Ants[27] live in communities. They are divided into fertile females, males and infertile females. Among the ants, the mining ants, which make long galleries in the earth, and carpentering ants, which perforate solid timber, are the best known classes. Some species, like the white ants of the tropics, the termites, are famous for their ravages.
The bees are divided into queens or females, drones or males, and workers. Each community or swarm has one queen, which lays the eggs. The bee is provided with a formidable sting.
This curious weapon of attack and defense is here magnified with the adjacent parts. It consists of an extensile sheath with two needle shaped darts that are exceedingly sharp. This spear is furnished with barbs near the point, and when it pierces the skin, if thrust with violence, it sometimes remains, not only making the wound more painful, but, having been wrenched from the bee, frequently causes its death. The sting is connected with a little sac containing a poisonous liquid which is thrown into the wound and increases the pain.
STING OF A BEE.
SUB-KINGDOM VIII.—TUNICATA.
This very small class of animals is distinguished by the leathery sac-like covering, from which they take their name of Tunicata (having a tunic). The Ascidian[28] is the best known representative. It is found fastened to rocks, shells, crabs, and other bodies. These animals are both simple and compound; the latter are often phosphorescent. They have neither feet, head nor shell, but a shapeless body with apertures at both ends.
SUB-KINGDOM IX.—VERTEBRATA.
This division includes the most perfect animals. Their chief distinguishing characteristics are an internal skeleton; a backbone; a dorsal nervous cord, separated from the body cavity; a complete circulation, and limbs not exceeding four. There are about 25,000 living species, beside the numberless host now extinct.
Lowest of the vertebrates, and closely related to the true fishes, are the Lancelet and Lamprey.[29] The former is a lance-shaped animal having no skeleton, but boasting the rudiment of a backbone in a string-like cartilaginous cord. The organs are very simple, the heart being a long sac in which colorless blood circulates. It breathes by taking in water through the mouth and letting it out through the gill-slits. The Lamprey belongs to the pouch-gilled vertebrates or Marsipobranchii.[30] It is an eel-shaped animal of about three feet in length.