64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
to any of two or three species. It is similar to H. remota (Eichwald) 
as figured by Tschernyschew (1902, pl. 47, fig. II). 
Suborder TEREBRATULOIDEA Muir-Wood, 1955 
Superfamily TEREBRATULACEA Waagen, 1883 
Family CENTRONELLIDAE Waagen, 1882 
Subfamily CENTRONELLINAE Waagen, 1882 
ROSTRANTERIS MERRIAMI Cooper, new species 
Plate 12B, figures 12-26 
Shell small, longitudinally ovoid in outline, globular in profile. 
Sides and front rounded; anterior costate; 5 costae marking the 
brachial valve and 6 are on the pedicle valve. 
Pedicle valve forming almost a semicircle in lateral profile with 
the maximum convexity a short distance posterior to the middle. 
Umbonal region narrowly swollen; beak strongly incurved over the 
dorsal umbo. Anterior two-thirds marked by a low fold consisting 
of 2 costae separating a narrow and fairly deep groove. Flanks 
convex and very steep to the margins, marked by 2 additional costae. 
Brachial valve having about half the depth of the ventral valve, 
gently convex in the posterior two-thirds but strongly geniculated 
in a ventral direction about 5 mm. anterior to the beak. Maximum 
convexity at the point of geniculation. Anterior half marked by a 
fold, defined only at the front and consisting of 3 costae, a median 
one corresponding to the ventral groove and 2 lateral ones. Flanks 
moderately convex but with steep slopes to the margins. In anterior 
view this valve is provided with a long tongue that dovetails with 
a reentrant formed by the fold of the pedicle valve. 
Measurements in mm. 
Length Width Thickness 
Floletypesd:. ssacing eae oh. aa ele al avec 8.0 6.2 9G 
Patatvpe UL25A0OD))-sc).2 2s hs Bis ds « steams 8.0 6.5 6.8 
Interior —Loop about 4 mm. long in a shell 6.5 mm. long and 5.4 
mm. wide; median process of loop extending nearly to the front 
margin and slightly more than 2.3 mm. long. 
Types——Holotype, U.S.N.M. 125409a; figured paratypes, U.S. 
N.M. 125409b, 125560; unfigured paratypes, U.S.N.M. 125409¢, 
126985a,b. 
