54 miss maud healey on [Feb. 1904. 



5. Notes on Upper Jurassic Ammonites, with special reference 

 to Specimens in the University Museum, Oxford : No. I. By 

 Miss Maud Healey. (Communicated by Prof. W. J. Sollas, 

 D.Sc, LL.D., F.K.S. Head November 18th, 1903.) 



[Plates IX-XII.] 



In the course of rearranging the Upper Jurassic fossils in the 

 University Museum, Oxford, my attention has been called to the 

 large amount of misconception which exists with regard to Sowerby's 

 species Ammonites plicatilis and Am. biplex. The former is rightly 

 recognized in England as the zone-fossil of the Upper Corallian, but 

 Dr. J. von Siemiradzki 1 gives the name to a specimen from the 

 omatus-zone. He makes the following surprising remark with 

 reference to it : — 



' Da Sowerby's Originate nicht erhalten sind, bleibt uns nichts anderes iibrig, 

 als die nachst alteste Figur von Pbillips als Typus der Art anzuseben.' 



The original specimen is in the Buckland Collection in the Uni- 

 versity Museum, Oxford ; but even if it had been lost, Sowerby's 

 figure would have had a better right to be taken as the type than 

 that of Phillips, for it has tbe priority and there is no ambiguity 

 about it, while the history of the latter is very involved and the 

 original, so far as I can ascertain, is not preserved. The reference 

 which Dr. Siemiradzki gives for it is • Geology of Yorkshire ' 

 (1829) pi. iv, fig. 29, that is, the first edition, in which the figure 

 in question is that of a keeled ammonite and is named Ammonites 

 Solaris ; while the figure 2 which he gives as an example of Peri- 

 sphinctes plicatilis makes it quite clear that he is really referring to 

 the third edition (1874), in which fig. 29 on pi. iv is that of a 

 species of Perisphinctes and is described in the explanation of the 

 plates 3 as 'Am. Solaris (erased 1874), Am. plicatis (replacing Am. 

 solaris),' but referred to on p. 265 as Am. plicatilis, Sow. It is 

 therefore most probable that 'jolicatis' was intended for ' plicatilis ' 

 on p. 325 ; but, granted that this is so, it in no way affects the 

 validity of Sowerby's 'type.' The second edition (1835) of the 

 ' Geology of Yorkshire ' is the same as the first. 



Perisphinctes bvplex is, in England, generally considered to be the 

 zone-fossil of the Upper Kimeridge Clay, Damon's figure 4 having 

 apparently been taken as the type instead of Sowerby's. Dr. Siemi- 

 radzki devotes two pages of his monograph fi to it, and gives a figure 

 of the original bijolew, which is preserved in the British Museum 

 (Natural History). Unfortunately, he had only a plaster-cast on 



1 'Monographische Beschreibimg der Ammonitengattuug Perisphinctes' 

 Palseontograpkica, vol. xlv (1898) p. 249. 



2 Ibid. pi. xxv, fig. 45. 



:i 'Illustrations of the Geology of Yorkshire' 3rd ed. vol. i (1874) p. 325. 

 4 « Geology of Weymouth ' Suppl. 2nd ed. (1880) pi. ix, fig. 9. 

 s ' Mineral Conchology' vol. iii (1821) pi. ccxciii, figs. 1 & 2. 

 (; Palaeontographica, vol. xlv (1898) pp. 265-07. 



