DEVELOPMENT OF CIEEIPEDIA. 
135 
contained in the enlarged blastodermic cuticle. In our case I liave not been able 
to make any observation of the kind, owing perhaps to the circumstance that in every 
Lepas one finds all the ova in one and the same stage of development, Avhich makes it 
very difficult and laborious to get at all the different stages. The circumstance that 
the cuticula (whether egg-shell or blastoderm) which contains the embryo is larger 
than the ova were (0 - 29 millim.) is perhaps in favour of such a moulting as has been 
observed in Sacculina , but might also be explained by a certain elasticity of the egg- 
shell. We find such a case in worms, where, for example in Bistomct megastommn, 
the shell is considerably extended*. When working out the first development of that 
Trematod, I have already remarked that something very like it has been observed. The 
same thing has been found in Bistomum veliporum by Guido Wagener, in Pteromalines 
by Ganin, and finally in Balanus improvisus by Buchholz. And as in every other 
respect the first development of Lepas has been found to be so similar to that of 
Balanus. I am inclined to think that it is also in this case the egg-shell which the 
embryo leaves, and not the blastodermic cuticle, which very likely still adheres to the 
young Nauplius. 
II. The successive Nauplius stages. 
The Nauplius, when escaping from the ovum (Plate 10. fig. 11), has a length of 
0-35 millim. It has been figured by Burmeister, but evidently (if it is at all the same 
as ours) as seen under a very low power, and without giving many details. I do not 
know whether, judging from this figure, one has a right to state that the variety of 
Lepas fascicularis at which he has been working is the same as ours or not. This 
being also the case wffth the figure of the Cypris stage, it is unnecessary for me to refer 
again to his paper, the object of which was more to show that such larval stages existed 
in Cirripedia, than to give details about their organization. 
We saw these embryos in our globes as soon as a ball of Lepas had been put into 
them. At this time of the year there are in every bunch some specimens which con- 
tinually dismiss from their ovarian lamellae large numbers of embryos. These swim 
slowly about, until they undergo their first metamorphosis, which consists in casting off a 
very thin skin enveloping their body and in pushing out their tail and their caudal spine, 
which, enclosed by that cuticle, have hitherto been pushed in like the tubes of a tele- 
scope and unable to extend to their full length (fig. 11, and fig. 11 h). I was at first, 
when I had not noticed this cuticle, very much puzzled by this ; for I saw that the tail 
ended in two spines, and the caudal spine in a single spiny process. When, however, the 
covering-glass had been pressing a little on the embryo, I noticed a long tail and a long 
caudal process, the longer the more it had been forced out from the animal’s body by the 
pressure exercised upon it ; then I discovered in animals which were perfectly unhurt 
the cuticle which envelops the animal’s body, and which is also clearly visible at the 
* “ Leber einige Trematoden und Nemathelminthen, yon E. v. Wihejioes-Stjum,” Zeitschrift fiir yriss. Zool. 
Bd. xxi. 
