104 



M.K. HOWARTH 



Oxfordian Ringsteadia as identified by Scott. In Yemen these two 

 zones are also the horizons at which the distinctive genus 

 Simaspidoceras occurs, so its occurrence four or five zones lower in 

 the Lower Kimmeridgian in Ethiopia (Zeiss, 1 97 1 : table 1 ) has to be 

 questioned. Somalia and Yemen were much closer together during 

 the Jurassic, before the formation of the Gulf of Aden, and the 

 successions show much similarity (Howarth & Morris, 1998: 25). 

 Spath's (1935) dating of the Somalian Kimmeridgian ammonites, as 

 summarized by Arkell (1956: 309), are generally confirmed by the 

 sequences in Yemen, though Spath had many indifferently preserved 

 Perisphinctids of doubtful affinity. The difficulties in dating the even 

 more poorly preservedTithonian ammonites from Somalia described 

 by Spath (1935) are little resolved, however, except for the "rescue' 

 of his poorly known genus Pseudoclambites by much better pre- 

 served specimens at the bottom of the Upper Tithonian in Yemen. 



Acknowledgements. The ammonites described here were collected 

 during visits to Yemen made possible by the kindness of several people at 

 British Petroleum Pic and Clyde Petroleum Pic, who are acknowledged in the 

 preceding paper in this Bulletin. I also wish to acknowledge considerable 

 help and support received from Dr Noel Morris, who accompanied me on 

 those visits, and from my wife, Dr Elena Popa, who helped with the 

 construction of the plates. 



REFERENCES 



Arkell, W. J. 1 952. Jurassic ammonites from Jebel Tuwaiq, central Arabia. Philosophi- 

 cal Transactions of the Royal Society of London. (B) 236: 241-313, pis 15-31. 

 1953. Seven new genera of Jurassic ammonites. Geological Magazine. London. 



90: 36-40. 

 1956. Jurassic geology of the world. Edinburgh and London, Oliver and Boyd, xv 



+ 806pp. 

 1957. In Moore, R.C. (editor), Treatise on invertebrate paleontology. Part L, 



Mollusca 4, Cephalopoda, Ammonoidea. xxii + 490pp. New York and Kansas, 



Geological Society of America and University of Kansas Press. 

 Amould-Saget, S. 1951. Les ammonites pyriteuses du Tithonique superieur et du 



Berriasien de Tunisie centrale. Annates des Mines et de la Geologie. Tunis. 10: iv + 



133pp., llpls. 

 Atrops, F. 1982. La sous-famille des Ataxioceratidae (Ammonitina) dans le 



Kimmeridgien inferieur de sud-est de la France; systematique, evolution. 



chronostratigraphique des genres Orthosphinctes et Ataxioceras. Documents des 



lahoratoires de geologie. Lyon. no. 83: 463pp. 

 & Melendez, G. 1993. Current trends in systematics of Jurassic Ammonoidea: the 



case of Oxfordian-Kimmeridgian perisphinctids from southern Europe. Geobios, 



memoire speciale, Lyon. 15: 19-31. 

 Bardhan, S., Haider, K. & Jana, S.K. 1 994. Earliest sexual dimorphism in Nautiloidea 



from the Jurassic of Kutch, India. Neues Jahrbuch fur Geologie und Paldontologic, 



Ahhandlungen. 193: 287-309. 

 Basse, E. 1930. Contribution a I'etude du Jurassique superieur (facies Coralhen) en 



Ethiopie et en Arable Meridionale. Memoires de la Societe geologique de France. 



(N.S.) 14: 105-148, pis 4, 5 (20, 21). 

 Behrendsen, O. 1891. Zur Geologie des Ostabhanges der argentinischen Cordillere. 



Zeitschrift der Deutschcn geologischen Gesellschafl. 43: 369^20, pis 22-25. 

 Berckhemer, F. & Holder, H. 1959. Ammoniten aus dem Oberen Weissen Jura 



Suddeutschlands. Beihefte zum Geologischen Jahrbuch. 35: 135pp.. 27pls. 

