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or shorter than the anterior edge of this joint. Ventrally this bristle always has at the middle
numerous long, stifE secondary bristles, sonie of which are arrangedin pairs; distally it has short,
fine hairs. In addition this joint has disto-laterally a bristle that is usually short and weak. with
short, fine hairs. The third joint has along its anterior edge a series of five or six bristles (cf. also
A. abyssicola, p. 536 of this treatise), of which the proximal one and the distal one are in most
cases of about the same length as the bristle on the anterior edge of the second joint, the others
being somewhat shorter. (On account of this only the approximate length of the anterior bristle
on the second joint is given in the following descriptions of species.) All these bristles are rather
powerful and point more or less forwards and are bent more or less upwards. The proximal
one (— bristle no. 1) has about the same equipment as the anterior bristle on the second joint;
most, sometimes all, of the remaining bristles are furnished at the middle with a greater or less
number of more or less long and stiff ventral secondary bristles and have short, fine hairs distally;
the one or more that remain have short hairs but no long secondary bristles. The equipment
of these bristles was, in the species investigated by me, fairly constant within the species. On the
short posterior edge of this joint there is only one exceedingly short and weak bristle. On the
short anterior edge of the fourth joint there is also only one bristle, which is of about the same
length and strength as the distal bristles on the anterior edge of the third joint and always has
short, fine hairs distally. Postero-distally on the same joint there issue two rather weak bristles
with fine, short hairs. These bristles are of moderate and rather different lengths; the length
of these bristles was observed to be rather different in a number of species, but within each
species it was subject to very slight variations. The fifth joint has only one bristle, „the sensory
bristle of the fifth joint“. In all the species of this genus that were investigated by me this
bristle consisted of a rather powerful, densely annulated trunk, of about uniform thickness,
.differing somewhat in length in different species and having disto-anteriorly six subequal and
rather thick sensorial filaments placed close ly together, of about the same length as or somewhat
longer than the trunk of the bristle. In a number of species there is an additional sensorial
filament on this bristle (thus making seven altogether) at about the middle of the anterior side
of the trunk; this sensorial filament is considerably narrower than the six former ones and is
in most cases not quite half the length of the trunk of the bristle. All these sensorial filaments
are of about a uniform thickness and are distally rounded, almost completely hyaline, bare and
provided with a short, fine sensory hair at the point. — It is to be noted that J. A. CuSHMAX,
1906, pi. 29, fig. 22 draws this bristle as simple without any lateral filaments, although sensorial
filaments are drawn on the bristles of the end joint in the same figure.* —The bristle on the sixth
joint was of the same type in all the species of this genus that were investigated by me, being
in most cases somewhat longer than the total length of the three distal joints, rather powerful
and furnished with short hairs. The small end joint, which is in most cases rather strongly
chitinized, has six or seven bristles. The a-bristle, situated anteriorly, was, in all the species
* C. Claus states, 1876, p. 93, that in A. ovalis this bristle has five sensorial filaments, but lie draws six;
evidently this writer counts one filament as the „trunk“ oî a bristle, a method which is perhaps the right one from
a theoretical point of view, but which has been rejeeted in this work for practical reasons; it is almost impossible to
decide which of these filaments is the d i < t a 1 part of the bri tic. all of llicm being perfectlv similar,
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