Mr. J. Morris on some, new species of the gentis Ancyloceras. 3 1 



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

 growth, all of them being attached to the dorsal portion of an 

 Ammonite, probably the A. Elizabethce; to the opposite side 

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

 which it has been thought unnecessary to figure. 



This specimen forms a portion of the valuable collection of 

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

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

 Malford, Wilts ; and I cannot but bear testimony to the very 

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

 engraving was executed. 



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

 Testa ? ; valvulis lateralibus planulatis, anticis trapeziformi- 



bus, longitudinaliter linea impressa divisis, posticis subelongatis, 



trapeziformibus, ad basin suboblique truncatis, apicibus acutis, 



marginibus anticis subcrenulatis. 



These three valves differ both in proportion and form from 

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

 in this genus ; the terminal or posterior valves are 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 Ancyloceras 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. The British 

 species of Ancyloceras hitherto described have been arranged 

 under 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 determined, 

 although considered as the equivalent of the Neocomian by some of the 

 French palaeontologists, and of the Hilsthon of Hanover by M. Ronier. The 

 Hamites intermedins and Beami (Phillips) belong to the genus Ancyloceras. 