 Besairie, H. 1936. Recherches geologiques ii Madagascar, I, La geologie du Nord- 



Ouest. Memoires de I'Academie Malgache. 21: 259pp.. 23pls. 

 Beydoun, Z.R. 1964. The stratigraphy and structure of the Eastern Aden Protectorate. 



Overseas geology and mineral resources; Bulletin supplement, no. 5: viii + 107pp.. 



I6pls, 3 maps. 

 Blanford, H. F. 1863. On Dr Gerard's collection of fossils from the Spiti valley, in the 



Asiatic Society's Museum. Journal of the Asiatic Society of Bengal. Calcutta, 32: 



124-138, 4pls. 

 Boehm, G. 1904. Beitrage zur Geologie von Niederlandisch-lndien. Erste Abteilung: 



Die Siidkiisten der Sula-Inseln Taliabu und Mangoli. 1, Abschnitt: Grenzschichten 



zwischen Jura und Kreide. Po/ofo/imgra/p/;/™. supplement 4 (1, 1): 11-46, pis 1-7. 

 Bogoslowsky, N. A. 1897. Der Rjasan-Horizont, seine Fauna, seine stratigraphischen 



Beziehungen und sein wahrscheinliches Alter. Materialy dlya Geologii Rossii. 18: 



1-157. pis 1-6. 



Breistroffer, M. 1947. Notes nomenclature paleozoologique. Proces-Verbaux des 



Seances mensuelles de la Societe des Sciences de Dauphine. 26 (195): 5pp. 

 Bruguiere, J.G. 1789-92. Histoire naturelle des Vers, i-xviii, 1-344 (1789); 345-757 



(1792). Part of Encyclopedic Methodique. Paris. 

 Buckman, S.S. 1918. Yorkshire Type Ammonites. Vol. 2, part 17: .xiii, xiv. pis 117-1 19. 



London. 



1920. Type Ammonites. Vol. 3, part 23: 19-24, pis 168-180. London. 



1921. Type Ammonites. Vol. 3, part 25: 31, 32, pis 195-205. London. 



Burckhardt, C. 1900. Profils geologiques transversaux de la Cordillere Argentino- 



Chilienne, stratigraphie et tectonique; part 2, stratigraphie et remarques 



paleontologiques. Anales del Museo de La Plata, Geologica y Mineralogica. 2: 19- 



136, pis 19-32. 

 1903. Beitrage zur Kenntniss der Jura- und Kreideformation der Cordillere; part 



1. Palaeontographica. SO: 1-72, pis 1-10. 



1906. La faune Jurassique de Mazapil, avec un appendice sur les fossiles du 



Cretacique inferieur. Boletin del Instituto Geologico de Mexico. 23: 2I6pp., 43pls. 



1912. Faunes jurassiques et cretaciques de San Pedro de Gallo. Boletin de 



Instituto Geologico de Mexico. 29: viii + 264pp., 46pls. 



1 9 1 9-1 92 1 . Faunas Jurasicas de Sy mon ( Zacatecas ) . Boletin de Instituto Geologico 



de Mexico. 33: 1-75 (1919), pis 1-21 (1921). 



1930. Etude synthetique sur le Mesozoique mexicain; part 1. Memoires de la 



Societe Paleontologique Suisse. 49: 1-123. 



Callomon, J. H. 1981. Superfamilies Haplocerataceae, Stephanocerataceae, 



Perisphinctaceae. pp. 118-127, 143-155. In. Donovan, D. T., Callomon, J.H. & 



Howarth, M.K. 1981. Classification of the Jurassic Ammonitina. Systematics Asso- 

 ciation, London. Special volume, no. 18: 101-155. London. Academic Press. 

 & Cope, J.C.W. 1 97 1 . The stratigraphy and ammonite succession of the Oxford 



and Kimmeridge Clays in the Warlingham borehole. Bulletin of the Geological 



Surx'ey of Great Britain. 36: 147-176, pis 6-12. 

 Campana, D. Del 1904. Faunula del Giura superiore di Collalto di Sologna (Bassano). 



