In Fig. 4b the Himantia villosa is represented, a rhizomorpha found in the mines of the Upper Harz Mountains, thus showing another form of this vegetable growth. Though it is difficult, as above stated, to recognize by their shape the rhizormorphæ as fungi, the origin of the peculiar Agaricus myurus of Hoffmann (Fig. 4a) will be much easier discovered, though a retrograde development and degeneration has taken place also in this fungus. It still shows, however, the elements of a regular toadstool, only that the stem is much elongated and looks like a thread or a tube, while the cap is small, and this explains how, by gradual degeneration, the cap may disappear entirely, leaving nothing but a stem, as, for instance, in the case of the Clavaria deflexa, the club fungus, shown in Fig. 3b.
In connection with the above it may be well to speak of the fungi constituting the mould which often covers the roof and the doors in the brown-coal mines of Halle, specimens of which are shown in Fig. 5.
Fig. 6.—THE SUN INFUSORIUM (ACTINOPHRYS).
We now come to the animal life in mines and pits. This is mostly represented, of course, by lower organisms, as infusoria and worms. Thus, in the slime on the bottom of the waters in mines, several species of amœbæ are found, which consist of microscopically small animated bodies, continually floating about, nourishing themselves by absorbing organic matter, possessing sensation, propagating, etc., and, in fact, having actually the qualities of real animal nature. Further, we find in those subterraneous waters a species of the sun infusorium (Actinophrys), which is especially frequent in the mines of Klausthal. Fig. 6. shows one of these peculiar little beings. Also the Stylonychia (Fig. 7) is a characteristic inhabitant of those places, and always present there.
Fig. 7.—THE RAPACIOUS INFUSORIUM (STYLONYCHIA).
It moves with great rapidity in the water by means of the numerous hairs covering its body, can turn quickly in any direction, and thus is enabled to catch suddenly the little beings on which it lives and which it hunts; for which reason the stylonychia is called the "rapacious infusorium."
The above are organisms which can be seen only through the microscope, but the fauna of mines contains also larger organisms, though they are not found as regularly and are not as characteristic for those places as the forms mentioned hitherto. Among these organisms there are several species of worms, spiders, gnats, and, above all, crustaceans of the lower class. The most interesting of the latter is perhaps a variety of the sand flea (Fig. 8—Gammarus pulex). The crustacean found in the pits of mines, which is related to the sand flea, shows, according to Dr. R. Schneider, a slight degeneration of the organ of sight, which has taken place in consequence of its adaptation to the dark places, in which this variety of the Gammarus pulex is found, which can make no use of eyes, while the sand flea possesses them fully developed. Otherwise, however, the two varieties are almost absolutely alike, differing only in some details.
