﻿254 INFERIOR OOLITE AMMONITES. 



in ribbing ; fig. 15 is the suture-line. PI. XLIII, figs. 5, 6, give a larger example 

 with similar features ; fig. 7 is the suture-line. 



Dumortieria radiosa, var. uuNDERSHOFENsis, Haug . Plate XXX, fig. 18; Plate 



XLV, figs. 13, 14. 



1830. Ammonites lineitus, Zieten (non Schlotheim). Verstein. Wurtt., pi. ix, 



% 7. 

 1879. Haepoceeas pseudoeadiosum, Branco. TJnt. Dogger ; Abh. z. geol. Spez.- 



Karte v. Elsass-Lothringen, Bd. 

 ii, pi. ii, figs. 2, 2 a only. 

 1884. — Aalense, Wright (non Zieten). Monogr. Lias Amm.; Pal. 



Soc, vol. xxxviii, pi. lxxxii, figs. 1, 2 only. 

 1887. Dumoetieeia eadiosa, var. gundebshofensis, Haug. Polymorphic^ ; 



Neues Jahrbuch fiir Mineral., &c, Bd. ii, 

 p. 140, pi. iv, fig. 7. 



Discoidal, compressed, carinate. Whorls broad, ornamented with subdirect, 

 ventrally-inclined radii. Ventral area sloping, fairly defined, ornamented with a 

 small, distinct carina traversed by fine growth-lines. Inner margin convex, 

 slightly defined, scored by the ends of the radii. Inclusion about two-fifths. 



Dr. Haug remarks that the typical form of Dum. radiosa, has fine 1 ribs in 

 youth, and in old age extremely fine, closely-set growth-lines ; but the variety 

 gundersJwfensis has in youth what may be called either large growth-lines or fine 

 ribs, and in old age blunt, distant ribs. The point, however, is that the variety 

 gundersJwfensis is ornamented just the reverse to what obtains in the type, or 

 among other species of Dumortieria. Instead of having coarse ribs becoming 

 finer, it has fine ribs becoming coarser. 



I fancy that the variety g under shofensis deserves to rank as a separate 

 species much more than Dum. radiosa; and I do not feel at all sure that it 

 is a variety of that form. I should be more inclined to consider it a mutation 

 of " radians." However, my material of radiosa and its variety being scanty, I 

 leave the matter as Dr. Haug placed it. 



The specimen, PI. XXX, fig. 18, exactly bears out Dr. Haug's remarks con- 

 cerning the ornamentation ; but the larger example has coarse ribs, at first, for 

 some time, then a period of half-a-whori of fine ribs, and then commences the more 

 distant ribs. This specimen is thinner than Haug's outline-figure 7 c, which, 

 however, does not appear to me to correspond to his fig. 7 b, because the whorls 

 are represented too narrow (from back to front) and too thick. The specimen 

 agrees in all respects with 7 a, b. 



1 My specimens have coarse ribs. 



