MOLLUSCA. ■ 823 



Say. The two forms differ chiefly in the outline of the cross- 

 section, B. compressus being much more compressed towards the 

 ventral side. The type of B. ovatus was from Monmouth 

 County, N. J., while that of B. compress'm was from the upper 

 Missouri country. The New Jersey specimens, so far as they 

 have been observed, all agree in essential details with the type of 

 B. ovatus, but in the west both forms seem to^ occur along with 

 intermediate forms which seem tO' connect the twoi types. In 

 his studies upon the Cretaceous faunas of the north-west, Meek^ 

 has recognized the two' forms as distinct species, identifying both 

 of them from the upper Missouri country, and he has usually been 

 followed by authors. Whitfield,^ however, would consider the 

 two forms as geographic variations only, of one general species, 

 and would refer all the Western examples to- B. compressus and 

 the eastern ones to B. ovatus. Whatever may be the status of 

 the twO' species, or whatever may be the relationship of the east- 

 ern and western forms, there can be nO' doubt as to the proper 

 reference of the New Jersey specimens toi B. ovatus, as this was 

 the first of the two forms described, and if either name is ever 

 abandoned it will be B. compressus; however, it will probably 

 always be a matter of convenience toi retain the two names for the 

 two forms of shells, even though it may be shown that in some 

 localities their characters intergrade. 



Formation and locality. — Merchantville clay-marl, Lenola 

 (163) ; Woodbury clay, Lorillard (102) ; Navesink marl, Atlan- 

 tic Highlands (108), near Holmdel (194), near Walnford 

 (148^), Crosswick Creek (147*, 195), Mullica Hill (1692). 



Geographic distribution. — New Jersey, Alabama, Dakota, 

 Montana, Colorado. 



Baculites asper Morton ?. 



Plate CIX., Figs. &-?. 



1834. Baculites asper Mort., Synop. Org. Rem. Cret. Gr. U. S., 

 p. 43, pi. I, figs. 12-13, pi. 13, fig. 2. 



' Rep. Inv. Cret. and Ter. Foss. Up. Mo. pp. 394-397- 

 ' Pal. N. J. vol. 2, pp. 277-278. 



