HORNERSTOWN MARL. 159 



(Locality 152). The chief of these species is C. vulgaris, which 

 may be a genetic successor of some member of the genus in the 

 lower formations, possibly C. Hppana. 



The most important fauna from this lower portion of the for- 

 mation was secured near New Egypt (Locality 142). Only three 

 species could be definitely identified with any certainty, a coral, 

 a brachiopod, and a pelecypod, all of which are specifically iden- 

 tical with forms occurring commonly in the Manasquan marl, 

 the youngest member of the Cretaceous formations of New 

 Jersey, immediately beneath the Shark River Eocene marl. A 

 fourth species recognized at the same locality belongs to the 

 genus Cucullaea, and is possibly C. vulgaris, the species which 

 occurs at Tinton Falls and near Hornerstown, but the examples 

 are all too imperfect for certain identification. The interesting 

 fact in 'regard to this fauna is that it is totally different, in its 

 essential characters, from the faunas of the subjacent formations 

 from the Tinton down, and that it is the first appearance of a 

 fauna which has its most typical expression in the Manasquan 

 marl, at the very summit of the Cretaceous series. 



The shell bed at the summit of the Hornerstown marl contains 

 a fauna which is closely related to the fauna of the superjacent 

 Vincentown beds, and it is possible that this shell bed should be 

 considered as the basal portion of the Vincentown instead of 

 the top of the Hornerstown, since it is frequently quite sandy 

 and sometimes almost completely sand. Where the bed is highly 

 glauconitic, it is not unlikely that it is only worked over and 

 redeposited greensand from the beds below, after the initiation 

 of the Terehratula harlani fauna in the region, being contempo- 

 raneous with nearly pure sand beds elsewhere, in the same general 

 region. The Terehratula harlani which appears at this horizon 

 in such abundance is clearly an immigrant from some other 

 region, probably from Europe, since it does not extend into the 

 south beyond Maryland and it has several more or less closely 

 allied species in the European upper Cretaceous faunas. After 

 its introduction at this time it becomes the dominant element in 

 the faunas in the northern portion of the region at least, through- 

 out the time of deposition of the Vincentown formation. 



