A Remarkable little fossil fish, Eucenturus paradoxus, was described by Traquair (1905) from a single specimen from the Calciferous Sandstone Series of Ardross, Fifeshire. Traquair's description is as follows: “This extraordinary little organism measures 2⅜ inches in length, of which ½ inch may be allotted to the head, and ¾ inch to the body, and 1⅛ inch to the tail. The head is a mass of calcareous matter, in which something suggestive of a broad curved mandible can be seen, but admits of no further description. The body, ⅜ inch broad in front, is composed of a greyish film, which, when examined by a strong lens, is seen to consist entirely of minute, slender, slightly-curved and sharp-pointed spinelets. The tail is tapering in form, consisting of amorphouslookingcalcareous matter, but on each side (assuming that the creature is crushed vertically) is a conspicuous row of double spinelets arranged exactly opposite each other. From a common base arise two spinelets, which are placed close together, and nearly parallel to each other; one of them, the anterior, being only half the length of the posterior one, which just behind the body may attain a length of 1/16 inch, though towards the end of the tail they become smaller; both spinelets are slender, slightly curved, round in transverse section, smooth externally, sharply pointed, and traversed internally by a central tubular pulp cavity. No trace either of internal skeleton, or of limbs, or of fins of any sort can be seen.”