Its integument is marked by a large number of transverse grooves simulating the segmentation of Annelids, and near the anterior extremity close to the mouth are two pairs of recurved chitinous hooks.
In some cases changes of intensity take place round the auroral zenith, simulating the effect that would be produced by a cyclonic rotation of luminous matter.
Hispidus), oryzonzys, Rhithrodontomys (with grooved incisors), Ichthyomys and Anotomys (fish-eating, aquatic forms, from the mountains of South America), Acodon, and the North American wood-rats, or Neotonza, in which the molars have a structure simulating that of the under-mentioned Microtinae.
Thus the artificial lakes and hills, the stones forming rockeries or simulating solitary crags, the trees and even the bushes are all selected or manipulated so as to fall congruously into the general scheme.
In Iridaea the thallus is an entire lamina; in Callophyllis a lobed lamina; in Delesseria it is provided with midrib and veins, simulating the appearance of a leaf of the higher plants; in Constantinea the axis remains cylindrical, and the lateral branches assume the form of leaves.
The hard haematite is occasionally cut and polished as an ornamental stone, and certain kinds have been made into beads simulating black pearls.
In acute gonorrhoeal arthritis, simulating rheumatic fever, salicylates are useless.