158 Trans. Acad. Sci. of St. Louis. 



Eocene, a slender and much elongated species, with a long 

 slender and gradually tapering beak. The series of small 

 rounded close-set nodules, forming the subsutural collar, are 

 completely independent of the relatively large and oblique 

 costae, which are less than half as numerous. The strong 

 even spiral lyrae are also a peculiar feature. 



Among other described genera of the tribe Pleurotomini, 

 special mention should be made of Eopleurotoma Coss., very 

 rich in species in the European Eocene and in the American 

 Lower and Upper Claiborne, where it is represented by such 

 species as nupera Con. ( = rugosa Lea and protapa De Greg.), 

 gemmata Con. ( = tupis De Greg.), liaeninghausi Lea, sayi 

 Lea ( = monilifera Lea), desnoyersi Lea (=Hntea Con. and 

 properugosa De Greg.) and nodocarinata Gabb. In Europe 

 Borsonia and Epalxis are well known fossil genera, but 

 Cordiera would seem to belong rather to the Pseudotomini, 

 as far as disclosed by published descriptions and figures, and 

 is apparently not closely allied to Borsonia. The American 

 Borsonia plenta belongs to Protosurcula , as stated before, and 

 is not related to the true Borsonia, which is exclusively 

 European. 



There are some other distinct genera among our fossil 

 species which are not further dwelt upon at present, princi- 

 pally because of lack of material. Among these types of 

 more or less isolated genera may be mentioned Drillia 

 prosseri Harr. and Pleurotoma plutonica Csy., which are 

 congeneric, and the following apparently unique types: car- 

 lottae, cainei and texanopsis, of Harris, exiloides Aid., nasuta 

 Whitf . and lesueuri Lea. 



Clavini. 



This tribe is less extensive than the Pleurotomini, but is 

 nevertheless composed of numerous generic groups, which are 

 less isolated among themselves than those of the foregoing 

 tribe, a condition due in a great measure to the fact — as be- 

 fore stated of the non-operculate series, — that the Clavini 

 are largely modern in development and include comparatively 

 few extinct types. Many Eocene fossils assigned to that most 



