LIBRARY OF THE

UNIVERSITY OF ILLINOIS

AT URBANA-CHAMPAIGN

550.5

FI

V

.12

3

this

re-

FIELDIANA . GEOLOGY

Volume 12, No. 11 March 24, 1969 Publication 1068

Scorpionida

The Holotype of Mazonia woodiana

Meek and Worthen, 1868

Erik N. Kjellesvig-Waering
Research Associate, Fossil Invertebrates

In 1868, Meek and Worthen described two scorpions from the
Mazon Creek area as Eoscorpius carbonarius and Mazonia woodiana.
This was the first announcement of Paleozoic scorpions from the
Western Hemisphere, although they were previously known in Eur-
ope. Both specimens became very well known and remain so to this
date. In particular, the specimen used as the holotype of Mazonia
woodiana assumed considerable importance for taxonomic studies, for
Meek and Worthen interpreted the preabdomen as having eight ter-
gites, instead of the seven present in all other known scorpions, fossil
or living. Petrunkevitch in 1913 and again in 1953 re-examined the
holotype, still the only known specimen of Mazonia woodiana, and
emphatically agreed with Meek and Worthen's early interpretation
that the preabdomen was indeed composed of eight tergites. This
interpretation, unfortunately, represented the main basis for the for-
mation of significant higher taxa, in this particular case even to the
formation of a suborder (Petrunkevitch, 1949, 1953 and 1955).

Wills in his remarkable and excellent paper on the anatomy of
some Carboniferous scorpions (1960, p. 231) expressed strong and
pertinent objections to the extra preabdominal tergite. Wills based
his conclusions in part on a good cast of the holotype and suggested
that the question might be settled by extracting another specimen of
Mazonia woodiana from an ironstone concretion, as he had been able
adroitly to do with various other scorpions. However, the holotype
is the only specimen known of this controversial form, and, of course,
it is impossible to apply the "Wills technique" to it. Moreover, its
state of preservation is such that the question of the eight-segmented
preabdomen can be easily solved, and some other details of consider-
able taxonomic importance revealed.

In December of 1963, I borrowed the holotype from the Univer-
sity of Illinois and studied it at the American Museum of Natural

Library of Congress Catalog Card Number. 68-59Jf87

171

172 FIELDIANA: GEOLOGY, VOLUME 12

History. The results of this study follow in the description and sum-
mation given below. In brief, evidence is presented that is entirely
at variance with the interpretation of an eight-segmented preabdo-
men as postulated first by Meek and Worthen and accepted by
Petrunkevitch. Other morphological details of considerable taxo-
nomic importance are also presented here for the first time.

Acknowledgements

I wish to thank Dr. Harold Scott of the University of Illinois for
the loan of the holotype, and Dr. Norman D. Newell of the American
Museum of Natural History for facilities and other courtesies ex-
tended to me during my visit and which made possible the note
which follows. I also wish to thank Mr. R. W. Harris, Jr., of Do-
minion Oil Limited, Port-of-Spain, Trinidad, who kindly made the
excellent photomicrographs included in Figures 91 to 101.

Order Scorpionida Latreille, 1817

Family Mazoniidae Petrunkevitch, 1913

Genus Mazonia Meek and Worthen, 1868

Mazojiia ivoodiana Meek and Worthen, 1868. Figures 91-99.

Mazonia woodiana Meek and Worthen, 1868, Geol. Surv. Illinois, 3, pp. 563-
565, figs. A-D; Miller, 1877, Am. Palaeoz. Foss., p. 224; Peach, 1883, Roy.
Soc. Edinburgh, Trans., 30, p. 409, pi. 23, figs. 24, 25; Miller, 1889, N. Amer.
Geol. Paleont., p. 571; Pocock, 1911, Palaeontogr. Soc, p. 11; Petrunkevitch,
1913, Conn. Acad. Arts Sci., 18, pp. 54-56, pi. 3, fig. 13; Lehmann, 1944,
Neues. Jahrb. Mineralogie, etc., pp. 177-185, figs. 1-4; Shimer and Shrock,
1944, Index Foss. N. Amer., p. 709, pi. 300, figs. 6-9; Petrunkevitch, 1949,
Conn. Acad. Arts Sci., Trans., 37, p. 132; 1953, Geol. Soc. Amer., Mem.
53, pp. 12-13, figs. 11, 119; 1955, Treatise Inv. Paleont., P, Arthropoda 2,
p. 70, fig. 38 (5); Wills, 1960, Palaeontology, 3, pt. 3, p. 321; Dubinin, 1962,
Fundamentals of Paleont., p. 428, figs. 1225, 1227; St0rmer, 1963, Norske
Vid.-Akad. Oslo, 8, p. 116, fig. 44.

