MUSEUM OF COMPARATIVE ZOOLOGY. oul 
The peculiarity of the filling up of the tips of the beaks does not consist in 
there being mere pedestals or sockets for the feet of the ossiculum. The 
whole cavity seems evenly filled, and the ossicle stands, as it were, on a sort 
of floor; this is quite visible from without, through the translucent shell. It 
is a common thing to find the early whorls of Gastropods filled solid with 
shelly matter, but such cases are rare among the Pelecypods, if we leave out 
of account the usual thickening due to growth. 
Famiry PANDORIDZ. 
Genus PANDORA Hwass. 
Suscenus CLIDIOPHORA Carpenter. 
Of the Pandoride the southern coasts and the Antilles have several species : 
Clidiophora trilineata Say ; another form, of which one valve was described but 
not named by Miss Bush; Pandora (Kennerlia) glacialis Leach, which passes 
Hatteras, its southern limit not yet known; P. carolinensis Bush, described 
from near Hatteras, probably entering the Gulf of Mexico, and P. Bushiana, 
received from West Florida. This group, being chiefly composed of shallow- 
water species, is represented in the Blake dredgings only by worn left valves 
of one species. 
I may add, that in this genus, as in others, I regard anterior and posterior, 
right and left, from the anatomical standpoint. A singular discrepancy exists 
among authors in treating of this genus, as we find the rostrated or siphonal 
end of the shell frequently treated as anterior. As a matter of fact, it is pos- 
terior, as in other Pelecypods. 
Pandora (Clidiophora) carolinensis Busu. 
Pandora carolinensis Bush, Trans. Conn. Acad., VI. p. 474, 1885. 
Pandora oblonga? Sowerby, Dall, Bull. M. C. Z., IX. p. 109, 1881. 
Plate VIII. Figs. 8, 8a. 
Habitat. Charlotte Harbor, Florida, 13 fms.; Yucatan Strait, 640 fms., 
detached valves only. 
I presume that the valves above mentioned should rightly be referred to 
Miss Bush’s species. Whether both are referable to P. oblonga is a question 
on which opinions may differ, as the type of oblonga is said to be lost. 
They are not referable to P. trilineata Say (not Gould, etc.), which is a 
much elongated, slender, narrowly rostrated species with the beaks more an- 
terior even than P. brevifrons Sby.; the base roundly arcuated, the posterior 
cardinal margin concave, the anterior rounded from the beaks to the base, the 
