262 
INFERIOR OOLITE AMMONITES. 
forms and tlie Cotteswold specimens could scarcely be united. The coarse ribs o£ 
the inner whorls certainly seem to favour the idea of descent from Bum. Levesquei. 
In PI. XLV four varieties of this species are delineated. As the type I 
take the specimen shown in figs. 1 — 3, which agrees the best with Branco's 
pi. iii, fig. 4. The specimen numbered figs. 4 and 5 is closely allied, but 
differs in its ribbing. (The artist has failed to bring out the irregularity of 
the ribs of the inner whorls in size and distance.) In figs. 6 and 7 is 
shown a specimen which is more compressed and finer-ribbed throughout ; 
doubtless its finer ribs are due to " earlier inheritance " of the ornamentation of 
the outer whorl shown in figs. 1 and 5. The specimen marked figs. 8 and 9 has 
flatter-sided whorls than the other examples. It is a poorly preserved fossil; 
and therefore the artist could not draw its ribbing with accuracy. The ribs in the 
inner whorls seem proportionately rather coarser than those on the outer ; and, 
therefore, I judge that its fine-ribbed characters are due to its being a more 
advanced form of the species pointing to divergence in another direction. It is 
very like Dum. exigua, but has flatter sides, more marked inner margin, and a 
more prominent carina set on a flatter ventral area. 
The small specimen shown in fig. 10 is the young of fig. 4. It is interesting 
for its Aptychus, which is drawn of natural size in fig. 11, and enlarged six times 
in fig. 12 ; the upper edge is not very clearly shown on the specimen — it points 
away from the mouth. 
The little specimen drawn in PI. XLIV, figs. 10 — 12, differs from the other 
specimens of Dum. subundiilata'm. being more included. The apparently-fasciated 
ribs are not due to the radii coalescing, but are really bulgings of the test, over 
which the radii pass separately in a normal manner. The artist has not brought 
this out with distinctness. The specimen is very like the young of JDiim. Moorei, 
but has a rather larger centre, and is somewhat thicker. In appearance, but not 
in point of descent, it is just intermediate between " Moorei " and certain forms of 
" suhundulata." 
I have already discussed the large -specimen depicted in PI. XLIII, figs. 8 
— 10, and for the present I must regard it as a large, perhaps local, variety of 
Dum. subundulata. 
DuMORTiBRiA GEAMMOCEROiDES, Hatog. Platcs XLYI, XLVII. 
1881. Habpocebas Levesquei ?, S. BucTcman. Inf. Ool. Ammointes, Quart. 
Journ. Geol. Soc, p. 60i. 
1887. DuMOKTiEEiA GEAMMOCEEOIDES, ' Polv luorphidfe ; ' jSTeues Jahrbuch 
fiir Miueralogie, Bd. ii, pi. v, 
fig. 5, and woodcut 6 c, p. 137. 
