TO GEOLOGY. 101 



urceolata (Lamarck). The genus has not been before 

 observed in this country, to my knowledge. 



GENUS ORBITOLITES. Lamarck. 



O. interstitia. Plate 6. Fig. 204 



Description. Orbitolites convex and cellular above, con- 

 cave, papillary and minutely porous below ; cells ovate ; 

 pores above interstitial ; pores below very numerous and 

 very minute. 



Diam. 3-20ths, Height nearly .1, of an inch. 



The segment is a magnified view. 



Observations. This is a beautiful little species, and re- 

 sembles somewhat in form the Orbulites lenticulata* (Lam- 

 arck). It is not, however, flat beneath. There being 

 no description of the pores, I cannot say if they differ in 

 this character. In the two specimens which I have of 

 this species, the grain of sand which occurs in the Lunu- 

 lites is not observable. They were not, however, taken to 

 pieces for examination. 



* Brogniart makes the following observations in referring to the 

 figure of this shell, " ce nom ayant etc deja donne par M. de Lamarck 

 a une coquille de la famille des ammonites, il m'a paru convenable de 

 restituer a ce polypier celui d'orbitolites que ce memo naturaliste lui 

 avoit donne precedemment, et qnr atrra ete probablement altere par 

 megarde." Desc. Geolo. des Environs de Paris, p. 398. 



