LYTOCERAS CORNUCOPIA. 411 



Ammonites fimbkiatus, Quenstedt. Flozgebirge, p. 260, 1843. 



— coRNUcopiiE, Giebel. Fauna der Vorwelt, Bd. iii, p. 396, 1852. 



— — Chapuis el Dewalque. Terr. Second., Mem. Cour. Acad. Roy., 



t. XXV, p. 60, pi. viii, fig. 2, 1854. 



— CORNUCOPIA, Simpson. Fossils of York. Lias, p. 40, 1855. 



— FASCIATUS, — Ibid., p. 41, 1855. 



— FiMBRiATUs, Brauns. Der untere Jura, p. 235, 1871. 



Lytoceras cornucopIjE, Neumayr. Zeitschrift Deutsch. geol. Gesell., Bd. xxvii, 



p. 893, 1875. 



— cornucopia, Tate and Blake. Yorkshire Lias, p. 298, 1876. 



Diagnosis. — Shell discoidal; whorls round and slightly depressed, encircled with 

 from eighteen to twenty prominent, annular, undulating fimbrise, with erect lamellae ; 

 surface of the shell covered with transverse and longitudinal striae, which cross each 

 other and produce a successive series of small quadrate cellular depressions in the shell 

 texture ; whorls nearly evolute ; siphonal area convex ; aperture flattened at the sides. 



Dimensions. — The figure is half the natural size. Transverse diameter 320 milli- 

 metres ; width of umbilicus 126 millimetres; height of aperture 120 millimetres; 

 transverse diameter of aperture 110 millimetres. 



Description. — This is a very handsome Ammonite, which sometimes attains consider- 

 able dimensions. The finest specimen I have seen is in the Geneva Museum, for which 

 it was purchased from a celebrated French collection of Upper-Lias fossils from Verpilliere, 

 Isere. By the kind permission and aid of my friend, Monsieur P. de Loriol, I had a very 

 accurate delineation of this specimen, of the natural size, drawn by Monsieur Lunel, of 

 Geneva, and have reduced his figure one half natural size to come into the plate. Having 

 failed to discover in any of our museums an English specimen good enough for delineation 

 in this work, I have had the Prench specimen drawn as a magnificent example of the 

 typical characters which this species exhibits and especially in the ornamentation of its 

 beautiful sculptured surface. 



The shell is discoidal and slightly compressed on the sides. The whorls are round 

 and nearly evolute, so that the whole of the inner whorls are fully exposed. The outer 

 whorl is encircled by eighteen annular undulating fimbriae, with erect, pointed lamellae 

 directed backward, the whole of the rest of the surface being covered with transverse 

 and longitudinal striae, which cross each other at right angles and evolve a consecutive 

 series of small quadrate or polygonal cellular depressions, with raised walls, in the texture 

 of the shell. The whorls are almost evolute, and the whole of the six volutions are exposed 

 in the fine specimen herein figured. The siphonal area is round, and on it the elegant 

 sculpturing of the shell is well displayed. The aperture is nearly round and only slightly 

 flattened on the sides. In the opening lies embedded in the matrix a specimen of 

 Harpoceras bifrons, one of the leading shells of the Upper Lias, and indicating the zone to- 

 which Lyt. cornucopia belongs. 



