42 CRETACEOUS PALEONTOLOGY. 



■ It is not possible to characterize fully the Cliffwood-Wood- 

 bury-Wenonah-Red Bank fauna by a single species, since no form 

 has been so far recognized in every locality of every horizon of 

 this :fauna. Lucina cretacea^ perhaps, more nearly characterizes 

 the fauna than any other single species ; it occurs in every locality 

 of the Woodbury which has been studied, and is always a com- 

 mon species, but in the other horizons it has been found at only 

 two of the five Cliffwood localities, -two of the four Red Bank 

 localities, and as yet has been found in neither of the Wenonah 

 localities. It is really a group of species, rather than a single 

 one which characterizes this fauna, but as a matter of convenience, 

 the whole assemblage may be spoken O'f as the Lucina cretacea 

 fauna. In the alternate formations of the series, viz., Mer- 

 chantville, Marshalltown, Mount Laurel-Navesink and Tinton, 

 Lucina cretacea does not occur, this species and its associates 

 being replaced by another general fauna tO' be discussed later, in 

 which the species of the genus Cucullaea take a conspicuous part. 

 Aside from this most characteristic element in the Cliffwood 

 fauna, a second group of species, viz., Pholadomya occidentalis, 

 Cardmm ripleyanwm and Corhula hisulcata^ occur, which seem 

 to be common to both of the two general faunas, but which are 

 restricted to the lower portion of the entire series of formations, 

 not being recognized at any horizon higher than the Woodbury. 

 Placenticeras placenta is a species which is highly characteristic of 

 all the formations beneath the Mount Laurel sand, and Anomia 

 argentaria, Tenea parilis, Leptosolen hiplicata, and Linearia 

 nt/etastriaia are species which are commonly distributed through 

 both of the general faunas. The. more diagnostic species of the 

 fauna which occurs in the Merchantville-MarshaJltown-Nave- 

 sink-Tinton formations, viz., Axinea suhaustralis and members 

 of the genus Cucullaea, are conspicuous for their entire absence 

 from the Cliffwood fauna, although the presence of Inoceramns 

 proximus is, perhaps, a sporadic occurrence of a genus which is 

 more characteristic of the second group of faunas. 



