GRAMMOCERAS NANNODES. 213 



thought it necessary to occupy space with figures. The points to be remem- 

 bered are those which I have noticed concerning this author's figure, and that the 

 specimens are, usually, slightly more umbilicate. 



Gh-'amm. dispansum must be considered a common fossil ; at the same time it 

 is very local ; while the condition of the specimens is generally very inferior on 

 account of the manner in which the matrix adheres to the test. 



This species characterises a definite horizon just above that which Gramm. 

 toarcense and Gramm. striatulum dominate; and consequently it may be considered 

 to occupy about the middle of the Jurense-zone. It occurs in Gloucestershire at 

 Buckholt Wood, Frocester Hill, Stinchcombe, North Nibley, Wotton-under-Edge, 

 &c. ; but it is very rare at Coaley Wood. From White Lackington, near 

 Ilminster, I have a fragment obtained from beds below the Yeovil Sands (section 

 xiii, page 165). 



The horizon of this species is so well marked, and the species itself is one 

 so little likely to be mistaken, that I have chosen its name^ for the strata which 

 succeed the Striatulum-heds (page 164). The species is not found at all in the 

 Cotteswold Sands, and is therefore not associated with Haugia variabilis or jugosa, 

 a fact which Lycett noticed in his papers on these Ammonites. In reality I have 

 never found it above or below the thin stratum to which I apply the name of this 

 species. 



For figures of this species, see Dr. Wright's Monograph as quoted in the 

 synonymy. My PI. A, figs. 41, 42, gives the suture-lines of two specimens. 



Grammocbras NANNODES, S. Buchman. Plate XXXIII, figs. 13 — 16. 



Discoidal, much compressed, hollow-carinate. Whorls very narrow, convex 

 from inner to outer edge, ornamented with very fine, ventrally-projected, sub- 

 arcuate strise. Ventral area undefined, carrying a very prominent hollow-carina, 

 conspicuously sulcate on each side, so that in section it appears not unlike a rail 

 from the railway, except that the outer — the flanged — part is more circular. Inner 

 margin undefined. Inclusion one-fourth. Umbilicus very shallow. Sutures 

 unknown. 



This most distinct little form is easily known by its dwarf size in comparison 

 with other members of the srenus : hence the name ^' nannodes.'^^ It is further 

 distinguished by its very fine striae, its compressed shape accompanied, singularly 

 enough, by evolute whorls, and by its trenchant, laterally-sulcate hollow-carina. 



1 " The Cotteswold, Midford, and Yeovil Sands," ' Quart. .Tourn. Geol. Soc.,' vol. xlv, p. 443 et seq. 

 ■^ vavvb)bini, dwarfish. 



