504 LONSDALE ON MIOCENE CORALS FROM N. AMERICA. 



mediate rows of foramina, and in the occurrence at the distal 

 extremity of each cell of a shallow circular hollow or chamber. 

 These structural differences appear to have a constant dependence 

 upon each other ; all the quincuncial species examined by the 

 describer having a similar chamber, and all with parallel rows 

 having intermediate series of large foramina. Moreover, in the 

 published figures of Lunulites with alternate cells, as those of 

 Lun. umbellata given by M. de France (Atlas, Die. Sc. Nat.), and 

 copied by M. de Blainville (Man. d'Actinol. pi. 72. f. 1.), the situ- 

 ation of the oral aperture and of the chamber is fairly expressed 

 in the general magnified figure, though less happily in the three 

 separate cells (fig. a) ; and in the representation of Lun. rhom- 

 boidalis given by Groldfuss (Petref. pi. 37. f. 7.) the chambers are 

 well delineated and have a strong boundary, but are alluded to in 

 the description as oral apertures. M. Michelin, also, in his account 

 of Lun. intermedia, a quincuncial species, says, " chaque grand pore 

 est accompagne d'un plus petit, qui lui est inferieurement place." 

 (Icon. Zoophy. p. 75.) In Crag and Touraine Lunulites the 

 arrangement of the cells equally influences the position of the 

 chamber ; and in the genus Fenestella * the species with parallel 

 cells have an intermediate row of pores or small chambers ; while 

 those with quincuncial series have a chamber analogous in position 

 with that at the distal extremity of the cells of Lunulites. It has 

 been deemed right to solicit attention to these characters, because 

 they do not appear to have received the consideration they merit ; 

 and because the perfect analogy between the position and nature 

 of the cavities in quincuncial species with the chambers in Eschara 

 and Escharina, supposed to be receptacles for maturing gemmules, 

 may assist in forming a correct opinion respecting the inter- 

 mediate rows of foramina or cavities in Lu?iulites and Fenestella. 



The specimen examined was only 2\ lines in diameter ; but 

 it presented many different conditions of the cells. Along the 

 irregular margin were a few round chamber-apertures, with well- 

 defined boundaries, but the plane of the opening was oblique to 

 that of the outer surface of the cells. Similar apertures, occupying 

 a nearly analogous position, occurred over the whole surface of the 

 specimen, and had preserved their characters unaltered, whatever 

 changes the cells had undergone. This invariableness appears to 

 be a property by which the chambers may be always readily dis- 

 tinguished from other structures. The cells immediately suc- 

 ceeding the margin exhibited large central open spaces more or 

 less fringed by projecting points ; and the development of the 

 outer covering was apparently effected, as in other species, very 

 irregularly, the process in some cells towards the margin being 

 more advanced than in others farther from it. In the most 

 matured cases, short of a perfectly continuous surface layer, a 

 small opening was preserved near the distal extremity, not very 



* See Appendix A. (vol. i. ), Fenestella, in Mr. Murchison, M. de Verneuil, 

 and the Count von Keyserling's work on the Geology of Russia. 1845. 



