LOWER LIAS OF ROBIN HOOD'S BAY 



141 



Parinodiceras parinodum (Quenstedt, 1884) 



1884 Ammonites striatus parinodus Quenstedt: 225, pi. 28, fig. 



16. 

 1938 Liparoceras (Parinodiceras) parinodum (Quenstedt); Spath: 



82, pi. 6, fig. 5 (from Radstock, Somerset), pi. 25, figs 1,4, 



5 (all from Wurttemberg. Germany). 

 1976 Liparoceras (Parinodiceras) parinodum (Quenstedt); 



Schlegelmilch: 67, pi. 32, fig. 3 (lectotype, from Ofterdingen, 



Wurttemberg, Germany). 



RANGE. Beds 546.3, 548 and 554, Brevispina and Jamesoni Subzones; 

 3 specimens. 



Family LIPAROCERATIDAE Hyatt, 1867 



Genus LIPAROCERAS Hyatt, 1867 



Subgenus LIPAROCERAS Hyatt, 1867 



Liparoceras (L.) cheltiense (Murchison, 1834) 



1834 Ammonites cheltiensis Murchison: 20, fig. 1. 



1904 Liparoceras cheltiense (Murchison); Buckman: pis 67, 67a 



(holotype, BM 74955a, from Gloucestershire). 

 1938 Liparoceras cheltiense (Murchison); Spath: 46. 



Range. Two specimens in bed 562, Masseanum Subzone. 



Liparoceras (L.) heptangulare (Young & Bird, 1828) 



1828 Ammonites heptangularis Young & Bird: 263, pi. 14, fig. 1. 

 1914 Liparoceras heptangulare (Young & Bird); Buckman: pis 



108 A-C (holotype, WM 170, probably from bed 575). 

 1938 Liparoceras heptangulare (Young & Bird); Spath: 59. pi. 7, 



fig. 1 (BM C.2685, possibly from bed 575). 



RANGE. Single specimens in beds 57 1 , 575 and 577, Valdani Subzone; 

 the best preserved is in bed 577. 



Liparoceras (L.) cf. naptonense Spath, 1938 



1938 Liparoceras naptonense Spath: 63, pi. 6, fig. 1 , pi. 9, fig. 7, 

 pi. 10, fig. 6 (holotype, BM C. 1 2638, from Napton, Warwick- 

 shire), pi. 14, fig. 6, pi. 16, fig. 10 (all from Warwickshire or 

 Leicestershire). 



Range. Single specimens in beds 580 and 582.3, Luridum and 

 Maculatum subzones. 



Liparoceras (L.) divaricosta (Trueman, 1919) PI. 8, fig. 1 



1919 Androgynoceras divaricosta Trueman: 278, pi. 22, fig. 1 

 (holotype, BM C.38326, from Lincolnshire). 



1938 Liparoceras divaricosta (Trueman); Spath: 68, pi. 5, fig. 1 

 (holotype). 



RANGE. A single specimen in bed 596.3, Figulinum Subzone. 



Genus AEGOCERAS Waagen, 1 869 

 Subgenus AEGOCERAS Waagen, 1869 



Aegoceras (A.) maculatum (Young & Bird, 1822) 



PI. 7, figs 12, 13 



1822 Ammonites maculatus Young & Bird: 248, pi. 14, fig. 12. 

 1828 Ammonites maculatus Young & Bird; Young & Bird: 259, 

 pi. 14, fig. 9. 



1829 Ammonites arcigerens Phillips: 163, pi. 13, fig. 9. 

 1835 Ammonites arcigerens Phillips; Phillips: 135, pi. 13, fig. 9. 

 1875 Ammonites arcigerens Phillips; Phillips: 270, pi. 13, fig. 9. 

 1 880/82 Aegoceras maculatum (Young & Bird); Wright: 368 ( 1 882), 



pi. 34 (1880), figs 1-3 (SM J18227). 4-7 (SM J18228). 

