506 



LONSDALE ON MIOCENE CORALS FROM N. AMERICA. 



a. Portion of Cellepora informata magnified four times in linear dimensions. 

 It exhibits the irregular arrangement of the cells ; the occurrence of semi-glo- 

 bular mouthless cells, and the columnar structure of a fractured section. 



b. Cells greatly enlarged, to give the characters of the tubercle near the 

 proximal edge of the mouth, and the position of the gemmuliferous (?) vesicle 

 or chamber. The vertical section shows the unobliterated pores in the surface 

 of inferior cells. 



irregular the position of the cell, and in the structure of the outer 

 covering, the resemblance to Eschara or Escharina was much 

 greater than to the typical species of Cellepora ; nevertheless it 

 was deemed advisable to refer the Virginia fossils to that genus 

 provisionally. 



In what was considered a series of immature cells, the mode of 

 distribution agreed with that of parasitic Flustrce or Escharince, 

 the development having arisen from the distal extremity of mature 

 cells ; and several successive rows had been produced without the 

 appearance in the first series of a decided commencement of the 

 outer surface. Though there was no difficulty in detaching a frag- 

 ment of one of the minute irregular columns, with a perfect surface 

 on each plane, and consisting of three or four cells uniformly super- 

 imposed, as if developed successively from the underlying one, yet 

 it is conceived that the agreement was only accidental, and that the 

 cells were produced horizontally by means of the foramina situated 

 near the base of the walls. No progressive stages, from the im- 

 mature to the mature state, were observed ; but one of the former 

 had a very narrow porous band, which agreed completely in struc- 

 ture with that of the perfect outer covering. No decided proofs of 

 changes incident upon extreme age were noticed on the general 

 surface of the specimen ; and in the cells which had been over- 

 laid by one or more generations, the mouth was not uniformly 

 filled up, nor were the pores always obliterated or coated over by 

 the flooring of the superimposed cells. Examples of mouthless 

 cells occurred both in the somewhat regular layers, and in those 

 confusedly aggregated, the shape in the former instances being 

 normal, but in the latter globular (see figs, a, b), or of every pos- 

 sible inequality of outline. The gemmuliferous (?) chamber was 

 often wanting ; and where it occurred, it was not always on the 



