628 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Triplesia ? ambigua Haut, 12th Rep. New York State Cab. Nat. Hist., p. 65, 1859. 
Camarella ambigua Mitier, Amer. Paleozoic fossils, p. 107, 1877. 
This species has long been difficult to place. The closely spaced and fairly 
long dental plates of the pedicle valve preclude placing the species in Camerella, 
and the lack of the forked cardinal process of the brachial valve excludes it 
from Triplesia. The brachial valve shows the same type of hinge plate as that 
of Drepanorhyncha, and the plates are attached at the posterior of the notothyrial 
cavity, the sutures showing as two short lines on the umbo of the brachial valve. 
Types—Figured hypotypes: 111344a,b. 
Horizon and locality—Hull formation in New York: At Trenton Falls, 
Russia, and Middleville. 
DREPANORHYNCHA OTTAWAENSIS (Billings) 
Plate 128, E, figures 20-31 
Porambonites ? ottawaensis Bittincs, Geol. Surv. Canada, Paleozoic fossils, vol. 1, p. 140, 
fig. 117 (adv. sheets, 1862), 1865.—MILLER, North American geology and paleontology, 
p. 362, fig. 508, 1880. 
Rhynchotrema ottawaensis (Billings) ScaucueErt, U. S. Geol. Surv. Bull. 87, p. 369, 1897. 
Orthorhynchula ottawaensis (Billings) ScHuUcHERT and Cooper, Mem. Peabody Mus. Nat. 
Hist., vol. 4, pt. 1, p. 42, pl. 16, figs. 6, 9, 13, 1932. 
Rhynchotrema ? ottawaensis (Billings) Witson, Geol. Surv. Canada, Bull. 8, p. 121, pl. 11, 
figs. 9-11, 1946. 
Horizon and locality Rockland formation in Canada: At Paquette Rapids, 
Ottawa River, Ontario. 
Types.—Lectotype: G.S.C. 1143g; paratypes: G.S.C. 1143?, 1143¢,h; figured 
hypotypes: 85338a,b. 
Family RHYNCHOTREMATIDAE Cooper, new family 
Rhynchonellacea with rudimentary deltidial plates and well-formed dental 
plates in the pedicle valve; brachial valve provided with a small cruralium, with 
or without a cardinal process, long crural processes. Cruralium without covering 
plates as in Camarotoechia. 
Genus RHYNCHOTREMA Hall, 1860 
Plate 138, A, figures 1-7 
Rhynchotrema HAtt, 13th Rep. New York State Cab. Nat. Hist., p. 68, 1860—Wane, Geol. 
Soc. Amer. Mem. 42, p. II, 1949. 
For many years this genus has been misunderstood. The only species name 
used with the genus when Hall first proposed the name was increbescens. Wang 
(1949, p. 11) points out that this species thus becomes the type of the genus. 
Under the heading Rhynchonella imcrebescens Hall defined the characters of 
Rhynchotrema from specimens taken at Iron Mountain, Wis., specimens that 
are now assigned to Lepidocyclus capax. In spite of this inconsistency the genus 
rests on R. increbescens. Wang finally fixed the type of R. increbescens as the 
