. Text-book of zoology for schools and colleges. Zoology. Fig. 55.—Trilobita. 1. AngelAna Sedgwiehii; % Diagram of the cephalic shield of a Trilobite (after Salter). semicircular shield, covering the head (Fig. 55, 2), a series of movable rings, constituting the thorax, and a tail-piece com- posed of amalgamated segments, and representing the abdo- men. On the under surface of the shell nothing had ever been discovered except the upper lip, but recently traces of limbs have been made out. The cephalic shield usually bears a pair of compound eyes (Fig. 55, % o), but these are sometimes wanting.
. Text-book of zoology for schools and colleges. Zoology. Fig. 55.—Trilobita. 1. AngelAna Sedgwiehii; % Diagram of the cephalic shield of a Trilobite (after Salter). semicircular shield, covering the head (Fig. 55, 2), a series of movable rings, constituting the thorax, and a tail-piece com- posed of amalgamated segments, and representing the abdo- men. On the under surface of the shell nothing had ever been discovered except the upper lip, but recently traces of limbs have been made out. The cephalic shield usually bears a pair of compound eyes (Fig. 55, % o), but these are sometimes wanting. It is probable that most of the Trilo- bites possessed the power of rolling themselves up into a ball, much as our modern wood-lice. The Trilobites are only known as occurring in the older rocks of the earth's crust, and they are chiefly characteristic of the period known to geologists as the " ; Oedbes Cladoceea, Copepoda, and Osteacoda.—These orders deserve mention more from the extreme abundance of their commoner forms than for any other reason. They in- clude a number of minute Crustaceans, most of which are commonly called " water-fleas," and abound in fresh waters in most parts of the world. They are, however so small that, though visible to the naked eye, they can only be satisfac- torily examined under the microscope. As an example of the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Nicholson, Henry Alleyne, 1844-1899. New York, D. Appleton and Co.
Size: 1803px × 1385px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
