THE FOSSIL FISHES OF THE CHALK. 203
specimen from the Upper Chalk of Grays. It is an elongated
fish, with an extended dorsal fin, and the body armoured with
a few longitudinal rows of thin bony plates. An allied genus,
Leptotrachelus, which is also found in the English Chalk, is
represented by nearly complete fishes in the Upper Cretaceous
of the Lebanon, and one of the known specimens (fig. 3) is
Fig. 3. Leptotrachelus triqueter, Pictet.
noteworthy as enclosing a fish which must have been swallowed
and accommodated in a distensible stomach. This provision
for feeding on large prey is well known to be one of the special
peculiarities of many of the existing deep-sea fishes. Here in
the Chalk is the earliest indication of it in a fish which probably
did not live at any great depth.
The Cretaceous Dercetidae do not appear to be very closely
related to any existing fishes, but the contemporaneous Encho-
dontidae may include the shallow-water ancestors of several
groups which are now specially characteristic of the deep sea.
They have a powerful tail, and are shaped for darting rapidly
at prey (fig. 4). The stout bones of their palate bear large
Fig. 4. Eurypholis eoissieri, Pictet.