200 : MR. LUBBOCK ON SOME FRESHWATER ENTOMOSTRACA. 
This segment strongly resembles, nay, is almost identical with the corresponding leg 
of C. serrulatus, which consists only of one segment; and we may therefore conclude 
that in this species neither the basal segment nor its spine are developed. As the peculiar 
arrangement and form of the three terminal setze are the same in these two species, while 
in other nearly allied forms they are altogether different, we may, I think, conclude that 
this organ, though minute, still subserves some important function in the economy of 
the animal, and doubtless one connected with the reproduction, for which its minuteness 
is one of the necessary conditions, and therefore affords no reason for considering these 
appendages as truly rudimentary organs. 
The abdomen and caudal setze agree with the description and figures given by Claus. 
Chiselhurst. February. 
Often of a dark greenish-blue colour. 
CYCLOPS BREVICORNIS, Claus, Z. c. p. 32. Antenne primi paris septendecim-articulate, 
breves, primum cephalothoracis segmentum paullulum superantes. Pedes quinti 
paris rudimentarii, simplices, bisetosi. Abdominis segmenta in postremo margine 
parvulis dentibus preedita. Long. fem. 3-5 mm. 
The figure given by Claus represents the hairs on the antennze shorter and more uniform 
than they are in my specimens. For instance, the large hair on the fourth segment, 
counting as usual from the base, is longer than the six succeeding segments. Again, the 
seta on the antepenultimate segment is longer than the three terminal segments. The 
two posterior penultimate sets, instead of being shorter than the two anterior setze of 
the same segments, are at least twice as long. These latter are correctly represented by 
Claus, but the former are not half long enough. The apex of the antenna is terminated 
by the usual number of setze, namely seven, while Claus only gives five. 
The second pair of antennz also is terminated by seven sete. 
The labrum is correctly figured by Claus: one specimen that I examined had eleven 
teeth, and another only ten. 
Maxilliped as in Claus's fig. 4, pl. 3, except that the terminal sezment had three spines 
and two hairs, instead of two spines and three hairs. 
The abdomen and caudal setze are as in the figure given by Claus, but the inner sete 
are rather thinner, and the lateral spine is weaker. The lamelle are 3335 of an inch 
in length, 3355 in breadth at the base, and 3:355 at the apex. The internal seta is 3000 
in length; the exterior of the four terminal setze is 412, in length. 
Common in ponds at Farnborough and Chiselhurst, in Kent, &c: 
The egg-sacs are elongated and narrow. 
CYCLOPS BREVICAUDATUS, Claus, 7. c. p.34. Antennze primi paris septendecim-articulate, 
secundum cephalothoracis segmentum superantes. Pedes rudimentarii ; secundus 
. annulus bisetosus. Sete apicales parum ciliate, brevissime, furcam longitudine 
paulo antecedentes. Long. fem. 2-4 mm. 
This species is principally characterized by the shortness of the caudal setae, which in 
