other members of the family Chetopteride, consists of 
three regions: the anterior or thoracic, median or branchial, and posterior or 
abdominal; but the number of segments found in the last two regions varies 
very greatly. It is not unusual to find adjacent to an individual, in which the 
anterior and median regions are fully formed, a detached portion consisting of 
abdominal segments (sometimes with a few branchial). In some cases the 
anterior region of the body has begun to regenerate. Even when this forms quite 
@ minute stump the whole number of thoracic segments may be marked out. 
There can be no doubt that the tube is constructed in the first place by a 
single individual, which is formed from a fertilised egg, and that this worm 
propagates itself by autotomy, the posterior part regenerating its anterior region 
after detachment. Modifications of the tube occur to suit the increasing popula- 
tion. An early stage of this phenomenon apparently occurs in the Phylloche- 
topterus socialis of Claparéde, the tubes of which each contain two or three indi- 
viduals of the same sex, but do not appear to branch, and have only a single 
aperture. Claparéde suggested that asexual generation occurred here, but was 
not able to verify this hypothesis. So far asexual reproduction in the Polychets 
has only been known among the Serpulids (Filograna, &c.), and it is now found 
to occur in the Chetopteridz, a family also showing high specialisation and with 
tubicolous habits. 
2. The Formation of Stolons in Trypanosyllis.. By F. A. Ports, M.A. 
In certain species of 7rypanosyllis the stolons (reproductive buds) are pro- 
duced from a ventral patch of tissue extending over the surface of the last 
segment or two. They are formed in successive transverse rows of seven or 
eight, and it is probable that from one to two hundred stolons are normally 
produced by a single individual. Proliferation takes place chiefly at the anterior 
border of the patch, and it is here that new rows are constantly added, pushing 
1 Cf. 1902, Johnson, American Naturalist, vol. 36, pp. 295-315; 1911, Potts, 
Ergebn. u. Fortschr. d. Zool., Heft 1, Band 3, pp. 14-20. 
2 
1912. LL 
