24 TYPE AMMONITES— III Sept. 



1920 



aperture. Burton Bradstock, Dorset [zigzag], S.B., ex Darell, Coll., 

 No. 3365, Holotype. 



Ebrayiceras — Proportions — order of umbilication. 



E. pseudo-anceps (Dorset) . . S. 24, 42, — , 32 



S. 29 38, 33, 34.5. 



E. pseudo-anceps (Type) . . F. 24, 42 — , 33 



F.29, 38 — , 35-5 



F. 36.5, 40,[36?]30 34[36 ?] 

 T. 36.5. 33.[36?]29 36 



E. vaschaldi S. 46, 32.5, 24, 39 



E. jactatum S. 35, 37, 31.5 31.5 



S- 47 32, 23.5 40.5 



E. ocellatum S. 24, 35.5, 31.5, 35.5 



S. 29, 33, 28.5 40 



E. ritrsum S. 28, 28.5, 26, 43 



By the time E. ocellatum had reached a diameter of 36.5 mm., the 

 size of type E, pseudo-anceps, it would have something like 42 per cent, 

 umbilication. 



Of.coptychius, Neumayr, 1878, Cephalopodentypen, Jahrb. k. k. 

 geol. Reichsanstalt, XXVIII (1), 68, Genotypes " Gruppe des Ammonites 

 refractus." Advisable to take as genolectotype Am. refractus, d'Orbigny, 

 Terr. jur. Ceph. cxxxn, 4, 5. [S.l. lobes short and simple, EL longer 

 than L l , trilobulate, L 2 single, quite short, about one-fourth the length 

 of L 1 — from a Bavarian example]. 



Callovian ; France, Germany. 



The difficulty of placing this genus in Morphoceratida: is the absence 

 of connecting links — Eningenian to Callovian. But the Sphaeroceratida; 

 show no forms with peripheral sulcus, the Morphoceratida^ do. 



CEcoptychoceras, g.n., Genoholotype, CEc. subrefractum, 

 n. PI. CLXXVI. A catamorph development of a sphserocone which 

 has acquired a gonioconic outline. From Oecoptychius it differs [in 

 mouth-border (see Brasil, Ceph. nouv. ; Bull. Soc. geol. Norm. XVI, 

 1893, p. 21, PI. iv, f. 12, 13)], and also in the ribs crossing the periphery 

 with very slight weakening, making an almost indiscernible median line, 

 not a distinct ventral interruption of ribs or sort of sulcus as in Oecop- 

 tychius. At beginning of body-chamber only there is a short hidden 

 sulcus on periphery — in cast not in test : the same is often to be seen 

 in Sphaeroceratidre and Morphoceratidae. 



EL and L 1 about same length, L 2 incipiently trilobulate, about £ of 

 L 1 . [Lobes more developed in 02c. grossouvrei, PI. CLXXV.] 



This genus cannot be ancestor of Oecoptychius, as it is already 

 more decadent in costation. The two genera are morphic equivalents 

 produced by similar causes from more or less distinct sources, as the 

 difference in periphery shows. CEcoptychoceras is perhaps connected 

 with Morphoceras, Oecoptychius with Ebrayiceras, at least according to 

 peripheries. 



England (Dorset) ; Normandy ; Germany ? cf. Neumayr, cit. p. 68, 

 Vesulian (Eningenian), truellei. 



CEcoptychoceras grossouvrei (Brasil), Loc. cit. Oecoptychius grossouvrei. 

 The example figured, PI. CLXXV, is the sphserocone stage before the 

 goniocone stage begins — most of body-chamber being lost. 



Burton Bradstock, Dorset, truellei — the matrix is unmistakable. 

 S. 8.5, 57, 76, — , which agree with Brasil's illustration at same diam. 



Qicoptychoceras subrefractum, S.B. MS. sp., Oecoptvchius grossouvrei, 

 S.B., Q.J.G.S., LIV, 1898, 456 (non Brasil). This "(PL CLXXVI) is 



