Mr. J. Morris on some new species of the genus Ancyloceras. 31 



at their bases by about twenty smaller ones, in difierent stages of 

 growth, all of them beinj;: attached to the dorsal portion of an 

 Ammonite, probably the A. Elizabeths ; to the 0])])0site side 

 of the Ammonite is attached a smaller but more imperfect series, 

 which it has been thoui;ht unnecessary to figure. 



This specimen t\)rms a j)ortion of the valuable collection of 

 fossil remains belonging to Channing Pearce, Esq. of liradford, 

 by whom it was oljtained from the Oxford clay, near Christian 

 ]\Ialford, ^^ ilts ; and 1 cannot but bear testimony to the very 

 elaborate drawing prepared by Miss C. Sowerby, from which the 

 engraving was executed. 



Pollicipes plnnulatus. (PI. VI. fig. 2.) 



Testa ? ; valvulis lateralibus planulatis, anticis trapezlformi- 



bus, longitudinaliter linca imjiressa divisis, posticis subelongatis, 

 trapeziformibus, ad basin suboblique truncatis, apicibus acutis, 

 marginibus anticis subcreuulatis. 



These three valves diifer both in pro])ortion and form from 

 those of the preceding species, and are much flatter than is usual 

 in this genus ; the terminal or posterior \ alves arc elongated and 

 truncated at the base, their upper portion being marked with a 

 slightly curved ridge running towards the lower edge or margin. 

 From the Oxford clay, near Christian Malford, with the last 

 species. 



IV'. — Description of some new species of the genus Ancyloceras. 

 By John Morris, Esq. 

 [With a Plate.] 

 The genus Ano/loceras was established by D'Orbigny for certain 

 species of Cephalopoda having the general form of Scaphites, 

 but differing from them in their spiral volutions being distinctly 

 separated from each other, as well as in some slight modifications 

 in the arrangement of the foliations of the septa. Tlie British 

 species of Ancyloceras hitherto described have been arran2;ed 

 imder Hamites and Scaphites, all of them belonging either to the 

 lower portion of the cretaceous series or the Speeton clay* of 

 Yorkshire. Mons. D'Orbigny, in the ' Terrains Cretaces,' p. 494, 

 mentions one species of this genus as characteristic of the in- 

 ferior oolite of Calvados, but has not yet detected it in any of 

 the superior deposits, until the commencement of the lower por- 

 tion of the cretaceous series, where, in the Neocomian strata, this 

 genus appears to attain its maximum of specific development, 



* The true position of this deposit is not yet satisfactorily deterniintt! 

 altliough considered as tlie equivalent of the Neocomian by some of the 

 French paleontologists, and of the Hilsthon of Hanover by M. Rbnicr. The 

 I fa miles in termed ins and Bcanii (Phillips) belong to the genus Aiici/loreraH. 



