54 Amielida Chcetopoda 
for the basal three-fourths, becoming suddenly conical 
externally. They gradually increase in length, and 
become flattened, triangular, but the outer fourth or fifth 
remains pointed, conical ; on a few of the last segments 
they again become shorter. 
The dorsal rami consist of a delicate finger-shaped 
dorsal cirrus, shorter than the branchiae. From a depres- 
sion at the base of this cirrus a bundle of long simple setae 
arises. Further back the dorsal cirri became as long as 
the branchiae, and have nearly the same form. 
The ventral rami, on the first 25-29 segments, consist of 
two transverse membranous lips, of which the anterior is 
very low, hardly perceptible ; the posterior a well marked 
plate, not reaching as far as the setae, and with a smooth 
rounded margin. Between these lips are four rows of 
stout blunt setae, straight or slightly curved (f. 123). 
These setae are all short, first series shortest, increasing 
progressively in length from first to fourth series. Between 
the third and fourth series in the upper part of the ramus 
are a few, usually two, long simple capillary setae (figs. 
124, 125). The ventral rami are short on the first seg- 
ment, increasing in length from the first to the sixth or 
seventh segment. At this point they extend from the 
dorsal to the ventral suiface, never encroaching on the 
ventral surface. The last seven or eight of this series of 
rami decrease in lengtli progressively, so that the last 
{25th-29th) is about the same length as the first, and con- 
tains about the same number of setae. The margin of the 
posterior lip of the last three rami is prolonged into a 
delicate cirrus. 
With the change of setae the anterior lip disappears ; the 
posterior lip becomes conical, truncated, bearing a cirrus- 
like prolongation on its lower outer border (f. 126), and 
its position is changed to the lateral margin of the dorsum. 
