(c) Construct a shelter.
The constructions are usually "individual" in the first period of work; afterwards, they are organized "collectively." The covers are: (1) for riflemen lying down, (2) for riflemen sitting down, and (3) for riflemen standing up.
Plate 27a.—Use of the cover without improvement.
Plate 27b.—First period.
Plate 27c.—Second period.
Progressive improvement of the cover.
Individual Organization of Natural Cover