240 



distinguished from that form in having narrower whorls, a larger 

 umbilicus, and very different septfe : compare, for example, the sutures in 

 plate 3, fig. 1, with those in plate 4, fig. 2a. 



Locality and Stratigrajyhical Position. — This is a veiy rare Ammonite ; 

 my specimen was collected from the Lower Lias, near Lyme Regis, its 

 precise horizon I could not ascertain ; Sowerby's specimen was found in 

 the Lias, near Yeovil; I have seen fragments from a railway cuttmg 

 through the Lower Lias of Somerset. 



Foreign Localities. — M. d'ORBiGNY collected it from the Lower Lias, 

 with Gryphma arciiata, at Ponilly, Cote d'Or, where it is rare. Professor 

 QuENSTEDT says it is most abundant in Germany, and is collected at 

 Vaihingen, Mohringen, Gmiind. Professor Hauer's figured specimen 

 was collected in tlie Yellow Kbssener beds at Enzesfeld, near Vienna. 

 Professor Studeb found it in the Lower Lias of the Berner Alps ; and 

 Lardy at Coalat and Fondement, near Bex. 



Ammonites bisulcatus, Bruguiere, (Plate 4, fig. 2 a, b, c.) 

 Rob. Plot's Natural History of Oxfordshire, tab. 5, fig. 14, p. 110, 1677. 

 Mai-tin Lister, Historia Angliae, de Lapidibus Turbinatis, tab. 6, fig. 3, 



p. 207, 1678. 

 Ammonites bisulcata, Bruguieres, (pars) Encyclojied. Method., tom. 1, 

 p. 39, No. 13, 1789. 

 II MULTicosTATA, Sowerhy, Mineral Conchology, tab. 454, 1824. 



II MULTICOSTATA, Zieteii, Versteinerungen Wiirtembergs, tab. 



26, fig. 3, 1830. 

 II BISULCATUS, cl'Orb., Paleontologie Fran., pi. 43,23. 187, 1842. 



II MULTicosTATUS, Queiisteclt, die Cephalopoden, p. 80, 1849. 



II MULTICOSTATUS, Quenstedt, Handbuch der Petrefactenkunde, 



p. 355, 1852. 

 II BISULCATUS, Hauer, die Cephalopoden aus dem Lias, pi. 1, 



fig. 3, p. 14, 1856. 

 II BISULCATUS, Oppel., die Juraformation, p. 77, 1856. 



II MULTICOSTATUS, Quenstedt, der Jura, p. 67, tab. 7, fig. 2, 1858. 



Diagnosis. — Shell, depressed, discoidal; back, tricarinated ; whorls, 

 svibquadrate, with 30 to 40 strong, sharp, bent ribs, having a tubercle 

 near the dorsal margia of each ; median keel, strong, with two sulci and 

 two lateral carinse; aperture, subquadrate, bisinuated anteriorly; lateral 

 septa with three lobes. 



Dimensions. — Transverse diameter, 8 inches; height of aperture, 2| 

 inches : width of aperture, 2^ inches. 



