342 THE PALEONTOLOGY OF MINNESOTA 
[Lingula philoniela. 
" The width at one-fourth the length from the beak is usually one-fourth less 
than it is at one-sixtH the length from the front margin. The following are the 
measurements of a specimen of the ordinary form: 
"Length, 12^ lines; width at 3 lines from beak, 6i lines; width at 2 lines from 
front, 9 lines. 
"The largest specimen found measures nearly one inch and a half in length." 
The surfaces of the valves from the mid-length to the anterior margin are 
marked by a few prominent radiating, continuous, or intermittent striations. The 
concentric growth lines in passing the radiating striae are more or less reflexed 
posteriorly. 
Of this species we have seen but a single example in a good state of preserva- 
tion. It was discovered some years ago by Mr. W. H. Shelton, and is from the 
Trenton Shales near St. Charles in Winona county, Minnesota. The rather strongly 
convex valves without indications of a median depression, and the gradually diverg- 
ing lateral outline, will readily separate it from Lingula quadrata Hall,=L. redilater- 
alis Emmons. 
Formation and locality.— From the Trenton shales, in section six, Fremont, Winona county, Minne- 
nesota. Also in the Blaclc River formation of Murray bay, lower St. Lawrence river, Canada. 
Mus. Reg. No. 4973. 
Lingula Philomela Billings. 
PLATE XXIX. FIGS. 7.8. 
1862. Lingula Philomela Billings. Palajozoic Fossils, vol. i, p. 49, tig. 53. 
1863. Lingula Philomela Billings. Geology of Canada, p. 161, fig. 133. 
1892. Lingula Philomela Hall. Palaeontology of New York, vol. viii, pt i, pi i, tig. 8. 
Original description. — "Very elongate oval; width a little less than half the 
length ; front margin rather narrowly rounded with a small space in the middle 
straight or sinuate ; sides for about two-thirds the length straight or very gently 
convex; the apical extremity appears to be obtusely angular, but this still remains 
doubtful, as no specimens with this part perfect have been collected. The shell is 
rather strongly convex, most prominent at or about the mid-length. There is a 
shallow concave sinus extending all along the median line from near the apex to 
the front margin. Surface with fine crowded imbricating striaj of variable size, 
the smaller just visible to the naked eye, and the larger partaking of the nature 
of squamose interruptions of growth. Color in the l)la:?k limestone black. A 
specimen in gray limestone showing the interior in a state of exfoliation is light 
grayish-brown, but this may be owing to some circumstance in the fossilization of 
the shell. 
"Length 16 lines; width 7 lines," 
