MOLLUSCOIDEA. 359 



width more than two-thirds of the length, the loop sharply 

 angular at the points of recurvature. Surface of both valves 

 marked by numerous lines of growth which are often crowded 

 towards the front of old specimens so as to form distinct varices. 

 Shell substance finely punctate, the punctae usually visible under 

 a hand lens, always more distinctly seen upon exfoliated surfaces. 



Remarks. This species is perhaps the largest Terebratuloid 

 shell known in any o<f the American faunas, and at the horizons 

 where it is found in the Cretaceous formations of New Jersey it 

 usually occurs in great numbers. It usually forms a very con- 

 stant bed at the summit of the Hornerstown marl where, through 

 several feet of sediments, the shells occur almost to the exclu- 

 sion of everything else. The species also occurs in the quartz 

 sand f acies of the Vincentown formation, sometimes in great num- 

 bers, but always in the form of internal casts. 



The specimen described by S. A. Miller as Terebratula gorbyi, 

 said to come from the Keokuk group at Edwardsville, Indiana, 

 is only an example of T. harlcmi. The type of this species, now 

 preserved in the Paleontological Collection of the Walker Mu- 

 seum at the University of Chicago, is a typical greensand speci- 

 men and never could have been collected from any Keokuk or 

 even any Paleozoic formation of America. Its true locality can 

 of course not be determined, but it has every appearance, litho- 

 logically and otherwise, of the specimens which occur in the Hor- 

 nerstown marl near New Egypt, New Jersey, and it is not im- 

 probable that the specimen originally came from that locality. 



Formation and locality. Hornerstown marl, near New Egypt 

 (i42 2 , I42 3 ), near Mullica Hill (182), near Woodstown (181) ;. 

 Vincentown formation, near New Egypt (146), near Deal (122),. 

 near Eatontown ( 1 1 1 ) . 



Geographic distribution. New Jersey ; ? Eocene of Maryland. 



Terebratula harlani van fragilis Morton. 

 Plate XXVIIL, Figs. 4-6. 



1829. Terebratula fragilis Mort, Jour. Acad. Nat. Sci. Phil., 

 ist ser., vol. 6, p. 75, pi. 3, figs. 3-4, (Not T. fragilis 

 Schloth.). 



