12 CRETACEOUS AND TERTIARY FISH. 



than are any of its constituent faunules from each other. Weller 

 has shown that this larger faunal unit is made up of two or 

 more distinct facies, one of which, the Cucullaea fauna, is char- 

 acteristic of the more glauconitic beds ; namely, the Merchantville, 

 Marshalltown, Navesink and Tinton, while the other facies char- 

 acterized by Lucina cretacea or its associates occurs in the clays 

 or clayey sands of the Cliffwood, Woodbury, Wenonah and Red 

 Bank formations. The two facies existed contemporaneously 

 and migrated backward and forward across the present outcrop 

 of these beds in New Jersey as deeper or shallower water con- 

 ditions prevailed. The larger faunal unit is closely related to the 

 Ripley fauna of Alabama, Mississippi and Texas. On faunal 

 evidence all the formations from the Magothy to Tinton inclusive 

 are referable to the Senonian of Europe, although on floral evi- 

 dence the Magothy might be regarded as Cenomanian. 



Hornerstown marl. — The Horner stown marl is a bed of 

 glauconite with clay and sand and not differing materially from 

 the Navesink. Its fauna is meager, but is totally different in its 

 essential characteristics from the faunas of all the underlying 

 formations. Terebratula harlani, Cucullaea vulgaris and 

 Gryphaea dissimilaris (Weller) are characteristic forms. A shell 

 bed at the top of the formation is a conspicuous feature at many 

 localities. The thickness is 30 feet or less. At the north it rests 

 with apparent conformity on the Tinton ; where that is absent it 

 lies on the Red Bank, and farther south it is continuous with the 

 Navesink, owing to the disappearance of the Red Bank. It is 

 conformably overlain by the Vincentown except where over- 

 lapped by Miocene formations. It is the Middle Marl of Cook, 

 the Sewell marl of Clark, and is a part of the Rancocas group. 



Vincentown sand. — The Vincentown sand presents two phases, 

 a calcareous or limesand, semi-indurated and largely a mass of 

 broken bryozoan, echinoid, coral and other calcareous remains, 

 and a glauconitic quartz-sand phase. The two phases occur in 

 alternating layers, although the former is more common in the 

 basal portion, particularly to the south, while the quartz-sand 

 phase predominates in Monmouth County. The fauna of the 

 limesand phase contains large numbers of bryozoa, echinoids and 



