144 

 1938 



1976 



1985 



Oistoceras angulation (Quenstedt); Spath: 1 7 1 , pi. 2 1 , fig. 5 

 (from France), pi. 22, fig. 5 (from Lincolnshire), pi. 26, figs 

 10, 12 (both from Lincolnshire). 



Androgynoceras (Oistoceras) angulatum (Frebold, 1922) 

 (sic); Schlegelmilch: 69, pi. 34, fig. 4 (from Germany). 

 Androgynoceras (Oistoceras) angulatum (Quensedt); 

 Phelps: 354, pi. 2, fig. 4 (from Germany). 



Range. Bed 599, Figulinum Subzone; 1 specimen. 



Remarks. Quenstedt ( 1 856: 1 2 1 ) had specimens from Metzingen 

 and Iggingen, Germany, and he figured one from the former locality. So 

 the original of Quenstedt (1884: pi. 34, fig. 11), refigured by both 

 Schlegelmilch (1976: pi. 34, fig. 1 1 ) and Phelps (1985: pi. 2, fig. 4), is 

 almost certainly a syntype and can be designated lectotype: its designa- 

 tion by Schlegelmilch as the neotype is not correct. A. (O.) angulatum 

 is more evolute, has more slowly expanding whorls, has no ventro- 

 lateral tubercles, and has fewer ribs on the inner whorls, than A. (O.) 

 figulinum. The angle of the ribbing varies between rectiradiate and 

 prorsiradiate in both species. 



Aegoceras (Oistoceras) figulinum (Simpson. 1855) 



1855 Ammonites figulinus Simpson: 47. 

 1855 Ammonites omissus Simpson: 47. 

 1876 Aegoceras defossum (Simpson); Blake: 282, pi. 8, fig. 9 



(SM J17988. see Donovan & Forsey, 1973: 13). 

 1911 Oistoceras figulinum (Simpson): Buckman: pi. 26A 



(holotype, WM 115). 

 191 1 Oistoceras omission (Simpson); Buckman: pi. 27 (holotype, 



WM 502, now lost). 

 1938 Oistoceras figulinum (Simpson); Spath: 162, pi. 19, fig. 10 



(BM C. 17988), pi. 22, fig. 8 (BM 37973a). 

 1938 Oistoceras omissum (Simpson): Spath: 170. pi. 21. fig. 3 



(BM 38561). 

 1955 Oistoceras aff. figulinum (Simpson); Howarth: 1 6 1 , pi. 11. 



fig. 4 (SM J35968. from bed 600.4). 

 1976 Androgynoceras (Oistoceras) figulinum (Simpson): 



Schlegelmilch: 69, pi. 34, fig. 3 (WM 115. holotype). 

 1985 Androgynoceras (Oistoceras) figulinum (Simpson): Phelps: 



353, pi. 2, fig. 1 (from bed 600.2). 

 1987 Oistoceras figulinum (Simpson); Dommergues: pi. 1 1, figs 



5.6. 



Range. Beds 600.2 and 600.4, Figulinum Subzone; 20 specimens. 



Remarks. This is the most highly developed species of Oistoceras. 

 which has fine ribs on the inner whorls, small ventro-lateral tubercles, 

 and well-developed chevrons in the ribs that are connected together 

 into a rudimentary pseudo-keel along the middle of the venter. 



Other species of Oistoceras from Yorkshire: 



1. A. (O. ) cunicome (Schloenbach, 1863);Spath. 1938: 164, pi. 19, 

 fig. 1 1 (BM C. 19228; indeterminate inner whorls), pi. 22, fig. 9 

 (BM C.6235); both of Spath's figured specimens were probably 

 from Staithes. not Robin Hood's Bay. 



2. ?A. (O.) anguliferum (Phillips, 1829: 163, pi. 13, fig. 19: 1835: 

 135, pi. 13, fig. 19; 1875: 270, pi. 13, fig. 19); the type specimen 

 is lost, and Phillips' figure cannot be interpreted. 



Genus ANDROGYNOCERAS Hyatt, 1867 



Androgynoceras heterogenes (Young & Bird. 1828) 

 1828 Ammonites heterogenes Young & Bird: 264, pi. 14, fig. 7. 



M.K. HOWARTH 



1880/82 Aegoceras heterogenum (Young & Bird): Wright: 370 



(1882), pi. 35, figs 4-6, (1880) (SMJ18229), pi. 36, figs 1- 



4 (1880) (BMC. 1870). 

 1912 Androgynoceras heterogenes (Young & Bird): Buckman: 



pi. 46 (holotype, WM 195). 

 1938 Androgynoceras heterogenes (Young & Bird); Spath: 1 13, 



pi. 13, figs 7a (BM C.19225). 7b (BM C.38457). pi. 20, fig. 



2 (BM C. 38496. as van gigas, from bed 590.61 ). 



Range. Maculatum Subzone: Bairstow found single specimens in 

 beds 583.2 and 588, but BM C.38496 definitely came from bed 590.6 1 . 

 and the other figured specimens are probably from bed 590.63. 



Order NAUTILOIDEA 



Family NAUTILIDAE d'Orbigny, 1840 

 Genus CENOCERAS Hyatt. 1883 



Cenoceras striatus (J. Sowerby, 1817) 



1817 Nautilus striatus J. Sowerby: 183. pi. 182 (3 figures, all 



syntypes. from Dorset). 

 1829 Ammonites annularis Phillips: 163, pi. 12, fig. 18: 1835: 



134, pi. 12, fig. 18; 1875: 263, pi. 12, fig. 8. 

 1855 Ammonites heterogeneus Simpson: 33. 

 1956 Cenoceras striatus (}. Sowerby); Kummel: 362, pi. 3, figs 1, 



2 (BM 43852, from Dorset). 

 1962 Cenoceras heterogeneum (Simpson); Howarth: 96. pi. 13, 



fig. 1 (holotype. WM 442). 

 1962 Cenoceras annulare (Phillips): Howarth: 96, pi. 13, fig. 2 



(holotype, WM 62). 



Range. Bairstow found single specimens in beds 464.32, 468 (both 

 Simpsoni Subzone) and 505.1 (Taylori Subzone). 



BIOSTRATIGRAPHY 



In the description below the ammonite distribution and the place- 

 ment of the boundaries are discussed for all the zones and subzones 

 in Robin Hood's Bay. Additionally, it is noteworthy that Wine Haven 

 at the south-eastern end of the bay has recently been proposed as the 

 world standard for the definition of the base of the Pliensbachian 

 Stage. 



The scheme of ammonite zones used here is based on that regular- 

 ized by Dean. Donovan & Howarth (1961), with a few later 

 refinements to the details of some of the definitions. Cariou & 

 Hantzpergue (1997) used the same scheme of divisions for the 

 Sinemurian and Lower Pliensbachian in eastern France and the 

 central Mediterranean area. The distribution of the ammonites, on 

 which the biostratigraphical divisions are based, is shown in detail in 

 Figs 2 1 , 22, 24 and 25, which give the number of specimens of each 

 species found in each bed. and a visual indication of the range of each 

 species. 



LOWER SINEMURIAN 



SEMICOSTATUM ZONE, Sauzeanum Subzone, beds 418- 

 429.64. No ammonites were found in beds 418-420. which are the 

 first 2.48 m of strata exposed above the lowest level to which the tide 

 ever falls in Robin Hood's Bay. Above this, Euagassiceras occurs up 

 to about the middle of the subzone. and Coroniceras (Arietites) 

 alcinoe occurs in a broad middle part of the subzone; both are 



