INSTITUTE OF SCIENCE, PHILADELPHIA. 247 



just that Lea's name should be retained. In the remarkable similarity of the 

 young to the genus Odontostouiia the derivation of the group is perhaps in- 

 dicated, as Odontostomia is found in considerably older beds. The Actaoii 

 magnoplicatiis H. C. Lea (Sill. Journ. 1841), which has been doubtfully re- 

 ferred to this species as a synonym, appears from the type in the Philadelphia 

 Academy's collection to be really a broken Odontostomia. Among other 

 Eocene forms which have been referred by Conrad to Pyramidella or Obelis- 

 ais, 0. melanelliLS (Lea sp.) Conr. is an Actcsoji ; 0. perexilis Conr. is a 

 Syriiola ; 0. siriatns (Lea sp.) Conr. is probably an Odontostomia : the type is a 

 fragment which cannot be certainly identified; P. terebellata (Conr. non 

 Sby. ^ Pasithea lunbilicata Lea) is a Niso. The American Tertiary forms all 

 belong to the section Longcliceus of Morch. 



Of IVIiocene American species referred to this group, Pyramidella retiai- 

 lata Emmons, and 0. elaborata H. C. Lea, are small mitras. 0. canalictilata 

 Gabb, from the Miocene of Santo Domingo, has not been figured. The sup- 

 posed types at. Philadelphia comprise three or four species belonging to sev- 

 eral distinct genera, all loose in one tray together. Besides these, 0. Candida 

 Morch is known from the Post-Pliocene of Texas, as well as the recent fauna. 



Pyramidella arenosa Conrad. 



P. arenosa Conrad, Proc. Acad. Nat. Sci. Phila. i. p. 309, Nov., 1843 (unfigured). Em- 

 mons, Geol. Rep. N. Car., p. 268, fig. 154, 1858. 

 P. suturalis H. C. Lea, Trans. Am. Phil. Soc. i.x. p. 258, pi. 36, fig. 63, 1845. 



Miocene of the James River, at Petersburg, Va., and of the Purdy and 

 Guion marl-pits. Cape Fear River of North Carolina; Pliocene of the Croatan 

 beds, North Carolina ; of the Caloosahatchie and Shell Creek beds in 

 Florida. 



This species is distinguished by having both sides of the sutural chan- 

 nel minutely crenulated from the next species, which has only the an- 

 terior edge crenulated. This is a very dubious and probably invalid charac- 

 ter, by no means constant in recent specimens, and I have little doubt that 

 the following species should be regarded merely as a variety of the present 

 form. In all other respects they are identical and vary through a similar 

 series of mutations in any one stratum. 



Pyramidella crenulata Holmes. 

 Pyramidella [Obeliscus] arenosaTuomey and Holmes, Pleioc. Fos. S. C, p. 126, pi. xxvi. 



%• 17. 1857- 

 Obeliscus crenulalus Holmes, Post-Pleioc. Fos. S. C, p. 88, pi. xviii., figs. 14, 14 a, 1859. 

 Pyramidella alveata Conr., Am. Jour. Sci., 2d Ser. ii. p 398, 1846 (name only). 

 Obeliscus floridantis Morch, Mai. Blatt. 1875, p. T58. 

 Pyramidella tessellata Arango, Mai. Cubana, p. 161, 1S80, non Adams. 

 Pyramidella crenulata Dal!, Blake Gastr. , p. 331, 1889. 

 Pyramidella (^Obeliscus') suprapulchra De Gregorio, p. 158, pi. 15, fig. 30, 1890. 



