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Part III. — Fifteenth Annual Report 



Body moderately stout and elongate ; the various segments are apparently 

 devoid of the usual fringes of cilia (fig. 1). Antennules somewhat slender, 

 eight-jointed ; the first four and the last joints are sub-equal and of 

 moderate length ; the fifth joint is smaller than the others ; the formula 

 shows, approximately, the proportional length of the joints : — 



Proportional lengths of the joints, 10 • 11 • 9 • 10 • 5 • 8 • 7 • 10 . 

 Number of the joints, . . 1 • 2 • 3 ■ 4 * 5 * 6 ' 7 ' 8 . 



Antennae elongate ; secondary joint small, one-jointed, and armed with 

 four spines (fig. 4). The biting part of the mandibles is attenuated and 

 somewhat feeble ; the palp is two-jointed and furnished with a few setae 

 (fig. 5). The first pair of feet are elongate and slender ; both branches 

 are three-jointed ; the inner branches are somewhat longer than the 

 outer, and the first joint is equal to about one and a half times the length 

 of the second ■ the second and third are sub-equal ; a moderately stout 

 seta springs from near the middle of the inner edge of the first joint ; 

 the second joint bears a seta on the inner distal angle ; and the end joint 

 has at the apex a small hair and two spiniform setae— one being con- 

 siderably longer than the other ; the joints of the outer branches are sub- 

 equal ; the marginal spines are elongate ; and the middle joint is provided 

 interiorly with a few marginal cilia, and has also a small hair near the 

 distal end (fig. 7). The inner branches of the second, third, and fourth 

 pairs are short and two-jointed, — the first joint being very small ; the outer 

 branches are elongate and three-jointed. Iu the fourth pair the inner 

 branches scarcely reach beyond the end of the first joint of the outer 

 branches ; the proximal joint of the inner branches is very small, and 

 bears one seta on the inner margin ; while the elongate end joint is armed 

 on the inner margin with two moderately long spines, and also bears one 

 long and one very short terminal seta (fig. 9). The fifth pair are small ; 

 the basal joint is somewhat broadly foliaceous, and scarcely produced 

 interiorly, and resembles in this respect the basal joint of the fifth pair in 

 Canthocamptus staphylinus ; on the posterior margin of the basal joint 

 are four moderately stout setae, — the two middle setae being considerably 

 longer than the others ; the secondary joint is of an oblong form, the 

 length being equal to about twice the breadth ; its armature consists of 

 one small seta near the distal end of the inner margin, two small setae 

 on the outer margin, and two elongate apical setae (fig. 10). Caudal 

 stylets are nearly as long as the last abdominal segment, and the prin- 

 cipal seta are very long and slender (fig. ). 



Description of the Male. — The male is similar to the female, except in 

 the following particulars : the antennules, which are modified for grasping, 

 have the fourth joint delated exteriorly into a lobe-like projection ; 

 the penultimate joint is also very small (fig. 3). The inner branches of 

 the third pair of swimming feet are three-jointed; the second joint, which, 

 like the first, is very small, is produced interiorly into a long spine-like 

 process that extends beyond the extremity of the third joint ; the third 

 joint, which is equal to fully twice the combined lengths of the first and 

 second, bears one short and one elongate apical seta ; the marginal 

 spines of the first and second joints of the outer branches are strong and 

 slightly curved at the end (fig. 8). The fifth pair are very small, the 

 basal joint being almost rudimentary ; the secondary joint is ovate, and 

 provided with two spiniform and two slender setae, as shown in the draw- 

 ing (fig. 11). 



Habitat. — Rescobie Loch, near Forfar, and Linlithgow Loch ; not 

 very rare. 



