Genus Haplocy theridea Stephenson, 1936 



Haplocytheridea multiclef ta Swain and Brown, 

 n. sp. 



Plate 2, Figure 4 



Shell subquadrate to subelliptical in side view, 

 greatest height a little posterior to middle ; dorsal 

 margin gently convex; ventral margin nearly 

 straight, slightly sinuous owing to small anterior 

 concavity; anterior margin broadly and more or 

 less uniformly rounded; posterior margin more 

 narrowly curved, extended below, subtruncate 

 above. Valves distinctly unequal in size, the left 

 larger, overlapping and extending beyond edge of 

 right along all except anterior margins. Valves 

 moderately convex, rising rather abruptly from 

 margins as seen in edge view, general surface of 

 right valve more or less flattened, that of left 

 valve more convex. 



Each valve has a narrow, anteromedian sinuous 

 furrow that extends from near dorsal margin to 

 slightly ventral to midheight, a low swelling oc- 

 curs anterior to furrow; left valve with a small 

 dorso-median submarginal elevation; subventral 

 furrows lie anterior and posterior to main antero- 

 median furrow ; bottom of these auxiliary furrows 

 pitted. 



Hinge of left valve consists of an anterior denti- 

 culate socket containing about seven cross den- 

 ticles, an interterminal very finely crenulate groove 

 and a posterior denticulate socket that has five 

 or six cross bars ; hinge of right valve, correspond- 

 ingly, bears terminal denticulate toothlike eleva- 

 tions and a crenulate bar. Inner lamellae narrow, 

 line of concrescence and inner margin slightly sep- 

 arated anteriorly ; radial canals short and number 

 about 20 anteriorly, not clearly seen along other 

 margins ; normal canals numerous, more or less 

 arranged in vertical rows corresponding to small 

 surface pits. Muscle scars not observed. 



Length of holotype shell 0.63 mm, height 0.38 

 mm, convexity 0.30 mm. 



Relationships. — The hingement and other gen- 

 eral shell characteristics ally this species to Hap- 

 locytheridea, although the elliptical form is some- 

 what atypical. The form of the shell is close to 

 Cytheridea amygdaloidea (Cornuel) Alexander 

 (1929, p. 69) C!=Dolocy theridea by Howe and 

 Laurencich, 1958, p. 273), but the pitted grooves 

 on the surface of the present species are distin- 



guishing features. J. H. Neale (personal commu- 

 nication) has pointed out the close similarity of 

 our species to Cyamocy theridea Oertli in oval 

 shape and hingement. That genus, however, is 

 described as having a distinct anterior vestibule, 

 a feature which is only weakly developed in our 

 species. 



Occurrence. — Rare in Lower Cretaceous, prob- 

 ably of Washita (Albian) age, DuPont water well 

 No. 6, Lenoir County, North Carolina, 733-743 

 feet. 



Haplocytheridea lunarea Swain and Brown, n. sp. 



Plate 2, Figures 3a, b 



Haplocytheridea ? sp. aff. H ? plummeri (Alex- 

 ander) Swain, 1952, U. S. Geol. Survey Prof. 

 Paper 234-B, p. 79, pi. 8, fig. 15. 

 The external features of the specimens from 

 the Hatteras Light well were described in detail 

 by Swain and the present specimens appear to be 

 the same species. The diagnostic characteristics 

 are the subpolygonal outline, angulatecl dorso- 

 median and posterodorsal margin, spinose an- 

 terior margin, and distinct widely spaced, medium- 

 size surface pits. 



Length of holotype shell 0.73 mm, height 0.46 

 mm, convexity 0.37 mm. 



Relationships — The outline of this species is 

 similar to that of H. ? bruceclarki (Israelsky) 

 (1929, p. 11) of the Marlbrook Marl of Arkansas 

 and to other species of the Upper Cretaceous, but 

 lacks well defined subvertical rows of median pits 

 in small furrows that characterize those species. 

 H. ? punctura Schmidt (1948, p. 425) of the Up- 

 per Cretaceous of Delaware is similar in general 

 shape and surface ornamentation but is more tri- 

 angular and with less angulatecl posterodorsal 

 margin and more pointed posterior end than the 

 present species. 



Occurrence. — Rare in deposits cited as of Eagle 

 Ford (upper part of Atkinson) age by P. L. and 

 E. Applin (written communication) in Coastal 

 Petroleum Company's No. 1 Larsh well, Jefferson 

 County, Florida, core 3,445-3,451 feet; also in 

 beds of Black Creek ( ?) and Eutaw ( ?) or Austin 

 age, Esso Standard Oil Company's No. 1 Hatteras 

 Light well, in drill cuttings from 3,550-3,560 feet 

 and below. 



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