PHYLOCENV OF FUSUS AND ITS ALLIES. I9 



species have as yet been recorded from the Old World Tertiary. 

 Modern representatives are found in the Antillean waters of the New 

 World, but they are not very common. The series is, however, well 

 represented in the Indo-Pacific seas where most of the living species 

 occur. 



Tertiary Species. 



FUSUS HENEKENI Sowerby. 



1850. Ftisus hcnekeni Sowerby, Quart. Journ. Geol. Soc, vol. 6, p. 49. 



1876. Fiisus hcnekeni Sowerby, Guppy, Quart. Journ. Gcol. Soc, vol. :i2, p. 52 ^, 



pi. 28, fig. 6. 

 Not Fusus hcnekeni G.^BB, Journ. Acad. Nat. Sci. Phil., 2d ser., vol. 8, p. 350, 



pi. 45, fig. 31. 



The protoconch of this species is typically fusoid, though some- 

 what more depressed than that of most .species. It consists of one 

 and one half volutions, the last half or two third volution being fur- 

 nished with numerous smooth, narrow and closely crowded vertical 

 ribs. The protoconch ends abruptly, though no strong varix occurs, 

 while the ornamentation of the conch begins as abruptly. The whorls 

 of the conch embrace rather closely ; they are round and are furnished 

 with round, broad and thick ribs, which arc separated by narrower 

 interspaces. Strong, nearly uniform spirals encircle the shell, the 

 three peripheral ones being somewhat more pronounced than the 

 others. Above these occurs another spiral, and below them two addi- 

 tional ones. The spirals remain simple as far as the sixth or seventh 

 whorl, when intercalated spirals appear. In the later whorls the lines 

 of growth are lamellose, producing a strongly cancellated appearance. 



The whole aspect of this shell, as well as its more detailed char- 

 acteristics, recall forcibly the recent species F. tiirriciiliis from Chinese 

 waters, and F. cucosmius from the Caribbean sea. Its most marked 

 distinction lies in the closer embracing whorls, which give the shell a 

 somewhat shorter and stouter aspect; and in the stouter ribs which 

 give it a somewhat more rude aspect. On the whole, it must be 

 confessed that very little difference exists between the recent and the 

 Tertiary species from the same region. 



In one specimen in the collection of the Philadelphia Academy 

 the intercalated spirals do not appear until the tenth or last whorl, 

 the ribs at the same time becoming obsolete. CXher specimens 

 with obsolete ribs on the last whorl have been observed. This 

 feature, showing individual senescence, also occurs in the recent 

 species. 



Localities: San Domingo (Phil. Acad. Sci.) ; Jamaica (Phil. Acad. 

 Sci.). 



Horizon: Bowden beds of the Upper Oligocene or Chipolan stage 

 (Dall— Table Tert. Hor. N. Am., p. 340). 



