COrEPODA. 
19 
In the fourth pair the Re 3 is not three times as long as broarl (16 : 6). The 
anterior antennae are a little longer than the cephalothorax. 
The i is a little smaller than the 9, and presents the same sexual differences as 
in other Euchaetae. The bunches of hairs on the last thoracic segment, so prominent in 
the 9, are absent in the S. 
The first feet have a three-jointed exopodite, the outer margin of which is not so 
concavo-convex as in the 9 , and its Se are short. 
In the second pair, the Se of the exopodite are also smaller, the Se of Re 2 only 
reaching the origin of the Se 1 of Re 3 ; the Se 2 of Re 3 being little more than half 
the length of the distal part of the segment. The fifth feet are characteristic. The 
penultimate segment of the left foot is prolonged on the upper margin into a strongly 
toothed process, and has a setose conical unhaired process on the distal margin, the 
last segment into a long process, narrow and with a strong bunch of hairs at the distal 
extremity, and with a large conical and strongly haired process. (This process is 
sometimes nearly as long as the principal process of the penultimate joint.) 
The first basal is short, the second basal long, and with very small and rudimentary 
endopodite. 
The right foot has short first basal, very broad second basal, long first and second 
Re (which are coalesced), and with the last segment blunt and rounded. 
Euchaeta similis. 
(Plate IV., figs. 1, 2, 3, 4.) 
This species occurs plentifully in the same samples in which E. antarctica is 
present. For a long time I regarded them as merely different stages in the history of 
the same animal, but the careful examination of a great number of individuals from 
different tow-nettings proves the constancy of the points of difference between the two, 
and as many of the E. antarctica and E. similis have spermatophores or egg sacs 
attached, I have come to the conclusion that, though so very similar in most characters, 
the two species must be separated on account of the invariably different characters of 
the abdomen and genital segment. 
E. similis is constantly rather larger than E. antarctica , 8’6 mm.-8 • 8 mm., and 
more robust, the head Hat and rostrum small, but strong and directed forwards and 
rather upwards. The cephalothorax is two and a half times as long as the abdomen. 
The last thoracic segment is produced forwards, slightly triangular shaped, with evenly 
rounded margin, .no spine, but a bunch of long hairs on each side. The abdominal 
segments, of which the genital is twice as long as the next, are coyered with fine hairs, 
nowhere with large bunches, and the posterior distal margins have only very small 
teeth, not large, as in antarctica. Furca with, on each side, a very short dorsal bristle, 
the ventral accessory bristle not geniculated at the base, though bent outwards, its 
length not more than about half of the two long tail bristles (next to the innermost). 
VOL. IV. 
M 
