Bulletin - United States National Museum . a Fig. 24.—SCALPELLUM ANTILLARUM X 3,WITH DETAILS OF 6, ROSTRUM AND C,CAKINA. THE BAENACLES IN THE U. S. NATIONAL MUSEUM. 63 The scutum is about twice as long as wide, rhomboidal, with acuteapical umbo. The occludent and lateral margins are subparallel andsomewhat convex. The tergal margin is concave, the basal straight. The tergum is triangular, conspicuously larger than the occludent margin is about three-fourths as long as that of thescutum and is strongly arched, the acute summit being thus somewhatrecurved. The scutal margin is a littl
Bulletin - United States National Museum . a Fig. 24.—SCALPELLUM ANTILLARUM X 3,WITH DETAILS OF 6, ROSTRUM AND C,CAKINA. THE BAENACLES IN THE U. S. NATIONAL MUSEUM. 63 The scutum is about twice as long as wide, rhomboidal, with acuteapical umbo. The occludent and lateral margins are subparallel andsomewhat convex. The tergal margin is concave, the basal straight. The tergum is triangular, conspicuously larger than the occludent margin is about three-fourths as long as that of thescutum and is strongly arched, the acute summit being thus somewhatrecurved. The scutal margin is a little longer than the occludent; thecarinal margin is a little hollowed near the apex, elsewhere convex. The carina is long and equably curved, its apical umbo at about theupper fourth of the carinal margin of the tergum. The roof is flat. Fig. 25.—Scalpellum semisculptum x 3, with details of rostrum b, and carina, c. between low but strong bordering ribs. The sides are narrow below,wider above; basal margin convex. The upper latus is trapezoidal, the scutal margin concave, carinalmargin very short, about one-third the length of the scutal. Thetergal and basal margins are about equal and straight. The umbo isterminal; a narrow rib runs from it to the baso-carinal angle. Theplate is finely, rather sharply striate radially. There is no rostrum, or merel}^ a sunken linear rudiment. Therostral latus is as high as wide, the basal margin very much shorterthan the others; scutal margin straight, horizontal. The umbo pro-jects a little at the upper occludent angle. From it a narrow diagonalrib runs to the lowei lateral angle, the surface below this rib beingradially striate. The two rostral latera rise in a low welt or irregu-lar ridge at their occludent suture. The inframediau latus is very narrow, almost linear, and about a
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
