300 THE LIAS AMMONITES. 



the same structural character around the whorl (fig. 3) ; the different examples of this 

 species which I have figured in PI. XXVI, figs. 5 — 14, show how permanent these 

 characters are in several varieties of this species from my collection. 



Affinities and Differences. — Arietites raricostatus stands out very distinct from all its 

 other congeners ; the short, straight, acute, sparse ribs on the sides, with wide concave 

 valleys between ; the narrow, slender keel, without lateral sulci on the area, and its simple 

 lobe-lines so widely apart, form an assemblage of characters which readily distinguish 

 this species from the congeneric forms with which it is associated. 



Locality and Stratigraphical Position. — I have collected this species in the neighbour- 

 hood of Cheltenham, associated with Hi/ppopodium ponderosum, Arietites nodotianus, and 

 Aegoceras densinodum ; the zone which it characterises I consider as the uppermost of the 

 Lower Lias. At Black Venn, near Charmouth, Dorsetshire, a very interesting variety 

 is found, unfortunately overcharged with iron-pyrites. The larger specimens, such 

 as the one figured, PI. VII, figs. 2, 3, are found in the limestone, and are well 

 preserved. 



At Robin Hood's Bay, Yorkshire coast, I found this species in nodules apparently 

 derived from the Oxynotus-zone, which is here closely united with the Baricostatm- 

 bed. 1 had a very fine series of this Ammonite sent me from the North of Ireland by 

 my old friend Professor E. C. H. Day, F.G.S., which he collected from the Baricostatus- 

 bed so well developed in the small Bay of Ballintoy. 



In France it is found with Gryphaa arcuata at Semur, and at Pouilly-en-Auxois, 

 Nolay, Cote-d'Or ; near Nancy, Meurthe ; Saint-Fortunat, Rhone ; Saint-Cyr, Rhone ; 

 Drevaine, Saone-et-Loire, and several other localities in the Valley of the Rhone. In 

 AVurttemberg it is found at Goppingen, Metringen, Oberdingen, Balingen, and Schlichen, 

 near Schomberg. 



Arietites nodotianus, tf Orbigny. PI. XXXVII, figs. 3 and 4. 



Ammonites nodotianus, d'Orbigny. Pal. Francaise, Terr. Jurass., i, p. 198, pi. 



xlvii, 1842. 



— Macdonellii, Portlock. Report on Londonderry, p. 134, pi. xxix a, 



fig. 12, 1843. 



— Charpentieri, Quenstedt. Bronn's Jahrbuch fur Mineral., p. 810, 1847. 



— Quenstedti, Schafh'uult. Geog. Sudbayr. Alpengebirg., p. 142, pi. xvi, 



fig. 22, 1851. 



— nodotianus, Savi e Meneghini. Geologia della Toscana, p. 122, 1851. 



— — Giebel. De Cephalopoden der Vorwelt, p. 734, 1852. 



— — von Huuer. Jahrbuch der k. k. geologischen Reiclisanstalt, 



p. 747, 1853. 



