36 
GEOLOGY 
back, with a strongly marked, but not prominent keel, and the quadrangular form of the whorl, giving it much re- 
semblance to the species A. varians, A- fricarinatus ^ A. Goupilianus , etc. (see: Pale'onlologie franQuise^ Terrains Cre- 
taces par d’Orbigny ,) , of the Crate Chlorite of France. The ribs do not all begin at the umbilicus , more than half 
of them begin at a third of the distance from the umbilicus; they are sinuous and at the back turn rapidly towards 
the mouth. Several of these ribs appear to be ornamented where they bend towards the keel , with a sort of round 
swelling, which seems also to exist near the umbilicus; but only on the ribs starting from the umbilicus, each one 
of these umbilical ribs being separated by two lateral ribs. This character of round swellings must not be consi- 
dered as certain , owing to the imperfection of the specimens , and even in the figures 2 and 2 a the artist has ne- 
glected to mark them. 
Observations. — This species has the general form of inflatus of Sowerby; but it is distinguished 
by the great difference in the ribs. 
Locality. — The Am, Novi-Mexicani is found not far from Albuquerque and also las Lunes, in 
the White Sandstone that constitutes the sandy mountain extending- between the Rio Grande del Norte 
and the Rio Puerco. I found it in company with fragments of Baculites and Inoceramus loo badly 
preserved to be described. I consider this white sandstone as lying immediately below the clay con- 
taining teeth of Ptyckodus Whipplei^ of the environs of Galisteo, and the whole as belonging to the 
Upper Cretaceous or the White Chalk of Europe. 
Explanation of figures. — Plate I, fig. 2. Side view showing a part of the umbilicus 
» I , fig. 2 a. The same , back view. 
ilAMlTES EREMONTI n. sp. 
Plate I, fig. 3 (falsely named Baculites Fremonti.). 
Uescription. — Shell elongated, forming an elliptic and very open spire; the shell is crossed obliquely, from 
the back to the front, with ribs, prominent, distant from each other, disappearing on the ventral side, and on every 
Ihiid rib on either side the back , is seen a truncated tubercle. These tubercles appear to have given rise to points. 
Mouth oval. Lobes unknown. 
Observations. — This species resembles the Hamites elegans d’Orb. and the Ham. armatus Sow. of the 
Cretaceous rocks of France and England. It is easily distinguished from the Ham. elegans by the much 
larger opening of its spire and by its more compressed mouth, and it differs from the Hamites armatus 
in having one tubercle on each side instead of two. 
Locality. — This Cephalopod is not rare in the Cretaceous rocks that border the Red river at 
the town of Preston, Texas; fragments are very common. I have dedicated it to Colonel J. C. 
Fremont, the celebrated explorer of the Rocky mountains and California. 
Explanation of figure. — Plate I, fig. 3. Natural size. Side view. 
INOCERAMUS LEROUXI n. sp. 
Plate II , fig. 3. 
Description. — Shell nearly round , very compressed , ornamented with concentric undulations , strongly marked 
and separated ; the hinge margin is very large and the shell appears to narrow rapidly towards the opposite side. 
The umbones are very prominent and nearly straight. 
Observations. — This species differs from all the others by the length of its hinge margin and the 
beaked form of its umbones. 
Locality. The stratigraphical position of this species is in the black sub-schistose marls, be- 
longing to the Upper Cretaceous, that forms the ravines along the Rio Galisteo, New Mexico, 
