198 INFERIOR OOLITE AMMONITES. 



Gbammoceras subcomptum (Branco). Plate XXX, figs. 11 — 14. 



1879. Haepoceeas stjbcomptttm, Branco. Untere Dogger ; Abhandl. geol. Spez.- 



Karte v. Elsass-Lothringen, Bd. ii, pi. v, 

 fig. 3 (not fig. 4, which is a Dumortierid) . 



1885. — — Haug. Beitrage Monog. Harp. ; Neuea Jahr- 



buch fiir Mineralogie, &c., Beil.-Bd., p. 070. 



1885. Ammonites aalensis, Quenstedi. Amm. Schwabischen Jura, pi. liv, figs. 



1—4 (5 ?) 



Diseoidal, compressed, carinate. Whorls broad, ornamented with numerous 

 ventrally-projected, subarcuate radii, which are irregularly fasciated on the 

 inner area. Yentral area very narrow, much sloping, and bearing a trenchant, 

 but ill-defined, solid carina. Inner margin distinct, steep, and inclining to 

 concave. Inclusion about one-half; umbilicus flat and open. 



In appearance intermediate between Gramm. aalense and Gramm dispansum ; it 

 differs from the former by its more numerous and more fascicled ribs, and slightly 

 smaller umbilicus ; while from the second, for which perhaps it is more likely to 

 be mistaken, it diSers in the fasciated portion of the ribs being longer, and not 

 so clubbed at the inner margin — in having a larger umbilicus — in possessing a 

 solid and not a hollow carina. 



In spite of its resemblance this species is not a very near relative of Gramm. 

 dispansum. It certainly is a form cognate to Gramm. aalense, but not, I think, an 

 actual descendant. 



All the specimens in my collection are smaller^ than the specimen figured by 

 Branco, which again is smaller than the adults of either Gramm. aalense or Gramm. 

 dispansum. With us the species does not attain a diameter of two inches. 



Branco gave figures of two specimens under the name Harpoceras subcomptum. 

 The fig. 4 is different in side view, and has a dijSerent suture-line to fig. 3, and 

 judging from these points I believe that it is a Dumortieria — probably a synonym 

 of Dum. radians. Fig. 3 is, therefore, the type of the present species. 



This species occurs in the Moorei-heds (Opalinum-zone) associated with 

 Gramm. aalense. Its position is thus very much above that of Gramm. dispansum, 

 a fact which it is well to bear in mind. 



I have obtained the majority of my specimens from Haresfield Hill (bed 16) ; 

 but the species also occurs at Coaley Peak. Apparently it is very local in its 

 distribution. It is generally only poorly preserved. 



PI. XXX, figs. 11, 12, give two views of a specimen of this species. Figs. 13, 

 14 show two views of another, rather thicker, specimen, with more fascicled ribs, 



^ Their riba also are rather more fascicled. Possibly they may best be considered a dwarf variety. 



