EOCENE EISUES. 
39 
numerous portions of many other individuals were found, which do not pre¬ 
sent specific differences. 
The cranial bones of the sujDerior walls are rather thick. Their supe¬ 
rior surface is thrown into obtuse folds, or ridges, which inosculate exten¬ 
sively, leaving interspaces of about their own width. The summits of these 
ridges are not ornamented with small plates, or bands, of enamel, as is usual 
in many Eocene species, except in some small dots near the borders of one 
of the thinnest cranial bones. It has occurred to me that this lack might 
be due to attrition; but the character is uniform in several specimens other¬ 
wise unworn, and with the enamel of their scales in good preservation, so that 
I cannot attribute it to this cause, and have given the species a name in 
allusion to it. About an inch of the basi-occipital bone is preserved. It 
displays the typical characters of Lepidosteus in its projection posterior to 
the exoccipitals and its strong inferior longitudinal groove. It is deeply 
excavated for the spinal cord. 
The vertebrae are all dorsals, beginning with the one succeeding the 
basi-occipital. The first is smooth and slightly excavated on the middle 
line below, and strongly excavated for the neural canal. The diapophysis 
is small and subcylindric, and there are two small pits at the base of the 
neurapophysis. The second dorsal has a flattened face below, which is 
marked with several shallow longitudinal grooves. Two stronger ones 
appear below the cylindric diapophysis, and a profound one at the base of 
the neural arch. The dorsals, which follow after a short interruption, begin 
to be a little longer, and have the characteristic deep longitudinal pit on the 
lower part of the side of the centrum. These leave the inferior face as a 
rather wide rib, which widens slightly in the posterior direction. Its sur¬ 
face is interrupted by a median and one or two lateral grooves. There is 
a deep longitudinal pit at the base of the neurapophysis, and a depressed 
smaller one at the superior posterior base of the diapophysis, and another 
like it at the inferior anterior base. Posterior to these vertebrae, the centra 
become a little longer, and narrower at the articular extremities. The 
median groove of the narrow inferior plane alone remains. The superior 
border of the articular cup is, in all the vertebrae preserved, excavated by 
the neural canal; the excavation of the ball is less marked or wanting. In 
