^RT. o NEW FOSSIL MOLLUSKS MAESHALL, AND BOWLES 5 



ECUADOREA, new genus 



Fossil pearly fresh-water mussels of the subfamily Hyrianae ^ 

 with plentiful radial sculpture similar to that of Diplodon and still 

 more similar to that of Hyria. The radial ribs are arranged in a V pat- 

 tern, each V nesting in a succeeding one. Posterior dorsal area with 

 several plicae crossing it obliquely to the margin. 



Type species. — Ecuado7'ea hibliana^ new species, described in this 

 paper. 



RemarTcs. — It is difficult to decide the relationships of this genus 

 to recent genera. Like Prodiplodon Marshall, from which it differs 

 mainly in the flutings on the posterior dorsal area, it stands midway 

 between Hyria Lamarck and Diplodon Spix. Its sculpture is more 

 like that of Hyria^ but it lacks the anterior clawlike projection, the 

 symphynote posterior wing, and the very oblique appearance caused 

 b}^ the anterior end being very narrow while the posterior end is very 

 broad. Several species of Hyria have somewhat similar flutings on 

 the posterior dorsal area. In form the shell is more like Diplodon, 

 but that genus in not so plentifully sculptured. 



ECUADOREA BIBLIANA, new species 



Plate 1, Figtjres 7, 8 



Shell rather compressed, subelliptic, slightly narrower in front. 

 Concentric sculpture of fine growth striae, with a few of the rest 

 periods a little accentuated. Radial sculpture of a number of riblets 

 so arranged as to form a series of V's, each nesting into the succeed- 

 ing one, and with other riblets at the front and back which if con- 

 tinued would form additional V's. The anterior prong of each V 

 is narrow, clear-cut, and nearly straight. The posterior prong is 

 heavier and more irregular and curves toward the front end of the 

 shell. At the lower end where the radial sculpture dies out the sur- 

 face is somewhat pimpled. The posterior dorsal area with several 

 (five or six) distinct cordlike flutings running across it to the margin 

 The dorsal and ventral margins both arcuate. 



Type. — U.S.N.M. No. 372843 measures : Length, approximately 33 

 mm; height, 24 mm; diameter, about 11 mm. It and a paratype 

 (U.S.N.M. No. 372844) come from Biblian, Province of Canar, 

 Ecuador. 



Remarks. — In sculpture this species closely resembles Ca^talia pazi 

 Hidalgo, of the Province of Imbabura, Ecuador, which, however, 

 does not have flutings on the posterior dorsal area. 



2 Simpson places this subfamily in the Unionidae, while Ortmann places it in the 

 Mutelidae. The latter will probably prove correct, but can not be accepted until the 

 supposed lasidium embryo of the latter is proved a mistake. See Marshall, Proc. U. S. 

 Nat. Mus., vol. 79, art. 23, p. 12, 1931. 



