176 INFERIOR OOLITE AMMONITES. 



species. The drawings for both figs. 9 and 10 were made for me by Mr. G-. C. 

 Crick, F.G.S., to whom I am much indebted, — fig. 9 from a rubbing of the surface, 

 fig. 10 from a tracing from the specimen. Plate XXVIII, fig. 16, shows the 

 side view of variety with somewhat coarser ribs and a smaller umbilicus; fig. 17 

 is the outline of the aperture. Figs. 18, 19 show two views of a compressed 

 young form from Stinchcombe ; it possesses no portion of its test. Figs. 20, 21 

 illustrate a small specimen with the mouth-border fairly complete — fig. 20 showing 

 what appears to be a spathulate lateral process incomplete upon its upper edge, 

 fig. 21 exhibiting the bluntly-pointed ventral process. In Plate A, figs. 43, 44 

 show the suture-line. 



Grammoceeas mactra^ (Dumortier). Plate XXX, figs. 3 — 7 ; Plate XXXI, 



fisrs. 1 — 4. 



"a" 



1874. Ammonites mactea, Dumortier. Etudes pal. Bassin du Ehone, iv, pi. 1 



figs. 4, 5. 

 1878. LuTJWiGiA MACTEA, Bayle. Explic. carte geol. France, pi. Ixxx, figs. 2, 3. 

 1886. Habpoceeas mactea, VaceJc. Oolithe Cap san Yigilio; Abh. d. k.-k. geol 



Eeichsanstalt Wien, Band xii. No. 3 

 pi. ix, fig. 14. 

 1888. — AALENSE, Wright (non Zieten). Monogr. Amm., Pal. Soc. 



vol. xxxvii, pi. Ixxv, fig. 10 only. 

 But not : — 1879. — mactea, .Srawco. Tint. Dogger, Abh. geol. Spezialkarte v 



Elsass-Lothringen, Bd. ii, pi. i, fig. 10 

 (Dumortieria Moorei, Lye). 



Discoidal, much compressed. Whorls nearly flat, ornamented with subarcuate 

 radii — generally very fine and numerous, often fascicled, but sometimes irregular 

 and coarser, especially in the inner whorls — always strongly projected ventrally. 

 Ventral area undefined, carrying a small carina, or (Plate XXXI, fig. 4) without 

 any distinct carina — the two edges meeting at a slight angle. Inner margin 

 variable — convex and undefined, or sharply defined and almost concave. Inclu- 

 sion one-third to one-half. Umbilicus open and flat, scored in the inner whorls 

 with fascicled ribs, or with irregularly-distant coarser ribs producing a somewhat 

 similar appearance. 



The general characters of this species — much-compressed whorls ornamented 

 with numerous very fine striae, render it fairly distinct, but in some features it is 

 liable to vary. The most typical specimen is (a) depicted in Plate XXXI, fig. 1, but 

 even this has a smaller umbilicus than Dumortier's figure. Another form, /3 (Plate 



1 fit'iKTpa, a kneading-trougb. For a very flat Ammonite like this the name ^eems inappropriate. 



