560 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
RHYSOSTROPHIA sp. 1 
Plate 32, D, figures 7, 8 
This is a small pedicle valve with deep sulcus and having a shallow spondylium. 
The ornamentation consists of narrowly rounded and closely crowded costellae. 
The specimen indicates a smaller species of the genus than hitherto seen in 
Nevada and one that is probably lower stratigraphically than the other known 
species. 
Figured specimen.—17228. 
Horizon and locality—Pogonip group (Desmorthis zone) in Nevada: On 
the west side of Goodwin Canyon, Eureka District. 
RHYSOSTROPHIA sp. 2 
Plate 112, A, figures I, 2 
This is a small species with rectangular outline but not so strongly transverse 
as R. transversa. The specimens measure 7 to 8 mm. wide and 5 and 6 mm. long. 
The pedicle valve is deeply sulcate, and the brachial valve has a strong, elevated 
fold. 
Figured specimens.—117162a,b. 
Horizon and locality—Table Head series (upper) in Newfoundland: At 
Table Point. 
Family BREVICAMERIDAE Cooper, new family ‘ 
Syntrophioidea having a sessile cruralium in the brachial valve. 
BREVICAMERA Cooper, new genus 
(Latin brevi, short; camera, chamber) 
Shell small, approaching 4 inch in width; broadly and transversely elliptical ; 
uniplicate ; surface paucicostate. Biconvex ; valves of subequal depth; hinge nar- 
row ; interareas reduced. 
Pedicle interior with small teeth ; spondylium short, dental plates short ; median 
septum short. 
Brachial interior with deep, narrow notothyrial cavity bounded by short sub- 
parallel brachiophore plates; brachiophores short, crescentic in section, tied to 
inner wall by short, inconspicuous fulcral plates. Brachiophores at place of ar- 
ticulation provided with a small articulating process opposite the fulcral plate. 
Brachiophore plates joining a callosity on the valve floor to form a sessile cru- 
ralium ; floor callosity extended anteriorly between muscle scars as a low median 
ridge ; muscle area small, divided into halves by the median ridge; posterior ad- 
ductors small and narrow; anterior adductors large and subcircular, situated 
posterolaterally of the anterior scars. 
Genotype.—Brevicamera camerata Cooper, new species. 
Discussion—The exterior features of this genus are suggestive of the syntro- 
phids in the long tongue of the pedicle valve and the corresponding high and nar- 
