264 DR. A. E. TRUEMAX OX THE [vol. lxxiv,. 



horizon is unknown, and apparently no comparable forms Lave 

 been discovered in this country. A. spinellii, also described by 

 F. von Hauer, 1 is the small young of the sphyerocone in which the 

 Capricorn stage is omitted 2 ; the sutural proportions are suggestive 

 of this genus. 



Of A. nautili for mis, Mr. Buckman figured two specimens, of 

 which the former (the holot}'pe) is somewhat stouter (1, vol. i, 

 No. 37). Some ammonites figured by Quenstedt (4, pi. xxix) agree 

 in whorl shape, suture, and position of tubercles ; the horizon given 

 by Quenstedt is similarly considerably higher than the horizon of 

 other sphserocones. 



(2) Series in which the Sphaerocones have Paired 



Tubercles. 



It is not possible to offer any detailed classification of these 

 forms, which do not occur commonly in this country and of which 

 very little material is available. It appears, however, that three 

 series may be recognized, namely : — 



(1) A parinode series with depressed whorl; this includes A. striatus 



Reinecke. No representative of the group has been recorded in 

 this country. 



(2) A parinode series with elevated whorl; this includes A. striatum 



parinodus Quenstedt (4, pi. xxviii, figs. 16-23), A. striatus Ixcis 

 Quenstedt (4, pi. xxviii, fig. 6), A. striatus reineclcii Quenstedt (4, 

 pi. xxviii, fig. 5). Sphasrocones of this series, in the collections of 

 Mr. S. S. Buckman and Mr. J. W. Tutcher, from the valdani zone 

 of Radstock, resemble the last-named species. 



To cover this series the genus Pari nod iceras is here proposed. 

 •Genoholotype, Ammonites striatus parinodus Quenstedt (4, pi. xxviii, 

 fig". 16). 



(3) A parinode series with round whorls ; the tubercles of the inner row 



are placed high up the whorl, so that the two rows are unusually 

 close together. Only three examples are known, in the collection 

 of Mr. J. W. Tutcher, who obtained them from the valdani zone 

 of Radstock. 



The name Vicininodiceras is proposed for this series. Geno- 

 holotype, V. simplicicosta, sp. nov. (PI. XXIV, fig. 4.) 



It will be noted that all the parinode forms which have been 

 observed in England occur at a lower horizon than any imparinode 

 forms, and probably represent a more primitive stage in evolution. 



Notes on Phricodoceras Hyatt, 1900. 



Genoholotype : Phricodoceras (Ammonites) taylori (A. d'Orbigny). (3, 

 pi. cii, figs. 3 & 4.) 



This genus of Liparoceratid ammonites is not fully considered 



1 • Ueber die Ammoniten aus dem sogenannten Medolo der Berge Domaro ' 

 Sitznngsb. K. Akad. Wissensch. Wien, vol. xliv (1861). 



- Ammonite* herileyi Hauer, ' Ueber die Cephalopodcn aus dem Lias der 

 Nordostlichen Alpen ' Denkschr. K. Akad. Wissensch. Wien, vol. xi (1856) 

 p. 60 & pi. xx, figs. '4-6, may be a coarsely-tuberculate form of this genus. 