 1912 Androgynoceras maculatum (Young & Bird); Buckman: 



pis 45 A, B (holotype, WM 493; from bed 590.61) 

 1938 Androgynoceras maculatum (Young & Bird); Spath: 126, 



pi. 20, fig. 6 (BM C. 17752, from bed 590.61). 

 1938 Androgynoceras maculatum (Young & Bird), var. rigida; 



Spath: 126, pi. 19, figs 2 (BM C.28175, from bed 590.61), 



13 (BM C.24601, from bed 590). 



1961 Androgynoceras maculatum (Young & Bird); Dean et al.\ 

 pi. 70, fig. 4 (BM C. 17752; from bed 590.61 ) 



1962 Androgynoceras arcigerens (Phillips); Howarth: 112. pi. 

 16, fig. 5 (holotype, BM 17139; from bed 590.61). 



1976 Androgynoceras (A.) maculatum (Young & Bird); 



Schlegelmilch: 162, pi. 33, fig. 9 (WM 493). 

 1985 Androgynoceras (Beaniceras) luridum (Simpson); Phelps: 



350, pi. 1, fig. 3 (from bed 583). 

 1985 Androgynoceras (Aegoceras) sparsicosta (Trueman); 



Phelps: 351, pi. 1, fig. 1 (from bed 585). 

 1985 Androgynoceras (Aegoceras) maculatum (Young & Bird); 



Phelps: 350, pi. 2, fig. 8 (probably from bed 590.61). 



Range. Beds 581-590.63, Maculatum Subzone; 35 specimens. 



Remarks. Ammonites in bed 590.61 have a distinctive style of 

 preservation, where the dark brown or black shell of the ammonite has 

 small near-circular patches of white calcite; such a well-preserved 

 example is figured in PI. 7, fig. 13. This type of preservation does not 

 occur at any other level and allows the horizon of many of the figured 

 specimens, including the holotype, to be identified precisely, as given in 

 the list of figured specimens above. The lowest specimens in bed 58 1 are 

 typical examples of the species, being much larger and more developed 

 than is found in transitions from Aegoceras (Beaniceras) luridum. The 

 lattertransitionsarerepresentedbytwospecimensinbed583.2determined 

 as A. (A.) maculatum var. atavum (see discussion below). The specimen 

 from bed 583 figured by Phelps as A. (Beaniceras) luridum is also an A. 

 maculatum ; it has ribs on the venter that are bold and well developed and 

 are not much reduced on a nearly flat venter as in B. luridum. 



Phelps (1985: 351) divided the Maculatum Subzone into a lower 

 'Sparsicosta Zonule' and an upper 'Maculatum Zonule'. His lower 

 division was based on the range of ammonites in the lower part of the 

 Subzone that have low rib densities on their inner whorls of 16-18 

 ribs per whorl, and were identified as Androgynoceras (Aegoceras) 

 sparsicosta (Trueman). Such rib densities are not different from the 

 rib densities of Aegoceras maculatum, and in any case sparsicosta is 

 not an appropriate name for them. The real Androgynoceras 

 sparsicosta (Trueman) (holotype figured Spath. 1938: pi. 5 fig. 7) is 

 a species that develops swollen, quickly expanding whorls and has 

 sharply bituberculate ribs from a diameter of about 25 mm. These 

 features are typical of the genus Androgynoceras, and Phelps' (1985: 

 pi. 1, fig. 1) 58 mm diameter ammonite from the lower part of the 

 Maculatum Subzone does not show such features - it is a typical 

 Aegoceras maculatum, as are all the specimens in Bairstow's collec- 

 tion. Subdivision of the Maculatum Subzone on the basis of these 

 ammonites is not followed here. 



Aegoceras (A.) maculatum (Young & Bird), var. atavum 

 Spath, 1938 PI. 7, fig. 8 



1938 Androgynoceras maculatum (Young & Bird), var. atavum 

 Spath: 127, pi. 20, fig. 3 (from Gloucestershire). 



