24 



basal joint. The maxilla are characterized by the inner branch 

 (fig. 4) being very much reduced. The outer branch carries at the 

 end 5 feathery brushes, and the reduced inner branch 3 extremely 

 small ones. On one of the lobes of the basal part sit 5 very 

 long feathery brushes, and on the other a group of at least 10 such. 

 The first pair of maxillipeds are characterized by a comparatively 

 long basal part, while the branches and lobes are very much re- 

 duced. At the distal end there are two groups of large brushes, 

 three in each. In the upper group (fig. 7) the two are bent 

 towards the end and set with fine points that give them a comb- 

 like appearance. In the other group two brushes are e(]ually 

 long and equally thick, while the third is thinner and scarcely 

 half the length of the two. The second pair of maxillipeds are 

 considerably thinner in structure than the first pair, especially the 

 second basal joint (b2) is much protracted, the length being 5 — 6 

 times the breadth. On the first basal joint b l sits a very charac- 

 teristic brush or thorn (fig. 14). It is curved and overlaps the 

 distal end of b2. Besides there are at the end of bl two short, 

 thin brushes and one thicker brush or thorn. Near the inner edge 

 of b2 is a row of small thorns. The lowest of the brushes (l) of 

 the uppermost basal joint sits a little above the middle of the 

 inner edge of the joint b2. Altogether there are on the inner edge 

 of b2 5 brushes. Of these (l) and (2) are smaller than (3), wich is 

 again smaller than (4). The branch consists of 5 joints, decreasing 

 in length towards the end. Of these the 4 first joints carry 3 

 brushes. 



In the first pair of feet the inner branch is almost as broad 

 as the outer branch, and the length about Vs of that of the outer 

 branch. The first pair of feet is shorter than the three following. 

 In the second pair of feet (fig. 8) the inner branch is not so long 

 as the two lower joints of the outer branch, which is also the case 

 for all the swimming feet 2 — 4; i3 is about twice as long as il, 

 and y3 longer than yl + y2. In 3rd pair of feet y3 is compara- 

 tively longer and broader than in any of the others (fig. 12). 

 (There is no perceivable difference in the structure af 3rd pair of 

 feet in the two sexes). 4th pair of feet is much like the 3rd, 

 though the point of y3 short a somewhat different appearance 

 (fig. 19). 5th pair of feet (fig. 3), like the others, consists of two 

 branches, with 3 joints in each branch. The outer branch is 

 about twice as long as the inner one; y l. lacks brushes, on y2 

 sits a thick curbed thorn, with the curbing turned inward (proxi- 

 mally). This thorn is a little longer than the inner branch. On 

 the inner side of y 3 are four rather long feather-brushes ; the first 

 brush is about half as long as the joint y3. Besides, i3 has 6 

 feather-brushes, and i2 has a thin, short brush, about half as long 

 as the joint. A similar one sits on il. 



Apart from the comparative size, the female of h. norvegiea 

 shows great likeness to h. jtapilligera $. The best distinguishing 

 mark I have found, is that the brushes on il and i2 on the .5th 

 foot are considerably thinner and shorter than the brushes on i3. 

 By the thin and short brushes on the two lower joints of the inner 

 branch, h. norvegiea shows a likeness to h: clausii, Giesbrecht. 

 From the latter, however, li. norvegiea is distinguished by lacking 

 the thorn-like brush on yl. Besides it may be noted that in 

 h. clausii the curbed thorn on y2 is shorter than the inner 



branch, while the final brush on y3 is more than half the length 

 of the joint. 



Length 



H. norvegiea cf. 

 Front body 2.52 mm. 

 Hind „ 1.08 „ 

 Total 3.6 



1st pair of antenna 4.0 mm., consequently longer than the 

 body. Greatest breadth 0.9 mm. The long furcal brush was torn 

 off, but the piece that was left measured a little over 2 mm., so it 

 is likely that it is longer than the body. 



The anterior left antenna is transformed into a clutching an- 

 tenna, and is distinguished from the corresponding one in the female 

 by several joints towards the distal end being joined into one (fig. (J). 



The segmentation of cephalo-thorax is like that in the female, 

 the hind body on the contrary consisting of 5 joints, of which the 

 4 uppermost have a row of small thorns at the hinder edge of the 

 dorsal side (fig. 5). In the structure of the jointed organs of the 

 l)ody there is great likeness between the two sexes, only in respect 

 of 5th pair of feet the likeness is lacking. The second basal joint 

 in the right 5th foot has a characteristic projecting formation that 

 is bent inwards towards the joint (fig. 20, 32); y2 has a knotted 

 proj'ection on the inner side; y3, which is of a lengthened and 

 vaulted form, is supplied with 3 brushes, of which one short and 

 thick and one longer and thinner sit at the point of the joint, the 

 third is on the under side of the joint. The lowest joint of the 

 inner branch is rather sJiort, and the connection between it and 

 the following one is obli(|ue, compared to the longitudinal direction; 

 il lacks brushes, i2 has 1, and i3 6. 



The length of y3 is about as y 1 -|- y2. 



Especially characteristic of left foot is the joint y3 (fig. 22). 

 BoECK says about it: 



"Third joint of the outer branch is shorter than the second, 

 and inwardly drawn out into a strong point, against which a curbed 

 claw from the point of the joint can strike". 



It is most likely that it is h. norvegiea I have found, but in 

 that case Boeck's description is not (juite correct. On the joint 

 y3 are 3 brushy projections. Of these the two short ones (s, t,) 

 distinctly articulate with the joint, whereas the articulation between 

 f and y3 is indistinct. 



Fifth pair of ieet in the male shows an astonishing likeness 

 to the corresponding one in h. abyssalis, about whose appearance 

 the excellent drawings of Giesbrecht give sufficient information 

 (Monographic, Taf. 20, fig. 29, 30). However, the knotted projec- 

 tion on y2 of fifth right foot seems to be relatively smaller in /(. 

 norvegiea than in h. al»yssalis\ the thin final brush is in norvegiea 

 shorter, forming about Va of the length of the joint (y3), while 

 in ahyssaliH it is more than half the length of the joint. What 

 chiefly seems to distinguish the two species is the appearance of 

 y3 in left fifth foot, the brushy projection f in norvegiea being 

 distinctly projected from the joint, while in ahyssalis they run 

 together with no definite limits. Fifth pair of feet in the male 

 further shows a distinct difference from the corresponding one in 

 the Mediterranean forms. 



