"The full definition drawn up by Professor Sars was probably based on the species L. lignorum alone. To include the other species undoubtedly belonging to the genus it requires some slight modification. Thus the epipod of the maxillipeds is not always lanceolate, and the outer ramus of the uropods is not always unguiform. Authors generally (myself included) have agreed in speaking of the trunk limbs as similar in structure, but, while no doubt they have some features in common, especially in regard to the terminal couple of joints, they are at the same time uncommonly well provided with distinguishing points. Between the first gnathopod and the fifth peraeopod the contrast is sufficiently striking.
In the well-known species of the Atlantic coast Harger notices that in the mandibles ' below there is a slight tubercle, apparently the rudiment of the molar process.' His conjecture is supported by the rather stronger development of this tubercle in L. segnis.
Between the acutely lanceolate epipod of the L. Ugnorum, and the forms with rounded apex in L. segnis and L. pfefferi, the narrow leaf shape in L. antarctica offers an intermediate term. In his elaborate description of the last-named species Dr Pfefifer broaches an extraordinary theory that ' the pleopods in general have not the value of a limb but of an epipod, so that accordingly the branchial plates of the Isopoda Like those of the Decapoda are epipods, and therefore in a certain sense equivalent formations.' That this view has met with no acceptance was to be expected." (Stebbing, 1904)
"The general appearance in close agreement with L. Ugnorum, like which it has the head almost globular, much narrower than the rest of the body, the first segment of the peraeon much the longest with a conspicuous dorsal V-shaped grooving, the side-plates of the second and third segnaents quadrangular oval, the four following pairs more or less acute, the upper surface of the body beset with hairs of varying length. In the pleon the angles of the first segment are a little less prominent than those of the four following segments; the fifth at the middle is as long as the first four together, and about half as long as the almost circular, flatly saucer-shaped telsonic segment, mth the proximal part of which it shares in forming a smoothly rounded median elevation.
The eyes are wide apart, very small.
The first antennae have the second joint subequal to the third, not shorter as in
L. segnis and L. Ugnorum, and the second joint of the flagellum is not so abruptly narrower than the first, as in the latter species. The long olfactory setae are present. The second antennae closely resemble those of L. lignorum. The epistome, lips, mandibles, and both pairs of maxillae agree with those of the last-mentioned species. The maxillipeds also are nearly the same in structure, but with a differently shaped epipod. This is little more than twice as long as broad, broadly rounded at both ends, reaching well beyond the long narrow second joint of the maxilliped, the ovoid form impaired only by the lower part of the inner margin being slightly concave. This appendage in L. segnis is about four times as long as broad, and is apically acute in the other two species.
The first gnathopods are as usual distinguished from the other limbs by the fifth joint underriding the sixth, and having no free hind margin. Along front and hind margins of the third and along the hind margin of the three following joints small blunt spines are discernible. At the hinder end of the sixth joint there is a prominent spine with a convex comb as in L. lignorum, and the finger just above its long curved nail has the well-known bifid spine. The other limbs agree closely in shape and armature with those of the last named species, the first and second peraeopods being the smallest, but distinguished by their position as confronting one another. The fifth peraeopods are the longest, with the second joint much narrower than in the preceding pairs ; the fourth joint is produced far over the hind margin of the fifth, the length of its slender spine-fringed process being particularly conspicuous in the new species; the fringe of pectinate spines round the fifth joint is found in all the species. The spine above the finger-nail is bifid only in the first gnathopods.
The pleopods except in the last pair have the inner plate narrowly oblong. The male stylet of the second pair I have not observed. Probably, as in the other three species, and as in the genus Eurydice, it is affixed near the middle of the inner margin.
The uropods have the inner ramus shorter than the stout peduncle, twice the length of the small straight outer branch, all the constituents being setose. The peduncle is much larger in comparison with the inner ramus than in L. segnis." (Stebbing, 1904)
"Rotten wood in lagoon, Minikoi." (Stebbing, 1904)
"Length of unrolled specimen 3.5 mm., breadth 1'25 mm." (Stebbing, 1904)
