5 
A critical comparison of the two figures is interesting as showing the 
importance of comparing figures of species point by point before coming 
to the conclusion that they represent the same species, certainly before 
accepting one figure as a copy of another. D’Grbigny’s figure has a quite 
straight end cutting across several ribs; it shows the ribs strong on the 
inner lateral area right up to the end, the ribs are also represented as 
regularly bifurcate about the middle of the side, no intercalate ribs being 
shown: there are 46 primary ribs — 2 unfinished =44 primaries and 89 
secondaries = 1 to 2: the curve of the ribs in relation to a straight line is 
somewhat S-shaped. 
Zittel’s figure has a decidedly jagged end, running roughly parallel to 
the ribbing; the primary ribs are represented as becoming quite indistinct 
on the inner part of the lateral area towards the end— about the last 
quarter of the whorl; the ribs are shown as sometimes trifurcate, with 
many intercalate ribs which run well on to the inner lateral area; there are 
about 35 to 40 primary ribs and about 118 secondaries = roughly 1 to 3; the 
curve of the ribs is somewhat arcuate with slight S-curve in places: a 
guide-line does not touch the arcuate ribs until arrival at venter. 
One can imagine that an artist in copying d’Orbigny’s figure could and 
would make certain mistakes; but it is difficult to imagine that he would 
make all these. He would scarcely draw a jagged border to an aperture 
where a straight one was shown; he would not draw obsolescent or rubbed- 
away ribs where they were shown quite strong and clearly; he would not 
draw persistently a trifurcate figure when the original exhibited uniformly 
bifurcate: he might make mistakes in the number of ribs and in their 
curvature, but he would rather tend to exaggerate the S-form than turn it 
into a bow-form. 
To my request for information Professor Edgar Dacque, of the Palaeon- 
tological Museum of Munich, most kindly made search among Zittel’s 
specimens and forwarded to me an example from Ehningen which agrees 
well with Zittel’s figure — the concave notch in the side of the aperture 
about the middle helps the identification. The figure is reversed and is 
reduced by one-third. The specimen has considerable likeness to Macro - 
cephalites macrocephalus race noetlingi (altered to madagascariensis p. 51) 
Lemoine (PI. Ill, 3) but Lemoine’s figure being reduced by one-third and 
yet larger than Zittel’s specimen, evidently represents a much more coarsely 
ribbed form — the difference being especially noticeable at the early part 
of the whorl where Zittel’s specimen has very fine ribs — in Zittel’s figure 
the primary ribs are drawn much too strongly. 
It is hoped to give in “Type Ammonites” figures of Zittel’s specimen — 
the genotype of M acrocephalites — at an early date. 
