EUPHAUSIACEA AND MYSIDACEA—TATTERSALL, 9 
OrpEeR MYSIDACEA. 
SuB-ORDER MYSIDA. 
Family Mystpar. 
Sub-jamily Mystnax. 
Genus TEnacomysis G. M. Thomson. 
Tenagomysis G. M. Thomson, 1900. 
This genus was instituted for a species, 7. nove-zealandia, found not uncommonly 
on the coasts of New Zealand, but I am not aware of any subsequent records since 
Thomson’s paper, nor of any further described species which may be referred to the 
genus. The species described below is very readily distinguished from the type form, 
though clearly referable to this genus. In view of the recent advances of our know- 
ledge of the Myside it seems desirable to re-define the genus, and to indicate its place 
in the family. 
The genus Tenagomysis may be defined as follows :—Carapace rather short, 
leaving at least the last two thoracic segments entirely exposed, produced anteriorly 
into a moderate frontal plate; eyes moderately large and well developed, pigment 
black; antennal scale lanceolate in shape, setose all round, with a distal transverse 
suture near the apex; throacic legs slender, sixth joint divided by vertical articulations 
into numerous subjoints (four in the type, ten to fourteem in the new species described 
below), seventh joint (dactylus) feeble; pleopods of the male essentially as in the genus 
Leptomysis, first pair with the endopod quite short and unjointed with the usual lateral 
plate, exopod long and multiarticulate; second, third, fourth, and fifth pleopods of 
the male well developed and biramous, the rami except in the fourth pair, subequal 
and without any specially modified armature; the exopod of the fourth pair longer 
than the endopod, with a strong spiniform and barbed seta on the outer side of each of 
the antepenultimate and penultimate joints; telson varying in ‘length, its margins 
armed with spines, cleft at the apex, the cleft armed with closely-set pectinations, 
and the centre of the cleft bearing two plumose setee; uropods rather long and slender, 
the exopod without a distal suture and without spines, the endopod with spines along 
the inner margins; female with three pairs of marsupial lamelle (fide G. M. Thomson); 
type, Tenagomysis nove- zealandia Thomson. 
Hansen (1910) has divided the Myside into six sub-families and one of these 
sub-families, the Mysine, into which Tenagomysis falls, is further divided up into four 
tribes: In all its essential features Tenagomysis agrees with Hansen’s definition of the 
tribe Leptomysini, but its inclusion therein will necessitate a slight modification of the 
characters assigned to the tribe. This is in the number of subjoints into which the 
tarsus of the thoracic legs is divided. Hansen’s definition runs “‘ Sixth joint of thoracic 
legs [tarsus] with two, rarely three, vertical articulations and no oblique articulation.” 
The new species described below though otherwise clearly belonging to this genus has 
2021S—B Vou, 5, Parr 5. 