Bolleitino delta Societa Geologica Ilaliana. 23: 240-269, pi. 7. 

 Canavari, M. 1 90 1 . La fauna degli strati con Aspidoceras acanthicum di Monte Serra 



presso Camerino; part 4. Cephalopoda, Simoceras, Perisphinctes, Aspidoceras. 



Palaeonlographia Italica. 6: 1-15, pis 1-6 (20-25). 

 Cariou, E & Hantzpergue, P. (editors). 1997. Biostratigraphie du Jurassique ouest- 



europeen et mediterraneen: zonations paralleles et distribution des invertebres et 



microfossiles. Bulletin de la Centre Recherche Elf Exploration Production. Memoire 



17: 440pp.. 42pls. 

 Charpy, N. & Thierry, J. 1977. Dimorphisme et polymorphisme chez Pachyceras 



Bayle ( Ammonitina, Stephanocerataceae) du Callovien superieur (Jurassique Moyen). 



Haliotis.6: 185-218, 5pls. 

 Checa,A. 19S5. Los aspidoceratiformes en Europat Ammonitina. fam.Aspidoceratidae: 



subfamilias Aspidoceratinae y Physodoceratinae). Tesis Doctoral. Facultad de 



Ciencias, Universidad de Granada. 413pp.. 42pls. 

 , Oloriz, F. & Tavera, J. M. 1986. Last records of 'Aspidoceras' in the Mediterta- 



nean. Acta Geologica Hungarica, 29: 161-168. 

 Choffat, P. 1893. Description de la faune Jurassique du Portugal; Classe des 



cephalopodes. Premiere serie; Ammonites du Lusilanien de la Contree des Torres- 



Vedras. 82pp., 20pls. Lisbon. 

 Collignon, M. 1959. Atlas des fossiles characteristiques de Madagascar. V; 



Kimmeridgien. Pis 96-133 (figs 365-505). Tananarive, Service Geologique. 



1960. Atlas des fossiles characteristiques de Madagascar. VI: Tithonique. Pis 



134-175 (figs 506-757). Tananarive, Service Geologique. 



1962. Atlas des fossiles characteristiques de Madagascar. VIII: Berriasien. 



Valanginien, Hauterivien, Barremien. Pis 176-214. figs 758-937. Tananarive. Serv- 

 ice Geologique. 



Conrad, M.A., Peybernes, B. & Weidmann, M. 1975. Presence de Trinocladus 



perplexus Elliott (Dasycladales) dans le Jurassique de France et d'Afrique du Nord- 



Est. Compte rendu des Seances de la Societe de Physique et d'Histoire naturelle de 



Geneve. 9: 14-29. 

 Cossmann, M. 1907. Rectifications de nomenclature. Revue Critique de Paleozoologie . 



11: 64. 

 Crick, G.C. 1908. In. Bullen Newton. R. & Crick, G.C.. On some Jurassic Mollusca 



from Arabia. The Annals and Magazine of Natural History, London. (8) 2: 1-29. pis 



1-3. 

 Dacque, E. 1905. Beitrage zur Geologie des Somalilands; 11 teii, Oberer Jura. Bf/Vragf 



zur Paldontologic und Geologie Osterreich-Ungarns und des Orients. 17: 1 19-159. 



pis 14-18. 

 1910. Dogger und Malm aus Ostafrica. Beitrage zur Paldontologic und Geologie 



Osterreich-Ungarns und des Orients. 23: 1-62, pis 1-6. 

 Damon, R. 1 880. A supplement to the geology of Weymouth and the Isle of Portland. 



Second (revised) edition. 20pls. London. 

 Diener, C. \925 . Ammonoidea neocretacea. Fossilium Catalogus. I. Animalia. part 29: 



244pp. Junk. Berlin. 

 Dietrich, W.0. 1925. Obereine dem MittlerenSauriermergel amTendaguru Aquivalente, 



rein Marine Kimmeridgebildung in Mahokondo. Deutsch-Ostafrica. 



Palaeontographica. supplement 7 (2, 1, 1): 1-23, pis 1-3. 



