958 MR. F. A. POTTS ON 
10 setigerous segments. The median region is composed of 
3 segments; in all, the notopodia are of the type described in 
the diagnosis of the genus. The posterior region contains @ 
large number (about 60) of segments; the short notopodia each 
with several capillary sete. 
Locality. Pacific coast of North America. 
MM. minuta, sp. n.—A very small slender Mesochetopterus, living 
in tubes of a translucent horny material coated with coarse sand. 
Prostomium large and conical ; peristomial collar well developed, 
but not so complete as in M. taylori. Just external to the tentacles 
is a pair of eyes. The anterior region contains 10-13 segments. 
The median region is composed of 2 segments; the first pair of 
notopodia are small and clavate, the second pair are of the type 
described above for the genus. The ciliated groove is expanded 
into a cup in the middle of the second median segment. The 
posterior region is composed of segments which are double ante- 
riorly, single posteriorly ; each notopodium has a single seta. 
Locality. Cape Verde Islands, Atlantic; Torres Straits, Pacific. 
MESOCH&TOPTERUS TAYLORI, sp.n. (Plates I., ITI., figs. 5, 6, 9; 
Text-figs. 1-5.) 
Occurrence and Habits —This animal was first found in De- 
parture Bay, near Nanaimo, Vancouver Island, on a wide stretch 
of sandy beach, which was partly bare and partly covered with 
beds of Zostera. Over the whole area, from the middle of the 
beach to the lowest tide-mark, there were to be found brown 
tubes about a quarter of an inch in diameter, lined with a brown 
parchment-like material, while the outer layer is membranous 
and coated externally with sand-grains. The tubes, which pro- 
ject very slightly above the surface, are not U-shaped as in 
Chetopterus, but go straight down through the sand generally 
for about eighteen inches. On reaching the shingle underneath 
they sometimes turned and ran horizontally. In one case, where 
especial care was taken to obtain the tube whole and uninjured, 
it was found to end blindly in a neatly rounded apex. The last 
art was much thinner, without the parchment lining. The 
total length of the tube in this case was three feet. It is, as a 
rule, however, very difficult to obtain the entire tube, owing to 
the fact that the sand is deeper in most places and the tube runs 
vertically through its whole extent. But without obtaining the 
whole tube it is almost impossible to examine entire speci- 
mens of its inhabitant, which rapidly retreats to the depths of 
its dwelling as soon as the spade strikes the sand. Most of the 
individuals collected consisted only of the first two regions. 
Later the animal was dredged in two or three fathoms of 
water at Nanoose Bay, and also observed on sandy beaches, 
between tide-marks, at Victoria on the south end of Vancouver 
Island and Olga in the San Juan Archipelago, just over the 
