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possesses an entire margin, but later this tends to break 
up from the edge inwards, thus giving rise to the minute 
teeth or processes which are usually seen on full-grown 
setee. The notopodial setee may attain a length of 75 mm. 
(in a specimen 250 mm. Jong). 
Each neuropodial cheta or crotchet consists of a 
shaft, generally somewhat curved, bearing at its distal end 
a beak-like rostrum placed at an angle to the shaft vary- 
ing from about 90° to about 150° (figs. 15-18). There is 
eenerally a slight dilatation of the shaft near the middle 
of its length. Near the end of most chet from young 
specimens, immediately behind the rostrum there are 
visible two or more minute pointed teeth, the tips of which 
are directed towards the tip of the rostrum, while below 
the rostrum at its junction with the shaft there is often a 
minute process—the subrostral process. On careful 
focussing shghtly above the level of the teeth and 
subrostral process there comes into view a number of 
other fine teeth situated on the sides of the rostrum, so 
that the latter projects from the centre of a series of teeth 
arranged round its base. The small subrostral process 
marks the position of the base of the lowest (and often 
the smallest) tooth of the series. Only unworn cheete 
show these lateral teeth. By isolating the entire band 
of neuropodial chetze the number in each neuropodium 
and the different stages in their growth may be seen. 
New chietee are formed at the ventral end of the series, 
the rostrum being first formed, then the teeth, and finally 
the shaft which is at first comparatively short (fig. 18). 
The néuropodia of the anterior segments are short 
and contain few setze, but those further back extend by the 
addition of crotechets ventrally so as to almost reach the 
mid-ventral line. The neuropodia of young specimens 
contain very few crotchets, but in old specimens there is 
