Maryland Geological Survey 455 



canal, larger body volution, and the somewhat sinuous outline of the 

 upper part of its outer lip, seem to require its separation, at least sub- 

 generically." — Meek, 1876. 



Serrifusus is one of the many ancestral types of Fusus which seem to 

 offer differences sufficient to warrant their isolation until a monographic 

 study is made of the entire group and the phylogenetic relationships 

 established once for all. 



Serrifusus nodocarinatus Whitfield 



Serrifusus (LirofususJ nodocarinatus Whitfield, 1892, Mon. U. S. Geol. Sur- 

 vey, vol. xviii, p. 64, pi. v, figs. 22, 23. 



Serrifusus nodocarlnatus Weller, 1907, Geol. Survey of New Jersey, Pal.. 

 vol. iv, p. 760, pi. Ixxxix, fig. 13. 



Description. — " Shell of medium size, abruptly fusiform in general out- 

 line; spire broad conical, the height from the broadest part of the body 

 volution being somewhat less than the diameter at its periphery ; beak 

 short, slender; volutions three or four (the specimen being imperfect), 

 somewhat biearinate in the middle where there is a nearly vertical, 

 obliquely flattened area or band, above which the surface slopes rapidly to 

 the suture and is very slightly concave ; below this point the volution con- 

 tracts very abruptly to the short, slender canal, leaving the body volution 

 somewhat compressed-discoidal or wheel-like in form, which in the speci- 

 men is possibly exaggerated by vertical crushing; periphery of the volu- 

 tions marked by rather strong, transverse node-like vertical folds, which 

 are also continued in less strength above and below, and the entire sur- 

 face is occupied by spiral ridges of considerable strength, but which alter- 

 nate in size on the lower part of the volution ; four or five of these revolving 

 ridges occupy the upper side ; about three mark the vertical space of the 

 periphery, and seven or more may be counted on the lower side of the 

 body volution, in the poorly preserved specimen used ; aperture not seen." 

 —Whitfield, 1892. 



This species is represented in Maryland by a single cast to which frag- 

 ments of the shell substance still adhere. 



Occurrence. — Monmouth Formation. Brooks estate near Seat Pleas- 

 ant, Prince George's County. 



