7 8 STUART WELLER 



beneath the base of the Navesink marl. The other locality is in a 

 fine, more micaceous and argillaceous bed, immediately beneath 

 the marl. 



In this Wenonah fauna there is a return of many Merchantville 

 and Woodbury species, among them being Trigonia eufaulensis, 

 Axinea mortoni and Panopea decisa. Idonearca is also present, but 

 is much less conspicuous than in the Merchantville or the Marshall- 

 town. Among the Woodbury species which occur in the Wenonah 

 fauna, may be mentioned Cymella bella, which, although rarely 

 present in the Merchantville, was much more conspicuous in the 

 Woodbury fauua. Leptosolen biplicata is one of the very common 

 forms in the Wenonah fauna which was present both in the Wood- 

 bury and the Merchantville. The ponderous Gryphaea and Exogyra 

 of the Marshalltown fauna are absent, but Ostrea plumosa is some- 

 times a very common species. 



The faunal change in passing from the Wenonah to the Navesink 

 formations in Monmouth County is far greater than the change in 

 passing over the line between any two of the formations below. In 

 the fauna of the Navesink marl a new factor is introduced which is 

 entirely foreign to the earlier faunas of the area, the most character- 

 istic species of this new element being the cephalopod Belemnitella 

 americana and the brachiopod Terebratella plicata, both of which 

 are especially abundant and characteristic of this zone. We also 

 find a recurrence of the massive Gryphaea vesicularis and Exogyra 

 costata which characterized the Marshalltown beds below, but the 

 Exogyra is usually less abundant than in the earlier fauna. Ostrea 

 larva also occurs in great abundance, as it did in the Marshalltown 

 fauna, but it is a somewhat different variety of the species. In 

 place of the cephalopods Placenticeras and Scaphites of the "clay- 

 marl" faunas, Nautilus dekayi occurs in this fauna and also in the 

 fauna of the Red Bank sand next above. In the fauna of the beds 

 just beneath the base of the Navesink marl, Placenticeras placenta 

 occurs more frequently than in any other bed of the New Jersey 

 Cretaceous, associated with many other species common also to the 

 Merchantville or Woodbury formations. These facts, taken together 

 with the marked lithological change at the top of the Wenonah, are 

 strong evidence for placing the major dividing line in this portion 



