042 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
This is à common and variable species from the Gulf of California to the 
Galapagos Islands. 
LEPTOTHYRA CARPENTER. 
Leptothyra (Carpenter Ms.) Dall, Amer. Journ. Conch,, 1871, 7, p. 130; type, 
Turbo sanguineus L. New name for Leptonyx Carpenter, preoccupied in 
vertebrates. 
Leptonyx Carpenter and Adams, Proc. Cal. Acad. Sci., 1864, 3, p. 176; not of Gray, 
1887. 
Collonia Philippi, Handb. Conch., 1858, p. 206; not of Gray, 1852, 
Cantrainea Jeffreys, P. Z. S. Lond., 1883, p. 109; type, Trochus peloritanus Can- 
traine; Monterosato, Nom. Conch. Medit., 1884, p. 49. 
Cantraineia Fischer, Man. de Conch., 1885, p. 812, 
Homalopoma Carpenter, Suppl. Rept. Brit. Assoc., 1863, pp. 588, 627, olim. for 
Turbo sanguineus Linné; name not validated, and withdrawn by Carpenter 
as preoccupied in Zodlogy. 
The shell which Carpenter regarded as the Turbo sanguineus of Linné and 
upon which his genus was really based, is described by Pilsbry as a distinct (Cali- 
fornian) species under the name of Leptothyra carpenteri. 
The Anadema caelata A. Adams was regarded as a subgenus of Omphalius by 
H. and A. Adams in 1854, but is considered to be a Leptothyra by Pilsbry. It 
has a very peculiar ample vaulted umbilicus and seems to me, though perhaps 
related to Leptothyra, to be sufficiently distinct to be retained. If not, the 
name would replace Leptothyra, having seventeen years priority, and not being, 
so far as I can discover, otherwise ineligible. 
Leptothyra panamensis DALI, n. sp. 
Plate 5, figure 9. 
Shell large for the genus, white, brilliantly pearly within, covered with an 
Opaque creamy white outer coat and a brilliantly polished translucent periostra- 
cum; apex eroded, followed by about three subsequent turbinate whorls; major 
spiral sculpture of three strong distant keels, of which one appears on the spire; 
close to the second the suture is laid, giving the effect of a very minute channel; 
on the last whorl the second is at the periphery and more distant from the first 
keel than from the third, which forms the margin of the base; the relative dis- 
tances of these keels may vary somewhat with the individual; beside the keels 
the whole surface is covered with fine spiral threads with wider interspaces, there 
are about a dozen between the first and second keels; there is no axial sculpture 
except lines of growth; base rounded ; aperture round except where angulated 
by the keels; body with a thin callus; pillar thickened, with a small obscure 
tooth at the anterior end, where the adjoining lip is slightly patulous; outer lip 
simple, throat pearly, smooth ; operculum lost. Height, 9.5; height of aperture, 
5.5; max. diam. 11.0 mm. 
