866 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
tears the shells apart and leaves them in too poor condition for good specific 
description. 
The fossils associated with C. trentonensis are those of the lower Edinburg 
or Oranda. Christiania is abundant in both of these formations, but it seems 
impossible to place C. trentonensis with either the Edinburg or Oranda species 
of Christiania. In the absence of more detailed information about the pedicle 
valve accurate comparison is impossible. The brachial interior of a single speci- 
men is not adequate for specific identification of specimens taken from widely 
different geographic and stratigraphic realms. 
Types——Cotypes: New York State Mus. 
Horizon and locality—Rysedorf conglomerate (pebbles of group 5) in New 
York: Rysedorf Hill, near Albany. 
CHRISTIANIA TRENTONENSIS BREVIS Butts 
Plate 215, D, figure 13 
Christiania trentonensis brevis Butts, Virginia Geol. Surv. Bull. 52, pt. 2, p. 100, pl. 95, 
fig. 1, 1942. 
This species is based on three cotypes. Two of these are young forms of 
Christiania auriculata Cooper, new species, and the other is a fine brachial in- 
terior of Bimuria lamellosa (Bassler). The writer here selects the latter speci- 
men, 97536a (pl. 95, fig. 1), as lectotype of C. trentonensis brevis Butts. This 
selection makes this species a synonym of B. lamellosa (Bassler) and clears the 
way to establish C. auriculata on adult forms. 
Figured specimen.—g7536b. 
Family STROPHOMENIDAE King, 1846 
Strophomenacea having either normal or reversed convexity of the valves and 
a small foramen in the pedicle valve. 
Genus KIRKINA Salmon, 1942 
Kirkina Satmon, Journ. Paleont., vol. 16, No. 5, p. 509, 1942. 
KIRKINA MILLARDENSIS Salmon 
Kirkina millardensis SaLmon, Journ. Paleont., vol. 16, No. 5, p. 599, pl. 87, figs. 34, 35, 1942. 
Types—Holotype: Columbia Univ. 25917; figured paratype: Columbia 
Univ. 25918. 
Horizon and locality—Pogonip group, Point of Rocks, Millard County, 
Utah=Lehman formation (zone N of Hintze). 
RHIPIDOMENA Cooper, new genus 
(Greek rhipidos, fan; mene crescent) 
Shells generally large, attaining a length of about 2 inches and a width of 
nearly 23 inches; generally wider than long, usually somewhat parallel sided; 
