SECONDARY AND TERTIARY FORMATIONS OF NORTH AMERICA. 145 



The position of the special pore in this is remarkable. It is placed invariably be- 

 hind the mouth, arises from the lateral third of the cellule and may be either on the 

 right or left hand side. Occasionally two contiguous cellules show the pore on differ- 

 ent sides, though this is rarely the case. The ovarian vesicle is moderate in size, 

 placed, as usual, immediately in advance of the mouth, and is semiglobular and en- 

 tirely without ornament. 



MULTIPORINA, G. and H. 



Colony testaceous, encrusting submarine substances, composed of numerous super- 

 imposed layers, always attached by their whole under surface and never rising in free 

 plates or branches. Cellules having the general characters of the family grouped 

 irregularly. Mouth terminal or nearly so, and having one special pore placed be- 

 hind it. 



Eesembling Reptoporina, this genus differs from it in always having in adult colonies 

 numerous layers superimposed instead of consisting of a single layer. In other words, 

 it bears the same relation to Porina and Reptoporina as Reptocelleporaria does to 

 Eschara and Cellepora. 



M. umbilicata, G. and H., fig. 27. 



Cellepora umbilicata, Lonsd. Quart. Jour. Geo. Soc, vol. 1, p. 507. Id., d'Orb. 



Proc, vol.3, p. 136, No. 2561. 

 Reptocelleporaria umbilicata, d'Orb. Pal. Fr., vol. 5, p. 423. 



Colony composed of numerous layers, encrusting shells, branches and other sub- 

 marine substances, in such a manner as to entirely hide their original form ; generally 

 taking en a very nodose or tuberculose appearance. Cellules, irregular both in size 

 and shape, arranged without order, and with the central and anterior portion generally 

 a little elevated. No distinct division between the cells externally. Mouth placed 

 anteriorly but not always terminal, transverse, varying from semilunar to subquadrate, 

 but always without sharp angles; border apparently thickened, slightly elevated, 

 especially at the proximal margin a special pore is placed about half way between 

 the mouth and the proximal end of the cellule. Surface marked by a row of pores at 

 the extreme edge of the cellule; and sometimes by a few pores scattered over the rest 

 of the cellule. 



Between the mouth and the special pore, generally two, sometimes three, and rarely 

 but one of these small pores will be seen. We observed no ovarian vesicles. 



Miocene, Petersburg, Va. 



Lonsdale says that the border of the mouth is not thickened. We have observed in 

 several well marked instances, decided thickening not only surrounding the mouth, but 

 extending down the middle of the cellule so as to reach and sometimes to form a 

 border to the special pore. In some cases this thickening is a little exaggerated, thus 



