144 
DR. R. YON WILLEM OES-SUHM ON THE 
I have never seen in these antennse glandular ducts ; but if I am right in supposing 
that the glands in the upper lip do not go into the stomach, a communication with 
them would be easily established when the great revolution takes place which changes 
the Nauplius into a Cypris. 
The appendages of the second pair are the largest and are branched (Plate 12. 
fig. 15, h ) ; the appendage has some setse and a strong manducatory process (fig. 15, r) 
on the second segment ; and on the third also there is a sort of manducatory organ 
with a very hairy surface, somewhat larger than the corresponding process figured by 
Dohrn in his Archizo'ea. The branch which starts from this segment has in our case 
nine (not seven) segments. The fourth segment is covered on its inferior side with 
very strong hairs ; the fifth is very long, and the sixth the shortest, with two long hairs 
at the top. 
The appendage of the third pair (Plate 12. fig. 15, c ) is also branched. It has on its 
second joint a conical process with a very strongly feathered short hair. Its branch, 
which starts from the third joint, consists of three segments, all of which have, as well 
as the fifth and sixth segment, long feathery hairs attached to them. 
During these Nauplius stages the embryo has been rapidly growing, and has taken 
in plenty of food, consisting of small algae which float at the surface. After the fifth 
moult it begins to accumulate materials for the pupa or Cypris stage, which it will 
now have to undergo, and during which no food is taken. Large masses of fat fill the 
space between the stomach and the carapace (Plate 14. fig. 22, cl), and make it appear 
quite • opaque, while the developing Cypris - shell under the Nauplius - carapace gives to 
these old Nauplii a darker brownish colour. 
Every thing is now ready for the next (sixth) metamorphosis, which diminishes the 
size of the larva in a most extraordinary way, and which is the most remarkable one 
which it has to undergo. 
The carapace with its long spine, the tail and the caudal spine, the second and third 
pairs of appendages, and the large labrum are now all cast off, and the Cypris under- 
neath is ready to swim about. 
III. The Cypris stage. 
The changes just mentioned take place evidently very suddenly, for I could never 
find a Nauplius which was just in the process of moulting, though I found plenty of 
empty and cast-off skins. After the metamorphosis the newly born Cypris takes to a 
different mode of life to that which was led by the Nauplius. The Nauplii come at 
night to the surface, but live in the daytime mostly in a depth of 60 fathoms, while the 
Cyprides are to be met with on the very surface, swimming in a lively way round the 
Velellce , and trying to fix as soon as possible on dead individuals of these siphonophores. 
I should think that this Cypris stage lasts only a very short time; for in the same 
places where hundreds or thousands of Nauplii were caught we obtained only a few 
free-swimming Cyprides, but saw them in crowds on the young Lepas colonies, on 
