146 
DE. E. VON WILLEM OES-STJHM ON THE 
the free-swimming Cypris they are to be seen in connexion with a gland (fig. 24, gl l ), 
which may be easily seen on the ventral side of the stomach, often filled with granular 
secretions, which make it appear dark w r hen seen by transmitted light. The duct of 
this gland runs up through the first and second joints of the antennae and opens in the 
centre of the sucker (fig. 27, dgl and acet). 
The antenna itself consists of four joints, not of three, as was formerly supposed by 
Darwin, who very likely had not seen the minute third one generally hidden by the 
sucker. Claus, however, and. very likely Pagenstecher, have already described the 
right number. The first joint attaches with a forked base to the muscles of the body, 
and has a strong curved spine. The second joint is nearly as long as the first. Its 
largest muscles run all towards the sucker, which is attached by a short peduncle to 
its exterior side. The diameter of the sucker is OT millim. It has a depression in the 
middle to receive the duct of the gland, and round this depression a wall of chitinous 
substance, on which seven large spines, two small spines, and four setse are attached. 
Another seta is found below the sucker on the second joint, in the same place where 
in the Nauplius we saw a feathered hair. The third joint, almost hidden by the 
sucker, is very small ; and the fourth only somewhat larger, but distinguished by four 
setse and two olfactory hairs, between which there is a broad paddle-shaped appendage 
which I cannot well classify (fig. 27, u ). Under an immersion-power you see a double 
contour line running up into it, but no hairs nor appendages of any kind at the top. 
Darwin has observed the same number of setse, hairs, and also this peculiar appendage 
in the pnpa of Lepas australis *. 
The second and third appendages of the Nauplius stages are entirely lost, and so is 
the large labrum ; only a small helmet-like prominent organ is to be seen where for- 
merly we found such a huge appendage, the two lateral glands of which have now very 
likely been converted into shell-glands. There are three parts of the mouth besides 
the upper lip (fig. 32, a, b, c), all very rudimentary. I have been unable to separate 
them quite satisfactorily, though I have tried ever so many times to get at them with 
fine needles. Claus, however, has succeeded in doing so, and has shown, when com- 
paring the whole of the Cypris stage with the Copepods, that these parts correspond to 
the maxillae and maxillipeds of these Entomostraca. 
I think there is no reason to doubt the disappearance of the third appendages ; for I 
have looked very carefully whether any remains of them could be found, but did not 
succeed, and I think that if any thing developed itself at all in these large appendages 
it would be easily seen. The parts of the mouth, it is true, are very small ; but with the 
exception of the labrum, which is easily found, they are all new formations. 
There are six pairs of branched natatory feet, five of which have been compared by 
Claus to the natatory feet of the Copepods, and the last pair to their genital appen- 
dages. These feet are adorned with a short seta, which is directed upwards, on the 
front of the last segment, and with long, very densely feathered setse at the end. 
* Daewist, loc. cit. tab. 30. fig. 8. 
