Journals of Two Expeditions of Discovery in North-West and Western Australia Volume I Part 7

Figure 4 upper part; Figure 5 lower; and Figure 6 the perfect animal.

Between c d apparently lay the entrance to its mouth; in the little bag marked (3) its long tentacula were concealed, and below these lay a little gut marked (4) which communicated with the point (L) by a small ca.n.a.l: (1) was its swimming apparatus, and by alternate contractions and expansions of this, it took in and expelled water, and thus acquired a rapid motion, the pointed end (L) moving forwards.

Its length was 1.7 inches.

Breadth, 0.7 inches.

Thickness, 0.35 inches.

Temperature the same as the water, 65 degrees Fahrenheit.

The sketch Ill.u.s.tration 4 Diphya, Sp. gives a faint idea of the most beautiful animal of this kind which I have ever seen. It was so delicate that, with the slightest touch, portions of it came off, hence the specimen we obtained is I fear useless. The body consisted only of a central ca.n.a.l, to which were attached a number of gelatinous bags, with large lateral openings, so large that other zoophytes were caught in them, and apparently annoyed the animal; who continued throwing water out until it expelled them. The whole was surmounted by a number of the most beautiful rose-coloured tentacula: I counted eleven on it, and found four more that were torn off, but there may have been more. Its top, when looked into closely, resembled some of the sea anemones; and inside of the large bright orange-coloured tentacula were placed circular rows of smaller ones. Its body was quite transparent, with the exception of the central ca.n.a.l, which was of a milk-white colour, and terminated in a small sac of the same hue.

It moved in a direction opposite to the tentacula, by taking in water at the lateral openings of the bags, in the position in which it is represented; then bending these towards the tentacula, and expelling it with great violence.

Temperature the same as the water, 65 degrees Fahrenheit.

Length of body (to tentacula from root of tail-like ca.n.a.l) 1.8 inches.

Length of tentacula, 1.2 inches.

Length of tail-like ca.n.a.l, 0.45 inches.

Breadth, 1.1 inches.

Thickness, 0.8 inches.

Long tentacula, flesh-coloured; large tentacula, rose-coloured; lateral bags, tinged with clear amber; the rest of the animal perfectly transparent.

We this evening caught several curious little animals (Clio ?) which when taken out of the water appeared like small b.a.l.l.s of the same matter as that of which a slug is composed. Presently a little head peered out, then the body expanded itself, and finally two little things like wings were spread forth, formed of a fine membrane; they moved these very rapidly, and swam with great velocity.

We caught several small crabs, and two kinds of sh.e.l.ls, of a beautiful purple colour. (Janthina exigua.) These were very small; I have preserved several of them.

Figures 1, 2, and 3 represent different views of an animal (Salpa) slightly electrical, that we caught this evening. Figure 1 is its appearance, one side being up; Figure 2 when the other side is turned up; Figure 3 is the side view of it.

I have never before seen one of the kind electrical. Temperature the same as the water, 65 degrees Fahrenheit.

Length, 1.5 inches.

Breadth, 0.6 inches.

Thickness, 0.3 inches.

Figure 1. The intestinal ca.n.a.l terminates in a little coloured bag, generally of a bluish tinge; there is an opening at each extremity, one a little to the left of the little bag, the other, as shown in Figures 3 and 1.

November 13. Lat.i.tude 30 degrees 7 minutes south; longitude 100 degrees 50 minutes 10 seconds east.

Figure 1. Represents a little sh.e.l.l (Hyalea) which was caught this day.

Figure 2. One of the tentacula of the animal I imagine to be the Physsophora rosacea. The point which is seen obtruding at the base resembles a little nerve; it runs the whole way down the tentacula.

Figure 3. A little shrimp-like animal (Erichthus vitreus) caught on the 14th November, lat.i.tude 29 degrees 26 minutes south; longitude 101 degrees 32 minutes east. Its head was protected by a s.h.i.+eld, such as is shown in the figure.

We caught this day several other Acalepha, two of which were of the wonderful genus DIPHYA. I yesterday drew a coloured figure of the lower part of one of these animals.

This animal in its perfect state (such as we found it in today) consists of two individuals, the part of one being encased in a cavity of the other. Figures 4 and 5 Ill.u.s.tration 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 ca.n.a.l 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 sh.e.l.ls and crabs of the same kind as yesterday.

