PLACENTICERATID/®. 239 
PLACENTICERAS MILLERI (Hauer). 
Ammonites miller’ Hauer, 1866, Sitzungsber. K. Akad. Wiss., Wien, LIII, p. 304, 
pl. 2. 
This species from Steirmark is quite distinct from any of the French 
forms described by Grossouvre, but it may be identical with some of the 
German forms already described having but one row of tubercles in an 
advanced stage of development. It has smooth sides, with only one row of 
tubercles on the outer volution, and apparently also in the earlier stages, as 
figured and described by Hauer. As stated by that author, it is very like 
bidorsatus, except that it has a convex and moderately broad venter. This 
last character also, as well as the peculiar form of the nodes on the edges 
of the venter and absence of inner lines of tubercles, separates it from 
Grossouvre’s species. Hauer had specimens from 2 to 34 inches in diameter. 
Age: Senonian. 
PLACENTICERAS SCHLUTERI Nn. Sp. Hyatt. 
Ammonites syrtalis var. polyopsis Schlitter, 1872, Paleontogr., Vol. XXI1, pl. 14, 
figs. 1-2. 
This species has ornaments very similar to those of polyopsis Dujardin, 
but these are quite distinct and peculiar in their ontogeny. The ephebic 
stage has two rows of large lateral tubercles, as well as ventral rows, and 
according to Schliiter’s figures and descriptions the inner row in the 
anagerontic substage recedes outwardly, becoming approximate to the 
second outerrow. The venter at the same time changes, becoming rounded 
and broader, but the ventral tubercles are still present. These figures are. 
similar to the American syrtale, but differ in being less involute and in the 
wider removal of the inner row of tubercles from the umbilical shoulders 
and the elliptical section of the gerontic stage. In syrtale this section is 
distinctly subtriangular and more compressed in the same metagerontic 
substage. 
Age: Lower Senonian. 
