DEVELOPMENT OF CIRRIPEDIA. 
145 
which, they had settled wherever there was the smallest place left for them. The 
Cypris evidently attaches itself on the very first occasion, preferring for its future 
domicile young colonies of Lepas or Velella-$\ieWs on which there are as yet only Cyprides 
and no Lepades at all. This is the reason why the worst places for collecting them are 
old colonies of the barnacles, in which most of the specimens are about of the same age, 
and in which only here and there younger or just-fixed Cyprides may be found. 
Lepas fascicularis is one of the barnacles which were studied by Claus when he 
worked out the last stages of the Lepadidae ; and I have no doubt he has seen and 
partially already described the same things which I am about to describe. In details, 
however (supposing the L. fascicularis of the Pacific to differ from the Atlantic one), 
there may be some differences. 
Moreover we have the classical description which Darwin * has given of the Cypris 
stage in Lepas australis , which from its large size (OT of an inch, about 3 millims.) is 
especially favourable for such a study, and which corresponds nearly in every detail 
with that of Lepas fascicularis. I shall therefore be very short in my description of 
the Cypris, as well as in that of the transition stage to the adult Lepas, in order not to 
repeat things at large which have already become the property of science ; but I must 
give an account of the chief changes which occur in order to make my description of 
the Lepas development complete. 
The size of the Cyprides is variable ; some of them have a length of To millim. and a 
width of 0 - 7 millim. ; but some specimens may be found to be a little larger and some 
a little smaller. 
The yellowish and rather transparent shell has an oval shape, but is pointed at the 
posterior end (Plate 15. fig. 24). When alive the whole animal’s body is so much ex- 
panded by the cells of adipose matter, that scarcely any thing but the antennae, the eye, 
and the setae of the feet can be seen. But after having been put into absolute alcohol 
and then made transparent every thing comes out very well, and one gets, even without 
dissection, a good idea of its anatomical peculiarities. 
The valves of the shell are kept chiefly together by a large musculus adductor 
(fig. 24, ma ), which partly covers the parts of the mouth if you look at the entire shell. 
The muscle occupies a very large spherical place of attachment, and keeps the valves 
very strongly together. 
The other muscles are those which run from the dorsal portion of the shell to the 
origin of the antennae, and those which attach the upper portion of the body, and espe- 
cially the head, to the upper portion of the shell. Two small muscles move continually 
the capsules which include the large compound eyes (fig. 24, m). 
The Appendages. — Between the antennae there are still remains of the two feelers 
which I saw when dissecting the pupa, but which I never could observe in situ. The 
antennae (Plate 15. fig. 24, a, and fig. 27) are very large and powerful organs. How 
they originated in the first appendages of the JSfauplius has been already described. In 
* Loc. cit. ii. p. 14. 
