392 BULLETIN: MUSEUM OF COMPARATIVE ZOÜLOGY. 
straight; pallial sinus deep; valves soleniform, truncate behind and rounded iu 
front; teeth lamellar, the posterior series much elongated, few in number. 
Unless the differences, when all the characters of Phaseolus ovatus are known, 
prove greater than now appears, Silicula can hardly rank higher than as a sub- 
genus of Phaseolus, especially if, as seems likely, species intermediate in form 
should turn up. 
Phaseolus (Silicula) patagonicus Darr, n. sp. 
Shell small, thin, elongate-oval, very inequilateral, anterior side shorter, 
anterior end rounded, anterior dorsal slope nearly straight; posterior slope very 
slightly curved and descending; posterior end bluntly rounded, not truncate, not 
emarginate, slightly smaller than the anterior end ; outer surface smooth except 
for faint incremental lines, covered with a thin, polished, pale olive periostracum ; 
beaks @eroded); a well-marked internal pit under them; anterior hinge line with 
two short horizontal teeth; posterior with four elongate, straight, overlapping 
lamellae ; interior of the valves white, porcellanous, with a large pallial sinus 
rounded behind, not very deep; muscular scars small; on the disk inside of the 
pallial line, extending backward and upward from the anterior adductor scar, 1$ 
a series of somewhat irregular but more or less continuous small scars which 
enclose a large oval area of which the upper boundary is the hinge line, and 
which reaches back to about the middle of the shell. Length, 8.4; anterior end, 
2.0; alt. 4.2; max. diam. 1.8 mm. 
U. 8. S. * Albatross,” station 2783, on the west coast of Patagonia, southern 
Chile, in 8. lat. 51° 2, in 122 fathoms, mud, bottom temperature 48° F, U. S. N. 
Mus. 96,914. 
Only a single valve of this species came to light, the umbo being eroded, but 
the characters are abundantly sufficient to separate it from the North Atlantic 
species, 
Arcacea. 
Limopsidae. 
LIMOPSIS Sasso. 
Limopsis Sasso, Giorn. Ligustico, di Sci. Let. ed Arti, Genova, 1827, 1, p. 476; type 
Arca aurita Brocchi, fide Sacco. 
Pectunculina Orbigny, Pal. Franc. Terr. Cret., 1844, 3, p. 182; 1st species, Pectunculus 
scalaris Sowerby. 
Trigonocaelia Nyst et Galeotti, Bull. Acad. Sci. Bruxelles, 1835, 2, p. 289; 1st 
species, Pectunculus granulatus Lamarck. 
Felicia Mabille et Rochebrune, Miss. du Cap Horn, Moll., 1889, 6, p. H 115, sole ex- 
F. jousseaumei M. & R., p. H 116, pl. 7, fig. 9a-b. 
Cosmetopis Rovereto, Note prev. Pelecip. Tongr. Lig, Atti Soc. Ligust., 1898, 
9, p. 177; type, Limopsis retifera Semper. 
