Prawns, crayfish and oysters are also obtainable, and turtle (Chelonia mydas) are frequently captured.
All the known forms of plant-life are either fungi or allied to them, and many are only microscopic. The most interesting inhabitants of Mammoth Cave are the blind, wingless grasshoppers, with extremely long antennae; blind, colourless crayfish (Cambarus pellucidus, Telk.); and the blind fish, Amblyopsis spelaeus, colourless and viviparous, from 1 in.
It has been discovered that at the beginning of the Eocene the lake of Rilly occupied a vast area east of the present site of Paris; a water-course fell there in cascades, and Munier-Chalinas has reconstructed all the details of that singular locality; plants which loved moist places, such as Marchantia, Asplenium, the covered banks overshadowed by lindens, laurels, magnolias and palms; there also were found the vine and the ivy; mosses (Fontinalis) and Chara sheltered the crayfish (Astacus); insects and even flowers have left their delicate impressions in the travertine which formed the borders of this lake.
In the brackish waters of the east coast sea fish are found, together with pike, perch and other fresh-water forms. The crayfish is common in many places in central and southern Sweden.
The relative proportions of these three divisions vary considerably, and the extreme abbreviation of the mid-gut found in the common crayfish (Astacus) is by no means typical of the class.
On its shores are tortoises, mud-turtles, crayfish and innumerable sand-hoppers; and at varying depths in the lake several species of Melania, Melanopsis, Neritina, Corbicula and Unio have been found.