12 ^V. M. TATTEESALL. 



latter size the species has all the adult characters, except perhaps the rostrum, whicl: 

 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 larvae of th( 

 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, 1906 (1). 



Locality of capture :—L&t. 66° 52' 09" S., long. 178° 08' 15" E., 2030 fathoms 

 one specimen, immature male, 23 mm. 



Carapace (Plate IV., Fig. 1), with a single lateral denticle posterior to the centre 

 of the lower margin of the carapace ; antero-lateral margins somewhat inflated 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 antennulai 

 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. 



AntennuJar 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. 



Ayitennal 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 marcin 

 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 



