1844.] 



319 



6. ESCHABA DIGITATA MortOH. 



a. b. Bifurcated branch, natural size and magnified, consisting of immature 

 cells with the outer surface almost wholly open, and with no indications of a 

 distinct mouth. • u r 



c. d. Portion of a bifurcated branch, with mature cells. To the right of 

 figure d is a cell with an uniformly depressed surface, and conjectured to have 

 performed the office of a gemmuliferous vesicle : to the left are irregularly 

 foraminated cells. 



e. /. Portion of an aged branch, with the characters of the mature cells 

 obliterated by external additions and the production of irregular tubercles. 



g. Magnified side view of a branch, to show the position of the lateral con- 

 necting foramina within the cells ; and of the small or defective cells exhibited 

 also in the edge of figure d. 



Branched, branches compressed, dichotomosed ; cells hexagonally 

 pyriform, separated by a fine lineal groove ; surface sloped inwards 

 from the periphery ; mouth semicircular or semi-oval; no accessory 

 or gemmuliferous vesicles observed; lateral connecting foramina 

 two, terminal one. 



See Dr. Morton's Synopsis Org. Rem., Cretaceous Group, United 

 States, p. 79. pi. xiii. f. 8. 1834. 



Dr. Morton states that this fossil strongly resembles Lschara 

 dichotoma of Goldfuss (Petref. tab. viii. f. 15.), a Maestricht 

 coral, and there is a perfect agreement in the mode of growth, as 

 well as a general resemblance in the form of the cell ; but a con- 

 siderable difference, in structural details, is visible when the two 

 fossils are compared. The cells in both cases are hexagonal, but 

 the sides of those composing the Maestricht Eschara, as given by 

 Goldfuss, are very nearly, if not quite equal, and they are shghtly 

 but uniformly curved ; whereas, in the Timber Creek specimens, the 

 sides are almost invariably unequal, the proximal and distal being 

 considerably smaller than the lateral, and the curvature is variable 

 in amount and direction, giving the cell a pyriform aspect. - The 

 relatively broad grooves between the cells in Eschara dichotoma 

 are represented in the American species by a fine line : the mouth 

 of both fossils is semi-circular, but more completely so m the 

 Maestricht than the Timber Creek coral ; in Goldfuss's species, 



