EUPHAUSIA GIBBA. 245 
as long as the diameter of the small eyes; the gastric area, seen from the side, 
somewhat feebly vaulted, and the median keel is well developed. 
Lobe from first antennular joint not half as broad as the end of the joint, 
directed obliquely forwards, upwards, and somewhat outwards; not quite as 
long as broad, somewhat oblique-triangular with the inner margin feebly convex; 
the end very acute, and besides frequently with an extremely low tooth or 
feebly produced, sharp angle near the base of the outer side. Second antennu- 
lar joint above with the distal inner angle showing an extremely small, sharp 
tooth; while at the outer side the lateral corner itself is rounded. Third joint, 
seen from the outer side (fig. 2a), with the dorsal keel decreasing gradually in 
height from the middle to its proximal end which is situated at some distance 
from the end of second joint, thus nearly as in #. paragibba H. J. H., but the 
distal part of the keel is a little higher than in the latter species. 
Dorsal process of third abdominal segment, seen from above, shaped as an 
oblong-triangular, distally acuminate and acute plate, very far from half as long 
as the fourth segment. Sixth abdominal segment as in F. paragibba. 
The copulatory organs (fig. 2b) differ extremely from those in all other 
species of the genus. The terminal process (p”.) is unusually small, subconical, 
thick at the base, and with the distal third slender, acute and suddenly bent 
obliquely forwards and outwards; the heel is proportionately long and very 
slender. The proximal process (p*.) is very long and strong, thickened at the 
base and then tapering nearly evenly to the acute end; somewhat before its 
middle it is curved somewhat inwards; and somewhat beyond the middle it is 
bent considerably outwards and besides forwards, its distal third being almost 
straight. The lateral process (p*.) is bent strongly inwards a little before the 
middle; its proximal part is thick, its distal part slender, and it has no dorsal 
tooth. The median lobe is very curious; its proximal third, to the insertion of 
the lateral process, is extremely broad, its middle third is considerably narrower, 
yet broader than long; the distal third originates from the outer distal angle of 
the preceding part as a kind of thin-skinned, very slender finger with the proximal 
half directed considerably outwards and the distal part bent conspicuously 
inwards. The auxiliary lobe of moderate length; the setiferous lobe as in allied 
species, with seven setae along its triangularly produced terminal margin. 
Length of adults of both sexes 11-15 mm., most frequently 12-13.5 mm. 
Remarks.— E. gibba G. O. 5. is closely allied and very similar to E. pseudo- 
gibba Ortm., EL. hemigibba H. J. H., and EF. paragibba H. J. H. These four species 
are in reality so similar in general aspect, in shape of rostrum, size of eyes, lobe 
