^H. talpoida.^ This animal, commonly known as the "sand-bug," differs greatly in appearance from a crab. When the appendages are folded under the carapace it somewhat resembles an egg, the body being ovate, about half as broad as long, and the sides forming a nearly regular curve. The carapace is about one and a half inches long, convex, yellowish-white, and nearly smooth. The abdomen is long and pressed under the body, reaching nearly to the front. The eyes are minute and on the ends of long, slender stalks. The antennæ are plume-like and about as long as the carapace. /Hippa/ lives on sandy beaches at or near low-water mark, exposed to the action of the waves. It burrows with great rapidity into the loose and shifting sands, using the short and stout second, third, and fourth thoracic legs and the appendages of the sixth abdominal segment [pg269] for pushing and digging. Crabs of this species are gregarious and may be seen in great numbers, though but few will be captured together by digging, as they rapidly disappear beneath the sand. Sometimes they are found swimming about in the tide-pools. They seem to live upon the organic particles contained in the sand, which they swallow, the mouth not being adapted for mastication. This species ranges from Cape Cod to Florida. (Plate LXI.) ^H. analoga.^ Similar to /H. talpoida/, but broader and flatter. It is bluish above, yellowish-white below, and the fringing hairs are black. Found on the California coast. GENUS ^Albunæa^ ^A. gibbesii.^ This animal is found with /Hippa/, and, like it, burrows rapidly in the sand. Its general outline is square. The surface of the carapace is marked off with denticulated lines, which make the back appear as if composed of plates. The front edge of the carapace has a row of teeth and a prominent spine at the anterior angles. The abdomen is doubled under itself (not fitting into a groove of the thorax, as in ordinary crabs), this animal being intermediate between the long- and the short-tailed forms. The eyes are on triangular, plate-like stalks. The antennules are very long and are fringed with hair. The chelipeds have claw-like joints, which close across the straight, broad end of the hand. The first two pairs of walking-feet have curious sickle-like terminal joints. The animal is about one and a quarter inches long. /Albunæa/ does not extend as far north as /Hippa/, its range being from Georgia southward. (Plate LXI.) FAMILY ~PORCELLANIDÆ~ The crabs of this family are little more than one quarter to one half of an inch across the back. The chelipeds are broad and flattened. The first three pairs of walking-legs are well developed, and the fifth pair are very small and are doubled over the base of the carapace. The sixth segment of the abdomen has a pair of biramous appendages, which, with the telson, form a swimming-fan. GENUS ^Porcellana^