^P. nebulosa.^ One half of an inch wide and three quarters of an inch long, circular or elliptical in shape; very flat and thin; olive-green on the dorsal surface, with a line of darker color on the posterior end, and whitish retractile tentacles on the back. Found creeping on under side of stones in tide-pools. GENUS ^Stylochopsis^ ^S. littoralis.^ About one half of an inch long; changeable in form, from broad oval to elliptical; color pale green, veined with a lighter shade on the dorsal side, flesh-colored on the ventral surface; numerous eyes arranged in irregular rows near the margin and in groups in front of the tentacles, also clusters of eyes on the tentacles. Found under stones between tide-marks. GENUS ^Leptoplana^ ^L. folium.^ Body flat; margin thin and undulated; shape leaf-like, but changeable; about one inch long and one half of an inch wide; color pale yellow, veined with a deeper shade; eyes in four groups near the anterior end. ORDER =TRICLADIDA= ("/Three-branched/") The triclads are divided into three groups: those of the fresh-water ponds and streams, those of the land and sea, known as planarians, and those of the sea. The planarians are the most interesting worms in the order. The triclads differ from the polyclads in being elongate in form and in having the intestine in three branches instead of in many. The mouth is midway in the length of the body, on the ventral side, and from it protrudes a pharynx, which is cylindrical or bell-shaped, and is capable of great dilatation. With the pharynx the worm, which is wholly carnivorous, envelops other worms, crustaceans, or any animal food. Several species are found on the under side of stones in tide-pools. [Illustration: PLATE XLVIII. Polyclad worm. Worm-tubes of Diopatra.] GENUS ^Planaria^ ^P. grisea.^ Oval or elliptical in form; anterior end truncate; posterior end rounded; color yellow or gray, with a light stripe; two black eyes surrounded with white; length one half to three quarters of an inch; width about one eighth of an inch. Found under stones between tide-marks. GENUS ^Procerodes^ ^P. frequens.^ One eighth of an inch long; brown or black above, gray below; has two kidney-shaped eyes; active and abundant. Found under stones near high-water mark. GENUS ^Bdelloura^ ^B. rustica.^ Body milk-white, smooth, thin. Found on /Ulva latissima/ (sea-lettuce). ^B. candida.^ Parasitic on the gills of the horseshoe-crab. GENUS ^Fovia^ ^F. Warrenii.^ Bright red, narrow, oblong. Found on eel-grass. ORDER =RHABDOCŒLIDA= Minute, active worms found among the red seaweeds. They are brown in color, and are marked by one or more transverse white bars. CLASS =NEMERTINEA=