552 mr. l. f. spate: on - [Dec. 1913, 



A brief formal diagnosis of the new genus might, then, be framed 

 as follows : — General form of the shell resembling Seguenziceras 

 as here emended : that is, more or less evolute ; compressed or 

 quadrate in section, and always keeled — the venter ranging from 

 acute to carinatisulcate. The ornament consists of falciradii, 

 varying within the limits defined in the foregoing table (p. 550). 

 Sutures like Seguenziceras. 



The introduction of subgenera will have to be delayed until a 

 study of the suture-lines has been accomplished. Further, I believe 

 that no careful observations have been made hitherto, as to the 

 succession in time of the various forms discussed here. Most of 

 them are quoted from the ' margaritatus ' zone ; but I think it 

 probable that the two subdivisions of the new genus here established 

 are later than, and have developed from, the older Seguenzicerates 

 of algovianum type, with increase and decrease of peripheral pro- 

 jection respectively, added to a flexiradius. Increased knowledge 

 may permit us further to separate from the forms described here 

 two apparently distinct lineages : that of ' Harpoceras (? J ' dilectum 

 Fuc., 1 which tends to develop a typical Harpocerate undercut 

 umbilical edge, but is still subfalciradiate ; and that of Ammonites 

 acutus Tate, a ' perfalciradiate ' form, in which the strong and 

 notched carina becomes so conspicuous a feature. 



Pkotogrammoceras oorbtacaldense (Tausch) var. zettgitanum nov. 

 (PL LIT, figs. 1 a & ] 6.) 



Comparable forms : — 



1867-81. Harpoceras pectinatum Meneghini, ' Fossiles du Medolo ' [in 



Stoppani's ' Paleont. Lombarde ' ser. 4, App.] p. 6 & pi. i, figs. 1-3. 

 1884. Harpoceras normanianum (d'Orb.) Wright, ' Lias Ammonites ' Monogr. 



Pal. Soc. p. 470 & pi. lxxxiii, figs. 1-2. 

 1890. Harpoceras cornacaldense Tausch, ' Fauna d. grauen Kalke der Sudalpen ' 



Abhandl. K.K. Geol. Reichsanst. vol. xv, pt. 2, p. 36 & pi. i, fig. 1. 

 1895. Harpoceras (?) cornacaldense Tausch, var. bicicolce Bonarelli, ' Fossili 



Domeriani della Brianza ' Rendic. R. 1st. Lombard, ser. 2, vol. xxviii. 



p. 339. 

 1900. Grammoceras normanianum (d'Orb.) var. inseparabile Fucini, ' Amm. 



del Lias Medio dell' Appennino Centrale ' Pal. Ital. vol. vi, p. 29 & 



pi. viii, fig. 5. 

 1900. Hildoceras cornacaldense Tausch, mut. medolense Bettoni, 'Fossili 



Domeriani della Provincia di Brescia' Mem. Soc. Paleont. Suisse, 



vol. xxvii, p. 63. 

 1909. Harpoceras cornacaldense (Tausch) Rosenberg, ' Liasische Cephal.- 



Fauna der Kratzalpe ' Beitr. Palaont. Geol. (Esterr.-TJng. vol. xxii, 



p. 307 & pi. (vii) xvi, figs. 1-2. 



The specimen is a cast in compact grey limestone, and has the 

 following dimensions : — 



Diameter 60 millimetres. 



Height of the last whorl 30 per cent, of the diameter. 



Thickness of the last whorl 18 per cent, of the diameter. 



Umbilicus 46 per cent, of the diameter. 



The whorls are much compressed, and show the peculiar wedge- 

 like thinning towards the periphery characteristic of all the forms 



1 ' Cefalop. Liass. del Mte. di Cetona ' pt. 4, Pal. Ital. vol. x (1904) p. 278 

 (244) & pi. xxxix (xviii), figs. 11-12. 