November 14. Lat.i.tude 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 Ill.u.s.tration 7. It was so delicate that I did not measure it for fear of its falling to pieces, but it appeared to be exactly the same size as the former one.

Its circle of large tentacula were of a bright pink, and were fifteen in number; inside this circle was a smaller one of the same number of shorter tentacula, which were not quite so bright a pink colour; in the centre of these were placed organs of a very extraordinary nature, apparently quite round, and not thicker than the very finest silk; they were arranged exactly in the form of a corkscrew, and from the beauty of their mechanism, the animal could press fold against fold, and thus render them less than a quarter of an inch in length, and I watched it almost instantaneously expand them to the length of nine inches. After having observed the animal closely for an hour I am writing this with it before me, alive in a large gla.s.s bottle of salt water, and measuring what I put down. The manner in which it expands these organs is by first uncoiling those folds nearest the body, and afterwards those most remote; so that when folded up it looks like a corkscrew with the folds pressed close together, and when expanded, like a long straight thin bit of flesh-coloured silk, with a little corkscrew of the same material at the end. The larger tentacula are shaped like the trunk of an elephant, and their extremity is furnished with a very delicate organ with which they can catch anything, and, if touched, they instantly turn some of these tentacula, which they have the power of moving in any direction, to the point so touched. They are not electrical: the lateral bags have a slight tinge of a bright amber colour. These animals sustain themselves in the water by means of the little bag marked (a) in the figure, which floats on the surface full of air, they there swim in the manner before described. I afterwards observed very minute globules, or lumps, in the long silk-like tentacula. When expanded these were very distinct.

Lat.i.tude 29 degrees 26 minutes south; longitude 101 degrees 32 minutes east.

We caught several small sh.e.l.ls (Janthina exigua) this afternoon: Ill.u.s.tration 9 represents one of them, with the string of air bubbles attached, by means of which they swim on the water. They appear not to be able to free themselves from this ma.s.s of bubbles: every sh.e.l.l I have yet found floating in the Indian Ocean possesses these bubbles in a greater or less degree; they were of a purple colour. I have seen the common garden snail in England emit a nearly similar consistency: they also emit a blue or purple liquid, which colours anything it touches.

The animals of the barnacles (Pentalasmis) attached to these sh.e.l.ls a.s.sume their purple colours, while the sh.e.l.l remains nearly pure white.

This afternoon we caught an animal (Glaucus, Ill.u.s.tration 10) I had not before seen. It seemed to represent the order reptilia in the Mollusca, being sluggish in movement, its eyes distinct, sensitive to the touch, its head much resembling a lizard in appearance, and having a very strong unpleasant smell when taken out of the water. During the hour I observed it in a bucket it remained sluggishly floating on the top, and occasionally swimming by moving its arms slowly along the surface. The first three that I saw pa.s.s the vessel I imagined to be feathers floating on the water.

Its description is as follows:

Length from head to tail, a c 1.8 inches.

Length from head to root of tail, a b 0.85 inches.

Length from head to first arm 0.2 inches.

Length from head to second arm 0.45 inches.

Length from head to third arm 0.7 inches.

1st arm.

From centre of back to end of round part, d e 0.3 inches.

From e to the end of short tentacula, e f 0.3 inches.

Ditto to long ditto, e g 0.75 inches.

Diameter of round part and attached tentacula 0.4 inches.

2nd arm.

From centre of back to end of tentacula. 0.4 inches.

3rd arm, do. do. 0.25 inches.

Breadth of body between the two first arms 0.13 inches.

Thickness 0.25 inches.

General colour of body, indigo blue, of a darkish tinge; down the centre of the back a white streak, terminating at the root of the tail; sides blue, tail blue, quite white underneath, its belly altogether resembling that of a frog; tail tapering to a point.

1st arm. 26 tentacula attached to the rounded paddle-shaped part of this arm, the centre tentacle more than twice the length of the others. These tentacula were so delicate that at the slightest touch they fell off.

Those nearest the body were so small as to be almost imperceptible, gradually increasing in length as they approach the centre, and then decreasing to the other side. Centre of paddle-shaped part white, tentacula blue and white, fringed with dark blue at the extremity.

2nd arm. 18 tentacula to this, centre ones the largest. Same colour as first arm.

3rd arm. 12 tentacula, not forming such a regular circle as on the two first arms, and apparently issuing directly from a very short limb attached to the body.

The general appearance of the skin was that of a frog. It had the power of contracting itself considerably.