18 
W. M. TATTERSALL. 
preanal spine well developed, provided with an external strong tooth and a comb-like 
row of finer teeth up to twelve in number. 
Antennular peduncle (Fig. 2) rather long and slender, considerably longer than half 
the carapace; basal joint rather flattened, considerably wider than the remaining two 
joints, bearing on its outer distal comer a rather long and slender spine, its anterior 
margin somewhat overlapping the basal part of the second joint, fringed with 
numerous set?e and exhibiting near the inner side a shallow fissure: terminal two 
joints very long and slender, subequal in length, their combined lengths slightly 
exceeding that of the basal joint. 
Antennal peduncle (Fig. 3) very long and slender, nearly as long as the scale, 
third joint less than half as long as the second. 
Antennal scale (Fig. 3) extending to about midway along the terminal joint of 
the antennular peduncle, almost five times as long as broad, outer margin terminating 
in a well-marked spine, inner margin sloping away obliquely towards the apex ; spine 
on the basal joint moderately long, slender and smooth. 
Mouth parts (Figs. 4-6) do not offer any marked differences from those of 
Thysanoessa gregaria as figured by Sars (1885, PI. XXII). 
Second thoracic limbs (Fig. 8), with the endopod remarkably long and well 
developed, in full-grown specimens equalling nearly three-quarters of the total length of 
the body from the eyes to the telson ; meral joint the longest, extending beyond the 
tip of the antennular peduncle; carpal joint a little shorter than the meral and more 
slender, nearly four times the length of the propodal joint, armed with four slender 
spiniform setae on the outer margin at the distal extremity, and five similar setae on 
the inner distal margin; propodal joint with five long spiniform setae on the outer 
and six on the inner margin ; terminal joint small, tipped with six spiniform setae. 
The remaining thoracic limbs (figs. 7, 9, 10) not differing greatly from the same 
limbs in T. gregaria. 
Copulatory apparatus (Fig. 11) on the first pleopod of the male exhibits a 
structure very similar to that figured by Sars for T. gregaria, except that the distal 
extremities of the two movable processes on the inner lobe do not seem to be serrate. 
Telson slender, apex acutely produced and smooth ; sub-apical spines smooth ; 
dorsal denticles two pairs, the first pair just anterior to the centre of the telson, the 
second pair a little anterior to the insertion of the sub-apical spines. 
Uropods exceedingly slender, inner one reaching the apex of the telson, outer 
slightly shorter. 
Length of the largest specimen, 28 mm. 
I have thought it well to describe and re-figure this species, since Sars’ original 
description was taken from admittedly young forms, and I cannot find that mature 
specimens have ever been described and figured. The changes that take place 
during growth affect principally the rostrum, the second thoracic (or elongate) limb 
and the preanal spine. 
