384 THE LIAS AMMONITES. 



Beyrich, Amal Sansovinii, Mojsisovics. In the Lias AmaWieus GreenovgU, Sow., Amal. 

 Guibalianus, d'Orbigny, Amal. oxpiotus, Quenst., Amal Lymensis, Wright, Amah marga- 

 ritatus, Montfort, Amal. spitiatus, Brug. In the inferior Oolite, Amal. discus, Sow., Amal. 

 Truelli, d'Orbig. In the Oxforclian, Amal. Chamusseii, d'Orb., Amal. cordatus, Sow. 



Amaltheus Greenoughi, Sowerhy. PI. XLIV. 



Ammonites Greekougei, Sowerhy. Mineral Conchology, vol. ii, p. 71, tab. 132, 1816. 



— — Be Haan. Ammonit. et Goniatit., p. 131, 1825. 



— — Lonsdale. Trans. Geol. Soc, 2nd series, iii, p. 272, 1832. 



— — Guidoni. Boue Journal de Geologie, iii, p. 276, 1831. 



— — Morris. Catalogue of British Fossils, p. 173, 1843. 



— — Giehel. Fauna der Vorwelt, iii, p. 554, 1852. 



— — Studer. Geologie der Schweiz, ii, p. 36, 1853. 



— — Von Hauer. Deutsch. Akad. Wissenschaften Cephalopoden 



Nordost. A]pen,p. 46, taf. xii, 1856. 



Diagnosis. — Shell large, discoidal, compressed ; whorls two-thirds involute, outer 

 whorl slightly convex, obscurely undulated by sixteen to eighteen straight, nearly obsolete 

 ribs ; inner whorls with prominent costae ; mouth-aperture elliptical and deeply indented 

 by the penultimate volution. 



Dimensions. — Plate one half the natural size. Transverse diameter of the specimen 

 440 millimetres; width of the umbilicus 150 millimetres; height of the last whorl 180 

 millimetres. 



Description. — I searched the Sowerbyan Collection of Ammonites in the British 

 Museum with green labels attached, Sowerby's mark of the figured species, for the original 

 Am. Greenhougld. The type was in such a state of decomposition from the iron 

 pyrites it contained that it could not be disturbed unless at the risk of its falling to pieces. 

 On searching among the Ammonites stored upon the top of the glass cases in the duplicate 

 room, I found a magnificent specimen of this Ammonite which forms the subject of 

 Plate XLIV, the figure being one half the natural size ; unfortunately it had no label 

 attached indicating its locality, but from the petrological character of the matrix in 

 which it was embedded, it probably came from the Lias at Lyme Regis. 



Sowerby' says " this rather singular Ammonite is often formed of pyrites of rich golden 

 and iridescent tints, and crystallised in the greatest variety of forms, from octaedron to 

 the icosaedron, following the undulations of the chambers and the most attenuated ramifi- 

 cations of the spreading foUicul^, sometimes forming in the place of shells, &c. &c., occa- 

 sionally filled with a great variety of crystals of carbonate of lime an inch or more in length." 

 Specimens vary in size from twelve to eighteen inches or even more. The outer whorl has 

 1 ' Mineral Conchology,' vol. ii, p. 71, 1816. 



