456 TACK sK()c.siii:i;G 



almost like a lamella and is about half the length of the basale (ef. p. 464 below); it grows rather 

 decicledlv narrower towards the point, is directed forwards and has its ventral edge pressed 

 against the dorsal side of the ])rotopodite. The e n d o p o d i t e has a constant number of 

 bristles: The first joint has a short, often bare, bristle on the anterior side, situated in most cases 

 somewhat distally of the middle of the joint. This joint has in addition postero-distally a long 

 bristle with short, fine hairs. The end joint has only one bristle, long antl with short, fine hairs. 

 The inside of the protopodite and the epipodial appendage are abundantly furnished with short, 

 fine hairs, arranged in groups or irregular rows. 



Fifth limb: — In all the species of this genus investigated by me this limb has 

 practically the same structure; it has not been used, as we shall see below, as a characteristic 

 for the species. — The comb is relatively narrow, with a uniformly curved dorsal edge. The 

 comb bristles are rather numerous; those situated nearest to the anterior point of the comb are 

 somewhat longer than the others; they are all pointed and finely annulated and are equipped 

 with abundant short, fine hairs. Most of the comb bristles are situated right on the ventral 

 margin of the comb, a few are displaced somewhat dorsally; tluis from three to five of these 

 bristles were always observed displaced somewhat dorsally up on the lateral side of the coml) 

 near the long bristle of the distal exopodite joints. The distal joints of the exopodite 

 are represented by a long, powerful bristle pointing forwards, extending in all the species 

 investigated by me a short distance beyond the anterior end of the comb and thickly furnished 

 with long, fine hairs arranged in the shape of a feather; cf. p. 465 below. Somewhat ventrally of 

 this bristle there are always two short, subequal bristles, pointed similarly forward; only in one 

 of the .species investigated by me, A. norvegica, was only one of these bristles observed. 

 Dorsally of the distal comb bristles there is a series of rather long and coarse hairs; a^AXt from 

 these the comb is to a great extent bare; at some places, however, short, fine hairs may be 

 observed. The e p i p o d i a 1 a p p e n d a g e is somewhat ear-shaped and is characterized 

 bv the fact that the bristles somewhat ventrally of the middle decrease very markedly in length 

 and then again increase strongly in length on the ventral lobe; a greater or smaller portion of 

 the distal part of these bristles is often bare or furnished with .short hairs, but, as far as one 

 can see, is not modified as a sensory organ. See fig. 14 of A. aberrata. 



Sixth limb: — Seen from the side it is lamelliform. The posterior margin is 

 straight or verv slightly concave or convex and is marked oft' from the ventral margin by an 

 always well-rounded corner. The ventral margin is slightly and in most cases fairly uniformly 

 convex. The anterior margin is more or less decidedly concave, with a- pointed corner marked 

 off from the ventral margin. Seen from beneath it is rather decidedly flattened anteriorly, 

 somewhat sole-shaped, with a well-rounded anterior edge; posteriorly it is narrow and lamelli- 

 form; cf. fig. 16 of A. Grinialdi. On the anterior edge there are usually two bristles with .short 

 hairs or bare (~- remains of endites on the protopodite and the exopodite?); (me of these is usually 

 atta(;hed at or somewhat above, the other somewhat beneath a point half way up the liiuli; 

 sometimes there is onlv one, the upjier one, of these bristles, .sometimes the ventral one is 

 duplicated; cf. also the description of this limb in A. ahi/ssicola. Along the .interior edge of the 

 .sole-shaped fiatteued part of the ventral sifl(> there is a small numb(>r of ratiier short bristles, 



