496 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Subgenus Echinochama Fischer, 1887. 
Shell nearly regular and equivalve, attached when young by the right valve; lunule large. 
Chama arcinella Linnaeus. 
Chama arcinella Linnseus, Syst. Nat., ed. xn, p. 1139, 1767; Reeve, Conch. Icon., iv, pi. v, fig. 26, a, b, 1846. 
Shell somewhat quadrate, inflated, solid, nearly equivalve, with the beaks curved forward over 
a large, wide lunule; ligament partly buried; surface covered with very coarse granulations or small 
pustules, often arranged in rows, and having from eight to twenty curved, radiating, more or less 
spinose ribs; left valve with one curved cardinal, in front of which is a wide pit with small, radial 
crenations within it; right valve with a large, sculptured cardinal, which fits into the pit of the left valve; 
anterior muscle scar elongated; posterior scar oval; beak cavities deep or shallow; border of the 
valves crenate. Color white without, white or purple within. 
Length of a large shell without the spines, 43; height, 40; diameter, 30 mm. Same shell, 
measuring over all, length, 53; height, 55; diameter, 40 mm. 
Mayaguez Harbor, Porto Rico, a number of valves. 
The shell is attached when young by the right valve in front of the beak, generally to a piece of 
shell or to a specimen of its own species. Usually before it becomes adult it is detached, but still 
carries the scar or a fragment of the object to which it was fastened. Reeve figures a cluster of 
specimens of this species attached to each other. The nepionic shell is crimson or brown, unattached, 
and distinctly carditoid. 
Family VESICOMYACIDtE. 
Genus VESICOMYA Dali, 1864. 
Shell small, smooth, or concentrically striate; hinge like that of Mdocardia, but without lateral 
teeth; epidermis polished; beaks moderately prominent; lunule circumscribed by a groove. 
Mr. Smith, of the British Museum, has removed this group from the vicinity of the original 
Callocardia which, according to his observations and those of Sowerby, would belong to Caryatis 
Roemer and be placed in the Veneridx. As the gill of Vesicomya is remarkably distinct in structure 
from any of the Veneridx and indicates that it must be placed in a distinct family, the family name is 
here modified to accord with the present arrangement, having previously been used as Callocardiidx. 
Vesicomya pilula Dali. 
Diplodonta pilula Dali, Bull. Mus. Comp. Zool., IX, p. 136, 1881. 
Callocardia ( Vesicomya) pilula Dali, Blake Report, pt. I, p. 274, pi. vm, fig. 13, 1886. 
A few broken, worn valves of this species were obtained at Mayaguez. 
Family PLEUROPHORIILE. 
Genus CORALLIOPHAGA Blainville, 1824. 
Shell irregular, oblong, oval, or subcvlindrical, rayed, smooth or lamellar, very inequilateral, 
thin; anterior side short; posterior end inflated; beaks rather prominent; hinge with two oblique 
cardinals in each valve and one posterior lateral; pallia! line with a wide but shallow sinus. 
Coralliophaga coralliophaga Gmelin. 
Chama coralliophaga Gmelin, Syst. Nat., pj. 3305, 1792; Chemnitz, Conch. Cat., x, p. 359, pi. 172, figs. 1673, 1674; Blainville Man., 
pi. 76, fig. 3, 1825. 
A fragment of a bivalve, consisting of the beaks and a small part of the valves, which may be 
this species, was obtained at Puerto Real, Porto Rico. It is common in coral throughout the West 
Indies. 
Family CRASSATELLITID7E. 
Genus CRASSATELLITES Kruger, 1823. 
Shell equivalve, solid, subtriangular, with a distinct lunule; resilium in an internal groove; 
hinge usually with three cardinals in the right valve and two in the left; adductor muscle scars deep 
and rounded. It is Crassatella of authors, but not of Lamarck, 1799. 
Subgenus Crassinella Guppy, 1874. 
Shells small, compressed, subtriangular, with two cardinals in each valve, the posterior one often 
obsolete. 
