114 MONOGRAPH OF THE FOSSIL POLYZOA OF THE 



desire, and shall therefore defer to the opinion of d'Orbigny, based on perhaps the 

 most extensive study of the subject ever yet undertaken. 



The generic divisions are based mainly on the mode of growth of the colony. This 

 is, as far as we are aware, a good distinction. The only deviation we have observed, 

 is in the case of a colony of our species Membranipora jperampla, in which three layers 

 are superposed. This one instance, however, appears to be accidental, just as one 

 species frequently encrusts another. 



Fam. ESGHARID^, d'Orb. 1851. 



Subfam. ESCHARIN^. 



ESCHAEA, Lam. 1801. 



Gen. char. — Colony flattened, dichotomous, rarely lamellar, with cellules on both 

 faces, arranged back to back, on each side of a germinal plate. Cellules simple, opening 

 near the anterior end and of moderate size. No special pores nor fossets, although 

 the top of the cellule is sometimes pierced by numerous irregular pores. This genus 

 can be distinguished from all others having the same mode of growth of the colony, 

 by the absence of special pores and fossets. From Latereschara it differs by the cel- 

 lules being arranged in longitudinal rows and quincunx instead of lateral rows. 



E. digitata, Morton, Synopsis Cretaceous, p. 79, pi. 13, f. 8. 



K digitata, Lonsdale, Quart. Jour. Geol. Soc. London, vol. 1, p. 73, figs, c, d, g, 

 (a and b ?) exclus. e and f. 



E. digitata, d'Orb., Prod. Pal. Strat. v. 2, p. 264, No. 1074. 

 Colony flattened, dichotomous, branching generally in the same plane. Cells hex- 

 agonal, arranged in quincunx, separated by a slightly depressed line ; surface concave, 

 especially towards the opening, which is slightly in advance of the centre. Opening 

 rounded anteriorly, posterior edge straight and bounded by a delicate raised lip, some- 

 times with a small tooth in the centre. The anterior and posterior margins of the 

 cells are straight, the anterior lateral margins curved outwards, and the posterior late- 

 ral margins are consequently concave. Abortive cells not uncommon, especially near 

 the margins. The extreme edges of the branches are perforated by numerous small 

 holes, apparently the openings of abortive cellules. We have never been able to 

 detect ovarian vesicles after examining several hundred specimens. This species is 

 by far the most abundant of the Cretaceous Polyzoa of New Jersey. We obtained 

 nearly two cubic inches of specimens from less than a pint of the soft limestone from 

 near Mullica Hill. 



In the Quarterly Journal of the Geological Society of London, vol. 1, page 73, 

 Lonsdale gives an extended description of this species, with several wood cuts. We 

 fear that that he has inadvertently confounded two, or perhaps three, species under 



