464 
THE PALEONTOLOGY OF MINNESOTA. 
LRhynchonella (?) antlcostiensis. 
Formation and locality. — A very characteristic and common species of the upper portion of the 
Hudson River group; a few specimens have also been secured from the upper portion of the Galena, which 
as far as can be determined, are referable to this species. In the Hudson River group at Spring Valley 
and Granger, Minnesota; Graf, Iowa: Iron Ridge, Stockbridge and near Clifton, Wisconsin: Wilmington, 
Illinois; near Cape Girardeau, Missouri; Ohio; Indiana; Kentucky, and Anticosti. In the Galena near 
Cannon Falls and near Rochester, Minnesota. 
Collectors— John Kleckler, M. W. Harrington, W. H. Scofleld and the writers. Also in the collection 
of Dr. C. H. Robbins, of WykolT, Minnesota. 
Mns. Reg. No. ]77, 4092, 4095, 5547, 8196-8199. 
Rhynchonella (?) ANTicosTiENSis BilUngs. 
a h c 
Fig. 34. Rhynchonella anticostiensis BiUings. a, b, c, different views of a specimen. From "Paheozoic 
fossils of Canada." p. 142. 
1862. Rhynchonella anticoatiensis Billings. Palaeozoic Fossils, vol. i, p. 142, flg. 119A-C. 
1863. Rhynchonella anticostiensis Billings. Geology of Canada, p. 211, fig. 212. 
Compare with Rhynchonella argenturbica White. Report of the U. S. Geological and Geographical 
Survey west of the 100th Meridian, vol. iv, p. 75, pi. iv, flg. 12. 
Original description : " Subpentagonal ; apical angle about 80° ; side nearly straight 
or slightly convex for rather more than half the length from the beak, then curving 
to the edge of the mesial sinus; front nearly straight for the breadth of the sinus; 
side view oblong; front, dorsal and ventral sides nearly straight; umbo of dorsal 
valve abruptly curved in to the base of the beak of the ventral valve, -which is 
conical, erect and scarcely incurved. Ventral valve with a deep mesial sinus, 
becoming obsolete at two-thirds the length from the base; dorsal valve with a 
strong mesial elevation which, on approaching the umbo, disappears and is succeeded 
by a scarcely perceptible sinus, which continues to the summit. Surface with 
eighteen or twenty radiating angular ridges, crossed by close zigzag imbricating 
striae; three ribs in the ventral sinus and four on the dorsal mesial elevation.'' 
The more or less erect beak of the ventral valve, and the conspicuous deltidial 
plates of R. anticostiensis, remind one much of species of Rhi/nchotreta Hall. This 
form is distinguished from R. neenah Whitfield by its greater triangular outline and 
in the four continuous plications of the less elevated median fold. 
Formation and locality. — Common in the upper beds of the Hudson River group at Wilmlpgton and 
Savannah, Illinois; Graf, Iowa; Wisconsin, and English Head, Anticosti. 
Collector.— C. Schuchert. 
Mus. Reg. Nos. 8201-8203. 
