118 



M.K. HOWARTH 



with the bottom of the cliff, then yards at right angles to the line up 

 to the position of the ammonite. By these means the geographical 

 position of each ammonite was recorded to approximately the near- 

 est square yard. This information, which is not included in this paper, 

 occurs on many of the original specimen labels that are with the 

 ammonites in his collection. 



In 1957 Bairstow prepared a bed-by-bed list of the identifications 

 of every ammonite in his collection. This is a large manuscript 

 amounting to 390 pages. Not only is it a list of the specimens then in 

 the collection (over the years a small number had decayed or were 

 lost), but its main value is as a record of the identifications made by 

 Dr L.F. Spath. He saw the specimens as Bairstow collected them, and 

 made identifications that date mainly from the period 1927^-0, 

 while a few were checked or reidentified by him up to 1956. In 

 preparing the list of ammonites for this paper, all the identifications 

 were verified, mainly in order to produce a consistent set of 

 determinations from which the account of the biostratigraphy could 

 be prepared, but also to revise the generic attributions of the species 

 according to modern usage of the various genera. In general Spath's 

 identifications were found to be accurate, and only a few needed 

 revision. The only previous publication of any of Spath's identifica- 

 tions was in his catalogue of the Liparoceratidae (Spath, 1938), 

 where all the Robin Hood's Bay Liparoceratidae collected up to 

 1937 were listed by register number. 



SYSTEMATIC DESCRIPTION OF THE 

 AMMONITES AND NAUTILOIDS 



This section is not intended be a full description of the ammonites in 

 the Sinemurian and Lower Pliensbachian of Robin Hood's Bay, but 

 all ammonites that have been figured before are included in a list in 

 systematic order, and this gives an indication of their synonymies. 

 All the Robin Hood's Bay ammonites that have been described or 

 figured by the following authors are included: J. Sowerby and J. de 

 C. Sowerby (1812-1846), Young & Bird (1822, 1828), Phillips 

 (1829, 1835, 1875), Brown (1837, 1889), Simpson (1843, 1855, 

 1884), Blake (1876), Wright (1878-82), Hyatt (1889), Buckman 

 (1909-30), Spath (1923*, 1924, 1925a, 1938, 1956), Trueman & 

 Williams (1925), Jaworski ( 193 1 ), Howarth (1955, 1962), Dean etal 

 ( 1 96 1 ), Howarth & Donovan ( 1 964), Guerin-Franiatte ( 1 966), Getty 

 (1973), Donovan & Forsey (1973), Schlegelmilch (1976, 1992), 

 Phelps (1985), Dommergues (1987) and Dommergues & Meister 

 (1992). 



All the ammonites listed are from Robin Hood's Bay. except 

 where indicated otherwise, and the beds from which the type and 

 figured specimens might have come are identified with varying 

 degrees of confidence, as indicated in the list; register numbers are 

 given, where known. The list also shows the data on which the 

 identifications in the paper are based (eg. by giving references to 

 the type specimens in most cases, including those that are not 

 Yorkshire specimens). 56 of the better preserved ammonites in 

 Bairstow's collection are figured to illustrate the identifications and 

 the contents of some of the subzones. Further discussion of 

 synonymies, identifications and distribution in the zones and 

 subzones is found in the section on Biostratigraphy, and more 

 details of the identifications of the type specimens of some species 

 can be found in Howarth (1962). All measurements are in millime- 

 tres (mm); D = diameter, Wh = whorl height, Wb = whorl breadth, 

 U = diameter of the umbilicus. 



Order AMMONOIDEA Zittel, 1884 

 Suborder PHYLLOCERATINA Arkell, 1950 

 Family JURAPHYLLITIDAE Arkell, 1950 

 Genus TRAGOPHYLLOCERAS Hyatt, 1900 



Tragophylloceras numismale (Quenstedt, 1845) 



PI. 1 , fig. 1 



1 843 Ammonites huntoni Simpson: 41 . 



1 845 Ammonites heterophyllus numismalis Quenstedt: 1 00, pi. 6, 



figs 4a, b, 5a, b, non figs 3a, b, 5c (figs 5a, 5b, from 



Germany, designated lectotype by Buckman, 1912: viii). 

 1855 Ammonites nanus Simpson: 38. 

 1921 Tragophylloceras huntoni (Simpson); Buckman: pi. 219 



(paratype or holotype, WM 477; ?from bed 5 17 or 520). 

 1926 Tragophylloceras nanum (Simpson); Buckman: pi. 679 



(holotype, WM 472; from bed 517 or 520). 

 1964 Tragophylloceras numismale (Quenstedt); Howarth & 



Donovan: 295, pi. 48, fig. 5 (BM C.67766; from bed 517 or 



520). 



Range. Beds 505.2-544.5, Taylori to Polymorphus Subzones; 1 7 

 specimens. 



Tragophylloceras loscombi (J. Sowerby, 1817) 



1817 Ammonites loscombi J. Sowerby: 185, pi. 183. 



1843 Ammonites ambiguum Simpson: 8. 



1843 Ammonites robinsoni Simpson: 42. 



1910 Rhacoceras ambiguum (Simpson); Buckman: pi. 16 

 (holotype, WM 89; ?from bed 569). 



1914 Tragophylloceras loscombi (J. Sowerby); Spath: 336, pi. 

 49, fig. 1 (holotype, from Dorset). 



1921 Tragophylloceras robinsoni Buckman: pi. 220 (paratype, 

 WM 478; ?from bed 569). 



1964 Tragophylloceras loscombi (J. Sowerby); Howarth & Do- 

 novan: 301, pi. 49, figs 4-7 (from Dorset). 



Range. Found in bed 569 only, Masseanum Subzone; 2 speci- 

 mens. 



REMARKS. This single specimen high in the Masseanum Subzone 

 is at a lower horizon than specimens in Dorset, where they have not 

 been recorded from below the Luridum Subzone (Howarth & Dono- 

 van, 1964: 293, 302). 



Suborder LYTOCERATINA Hyatt, 1889 



Superfamily LYTOCERATACEAE Neumayr, 1875 



Family LYTOCERATIDAE Neumayr, 1875 



Genus LYTOCERAS Suess, 1865 



Lytoceras fimbriatum (J. Sowerby, 1817) 



PI. 1, fig. 3 



1817 Ammonites fimbriatus J. Sowerby: 145, pi. 164. 

 1919 Fimbrilytoceras fimbriatum (J. Sowerby); Buckman: pi. 

 130A-C (from Dorset). 



Range. Beds 570-578.5, Ibex Zone; 25 specimens. Two Lytoceras 

 of indeterminate species were found in beds 568 (top) and 584. 



Remarks. Lytoceras fimbriatum is confined to the Ibex Zone in 

 Robin Hood's Bay, except for one poorly preserved specimen in bed 

 584 (Maculatum Subzone) that can only be determined as Lytoceras 

 sp. indet. Many of those in the Ibex Zone are large and well- 

 preserved, and one of the best specimens is figured in PI. 1. fig. 3. 

 Sowerby's figured specimen, now lost, was from Dorset. 



