190 W:. BLAXLAND BENHAM. 
recognise the fan-shaped bundles of dark palmate chete on 
Segments v to xu! (fig. 3). 
The ventral chetze (figs. 12, 18) are practically all alike, to 
wit, crotchets or “ furcate”’ chetz ; although the size of the 
prongs and the angle between may vary in different parts of 
the body. The dorsal chetz, with the exception of those on 
Somites v to x1i1 (both inclusive), are similar to the ventral 
chetee. These are shown in figs. 10, 11. 
The dorsal chetze of Segments 11, 111, 1v, have the two 
prongs very nearly equal, the lower (or proximal) prong being 
slightly smaller than the upper or distal prong; the two 
prongs are not greatly divergent (fig. 10). The dorsal chetz 
of the hinder segments are slightly stronger than the anterior 
ones ; the proximal prong is shorter than the distal prong, and 
has a decided curve away from the latter, so that the angle 
between them is slightly more obtuse than that of the anterior 
dorsal chetee (fig. 11). 
The ventral chetz present a similar difference according to 
their position—namely, those of the more anterior segments 
(fig. 12) have less divergent prongs than have those of the 
more posterior segments (fig. 13); and there is the same dif- 
ference in size of the prongs as occurs in the dorsal bundles. 
These differences agree with those figured by Professor Lan- 
kester for Psammoryctes umbellifer (‘ Ann. Mag. Nat. 
Hist.,’ 4th ser., vil, 1871, p. 92). Similar differences have 
been noticed in other members of the family Tubificide. 
The dorsal chetz of Segments v to xu closely agree in 
appearance with those described and figured by Lankester as 
characteristic of Psammoryctes umbellifer; where they 
occur, however, in Segments 11 to x. 
Each of these palmate cheete has the appearance presented 
by fig. 4. The stalk or axis of the cheta is straight, swollen 
at the point where it passes through the skin in a protruded 
1 The numeration that I here adopt is that usually followed by recent 
writers on Oligochete anatomy—namely, to regard the first chetigerous 
segment as the second [11] body-segment ; the buccal or peristomial segment 
being the first [1] segment. 
