of British Entomostraca. All 
inferior or large antennz, the rami of Straus. In these three 
genera, which have been all adopted by Milne Edwards, the su- 
perior antennz (antennules of M. Edwards) in most of the species 
are exceedingly small compared with the inferior, so much so 
indeed, as almost to have escaped the notice of Miiller altogether, 
They are also situated beneath the beak. In the two species 
however which I have mentioned above, they are very much 
larger than in the others, and instead of springing from the 
head under the beak, hang pendulous from or are articulated 
to the beak itself. In the Daphnia rosea (Macrothrix roseus) 
they are flat, one-jomted and distinctly pendulous from the beak, 
occupying such a position that they cannot be mistaken or over- 
looked. 
In the Daphnia cornuta however, from the extremely minute 
size of the little animal, they have been hitherto constantly mis- 
understood by observers, and though much too large and promi- 
nent to be overlooked, they have been described as a totally dif- 
ferent organ. Having last autumn met with this curious little 
creature in great abundance in the water from the Hampstead 
ponds, I have been enabled to place it under a microscope of high 
power, and have thus succeeded in ascertaining the real struc- 
ture and position of these organs. In the notices of this species 
by Miller, Jurme and M. Edwards, the antennules are not men- 
tioned at all, but the animal is described as possessing a long 
beak *; and certainly at first sight and with a low magnifying 
power these organs appear as being merely a prolongation of the 
anterior part of the head, similar to what we see in many of the 
Lynceide. This is not so however, and upon a careful investi- 
gation I have found this apparent beak to consist of two long, 
eurved, cylindrical bodies, consisting each of about twenty small 
articulations, and united to the beak or anterior part of the head 
by a distinct jomt. In structure these organs resemble very much 
the antenne of the Cyclopide, but like the antennules of the other 
Daphnia possess very little motion. Miiller considered this ani- 
mal to be a Lynceus, and led away by the above-mentioned re- 
semblance to the beak of many of that genus, he has described 
it under the name of L. longirostris+. Jurine has described it 
under the division of Monoculi belonging to the group of the 
Daphnide, under the name of Monoc. cornutus, and has been fol- 
lowed by Desmarest and M. Edwards. In the ‘ Ann. Mag. Nat. 
Hist.’ I have also described it under the name of Daph. cornuta, 
not haying then distinctly seen the structure of the antennules. 
- These are so peculiar however in their structure and position, and 
so distinct from those of the other Daphnide, that in the ‘ Trans, 
* “Le bec est long et gros.”—Edwards. 
+ Entomostraca, p. 76. t. 10, f. 7, 8. 
2EF2 
