The line marking the junction of the front part and the front middle part is wavy. There are 28 of these in a line parallel to the ventral border of the front part. Of these ridges, 14 can be counted in a line parallel to the ventral border of the front.
Shell small, subglobular, white, the extreme portion of the anterior portion with a moderately deep sinus covered with a. The anterior part of the median part is crossed by 28 strong, toothed ridges which are separated by mere impression. Of these ridges, 21 are projected in a straight line from the ventral border of the anterior portion across the anterior portion of the median portion.
The middle part of the median part is concave and crossed by the weakened continuations of the tooth ridges. The middle part of the middle part appears as a rough groove, at the ventral end of which the strong knot is present. From this edge, strong denticulated ridges radiate fan-shaped over the rest of the anterior part.
Posterior Auricle narrow, almost claw-like, separated from the posterior part of the median part by a strong constriction.
SHIPWORMS OF THE PHILIPPINE ISLANDS BARTSCH 547
The outermost anterior part of the anterior part forms a shallow sinus and is covered by a fairly thick callus, which is partially reflected over the outer part of the anterior region. Posterior to this callus, the anterior part is crossed by slender ridges, which radiate fan-shaped from the callus posteriorly, and are closely approximated; actually fused with the callus and separated by spaces slightly wider than their posterior margin. Of these ridges, there are 51 in the type, and many have been lost to erosion.
The anterior part of the median area is narrow and marked by thin deticulate ridges, which are much narrower than those anteriorly and separated only by simple lines. Of these ridges, 26 are located in a straight line along the front of the median area parallel to the ventral border of the front. The intersection of the front part and the front part of the middle part forms a somewhat sinuous.
The middle part of the median part is almost as wide as the front part and is traversed by a continuation of strongly curved dentary ridges, which are here without serrations. The posterior part of the median part is considerably wider than the anterior and middle parts of the median part combined and is crossed by the continuation of the strong lines that cross the middle part.
SHIPWORMS OF THE PHILIPPINE ISLANDS BAETSCH 549
The junction of the anterior part with the front edge of the median part forms a shallow curve. The anterior part of the median part is marked by slender serrated ridges, which are arcuately separated by deep, narrow grooves. Of these ridges, 17 are present in a straight line across the anterior midportion from the basal margin of the anterior portion.
The individual teeth of these ridges bear doubly serrated cups, and the front teeth are about twice as large as the back. Middle part of median part wide, the anterior half of which is slightly convex, while the posterior half is slightly concave; both are traversed by the continuation of the anterior dental ridges which here take a decided turn, becoming much attenuated and toothless. posterior part of median almost as wide as anterior and middle together. It passes into a gentle depression directly at the rear ear and maintains a continuation of the undulating sculpture of this part.
The posterior auricle is counter-. rather large and poorly differentiated from the posterior part of the median part. The front and middle parts are connected in a distinct raised thread; the middle midrib is slightly rugose and terminates ventrally in a strong rounded knob; the auricle merges with the posterior median without any markings or shelves; it is for that reason that I am. to place this shell in the subgenus Psiloteredo, with a question mark;. the umbilical bones are strong and from their ventral edge an oblique. some irregular leaf extending parallel to the middle area through four-fifths of the length of the shell. has not been found and it will require their presence before we can give a firm systematic status to this species. THE SKI BORM OF THE PHILIPPINE ISLANDS BARTSCH 551the inward projection of the posterior part of the shell.
SHIPWORMS OF THE PHILIPPINE ISLANDS BARTSCH 551 the inward projection of the posterior part of the shell. Pallets un-
On the underside of the rni, in the lower part of this shelf, the broad blade bends down towards the ventral knob. Medium-sized shell, subglobular, anterior area with a rather large sinus, which is bordered by a thin callus that is reflected over the anterior area at the rim. Of these ridges 56 are present in the type, and many more have been eroded into the umbone.
Of these ridges, 40 appear in a plane projected across this area from the ventral edge of the front. The middle part of the median part is slightly concave and marked by a continuation of the dental ridge on the anterior part, which is here bent and toothless. The posterior part is about as wide as the anterior part of their middle part and differs from the posterior urculus by a deep constriction.
The posterior part is definitely projected over the posterior part of the median part, and extends nearly half into the cavity of the shell.
SHIPWORMS OF THE PHILIPPINE ISLANDS BARTSCH 553
It forms an enormous ear muscle that is very high and that is characterized by weak concentric lines coinciding with its basal margin. The posterior party swing-shaped, very widely expanded and placed in such a way on the posterior part of the median part. that over a definite shelf which is very thick at its free edge, it contains a large cavity behind which extends to the ventral margin. The umbonal portion, that is, about one-fourth the length of the posterior portion, is narrow and much thickened, while the rest is very widely expanded and concave, and marked by wave-like undulations coinciding with the ventral margin in apposition.
There is a strong blade that extends obliquely from the umbilical cord towards the belly button.
EXPLANATION OF PLATES
S. NATIONAL MUSEUM BULLETIN 100, VOL
