Contributions to British palæontology : or, First descriptions of three hundred and sixty species and several genera of fossil Radiata, Articulata, Mollusca, and Pisces from the Tertiary, Cretaceous, Oolitic, and Palæozoic strata of Great Britain. . ight slightly exceeds itslength; its anterior extremity is vertically over the middle ofthe anal fin, the posterior extremity extending slightly be-hind the extremity of the anal; caudal very large, deeplyforked, but the upper lobe twice the length of the lower; ful-cral scales very slender, about half an inch long and half aline wide, granulated;
Contributions to British palæontology : or, First descriptions of three hundred and sixty species and several genera of fossil Radiata, Articulata, Mollusca, and Pisces from the Tertiary, Cretaceous, Oolitic, and Palæozoic strata of Great Britain. . ight slightly exceeds itslength; its anterior extremity is vertically over the middle ofthe anal fin, the posterior extremity extending slightly be-hind the extremity of the anal; caudal very large, deeplyforked, but the upper lobe twice the length of the lower; ful-cral scales very slender, about half an inch long and half aline wide, granulated; scales rhomboidal, four in the space ofone line, gibbous, strongly sulcated diagonally except at theposterior angle. Total length 11 great proportional size of the head distinguishes this fromall its congeners except the C. curtus (MCoy), from which itdiffers in the form and position of its fins, large tail, and dia-gonally sulcated scales. Rare in the old red sandstone of Orkney.(Col. University of Cambridge.) [Saurodipteridce.) Diplopterus (Ag.). M. Agassiz has described the species of this genus as having heterocercal tails, and in his Monog. des Poissons Foss. du Vieux Gres Rouge he gives a restored figure of the genus with c2. 36 FISH OF THE OLD RED SANDSTONE. a heterocercal tail, the caudal fin large, obliquely subtruncate orslightly concave in the middle of the posterior margin, and con-fined to the lower side of the spine. I find, from the examinationof probably more perfect specimens than were at the disposal ofProf. Agassiz, that the tail of this genus really presents a verydifferent and peculiar structure; so far from being truly hetero-cercal*, there is almost as great a development of fin-rays aboveas below the spi-nal prolongation,the caudal fin ha-ving a rhomboidalform, the poste-rior margin point-ed in the middle;the spinal prolon-gation is much at-tenuated_, reach-ing nearly to theextremity of thefin; it is not pre-cisely in the mid- ^. , 1 *
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectpaleontology, bookyea
