182 SYSTEMATIC PALEONTOLOGY 



prominent, profoundly channelled at the suture, the margin of the 

 channel carinated in young shells. Length, 3 inches. Conrad, 1861. 



" Compared with F. coronatus, this species, when adult, is compari- 

 tively shorter and more inflated, with a shorter spire, much coarser 

 revolving lines, which with the more numerous, more obtuse tubercles, 

 give the shell a very different appearance from the coronatus. In an 

 adult specimen of the latter species there are 13 spiniform tubercles on 

 the body whorl. In the allied species, when adult, there are 17 much 

 less elevated, more irregular, and more obtuse tubercles." Conrad, 

 1843. 



This variety stands intermediate, as regards the development of 

 tubercles between the typical coronatum and canaliculatum. The first 

 four whorls of the latter species are indistinguishable from those of 

 rugosum. This caused the confusion of the species so evident in the 

 early literature. In the later stages of development there was a ten- 

 dency for the tubercles to disappear, and some of the Miocene forms 

 show in the adult an approximation to this character of their descend- 

 ants. The species is perfectly distinct from the adult of canaliculatum. 



Length, 170 mm. ; diameter, 90 mm. 



Occurrence. — St. Maey's Formation. St. Mary's River, Cove Point. 

 Choptank Formation. Jones Wharf, Greensboro. Calvert For- 

 mation. Plum Point. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 U. S. National Museum, Philadelphia Academy of Natural Sciences. 



FuLGUR ALVEATUM (Conrad). 



Busycon alveatum Conrad, 1S63, Proc. Acad. Nat. Sci. Phila., voL xiv, p. 583. 



Busycon alveaiurn Conrad, 1866, Amer. Jour. Conch., voL ii, p. 68, pi. iii, fl^. 7. 



Fulgur pyrum var. incile, Dall, 1890, Trans. Wagner Free Inst. Sci., vol. iii, pt. i, 

 p. 113. 



Description. — " Fusiform; spire prominent, scalariform; angle of 

 whorls situated much above the middle, not tuberculated ; summits chan- 

 nelled and margined with a carina, which is most conspicuous on the 

 tody whorl, and beneath it is a flattened space. Length 3^^ inches, 

 width U. 



" Locality, St. Mary's River, Md. 



