934 PSEUDOCERATITES OF THE CRETACEOUS. 
certainty whether this is a species of this genus or not, and the details of 
the sutures, so far as my hasty examination went, were too imperfect to 
enable me to make a reasonable guess with regard to their affinities. 
Locality: New Jersey. 
Age: Upper Cretaceous. 
PLACENTICERAS ? FALLAX Castillo and Aguilera 
Placenticeras ? fallax Castillo and Aguilera, 1895, Bol. Com. geol. de México, No. 
ep liisaplo: 
This species is here mentioned because it is likely to be quoted as a 
species of this genus, whereas both the remarks of the authors and the 
figures show that it should be quoted as probably not a member of this 
genus. The authors consider the sutures as placenticeran, but very rightly 
regard the form as more like that of Phylloceras. I have not as yet seen a 
specimen of this genus that has such a rounded volution even in the gerontic 
stage, and this Mexican specimen was only 104 mm. in diameter. 
Locality: Mexico. 
Age: Lower Cretaceous ?. 
PLACENTICERAS EBRAYI (de Loriol). 
Amaltheus ebrayi de Loriol, 1882, Mém. Soc. Pal. Suisse, Vol. LX, Pl. I. 
Placenticeras ebrayi Kossmat, 1895, Beitr. Pal. und Geol. Oesterreich-Ungarns und 
des Orients, Vol. IX, p. 170. 
This figure shows a large and aged specimen of 250 mm. in diameter. 
The anagerontic substage is given upon the first part of the outer volution, 
and during this time the venter remains flattened and has large alternating 
tubercles of the usual elongated form on either side, but the edges of this 
zone are not sinuous. There are fold-like single costze appearing in this 
substage, and these are prominent, but have no tubercles if the views are 
correct. These single folds are continued in the metagerontic substage 
when the ventral line of tubercles disappear and three lines of lateral 
tubercles appear for the first time on the coste. In the paragerontic 
substage these tubercles disappear, first the outer, then the inner lines, and 
then the central line. The folds also tend to disappear and the venter is 
seen to be completely rounded and smooth in this substage and the involu- 
tion has become considerably diminished, judging from the aspect of the 
