216 SYSTEMATIC PALEONTOLOGT 



ESCHAEA (??) DIGITATA Morton.' 



Plate LX, Figs. 10, 11. 



JEschara digitata Morton, 1834, Syn. Org. Rem. Cretaceous Group, p. 79, pi. siii, 



fig. 8. 

 Eschara digitata Lonsdale, 184.5, Quart. Jour. Geol. Sec. London, vol. i, p. 73, figs. 



c, fZ, g, {a and h?) exclus. e and/. 

 Eschara digitata d'Orbigny, 1850, Prod. Pal. Strat., vol. ii, p. 264. 

 Eschara digitata Gabb and Horn, 1863, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. 



V, p. 114. 



Description. — Zoarium bifoliate, branching dicliotomously ; branches 

 flattened, acutely elliptical in cross-section, iisnally 2.5 to 3.0 mm. wide. 

 Zooecia hexagonal, regularly arranged in quincunx, about 0.55 mm. long 

 and 0.38 wide, bounded by a slightly imjDressed line; surface concave, 

 especially toward the aperture which is situated usually just in front of 

 the center. Aperture semielliptical, rounded in front, straight behind, 

 0.10 to 0.12 mm. wide. Normally developed and perfect, the posterior 

 border of the aperture is slightly raised and bears a delicate lunarium- 

 like curved plate which extends into the aperture. Abortive cells, pos- 

 sibly of the nature of vicarious avicularia, are frequent but seem to be 

 entirely restricted to the edges of the zoarium and to those portions 

 lying just beneath the axes of bifurcation. They are distinguished from 

 the other cells by their subcircular and usually much smaller apertures. 

 Ooecia unknown. The species occurs abundantly in the Upper Creta- 

 ceous at Mullica Hill, Timber Creek, and Vincentown, IST, J. 



Occurrence. — Aquia Poemation. Upper Marlboro (rare). 



Collection. — Maryland Geological Survey. 



I Of course this species does not belong to the genus Eschara as now understood. 

 Like Bijlustra torta it belongs near or to the genus Onychocella Jullian, which is 

 variously regarded, by some as a mere section of Ifembranipora, by others as a distinct 

 genus or even as the type of a new family, while Gregory makes it a member of the 

 Microporidae. At present I regard Onychocella, taking such a form as Ifembrauipora 

 angulosa Reuss, as a typical species, as clearly entitled to generic rank and as probably 

 representing a distinct family. It would, however, to say the least, be premature to 

 place either Bijlustra torta or Eschara digitata under Onychocella, since neither accords 

 strictly with the more typical species of the proposed genus. When raised to the 

 rank of a family it is highly probable that other generic groups will be established 

 into which these species would fall more naturallj' than into Onychocella proper. 

 Careful Mr. Waters has already instituted a second genus of the Onychocella type — 

 Vibracella — for Flustrellaria trapezoidea Reuss, while it may yet become desirable to 

 employ some of the names proposed by d'Orbigny for related types. Under these 

 circumstances I prefer leaving the species where Gabb and Horn placed them. 



