W. Lilljeborg on the Genera Peltogaster and Liriope. 167 
the Cirripedes. During the development of the ova the ovaries 
become enlarged, until at length they fill the whole cavity of the 
body, and at the same time they unite so closely, or even become 
so confounded, that it is sometimes impossible to discover their 
original limits. They then present the appearance of a single 
sac surrounded externally by the inner membrane of the body- 
cavity. When the skin is removed, the sacs of eggs appear as a 
single sac, the walls of which are formed by the membrane which 
lines the cavity of the body, but beneath this they are found to 
ssess their own proper coats. These walls are less transparent 
and solid, cellular in structure, and contain formative substances, 
from which it follows that the sacs themselves act as matrices, 
and not the cavity of the body as supposed by Rathke. When 
the membrane enveloping the ovisacs bursts anteriorly, the 
young escape directly by the anterior aperture of the body- 
cavity. Probably the existence of the parent terminates with 
the accomplishment of its propagative destiny, as in other para- 
sites ; and thus we may explain the transformation of the ovaries 
into such enormous sacs. The author found two specimens of 
Peltogaster sulcatus, dead and completely empty, but still attached 
to the abdomen of Pagurus chiracanthus, Lill}. He has also found 
in the same matrix ova and newly-hatched young; it therefore 
appears that the development of the eggs does not take place 
simultaneously, although the difference is not great. 
The organ of adhesion, being generally in the form of a funnel 
with a neck of greater or less length, is always of a harder tex- 
ture than the surrounding skin, and more or less horny accord- 
ing to the age of the animal. Young individuals, in which the 
secretion of cement has been less, have the organ softer and 
lighter in colour; in older specimens it is hard and solid, at 
least in part, and its colour is then brown*. It has always an 
aperture in the middle (fig. 8), through which the Peltogaster 
probably sucks its nourishment from its host. This orifice is 
continued through the neck of the organ of adhesion, and also 
through the epidermis and dermis. Rathke denies the existence 
of this aperture, believing that the orifice at one extremity lead- 
ing into the cavity of the body was the mouth. But the form 
of the organ of adhesion and the mode in which it is attached to 
its host appear to prove that it is formed, as in the other Cirripedes, 
at least partially, by the secretion of cement+. As in the other 
Cirripedes, it appears that this organ is also formed by a trans- 
formation of the outer or second pair of antenne, formed in the 
* The substance of which it is formed is probably chitinous. 
t Ina specimen of P. Paguri, the author once observed a portion of a 
canal attached by one of its extremities to the inner part of the epidermis; 
this might have been a cement-canal. 
