1926 SYSTEMATIC 13 



Oppel, A., Die Juraformation, 1856, pp. 75, 76, writes : " In 

 Yorkshire erhielt ich Amm. angulatus in mehreren Exemplaren. In 

 den dortigen Sammlungen liegt er entweder mit dem Phillip'schen 

 Namen : Amm. anguliferus , oder nach Young und Bird : Amm. Redcar- 

 ensis bezeichnet. Letzteres mag auf Irrthum beruhen, denn die 

 Young'sche Angabe (pag. 248), dass Amm. Redcarensis einen scharfen 

 kiel trage, stimmt mit der aussern Form des Amm. angulatus nicht 

 iiberein." 



Blake, J. F., (Cephalopoda, in Tate & Blake, The Yorkshire Lias, 

 1876, p. 271), says of Aegoceras angulatum Schlotheim : — " This was first 

 recognised by Young and Bird [as A. Redcarensis], but the figure given 

 is erroneous. It was identified by Oppel as belonging to the previously 

 described species of Schlotheim. There are two varieties : (a) most 

 involute, the outer whorl being more than J the diameter — the common 

 Redcar fossil ; {&) less involute, with outer whorl J the diameter, 

 occurring chiefly in the southern area. The largest known is about 

 3 inches in diameter." 



The types of Young & Bird's two editions came to the Whitby 

 Museum, so Martin Simpson, the Curator, was in the best position to 

 know the sf)ecimens. He is quite f)ositive that Am. redcarensis is a 

 sulcate. The example now figured (T.A. DCVIII) is presumably that 

 which Simpson called " Young's original Redcar specimen " — Simpson's 

 measurements were often only approximate. If so, it will be best to 

 accept the sulcate specimen and to call it the lectotype. Its locality 

 would then be Redcar : Young & Bird seem to have been in the same 

 confusion about the locality as about the specimen. 



Pallasiceras, Spath MS. cit. by Lamplugh, Kitchin & Pringle 

 (Concealed Mesozoic Rocks in Kent ; Mem. Geol. Surv., 1923, p. 222) : 

 " Pallasiceras ' pallasianum ' " and footnote 2 " Ammonites pallasianus 

 as hitherto understood by British geologists. Dr. L. F. Spath permits 

 us to say that, in a work now in the press (to be published by the 

 Geological Survey of India), he proposes for this group the generic 

 name Pallasiceras : genotype Ammonites rotundus J. Sowerby, ' Mineral 

 Conchology,' vol. iii, pi. 293, fig. 3, 1821. The genus does not include 

 A. pallasianus of d'Orbigny." 



This is the first published mention : it fixes the genotype definitely 

 on Sowerby's specimen. Unfortunately, this is only a body-chamber 

 fragment, much worn, and giving Httle indication of suture-hne. This 

 holotype is figured in T. A. DXC, 1925. Topotypes show that the 

 suture-line is short-lobed, and that the inner whorls are multicostate, 

 somewhat of virgatite pattern, not dissimilar from those of young 

 Lydistratites (T.A. DCVb). So far as can be at present ascertained, 

 the difference of Pallasiceras from the prior-named Lydistratites is that 

 in Pallasiceras the species remain comparatively small and the suture-line 

 comparatively simple with short lobes. Pallasiceras would appear to 

 be the phaulomorph of Lydistratites, having about the same relation 

 to that as Otoites has to Emileia. 



Pallasiceras rotundum occurs in the Nodule Bed of the so-called 

 Kimmeridge Clay of Chapmans Pool, Isle of Purbeck, Dorset (T.A. 

 DXC) — this Nodule Bed being about fifteen feet above the shore, and 



