^P. frondosa.^ This animal is commonly called the sea-cucumber, and the popular name somewhat expresses its form, but it has the power of changing its shape in a most surprising manner. Sometimes it will be nearly globular, again long and thin, or it may be constricted like an hourglass. When at rest the body is ovate and somewhat pentagonal. On the angles are double lines of suckers, and in the interambulacral zones are a few scattered false ambulacra. The surface is nearly smooth, very dark purple on one side, and inclined to whitish on the other. Ten much-branched tentacles surround the mouth. The animal, when grown and expanded, measures fifteen to eighteen inches in length. This species is found throughout the whole length of both the east and the west coasts. It is very plentiful on the Maine coast in tide-pools and on the rocks at low-water mark. The genus ranges over the greater part of the globe. The tough muscular body is said to be edible, tasting somewhat like lobster, or trepang (/Holothuria edulis/), which is found on coral reefs in Eastern seas and is much valued as food by the Chinese. The internal organs of /P. frondosa/ are highly colored, making its anatomy easy to trace. The muscular system is plainly defined. GENUS ^Lophothuria^ [Illustration: /Lophothuria fabricii/, showing under surface with three rows of ambulacra.] ^L. fabricii^ (Verrill), ^Psolus fabricii^ (Düben), ^Cuvieria squamata^ (D. and K.: Agassiz). The body in this species is covered with rounded overlapping scales and numerous granulations, and when it is retracted is about two and a half to three inches long and about one inch thick. [pg233] Rows of tube-feet lie near together, on a flat under surface, and form a kind of sole on which the animal creeps. The oral end of the body is a little raised and bears ten tentacles; these tentacles are profusely and finely branched, and when expanded are about as long as the body. The aboral end is obtuse and a little raised. Around the oral and anal openings the scales are grouped, forming circles in those regions. This holothurian is bright red in color, and when expanded is a beautiful object, perhaps the most attractive in appearance of any in the class. When retracted it has the aspect of an ascidian, and for a time was supposed to belong to that group. It is found on the New England coast on the under side of large shelving rocks. ORDER =APODA= GENUS ^Synapta^