Eoscorpius (Mazonia) woodiana Meek and Worthen: Grabau and Shimer, 1910,
N. Amer. Index Foss., 2, p. 416.

The holotype is a fragmentary but very well preserved scorpion
in dorsal aspect in a typical Mazon Creek ironstone concretion. Only
the carapace, preabdomen and right pedipalp are preserved. The
counteipart of the concretion has been lost. The part described here,
and previously studied by Meek and Worthen (1868) and by Pe-
trunkevitch (1913, 1953) is registered as No. X-491 in the Geological
Museum of the University of Illinois. Inasmuch as there has been
so much confusion and misinterpretation concerning this specimen,

Fig. 91. The holotype of Mazonia woodiana Meek and Worthen. Left: The
specimen has been coated with ammonium chloride. Right: Natural, unretouched
photograph. X2.7.

173

Fig. 92. Mazonia woodiana Meek and Worthen, schematic drawing of holotype
with tergites numbered. Diagonal arrows indicate direction of displacement.
Sternites shaded. A: central division line of lobostern abdominal plate.

174

KJELLESVIG-WAERING: SCORPIONIDA

175

Fig. 93. Reconstruction of the dorsal side of the carapace and preabdomen of
Mazonia woodiana Meek and Worthen. X2.7.

it is here redescribed. Certain important morphological parts are
revealed for the first time and others are interpreted differently than
before. Only one specimen of this species is now known.

For a proper understanding of this specimen it is necessary to
keep in mind that it is broken into at least five disjointed parts. The
largest of these units comprises the pedipalp, carapace and first two
tergites. The second unit, consisting of the third to fifth tergites^ —
all of which are in a fragmentary state — has been displaced to the left
of the axis of the carapace. The third part is represented by a frag-
ment of the sixth tergite which lies in normal left-right position with
relation to the fifth tergite. The last section, and here is where the

176

FIELDIANA: GEOLOGY, VOLUME 12

cause for the confusion exists, comprises most of the sixth and sev-
enth tergites, displaced posteriorly and rolled over to the right of the
axis of the specimen. Thus the last tergite preserved, the seventh of
the preabdomen, reveals only the central and left part of the tergite.

Fig. 94. Part of the integument of the middle part of the femur of the holotype
showing both sides of integument (the darker areas include both ventral and dorsal
surfaces). On the extreme left side are revealed three possible trichobothria in
linear series, and cellular pore canal structures are clearly visible. X75.

This is proven by the ornamentation and will be described further
below (p. 183). In between this section and the third are large frag-
ments of the "sternites" (actually the anteriorly-hinged abdominal
plates^ — see St0rmer, 1963, p. 110) of the underside which lie diag-
onal to the axis of the scorpion and again show that displacement
occurred, probably during ecdysis, moving the last two tergites to the
posterior of the rest of the preabdomen and to the right of the axis.

Prosoma

The carapace is preserved as a dorsal impression revealing most
of the surface but is broken away at the extreme anterior, the left
thoracic part, and the entire extreme right quarter. Enough, however,
is present for an accurate description. The carapace is essentially
sub-quadrate in general aspect, with round anterolateral margins, and
with a short pointed protrusion along the central part of the anterior
margin, now almost entirely broken away. The length of the cara-
pace is 10.2 mm., but with the anterior process it probably measured
11.2 mm.; the width is only slightly greater.

KJELLESVIG-WAERING: SCORPIONIDA 177

Fig. 95. Socket of tactile hair (trichobothrium?) of specimen shown in Figure 94.
This is the uppermost socket on the piece of integument which reveals the thick
marginal or limbated rim. X600.

The central eye node, located anteriorly on the carapace, is the
most conspicuous feature of this genus and this is lacrimiform, with
the widest part anteriorly placed, and very protrudent above the
carapace (see Meek and Worthen's 1868 original figures B-D, which
are accurate). On the anterior blunt end of the node are two con-
spicuous, large, round, protrudent eyes, each surrounded by a very
narrow fossa. The eyes measure 1.2 mm. in diameter, are separated
from each other by a shallow sulcus, and because they are located on
the elevated node were, therefore, capable of vision in all directions
but with perhaps a blind spot very close (a few millimeters) to the
dorsal part of the eyes where the eye node integument separated them.
Inasmuch as this species appears to be aquatic (the "sternites" indi-
cate that it belongs in the Lobostemi) one might speculate that the
scorpion was admirably equipped to lie in wait for prey, covered by
mud except for the protrudent eye node and with the large, strong
pedipalps ready to seize the unwary.

