CONCflOLOGY. 



31 



3. Genus Balamis. PI. V. 



Animal. Body sessile, inclosed in an operculated shell ; 

 branchiae numerous, placed ' in two rows, unequal, articulated, 

 cilliated ; each composed of two cirri, supported by a peduncle, 

 and exsertile ; mouth with four transverse dent&ted jaws, with four 

 hairy palpi-like appendages. 



Shell. Formed of six distinct coronary valves, one dorsal, one 

 ventral, and two pairs of laterals, with a calcareous support ; 

 operculum forming a sort of pyramid, by four articulated pieces 

 in the aperture of the shell. Inhabits the Frith of Forth. Twenty- 

 nine species. 



Balanus angulosus. 

 B. negrescens. 

 B. roseus. 

 B. amphimorphus. 

 B. crispatus. 

 B. stalaciferus. 

 B. patellaris. 

 B. perforatus. 

 B. rugosus. 

 B. latus. 

 B. plicatus. 

 B. galeatus. 

 B. spinosus. 

 B. placianus. 



B. 



Balanus tintinabulus. 



B. calycularis. 



B. miser. 



B. subimbricatus. 



B. palmatus. 



B. dupluconus. 



B. semiplicatus. 



B. Isevis. 



B. punctatus. 



B. sulcatus. 



B. cylindraceus. 



B. ovularis. 



B. radiatus. 



B. fistulosu9. 

 Lyonsii. 



4. Genus Acasta. PI. V. 



Animal. Body without a peduncle, and inclosed in a multi- 

 valve shell, found in sponge or marine bodies, mouth and tenta- 

 cula placed in the apex, or upper part of the body. 



Shell. Patella-shaped, sub-conical ly oval, formed of six lateral 

 unequal valves forming the base, which being convex prevents 

 the shell from standing by itself in an erect position, when de- 



