186 



The family is represented by 24 living species, two of which 

 antedate to Pliocene times ; by 15 Eocene species, 4 of the Paris- 

 basin, 1 from Alabama, and 10 herein described. 



Genus Trichotropis. 



synopsis of species. 

 Spire-whorls medially angulated. 1. T. angulifera. 



Spire-whorls flattened or sloping behind. 



Costated, lira.' crenulated ; outer lip lirate. 



2. T. tahulata. 

 Transverse and spiral ornament of fine threads. 



3. T. suhquadrata. 

 Spire-whorls rounded. 



Spirally lirate, transverse ornament not prominent. 

 Lirae 3, pullus lirate ; outer lip sulcate within. 



4. T. triplicata. 

 Lir?e 5, pullus smooth ; outer lip smooth within. 



Whorls rapidly increasing, lin\? equal. 



5. T. accrescens. 

 Whorls slowly increasing, medium lira prominent. 



6. T. quinqueUrata. 

 Lir^e 10 or more, pullus and outer lip lirate. 



Lir^e equal. 7. T. apicilirata. 



Lira3 alternately stout and slender. 



8. T. intei'Iineata. 

 Spirally lirate and conspicuously costate. 



Lirse many slender, pullus obscurely lirate. 



9. T. costata, 

 Lira3 4 prominent, pullus lirate. 10. T. fenestixita. 



The species may be arranged into two sections, according to 

 whether the embryonic whorls be ornamented or not. Section I., 

 in which the embryonic whorls are lirate, contains tahulata, suh- 

 quadrata, triplicata, apicilirata, interlineata, costata, fenestrata ; 

 Section II., w4th smooth embryonic wdiorls, includes angidifera, 

 accrescens, and qui7iqueHrata. There are no close alliances with 

 Parisian species, though T. triplicata presents some analogy with 

 Mesostoma grata, Desh., and T. angulifera has a distant resem- 

 blance to J/, angidata, Desh. 



1. Trichotropis angulifera, >q-)ec. nov. 



Shell minute, thin, slenderly fusiform, imperforate. Whorls 

 six ; spire elevated, ending in a prominent obtuse apex consist- 

 ing of two smooth whorls, the first of which is relatively small 

 subglobose, with tip centrally immersed. 



Spire-whorls three, medially angulated, the periphery defined 

 by a broad flat rib, between which and the anterior suture are 



