250 NEW-YORK FAUNA — MOLLUSCA. 
ORDER V. CIRRHOPODA. 
Anima. enveloped with a mantle in the form of a sac, which is open only behind, enlarged 
at the inferior portion, terminated above by a certain number of pairs of cirri, which are 
long, corneous, articulated, ciliated and curving at the summit. Head not distinct, wtth- 
out eyes or tentacles ; mouth with lateral corneous dentated and articulated jaws. Gills 
in pairs on each side at the base of the first cirri ; anus central at the base of this tube. 
Sueut very variable in form, and composed (except in one genus) of many valves, ad- 
herent either directly or indirectly by means af a fleshy tube. Marine. 
FAMILY BALANIDA. 
Anima resembling those of the Lepade, but without peduncle, and with its branchi@ in the 
form of two fringed wings attached to the internal surface of the mantle. Marine. Suet 
solid, conical or cylindrical, formed of one or more pieces united laterally, open at the base, 
or closed by a membranous or calcareous partition by which it adheres ; always open above, 
but furnished there with a pyramidal opercle consisting of two or four valves. 
Oss. About ten generic groups have been described. 
GENUS CORONULA. Lamarck. 
Animal with the characteristics of the family. Shell depressed, formed of six triangular 
pieces, conoid, truncated at its extremity; walls very thick, with radiating cells. Opercle 
of four smal] triangular valves, joined to the opening of the tube by a membrane. 
CoRONULA DIADEMA. 
Lepas diadema, Lin. C. id. Gourp, Invertebrata of Mass. p. 12. 
Description. Shell globose-conical, truncated at the tip. Surface with twelve triangular 
compartments : six with the tips downwards, plain and transversely striated; six with the 
tips upwards, and with four rounded ribs marked across with beaded folds. Orifice mostly 
closed by a membrane, through a fissure in which, closed by two valves, the arms are pro- 
truded. 
Height, 1°0. Diameter, 1°5 - 2:0. 
