MALENTOZOA. PEDUNCULATA. 355 



acute, transversely rugoso-striate ; the base a thin calca- 

 reous, divergingly striate plate. Balanoides, resembling 

 an acorn. 



2. Bdlanus pusillus. Shell conical, truncate, with 

 the valves separated by narrow grooves, and longitudinally 

 rugose, with the surface roughish or punctured; the 

 opercular valves striate, the dorsal with their tips incur- 

 vate and rather obtuse. Pusillus, diminutive. 



3. Bdlanus communis. SheU conical, truncate, with 

 the valves often indistinct, longitudinally sulcate, with 

 prominent, compressed, obtuse, rugose ridges. Corn- 

 munis, common. 



4. Bdlanus costdtus. Shell conical, truncate, with 

 the aperture small, the valves indistinct, with prominent, 

 compressed, strong, ribs. Costdtus, ribbed. 



5. Bdlanus elongdtus. Shell conical, cylindrical, 

 clavate, or diversiform, with the base membranous, the 

 pieces close or united, transversely rugose at the base 

 and summit, longitudinally striate or costate. Elonydtus, 

 lengthened. 



A. B. elongdtus rugosus. Wrinkled. 



B. B. elongdtus angulosus. Angulated. 



C. B. elongdtus fistu losus. Pipe-like. 



D. B. elongdtus clavdtus. Club-shaped. 



6. Bdlanus cdndidus. Shell conico-cylindrical, with 

 the valves distinct, separated by wide depressed, longi- 

 tudinally striated areas. Cdndidus, white. 



GENUS 2. CLITIA. Shell orbicular, depressed, convex, 

 of four radiatingly ridged, interlocking valves. KXto-m, 

 a tent, or cottage ? Leach. 



1. Clitia Verruca. Shell of two very large and two 

 very small valves, all with large radiating, transversely 

 striated ridges. Verruca, a wart. 



GENUS 3. CETOPIRUS. Shell hemispherical, of six 

 pieces, with six elevated, longitudinally sulcate areas, and 

 six depressed minutely striated spaces ; operculum of 

 four inarticulated valves. Krjros, a whale ; 7mpa>, to pierce. 



1. Cetopirus balandris. Shell subhemispherical, with 

 the elevated areas deeply sulcate, and having from three 



