234) MR. Ae T. WATSON ON THE STRUCTURE 
in the penultimate and antepenultimate. The anal segment 
has no sete of either kind, and is truncated so that the ventral 
face, which is terminated by two small lobes (a.p., Pl. 25. 
fig. 20), extends slightly further than the dorsal. These lobes, 
as will be seen hereafter, are of special interest. The margin of 
the anus is ciliated and crenated. In a dorsal, external view 
of the animal, longitudinal, paired, milk-coloured bands are seen 
extending as far as the fifth torus (12. p. 10). These are due to 
a thickening of the epidermis. The first pair take their rise 
laterally, and, curving towards the back, terminate at points 
against the bundies of sete of the first torus. From these 
points there spring a wider pair of bands, which, in the form of 
bows with their convex sides facing each other, tie together the 
sete of the first torus to those of the second. Similar bows bind 
together the sete of the three following segments. 
An olive-green zigzag canal runs almost from end to end of 
each of the bands of the second “abdominal’’ segment (e.c¢., 
Pl. 23. fig. 6). Nephridia have not yet been found in the 
Ammocharide ; but it seems probable that these canals, with 
their internal funnel-shaped mouths and external slit-like 
openings, represent those organs, though Gilson is mistaken 
in supposing that they play a part in the emission of the 
genital products (27. p. 379). These, as I shall show, are 
discharged through characteristic pores at the anal extremity. 
A lateral view of the “ thoracic” segment shows an interest- 
ing point of adaptation of the animal to its mode of life. Von 
Drasche (12. p. 9) has noted the fact that, although the markings 
are not quite constant, there is, in the dorsal part of the collar, 
a transverse patch of brown colour, often divided into two 
portions by the dorsal line. This coloration extends as a line 
on either side round the fore-edge of the thorax, and swells into 
the round pigment-spots (eye-spots ?) already mentioned. From 
these spots the lines descend, and, still going forward, meet at 
an acute angle on the ventral line, about the level of the first 
bundle of bristles. He also observes that, in the anterior part 
of the animal, the course of the nervous system is practically 
indicated by this coloration ; the dorsal patch marking the brain, 
whilst the lateral lines indicate the cesophageal commissures 
uniting in the large ganglion, from which springs the ventral 
cord. This consists of a dotted band, without ganglia or large 
nerve-fibres, which runs the whole length of the animal. 
