POLYCH HLA FROM THE N.E. PACIFIC 969 
individuals), and they differ very little from the abdominal 
segments. But the other two points are, without doubt, primitive 
characters, and the long tentacles (but not the ciliated groove) 
are shared with the Spionids. 
Mesochetopterus forms the connecting-link between these 
primitive forms and the specialised Chetopterus. 
In the possession of long tentacles and a continuous ciliated 
groove it resembles Phyllochetopterus. In the development of a 
very distinct median region composed of a small number of 
segments with grooved notopodia, which possibly assist in the 
collection of food, it comes near to Chetopterus. 
TaLEPsAvus Gabr. Costa. 
Only two species of this genus have been described hitherto: 
these are 7’. costarum Claparéde, from Naples (1), and 7’, bonhouret 
Gravier, from Djibouti in the Red Sea (5). 
TrLEpsavus sp. (Text-figs. 6-8.) 
Though this Polycheet is a very common and widely distributed 
member of the beach fauna of British Columbia, my collection 
contains only one specimen which is at all well preserved, and in 
this the head is incomplete. Such individuals as were preserved 
in their tubes were quite worthless, owing to the impermeability 
of the material, which thus differs from that formed by Phyzllo- 
chetopterus considerably more than their appearance seems to 
show. The following account of the species is thus very incom- 
plete, and I refrain from giving a name until the species can be 
better defined. I should also like to state my opinion that the 
validity of Gravier’s species is questionable until an actual 
comparison of the Mediterranean and Red Sea forms is made. 
Occurrence.—On the same sandy beach at Departure Bay, 
which I have described in my account of MJesochetopterus, the 
tubes of a second smaller Cheetopterid were discovered. They 
are composed of a translucent horny material and are annulated, 
the joints occurring at short intervals. In length they some- 
times exceed a foot and a half, running vertically down through 
the sand and ending in a neatly rounded apex. In diameter the 
tube is less than 2 millimetres, the worm fitting fairly tightly 
within its habitation. A single individual occurs in each tube, 
with its long peristomial tentacles often projecting from the 
aperture. 
The distribution of Zelepsavus has been found to be a wide 
one. Generally it may be said to occur wherever Mesochetopterus 
exists. I have collected both together in Departure Bay, at Olga 
in the San Juan Archipelago, on Ballard Beach, Seattle, U.S.A., 
and by dredging in two or three fathoms of water at Nanoose 
Bay, Vancouver Island. : 
At the end of August 1911, too, I found Zelepsavus at Skide- 
gate in the Queen Charlotte Islands, 500 miles to the north, 
living in muddy gravel. Here and at Departure Bay at the 
