REPORT ON THE CIRRIPEDIA. 
13 
puzzled by this fact. A part of the body of this male corresponds to the peduncle of the 
pedunculated Cirripedia, and as this is also filled up with connective tissue, — with the 
exception of a rather narrow tubular cavity towards the rostral side, — I at first endeavoured 
to homologize the connective tissue of the male with that of the peduncle. Extending 
my researches also over the body of the hermaphrodite or female Scalpellum, over Lepas 
and other genera of Cirripedia, I found that the occurrence of a well-developed mass of 
connective tissue between the different organs within the body is the rule in all the 
Cirripedia. In the interesting essay on the coelom-theory by the brothers Hertwig 1 we 
read that all the Arthropoda possess a very capacious body-cavity, and that in the full- 
grown animal the intestinal tract passes freely through this cavity, a dorsal mesentery 
uniting the intestine to the wall of the body being observed only in a younger stage of 
the development. Whether the plurality of typical forms of Arthropoda have been 
sufficiently investigated so as to allow of this conclusion to be drawn, I will not decide. 
Doubtless, however, the Cirripedia have a very rudimentary body-cavity, and a well- 
developed mass of connective tissue nearly fills up all the space left open between the 
wall of the body and the internal organs. So the complemental males in this respect also 
correspond in structure to the female and hermaphrodite animals. 
The internal organs consist of the well-developed genital apparatus, the nervous 
system, the cement-glands, and the totally rudimentary and evidently functionless 
oesophagus and stomach. 
Fig. 1 of PI. I. shows these parts in their normal position ; fig. 2 represents part 
of these organs more strongly magnified. Testis ( t ), vesicula seminalis (vs), and 
vas deferens (vd), can easily be made out in all the specimens. Neither do the other 
organs (the nervous system, and the oesophagus with the stomach), present any further 
difficulties after comparison with the structure of the Cypris-larva (PI. II. fig. 3). 
Digestive tract. — The oesophagus and the stomach have nearly preserved their original 
condition ; the mouth has grown totally functionless ; its place is indicated by the 
presence of a group of cells (PI. I. fig. 2 m), which are placed in the connective tissue 
bordering the cavity in which the thorax is situated. The oesophagus is a narrow tube 
which imperceptibly widens and passes over into the stomach. The latter is a pyriform 
pouch closed on all sides, having a rudimentary intestine at the extremity opposite 
to the carclia. It has a double wall, as can be best studied in the transverse sections 
(PI. III. figs. 6 and 7). Probably the internal wall represents a chitinous cuticle which 
has been shed, but which could not be removed, the mouth being closed. Perhaps the 
interna] wall represents the chitinous tube, or model of the stomach filled with excrement, 
Darwin describes in the alimentary canal of Cirripedia. 2 In the full-grown male the 
stomach is almost empty ; in a younger condition (PI. IY. fig. 1), the stomach is filled 
1 0. and R. Hertwig, Die Coelomtheorie, Jenaische Zeitschr., Bd. xv. p. 76, 1882. 
2 Darwin, Balanidse, p. 86, 1854. 
