^S. empusa.^ This animal suggests somewhat the lobster, though very unlike it. The carapace is much smaller and softer, and leaves the last three segments of the thorax uncovered. The abdomen is larger and longer in proportion, while the legs and organs are quite different. The whole body is depressed, instead of laterally compressed. It measures from eight to ten inches in length and two inches in breadth. Instead of chelæ, the last joint of the great claw has six sharp curved spines, which fit into sockets in a groove on the second joint. By this singular organ they hold their prey securely. The abdominal feet carry the gills. The antennal scales are oblong and fringed with hair. The antennules terminate in three flagella. The caudal appendages and telson are long, strong, and armed with spines. This animal lives in burrows in the mud below low-water mark, forming large, irregular holes, but is frequently washed ashore. In color it is pale yellowish-green, each segment being bordered with darker green and edged with yellow. It is found from Cape Cod to Florida. ORDER =CUMACEA= GENUS ^Diastylis^ ^D. quadrispinosus.^ Among the minute /Crustacea/ which swim on the surface of the water, this species, with other small forms, may be captured by using a muslin net. It is a quarter of an inch or less in length. It is easily distinguished by its large carapace, the posterior portion of which is marked off in transverse ridges, the anterior end running into a sharp-pointed rostrum. It has a long, slender abdomen, the sections of which [pg289] are distinctly marked, and it terminates in long, forked spines, which are longer than the telson. It is found from New Jersey northward. ORDER =ARTHROSTRACA= SUBORDER ~AMPHIPODA~ The /Amphipoda/ have a laterally compressed body, with gills on the thoracic feet and an elongated abdomen. The segments of the thorax are not united, nor covered by a carapace, but the whole body is covered with a segmented, polished, flexible cuticle. The three anterior legs of the abdomen are for swimming-feet, and the posterior ones are adapted for springing. The antennæ are long and hairy. The amphipods comprise the beach-fleas and many other small crustaceans which abound between tide-marks on all beaches. Besides serving in no small measure as food for fishes, they are scavengers of the beach, and consume large quantities of waste matter. They are sometimes used in preparing skeletons for anatomical specimens. Animals to be skeletonized, being fastened to boards and anchored just below the surface of the water in sheltered places, are divested of all flesh in a few hours, and the bones are more completely cleaned than if prepared by a naturalist. GENUS ^Orchestia^ [Illustration: /Orchestia agilis/; male.]