of two individuals, the part of one being encased in a cavity of the
other. Figures 4 and 5 Illustration 4 will give a correct idea of the way
in which this junction is effected. The least motion separates these two
parts, and each forms a perfect animal, which performs all the functions
of life. This is the more extraordinary, as the containing animal is
furnished with an organ not possessed by the contained, and which in
their united state is used by both. Figure 5. From the little bag (f) at
the bottom of the cavity (g) the receiver produces a chaplet, which
traverses the canal in the received marked (2) in Figure 6, and which is
here drawn the size of life, was sometimes expanded to the length of one
foot eight inches. This organ, according to M. Cuvier, is composed of
ovaries, tentacula, and suckers.

The swimming apparatus, marked (1) and (4) in Figure 6, act
simultaneously; they are of a bright amber colour, and their mouth (a)
and (h) are closed with little valves, nearly invisible even when in
motion; the points round their upper aperture seem to form the hinges for
these. In twenty seconds I counted seventy expansions and dilatations of
this apparatus. The chaplet and the bag that holds it are flesh-coloured;
the rest of the body is gelatinous and diaphanous. They live in families,
and swim with great rapidity in the same manner as the other Acalepha.

Caught also shells and crabs of the same kind as yesterday.

November 14. Latitude 29 degrees 26 minutes south; longitude 101 degrees
2 minutes east.

Physsophora rosacea, Cuvier, see below. We caught another animal of the
same kind as the one taken on the 12th of November, and figured in
Illustration 7. It was so delicate that I did not measure it for fear of