12 
TV. M. TATTER8ALL. 
latter size the species lias all the adult characters, except perhaps the rostrum, which 
has the margins hardly as concave as fully adult specimens. Examples of 13 mm. 
in length are to be met with in January, and so were presumedly larvee of the 
preceding season, from which it would appear that the species takes at least- one 
year, and very probably longer, to reach the final adult size of 32 mm. 
Euphausia triacantha. 
(Plate IV., Figs. 1-3.) 
Euphausia triacantha , Holt and Tattersall, 190G (1). 
Locality of capture: —Lat. 66° 52'1)9" S., long. 178° 08' 15" E., 2030 fathoms; 
one specimen, immature male, 23 mm. 
Carapace (Plate IV., Fig. l), with a single lateral denticle posterior to the centre 
of the lower margin of the carapace ; antero-lateral margins somewhat in Hated over 
the eyestalks, and then produced into a long-and very acute rostrum, which extends 
beyond the eyes and almost to the distal end of the basal joint of the antennular 
peduncle ; a faint keel is present on the carapace behind the rostrum. 
Pleon (Plate IV, Fig. 1) with the posterior dorsal margin of the terga 
of the third, fourth, and fifth segments produced into rather long, slender, very acute 
and slightly curved median spines; sixth segment rather long, nearly twice as long 
as the fifth segment without the spine. 
Eyes somewhat damaged in the single specimen, but apparently rather small, 
pyriform in shape. 
Antennular peduncle (Plate IV., Fig. 2) bearing on the inner distal corner of 
the basal joint a well-developed bifid leaflet, the lappets of the leaflet of about equal 
size ; outer corner of the basal joint rounded and adorned with numerous rather long 
plumose setae ; a row of six curved plumose setae on the dorsal surface of the basal 
joint; second joint with a simple acutely spiniform lappet arising from the median 
anterior margin ; third joint slightly narrower and shorter than the second. 
Antennal peduncle shorter than the scale, the third joint a little shorter than 
the second. 
Antennal scale reaching very slightly beyond the distal extremity of the second 
joint of antennular peduncle, broadly oval in shape, about three times as long as 
broad, apex broadly and obtusely rounded, spine at the distal end of the outer margin 
small but distinct; spine on the outer distal corner of the basal joint long, slender 
and smooth. 
First pleopods of the male (Plate IV., Fig. 3) obviously not fully metamorphosed, 
since both the proximal and distal movable processes on the endopod are small 
and simple, and the uncinus on the middle lobe is without a secondary spinule. 
Telson with the portion between and posterior to the sub-apical spines acutely 
produced and smooth ; sub-apical spines extending beyond the apex of the telson, 
