[Illustration: FIG. 141.--Sand flea (_Talitrus_).] [Illustration: FIG. 142.--_Arcturus longicornis_, enlarged.] One of these crustaceans, Limnoria, is among the most destructive of all animals to the work of man. On the Pacific coast they vie with the teredo, and on the coast of southern California are the chief aggressors, the life of a prepared pile being less than two years. The little creatures completely perforate it, so that the wood literally falls in pieces, being so closely filled with circular borings that the entire interior of the pile seems to have disappeared. One of the most beautiful of all the crustaceans, in my estimation, is the mantis shrimp, or Squilla (Fig. 143), which I have kept alive. It is found in deep and shallow water, and is a most remarkable creature both in shape and color. Its head is ornamented with beautifully tinted antennæ, vivid blues, greens, and yellows predominating. Its claws are sharp pointed, and deadly weapons when used against its prey. The finlets are richly tinted and in such rapid motion that they appear to be a mass of revolving wheels, so that the Squilla resembles some strange product of the imagination rather than a living animal. Its young are even more remarkable. [Illustration: FIG. 143.--Mantis shrimp (_Squilla_).] One of the best-known groups of crustaceans is represented by those with ten feet, of which the common lobster (Fig. 144) is a familiar example. In this instance the first pair of legs are developed into enormous biting claws; yet when the lobster sheds its skin all the flesh in the large claws is drawn through the very small joint. The lobster is a product of the colder waters of the North Atlantic, not being known on the Pacific slope, although attempts have been made to introduce it there. South of Long Island Sound it is very rare, and despite the stringent laws for its preservation, is rapidly being exterminated. Lobsters are caught in traps, called lobster pots, which are lowered into the kelp and seaweed. Twenty years ago the annual catch for the state of Maine was nearly fifteen million pounds, valued at $250,000. It is far less to-day. The lobster sometimes attains a weight of fifty pounds; but specimens weighing four or five pounds are now rare, due to overcatching, and the destruction of the undersized young. The color of the animal when alive is a dark green. The familiar red hue is the result of cooking. The eggs of the lobster are laid in March, and are masses of green spheres which are carried about by the female attached to her swimmerets. [Illustration: FIG. 144.--Common lobster.]