FORMATION CORRELATIONS WITHIN THE PROVINCE. 351 



been recognized from the later horizons. Many of the other molluscan 

 types are unknown except in the Matawan, or are found less frequently 

 in the succeeding Monmouth. Other forms, on the other hand, occur 

 with about equal frequency in both the Matawan and the Monmouth. 

 A good many species hitherto recorded from the lower greensand marls 

 are found upon examination of the localities to have come from beds 

 beneath the Monmouth, so that a careful revision of the statements of 

 earlier authors regarding the horizon from which the fossils have been 

 derived is necessary. Belemnitella americana, so common in the Mon- 

 mouth formation, has never been observed in the Matawan, while the 

 shells of Exogyra costata and Gryphsea vesicularis, so common in the 

 Monmouth, although occurring in the lower portion of the Matawan. are 

 not at all frequent until the upper beds are reached. 



The Monmouth formation is very rich in organic remains, both in 

 number of species and individuals, the most common and widely dis- 

 tributed forms being Gryphsea vesicularis, Exogyra costata, and Belemnitella 

 americana, which characterize all three divisions of the formation. Large 

 numbers of other molluscan species, as, for example„0s£rea larva, Idonearca 

 vulgaris, Crassatellavadosa, Cardiumperelongatum, and Turritella vertebroides, 

 are widely distributed, so that the faunal characters of the formation are 

 sufficiently distinctive to establish its occurrence at all points without 

 difficulty. 



The Rancocas formation, although highly fossiliferous from the stand- 

 point of individuals, is characterized b}^ very few species. The most 

 typical form is the Terebratula harlani, w T hich, throughout New Jersey, is 

 so widely found at the top of the lower greensand member, but which 

 in Delaware and Maryland also occurs within and at the top of the lime- 

 sand division. Among the characteristic forms are Idonearca medians, 

 Gryphxostrea vomer, and the several types of Echinodermata mentioned 

 above in the list of fossils from the Rancocas formation. 



The Manasquan formation is not as rich in organic remains as the 

 Rancocas, but there are several types which are extremely common and 

 characteristic, among them being Odrea glandlformis, Gryphsea bryani, 

 Crassatella conradi, and Caryatis (?) veta. With few exceptions, the species 

 are quite distinct from those of the preceding and succeeding formations. 

 . The Shark River formation is characterized by an abundant fauna 

 within the limited area in which it has been observed. With one or two 

 exceptions, the forms are quite distinct from those of the preceding for- 

 mations, and the genera represented point to a more recent fauna. 



An examination of the faunal zones shows that some are much more 

 sharply delimited than others. The Matawan and Monmouth faunas, 

 for example, are much more closely connected with one another than are 



