GRAMMOCERAS S^MANNI. 208 



This unique example, which is very nicely preserved, came from the 

 Dispansum-loeds of Cam Down. 



PL XXXVI, fig. 3, illustrates the side view ; fig. 4 the back view ; and fig. 5 

 an outline of the whorl and the inner margin to compare with fig. 8. Herein it 

 may be observed that, on account of the whorls being thickest at the inner edge 

 and then falling away, the inner margin is much deeper than in fig. 8. 



Geammooeeas S^manni (Dumortier). Plate XXXIV, figs. 1, 2; Plate XXXVI, 



figs. 6—8. 



1874. Ammonites S^manni, Dumortier (non Oppel). Etudes pal. Bassin Eh6ne, 



iv, pi. xiii, figs. 4 — 6. 

 1885. HiLDOCEEAS S^manni, Saug. Beitr. Monogr. Harpoceras ; Neues Jahr- 



bucli fiir Mineralogie, &c., Beil.-Bd. iii, 

 p. 638 (pi. xi, fig. 18, suture-line). 

 1887. Ammonites (Hildoceeas) S.ffl!MANNi, Denckmann. Fauna Ob. Lias ; Abh. 



geol. Specialkarte von Preussen, 

 Bd. viii, Heft 2, pi. iii, fig. 2 ; pi. x, 

 figs. 18, 19. 

 1885. — BADiANS, cf. QUADEATUS, Quenstedt. Amm. Schwabischen 



Jura, pi. Iii, fig. 3. 



Discoidal, compressed, hollow-carinate. Whorls compressed, ornamented 

 with ventrally-projected, subarcuate ribs, which begin at the bottom of the inner 

 margin. Ventral area rather broad, carrying a distinct hollo w-carina ; but, in the 

 absence of the test, a small false carina, bordered by two plain, slightly depressed, 

 sometimes sulcate areas, is present. Inner margin sloping, fairly steep, and 

 distinctly marked by the ribbing. Inclusion two-fifths. Umbilicus depressed in 

 the middle, and somewhat quickly-coiled. 



A certain amount of history attaches to the name Scemanni. Oppel first 

 applied it (' Juraf .,' p. 242) to a species from the Alum-shale of Yorkshire. In 

 the absence of a figure it has been concluded^ that the species he described was 

 what had been previously known as Am. Zevisoni, Simpson, also unfigured at 

 the time. Dumortier has, however, interpreted Oppel' s description otherwise, 

 and has figured the form which is the subject of this article under the name 

 " Scemanni.^' This name may be retained for this form without any question ; 

 but, since there is reasonable doubt if Dumortier has rightly interpreted Oppel's 

 views, it avoids confusion to assign the authorship of the specific name to 

 Dumortier, treating it as a new creation, as at the heading. 



1 Meneghini, 'Monogr.' ; ' Pal. Lombarde,' 4e Serie, p. 198 ; also Haug, op. cit., p. 639. 



