cragin.] DESCRIPTIONS OF SPECIES. 81 
II etc., at the western base of Malone Mountain, a short distance north 
?of its southern end, the cast bearing indications of feeble ribs about 
as in marcoui, but this form— perhaps modified by orogenic move- 
ments of the matrix— being longer, lower, and smaller-calibered than 
it is normally in the latter species. 
The species is named for the late Mr. Jules Marcou. 
Pholadomya paucicosta Roemer? 
PI. XVI, tigs. 5, 6. 
Pholadomya paucicosta F. A. Roemer, 1836. Versteinerungen ties Nord- 
deutschen Oolithgebirges, p. 131, PI. XVI, fig. 1. 
Form stout, curved-euneate-pyriform ; the umbonal region widely 
Bated transversely to the length of the shell; anterior region short- 
ned almost back to the large, prominently elevated, tangent umbones, 
vhich are thus made almost terminal; the anterior margin slightly 
raping; posterior region widened in the median plane, compressed, 
nost strongly so in the upper part, which tends to a keel-like form 
md gapes considerably ; base drawn upward rapidly in the anterior 
:>art, so that, in connection with the very salient beaks, the whole 
interior (including umbonal) moiety of the shell has an upturned 
ippearance; surface ornamented with coarse, unequal, concentric, 
j-ostelliform growth plications and furrows and apparently with 4 
\r 5 low folds radiating from the beaks forward and downward to 
he basal margin. 
Measurements. — The dimensions can be given only roughly. They 
jippear to average, for the larger specimens : Height, 52 mm. ; length, 
51 mm. ; breadth, 48 mm. 
Occurrence. — Not rare in the Malone Hills, a mile and a half east 
fi Malone station. Among 26 specimens there collected the mechan- 
cal distortion has been such that no two are quite alike. There is, 
jiowever, a central phase about which they are grouped and to which 
everal of them closely approximate, affording a sufficiently correct 
dea of the normal form ; and so different is the shell from any other 
! ound in these beds that it can be recognized in any of its false shapes, 
hough the radial markings are rarely well preserved and often not 
hown at all. A specimen was obtained by Doctor Stanton near the 
ailroad, about 2 miles east-southeast from Finlay station, in the 
lorthwestern foothills of Malone Mountain. 
Accepting for the European Upper Jurassic Pholadomya pav.ci- 
osta Roemer, the wide range of specific variation indicated for it by 
Moesch, a it seems impossible to separate the above-described Malone 
•pecies from it. 
"Monographic der Pholadomyen. In Abhandl. Schweiz. pal. Gesell., vols. 1 and L>. 
Bull. 266—05 m 6 
