354 MALENTOZOA. SESSIL1A. 



1. Upas anatifera. Shell ovato-triangular, obtuse, 

 much compressed ; the lateral valves faintly striate, the 

 dorsal linear, arcuate, smooth or denticulate along the 

 middle, sulcate on the sides. Anas, a duck ; fero, to 

 bear or produce. 



2. Lepas striata. Shell ovato-triangular, obtuse, or 

 biangulate at the tip, much compressed ; the lateral 

 valves distinctly striate, and decussate, the dorsal linear, 

 arcuate, convex, subcarinate, deeply sulcate on the sides. 

 Stridtus, streaked. 



3. Lepas sulcdta. Shell ovato-triangular, acute, com- 

 pressed; the lateral valves deeply sulcato-striate, the 

 inferior with a distinct rib toward the margin, the dor- 

 sal linear-lanceolate, arcuate, convex, carinate, sulcate 

 on the sides. Sulcatus, furrowed. 



GENUS 2. SCALPELLUM. Animal much compressed, with 

 twelve pairs of much curved cirri ; shell oblong, acumi- 

 nate, gibbous on the dorsal margin, of thirteen pieces. 

 Scalpellum, a small knife. Leach. 



1. Scalpellum vulgar e. Shell oblongo- acuminate. 

 Vulgaris, common. 



ORDER II. MALENTOZOA SESSILIA. 



Shell conical or cylindrical, directly affixed. Sessilis, 

 sitting, or not supported by a stalk. 



FAMILY I. BALANINA. 



Animal sub cylindrical, convex, or depressed, suspended 

 in a testaceous covering; the branchiae two, laminar, 

 attached to the inner surface of the mantle ; the shell of 

 one or several pieces, united by their sides, open above, 

 but having there a pyramidal operculum of two or four 

 valves. Name from the genus Balanus. 



GENUS 1 . BALANUS. Shell conical or cylindrical, of six 

 pieces ; operculum of four triangular valves. BaXai/oy, 

 an acorn. 



1. Balanus balanoides. Shell conical, truncate, with 

 the valves smooth, or faintly striate, the opercular valves 



