208 W. BLAXLAND BENHAM. 
Segment x, behind which there are three per bundle. In 
Segments v and vi I noticed six per bundle. 
The webbed chet are usually two, rarely three per bundle. 
The length of the latter is ;,%,, mm., and of the capilli- 
form chete ;22, mm., though those of the Segments v1, vir, 
VIII are =4°, mm. 
I have little to add to Eisen’s description and figures. The 
body-wall is so opaque that it is difficult to see accurately the 
contained organs. By compressing the worm I released the 
genitals, which agreed almost exactly with Hisen’s figures, 
except that the sperm-rope, of which I found only one in 
each spermatheca, is much less, and less regularly, coiled than 
he represents. 
Note on Psammoryctes. 
It is worth recording that a species which I, for the time, re- 
gard as Ps. barbatus, Vejd. (Tubifex umbellifer, Lan- 
kester), occurs in the Cherwell, in the mud amongst the roots 
of reeds. As far as I am aware it has not been recorded 
from a British locality since Professor Lankester! found it at 
Barking in brackish water. 
The palmate chete (fig. 33, a), are rather different from those 
of Heterocheta, in that the “ head”’ makes a slight angle 
with the “ stalk,” a fact which is not represented in Vejdovsky’s 
nor in Lankester’s drawings. It may, perhaps, be character- 
istic of a new species, 
The ridges on the membrane are usually twelve or thirteen 
in number, and the head has the same curvature (fig. 33, 5) as 
in Heterocheta. In existing drawings of these chzetz the 
outermost prongs are represented as stronger than the rest. 
This is not the case in my specimens. It is a matter of 
focussing, as in Heterocheta. 
I figure also the ventral chet from different regions of the 
body. Those of the posterior segments (fig. 33, e) haveaslightly 
different curve from that represented in existing figures. These, 
too, may turn out to be specific differences. But I will wait 
1 «Annals and Mag. Nat. Hist.,’ 4th ser., vol. vii, 1871. 
