never the case with other groups of marine organisms and it is not logical to suppose that the eurypterids should in so many instances have suffered complete annihilation, leaving only one fragment behind to show that they had lived in the sea of that period. It has been suggested that the eurypterids, like modern crabs and horseshoe crabs, were cannibalistic, not only devouring living members of their own family, but also the molted exoskeletons, in this way destroying most of the hard parts which might otherwise have been preserved. This is an ingenious explanation to account for the fragmentary condition of the eurypterids so frequently observed, but when we attempt to explain similarly the appearance in the rocks at a given horizon, of only one fragment, the result is a reductio ad absurdum. For unless we are to believe in a miraculous mutual devouring, such as that which took place between the "Gingham Dog and the Calico Cat" as so vividly described by Eugene Field, we would still expect survivors from the feast. Are we to let imagination run wild and to picture to ourselves a fierce struggle in those ancient seas between the members of the eurypterid family, a struggle which caused the destruction of young and old alike, friends, neighbors, and relatives, until a single maimed, but victorious individual remained? But, if we go so far, we must look at the last scene, must gaze upon the painful sight of that last survivor, demented by his orgies, tearing his own limbs apart and devouring them until—well, we would expect that his jaws and ectognaths would have been the final things to remain, but strangely in the Utica sea it was a claw which remained. It is painful to think of the destruction of the young merostomes in these periodic holocausts, that whole faunas should have perished leaving no descendants, and of the infinite labor Nature must have had to create a new genera and species for succeeding seas! Yet, when the early Palaeozoic periods were past these frightful scenes of wholesale destructon gave way to gentler, more pacific modes of life, so that in the Upper Siluric in central and western New York and on the Island of Oesel we find indications from the fossils that the eurypterids lived amicably to a ripe old age, dying a natural and peaceful death and enjoying a decent and fitting burial in the fine muds of those times. Thus we see again the steady progress in evolution from the early days of barbarism to the later ones of communal altruism. (b) It is impossible to explain the occurrence of one well preserved eurypterid with no other associates, such for instance as E. prominens; for, if the conditions for perfect preservation obtained, then the
