308 BULLETIN OF THE 
shell described by D’Orbigny as 7. rugosa ‘‘ Conrad,” but which Conrad had 
never described. I have not seen D’Orbigny’s figure. 
Thracia phaseolina Kiener. 
(2?) Thracia phaseolina, Kiener, Dall, Bull. M. C. Z., TX. p. 110, 1881. 
Habitat. Yucatan Strait, 640 fms., one valve. 
The comparison of this specimen with the fine series of this species in the 
Jeffreys collection has confirmed the original identification. 
Gexus ASTHENOTHAIRUS (Cpr. Em.) Dat. 
Asthenotherus Carpenter, Ann. Mag. Nat. Hist., XIII. p. 311, 1864. 
Shell inequivalve, inequilateral, truncate and slightly gaping behind, resem- 
bling Periploma in shape; beaks not fissured; no external ligament; hinge 
linear, toothless and without fossetue; a wide X-shaped ossicle attached to the 
posterior slopes of the domes of the beaks above and behind the hinge-margin. 
Pallial sinus deep; gills like Periploma, siphons separated ¢ foot small. Type 
A. villosior Cpr., Cape St. Lucas. 
This group differs from Lyonsia in its Periploma-like shell, in having a trans- 
verse wide ossicle instead of a longitudinal narrow or triangular one; in being 
anteriorly prolonged instead of posteriorly extended, and probably in the 
character of the soft parts, which could not be well studied in the single dry 
specimen available. It would, indeed, seem to be a Periploma or Anatina, 
destitute of the fossettes and their contained cartilage; in which the transverse 
ossicle remains and the beaks are unfissured. The brown ligamentary basis on 
which the divaricating feet of the bridge-like ossicle are planted, is visible on 
each side through the shell, the brown lines simulating in position and appear- 
ance, to a hasty glance, the fissures of Periploma. It is sufficiently separated 
from Alicia by the edentulous hinge. 
The original and not very clear diagnosis of Dr. Carpenter does not mention 
the ossicle, though the latter is still adhering (though not in its place) to one 
of the valves of the type in the National Museum. The “spongy ligament” 
he refers to, is the brown cementum which originally held the ossiculum. 
The original publication was to be followed by detailed notes, which remained 
unpublished at the time of the author’s death, which took place all too soon 
for science. 
Asthenotherus Hemphillii, n. s. 
Shell small, yellowish white, concentrically striate, with a filmy epidermis, 
left valve slightly smaller than the right, subovate, posteriorly truncated and 
slightly gaping; beaks in the posterior third of the shell, the anterior part 
rounded like the small end of an egg-oval; base rounded, rising toward the 
