COLLECTED BY CAPTAIN TOYNBEK. 181 
from the apex; but, whereas in Dana's species the three terminal segments diminish in 
size towards the apex, in the present species the apical segment is as long as the three 
preceding put together. Like Dana, I was unable to satisfy myself as to the form of 1 lie 
appendage. The two terminal setae appear to be shorter Hum in the species from tli 
Pacific. The basal part of the antenna had moreover only three segments. 
There are four pairs of natatory legs. All the branches had three segments, lliou.h in 
the first pair it was doubtful whether there was any real joint. In all the legs the inner 
branch was the longer of the two, while in the great majority of the Cyclopoidea the 
reverse is the case. 
The second and third segments of the abdomen have almost completely coalesced, their 
original separation being indicated by a distinct indentation. The last segment is deeply 
bilobed. 
Dana says nothing about the sexual characters in this genus; and I have had no oppor- 
tunity of examining a specimen which I knew to be a male. It is moreover quite possi- 
ble that the present specimen may have been immature. 
It was very active. According to a sketch made at the time by Mrs, Toynbee, it teems 
to have been of a lightish lilac colour, with green and yellow tints inside, and the eye red. 
Collected April 15, 1858, in lat. 24° 20' S., long. 62° 53' E., at 8 r m. 
7 
Setella. 
Setella tenuis, n. s. Corpus 9-articulatum. Antenna? antieae crassiusculae, breves, 
articulis prhnis duobus subaequis, tertio quintoque longioribus, quarto appendicular. 
Maxillipedis digitus fere dimidii articuli secundi longitudine. Styli caudales elon- 
gati ; setae caudales corpore vix longiores. 
This species differs from S. tenuicornis and S. longicauda in the shortness of the ante- 
rior antennas and the length of the caudal lamellae, from all the species except S. Acicvlm 
in having only nine segments to the body, and from all in the shortness of the abdominal 
setas, which are but little longer than the body. I was at first inclined to think that this 
character ought perhaps not to be relied on, and that the setae might perhaps be imper- 
fect ; they taper, however, so gradually, and to so fine a point, that they can have lost 
very little, if any, of their length. 
The deficiencv of a segment in this species and in S. Ac'iculus evidently arises ft 
coalescence of the first two abdominal segments 
pairs of appendage 
both attached to one segment. The anterior antennae have only six distinct segments, 
though there are indications of others. The fifth is the longest, then comes the third, 
while the two basal and the fourth are short and subequal. 
The appendage which is, as usual, attached to the fourth segment is rather more than 
half as long as the apical portion of the antenna. The frontal appendage is shaped as in 
S. crassicornis. The caudal lamellae are elongated. 
The separation of the segments is, however, often so indistinct that I am indisposed to 
attach much weight to the characters thus afforded. 
Collected June 26. S. lat. 0° 40' ; W. long. 
Pl. XXIX. % 12,x30. 
VOL. XXIII. 
20' 
B 2 
