SUPPLEMENT.— GRAMMOCERAS. cxxxi 



The distinction of Grammoceras and its allies as a sub-family from Lillia, 

 Ludioigia, etc., would seem advisable. The difficulty, however, is with definition ; 

 because the degenerates in both series, passing through similar phases of decline, 

 simulate each other's characters so much, and lose the features once severally dis- 

 tinctive ; therefore broad demarcation seems to be difficult. 



A. Non-septicarinate. 

 LIV. Genu* — Grammoceras, Hyatt. 

 (Type : Grammoceras striaUdum, J. D. C. Sow., sp.) 

 1890. Grammoceras, This Monogr., p. 158 (pars). 



1900. Dumortieria, 1 Hyatt, in Text-book of Palaeontology, by Zittel-Eastmau, 

 vol. i, p. 576. 



Definition. — Substenoleptogyral, latumbilicate ; pauciseptate ; subbrevisublati- 

 lobate ; laterally subflexiradiate ; peripherally subacutanguliradiate, fastigate, parvi- 

 nonsepticarinate. (Radial line, fig. 108, p. clxv.) 



Note. — The definition applies to the genotype which is already degenerate. 

 Such characters as the fastigate periphery and leptogyral shape mark degeneration : 

 a subtabulate periphery, and subleptogyral, even subpachygyral, whorls are 

 characters of less degenerate species of the genus. 



Remarks. — The species figured by Wright, ' Monogr. Lias Aram.,' Plate xlix, 

 figs. 4, 5, as Harjpoceras nitescens has, according to a specimen kindly given 

 to me by Dr. Vaughan, the simple suture line," rib characters and general 

 shape of Grammoceras ton role use, with this difference: it is knobbed on the 

 peripheral margin. 



As my specimen is certainly a Grammoceras, it takes the genus a step further 

 back into the tuberculate stage, with the important distinction from Lillia that 

 the tubercles occupy the outer, not the inner, edge of the whorl. 



A carina between two definite furrows is also a character of my specimen, 

 though the furrows become obsolete with age. Wright shows the furrows more 

 persistent. 



Separation of the species formerly (p. 158 et seqq.) placed under Grammoceras 

 has become necessary. 



1. Grammoceras, sp. A., Plate XXXIV, fig. 12. 



1890. Grammoceras toarcense, var., This Monogr.. PI. xxxiv, fig. 12; p. 1<>!». 



Remarhs. — A distinct form with a wide umbilicus, a carinati- subtabulate 

 periphery and occasional connate costse. 



1 The Fig. 1201 labelled " Dumortieria, sp.." is Grammoceras toarciense. It has neither tin' 

 ribbing nor the suture line of Dumortieria. 



- The lobe line given by Wright, fig. 3, seems doubtful. At least, my specimen lias quite the 

 simple suture liue of Grammocenix. 



