One of the strangest organisms of the formation is a fossil lobster, of such huge proportions, that one of the average sized lobsters, common in our markets, might stretch its entire length across the continuous tail-flap in which the creature terminated. And it is a marked characteristic of the fossil, that the terminal flap should be continuous; in all the existing varieties with which I am acquainted, it is divided into angular sections. The claws nearly resembled those of the common lobster; their outline is similar; there is the same hawk-bill curvature outside, and the inner sides of the pincers are armed with similar teeth-like tubercles. The immense shield which covered the upper part of the creature's body is more angular than in the existing varieties, and resembles, both in form and size, one of those lozenge-shaped shields worn by knights of the middle ages on gala days, rather for ornament than use, and on which the herald still inscribes the armorial bearing of ladies who bear title in their own right. As shown in some of the larger specimens, the length of this gigantic crustacean must have exceeded four feet. Its shelly armor was delicately fretted with the forms of circular or elliptical scales. On all the many plates of which it was composed we see these described by gracefully waved lines, and rising apparently from under one another, row beyond row. They were, however, as much the mere semblance of scales as those relieved by the sculptor on the corslet of a warrior's effigy on a Gothic tomb--mere sculpturings on the surface of the shell. This peculiarity may be regarded as throwing light on the hitherto doubtful impressions of the sandstone of Forfarshire--impressions, as has been said, of smooth surfaces carved into seeming scales. They occur as impressions merely, the sandstone retaining no more of the original substance of the organism than the impressed wax does of the substance of the seal; and the workmen in the quarries in which they occur, finding form without body, and struck by the resemblance which the delicately waved scales bear to the sculptured markings on the wings of cherubs--of all subjects of the chisel the most common--fancifully termed them _Seraphim_. They have turned out, as was anticipated, to be the detached plates of some such crustacean as the lobster of Balruddery.