178 CRETACEOUS PALEONTOLOGY. 



If the foreign. Belemnitella element introduced in the Mount 

 Laurel-Navesink fauna had persisted, and had supplanted in any- 

 notable degree the older faunas in the region, instead oi being a 

 minor, although important episode in the faunal history, merely 

 being one element in a fauna which as a whole was closely related 

 tp an earlier one, and which was followed by another one in which 

 the Belemnitella element was absent, and which was essentially a 

 recurrence of an earlier fauna, then there would be good paleonto- 

 logical reasons foT recognizing the Matawan and Monmouth as 

 distinct major divisions. But this is not the case. 



Neither are there two distinct lithologic divisions in New Jersey 

 which can be properly designated as the Matawan and Monmouth 

 formations. In fact the accepted line between these two 

 divisions cannot be mapped with any accuracy through a large 

 portion O'f its extent in New Jersey, and although a very important 

 greensand marl deposit is included in the Monmouth, yet in the 

 Matawan the Marshalltown formation is for the southern half 

 of its outcrop so nearly a pure greensand marl that it was mis- 

 taken by Cook in the earlier investigations of the Survey for the 

 marl bed oi the Monmouth, i. e., the Navesink marl of Monmouth 

 County. The Merchantville formation, also, in some places, con- 

 tains so much glauconite that it has been dug for fertilizing pur- 

 poses. On the other hand, the Mount Laurel and Red Bank sands 

 of the Monmouth are formations which, for the most part, are as 

 free from glauconite as any of the formations of the Matawan 

 xlivision. With a full consideration O'f the data involved, there 

 seems to be no utility whatever in New Jersey foy the reco'gnition 

 of divisions to be known as the Matawan and Monmouth, except 

 possibly as an aid in correlating the New Jersey formations with 

 those found farther south. 



The discovery in the Homerstown marl of a fauna having the 

 ■essential characters of that of the Manasquan marl removes all 

 paleontological foundation for the recognition of the two major 

 divisions, Rancocas and Manasquan, for the upper portion oi the 

 series. 



The line separating the twoi natural paleontological divisions, 

 which have been indicated, lies between the Tinton and the 

 Hornerstown formations of Monmouth County, but tO' the south. 



