SUPPLEMENT.— PLEYDELLIA. cxxxvii 



13. Cotteswoldia ceinita, 8. Buckman. Plate XXXI, figs. 3, 4 ; Suppl., Fig. Ill, 



p. clxv. 

 1890. Grammoceras mactra 0, This Monogr., PI. xxxi, figs. 3, 4 ; p. 176 (pars). 

 1902. Cotteswoldia crinita, Emend. Amm. Nom., p. 3. 



Description. — Striate; periphery tending to be convex with no definite carina. 



Distinction. — From C. bifax, greater compression, more of striate stage. 



Remarks. — The costate stage, similar to that of < '. bifax, but on a reduced 

 scale, ends about a whorl earlier than in that species. Tachygenesis in this 

 feature, and in regard to the periphery, in comparison with G. bifax, seems well 

 marked. 



The side view in the monograph is by no means a satisfactory representation. 



Locality and Stratum. — Gloucestershire : Coaley Peak (Frocester), Cephalopod 

 Bed, Moorei [Aalensis ?~\ Beds. 



Date of Existence. — Moorei [Aalensis?) hemera. 



LVI. Genus — Pleydellia, 1 S. Buckman. 



(Type : Pleydellia aalensis,' 2 Zieten, sp.) 

 1899. Pleydellia, This Monogr., Expl. of Snppl., PL x. 



Definition. — Subplatyleptogyral, sublatumbilicate ; subpauciseptate ; brevi- 

 sublatilobate ; laterally subflexiradiate ; peripherally anguliradiate, acutifastigate, 

 carinate. (Radial lines, figs. 112, 113, p. clxv.) 



Distinction. — From Cotteswoldia, more compressed form of whorls, though 

 hardly enough to be called perleptogyral, more laterally flexed radial line (from the 

 type series), sharper periphery, distinct carina. 



Note. — Ammonites candidus, d'Orbigny, Pal. franc.; Terr, jurass. ; PI. lxiii, 

 figs. 1, 2, would appear to be a species of this genus. 



1. Pleydellia aalensis (Z i kten). Plate XXXII, figs. 3 — G; Suppl., Figs. 112, 113, 



p. clxv. 

 1890. Grammoceras aalense, This Monogr., PI. xxxii, figs. 3 — 6; p. 192 (pars). 

 1902. Pleydellia aalensis, Emend. Amm. Nom., p. 4. 



2. Pleydkllia fluens, 8. Buckman. Plate XXXI, figs. 1, 2 ; Suppl., Fig. 11-1, p. clxv. 



1890. Grammoceras mactra, This Monogr.. PI. xxxi, figs. 1, 2; p. 176 (pars). 

 1902. Pleydellia fluens, Emend. Amm. Nom., p. 4. 



Description . — Connati-parvicostate to obscuricostate. 



1 In compliment to Mr. J. C. Mansel PlevdeH, J. P., F.L.S., F.G.S., etc., for so many years 

 President of the Dorset Field Club. 



2 The type of the genus is the species figured in this Monograph, PI. xxxii, figs. 4 — 6. 



