472 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Order TELEODESMACEA. 
Superfamily MY ACE A. 
Family GASTR0CH4BNIDiE. 
Genus GASTR0CH7EN A (Spengler) Cuvier, 1817. 
Shell regular, equivalve, inequilateral, ovoid, with the beaks anterior, widely gaping at the 
anterior base. Sculpture concentric. The animal forms flask-shaped excavations in shells, corals, 
and coral rocks; sometimes it is without a burrow, when it forms a shelly, inclosing tube covered 
with extraneous material. 
Gastrochaena cuneiformis Spengler. 
Gastrocluena cuneiformis Spengler, Nova Act.. Sot'. Hafn., II, p. 179, figs. 8-11, 1788. 
Shell much inflated, subsolid, suhovate or pear-shaped, gaping excessively at the anterior base, 
the gap narrowing and extending nearly or quite to the posterior end; beaks low, placed at the 
extreme anterior part of the shell, which is narrow and sharply angular below at the gap; there is 
sometimes a wide, shallow depression running from the beaks to the posterior base; sculpture rudely, 
irregularly concentric. Color white. 
Length, 18; height, 10; diameter, ,8 mm. 
Several specimens in coral, Mayaguez, Porto Rico. 
Family SAXICAVIDvE. 
Genus SAXICA VELLA Fischer, 1870. 
Shell small, equivalve, thin, inequilateral, gaping, subtrapezoidal, obliquely angular behind; 
hinge with a subobsolete tooth in the right valve, fitting into a cavity in the left cardinal margin; liga- 
ment short, prominent; pallia! line with a wide shallow sinuosity. 
Saxicavella sagrinata, n. sp. Plate 55, fig. 16. 
Shell small, rounded triangular, compressed, umbones small, flattened; anterior end shorter; 
surface irregularly concentrically undulated as if by stages of growth, dull, minutely granular or 
sagrinate, as if dusted; form as figured, with no defined angle or earina extending downward and 
backward from the umbo; periostracum very thin, pale yellowish, hardly discernible; the substance 
of the shell subtranslucent; interior polished; hinge with a single obscure tooth in front of a small 
nymph for the ligament. 
Length, 5.5; height, 3.7; diameter, 2 mm. 
One right valve at station 6062, Mayaguez Harbor, Porto Rico, in 30 fathoms, sand. 
This species is shorter, more compressed, and less angular than the S. plicata of Europe; it 
somewhat resembles a BaMerotia, hut has a different hinge. 
Family CORBULIILE. 
Genus CORBULA ( Bruguiere ) Lamarck, 1797. 
Valves unequal, the right usually larger, both more or less beaked behind; in the right valve 
there is a single, large tooth below the beak, with a deep resiliary pit behind it and no lateral laminae; 
left valve with a deep pit below the beak, into which the tooth of the right valve falls, having an 
elevated process in front of it and sometimes a sort of tooth behind the pit; beaks prominent, that of 
the right valve usually superior to that of the left; sculpture often discrepant; pallial line with or 
without a sinus. 
Section ALOIDIS Megerle, 1811. 
Corbula disparilis d’Orbigny. 
Corbula disparilis d’Orbigny, Moll. Cubana, n, p. 283, pi. xxvii, figs. 1-4, 1845. 
Shell solid, very inequivalve, the right valve gibbous, with a very high beak, which is curved 
inward and forward, and a high, sharp, posterior ridge sculptured with strong concentric ridges which 
mostly fade out on the posterior slope; hinge tooth small, placed well forward; ligamental pit large; 
left valve much smaller and less convex than the right, having faint, concentric sculpture and few to 
rather numerous radiating ribs which do not reach to the beak, which often look like cracks in the 
