538 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 127 
Brachial interior with short and narrowly triangular chilidium ; cardinal proc- 
ess moderately long, slender, myophore forked, prongs moderately divergent. 
Measurements in mm,—Holotype (brachial valve), brachial length 8.3, width 
10.2, hinge width 4.6, thickness 7.1. 
Types.—Holotype: 117095a; unfigured paratype: 117095b. 
Horizon and locality—Pratt Ferry formation in Alabama: 0.2 mile southeast 
of Pratt Ferry, Blocton (15’) Quadrangle. 
Discussion.—Inasmuch as the true nature of the pedicle valve of this species 
is somewhat uncertain, the species is based on the brachial valve as holotype. 
This valve is distinctive and differs from all others known by its great depth, 
inflated flanks and fold, and subcarinate and strongly elevated fold. 
The species most suggestive of the Pratt Ferry one is Cliftonia grayae (David- 
son) from the Stinchar limestone group, Craighead, Girvan District, Scotland. 
TRIPLESIA SUBCARINATA Cooper, new species 
Plate 100, H, figures 35-40 
Shell small for the genus, syntrophoid in outline and profile. Valves unequally 
convex, sides narrowly rounded and hinge narrower than the shell width. Smooth 
exterior but exfoliated specimens with fine distant costellae. 
Pedicle valve slightly convex in lateral profile with a central tongue bent almost 
at right angles to the length. Sulcus originating at about the middle widening 
rapidly to occupy about three-fourths the width at the place of geniculation of 
the tongue. Flanks gently convex; slopes to margins moderately steep. Sulcus 
and tongue marked by a narrow, shallow median groove. 
Brachial valve moderately convex in lateral profile with the greatest convexity 
at about the middle; steeply subcarinate in anterior profile. Beak small, umbo 
narrowly rounded with a slight elevation continued anteriorly to join the fold 
which originates at about the middle. Fold narrowly rounded with somewhat 
swollen sides, separated from body of shell by narrow grooves. Flanks slightly 
inflated, with steep lateral slopes. Cardinal process a long slender fork. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
Holotype (pedicle valve) ........... 0.4 ? 11.0 8.0? 2.0? 
Paratype (brachial valve 117094b)... ? 9.2 11.0 8.0? 5.9 
Types.—Holotype: 117094a ; figured paratype: 117094b; unfigured paratypes: 
117094c-e. 
Horizon and locality.—Lebanon formation in Tennessee: At Columbia, Maury 
County. 
Discussion.—Triplesia subcarinata is suggestive of T. extans of the New York 
Trenton but differs in having the fold and sulcus originating near the middle 
of the valve instead of on the umbo as in the latter species. Besides this important 
feature the Tennessee species is smaller in size and has a sharper fold. Further- 
more, the young of 7. extans that correspond in size to 7. subcarinata are 
not nearly so deep nor so rotund as the New York species. 
