KEUPER STRATA. 
63 
Ammon . Brotheus, Munst. 1. c. fig. 28, itself, probably, only 
a young shell, very much resembles our species. 
AMMONITES WINTERBOTTOML-AT Sp. 
Plate 7, fig. 5. 
Compressed: at the umbilicus it is not thicker than on the 
disk; diameter, 2 inches: thickness, ^ an inch. The back is 
rounded, smooth, and neither keeled or ribbed. Umbilicus 
large, open ? Our figure represents it so, but it is rather 
broken in the specimen, and may have been much more closed. 
Bibs coarse, not much curved or bent, directed forwards. 
They are but faint for the inner half, where they form a tu¬ 
bercle, and thence pass, with a very slight bend backward, to 
the more prominent marginal tubercle. Here and there one 
is branched from the first tubercle, but this is verv rare. 
It need not be compared with such sub-globose species as 
A. Ramsaueri (Hauer), in which the umbilical margin is the 
thickest part of a thoroughly involute shell. I would, how¬ 
ever, compare it with KlipsteiiPs A. cequinodosus, (Ostl. Alp. 
t. 7, fig. 1), and it is possibly still nearer to his A. Mandels - 
lohi (t. 6, fig. 2). This last is, evidently, a near ally, but the 
figure is a bad one. The ribs are more branched and are con- 
tinued beyond the outer tubercle, while the back of our 
species (fig. c) is smooth, or only with fine concentric stria3. 
A. bicrenatus , Hauer, is a yet more remote ally. 
AMMONITES PLANODISCUS.-A. Sp. 
Plate 8, figs. 5, 6. 
Diameter, nine-tenths of an inch; breadth of last whorl, 
four-tenths; thickness, two-tenths. Whorls much flattened 
one-tliird embracing each other, with bluntish round-keeled 
back, and no ribs or indentations; section ovate-sagittate. 
[Sutures ? in the young, fig. 6, Ceratite-like.] 