The lacrimiform eye node is surrounded by a deep sulcus which
reaches almost to the base of the carapace. Lying above this sulcus

178 FIELDIANA: GEOLOGY, VOLUME 12

Fig. 96. The socket for a tactile hair (trichobothrium?) of specimen shown in
Figure 94, to reveal the thickened marginal rim. This is the lowest socket shown
in Figure 94. X600.

is the elevated, shield-shaped cephalic area of the carapace. The
thoracic area, to the rear, and the genal angles are flat. Along the
posterior border is a rounded, narrow rim which extends to the genal
angles. This has been mistaken for part of the first tergite, but it is
definitely a prosomal basal rim.

At the side of the elevated cephalic area, toward the anterior part
of the lateral margins, but well away from the margins and behind
the central eyes, is a short, small, curved, narrow ridge which Pe-
trunkevitch designated an "ocellar ridge" (1953, p. 13). This is a
narrow, slightly incurved, cuticular thickening, but it does not fol-
low that it is an "ocellar ridge," nor that it has any relation to lateral
eyes, which are not present. Petrunkevitch states that lateral eyes
were "probably present," but this is highly unlikely (unless they are
ventral structures) and should not be seriously considered. I base
my disagreement on two factors: First, in a very well preserved, al-
though partly shattered, specimen such as this the lateral eyes would
have been preserved if there were any. Secondly, the minute punc-
tations that occur immediately behind the lateral ridges are dis-

KJELLESVIG-WAERING: SCORPIONIDA 179

tinctly preserved and if the lateral eyes had been present they would
also certainly have been preserved. Meek and Worthen (1868,
p. 563) also were unable to find any lateral eyes. The function of the
cuticular thickening, or lateral ridges, is unknown but it might have
served as a point of attachment for some of the muscles which helped
suspend or move the large and exceedingly long pedipalps. The
position in relation to the trochanter of the left pedipalp indicates
such a function.

Of the prosomal appendages, only parts of the left chelicera and
the right pedipalp and one of the basal podomeres of the first walking
leg are preserved. On the left side of the carapace are some parts of
the legs which I could not interpret with any degree of certainty.
Also at the left posterior is an elongated fragment which probably
represents either a part of the coxa of the last walking leg or perhaps
the posterior doublure of the carapace.

The chelicerae, hitherto unnoticed except for an undiagnostic
basal fragment (Petrunkevitch, 1913, p. 56), are not well preserved
except for the free ramus on the left side. This is preserved only in
outline and occurs anterior to the carapace, thus, if not dislocated,
indicating rather long chelicerae in this genus. This is likely as it
would be in keeping with the very elongated pedipalps. The free

Fig. 97. Part of integument from the inner part of the prefemur of the holotype
of Mazonia woodiana showing round perforation which may have represented a site
for a tactile hair, possibly a trichobothrium. The rounded limbate lip of the per-
foration is clearly shown. X 75.

180 FIELDIANA: GEOLOGY, VOLUME 12

ramus may be seen in Figures 91 and 92. It is hook-like and does not
reveal any denticles, although these may remain embedded in the
matrix. A fragment of the base of the chelicera is present but is
too incomplete for description.

The pedipalps are notable for their extreme length. Only the
three central joints are preserved; the chela unfortunately is not pres-
ent, having been truncated by the edge of the nodule. The trochanter
is an unusually long joint, wider distally than at the base and approx-
imately half as long as the prefemur, although slightly wider.

The prefemur measures 12.9 mm. along the posterior edge, and
1.8 mm. across the midsection. The femur is narrower, but probably
as long as the prefemur, although it is not complete. The entire
pedipalp suggests a very long appendage with likely a very narrow
hand and fingers. Little of the original chitin is left, but a small piece
that was curling off the prefemur, near the trochanter, was taken off
and mounted in Canada balsam. Another piece of integument was
taken from the femur at midsection. These pieces of integument,
which preserve the original colors, are dark rufous-brown, not unlike
the color of some of the Recent scorpions. Photomicrographs reveal
round perforations, bordered by a slight limbated lip, and these may
well be sites for trichobothria (see figs. 94-99) . No tactile hairs were
preserved however.

The question whether aquatic scorpions of the Paleozoic may have
developed trichobothria cannot be answered with any degree of cer-
tainty. The structures observed on the pedipalps of Mazonia woodi-
ana are remarkably similar, at least in external cuticular structure,
to the trichobothria on the same region of the pedipalps of Recent
scorpions (see figs. 100-101), but may not actually represent tricho-
bothria. Although only the stump of one of the setae was preserved,
it appears likely that they were short, as noted in other Carbonifer-
ous scorpions. It is therefore possible that these structures (see also
Gigantoscorpio willsi St0rmer, 1963, p. 122) are either primitive tri-
chobothria or trichobothria adapted for function in a water medium.
St0rmer (1963, p. 122) suggests the sensory adaption of the short,
rigid pedipalpal setae for an aquatic medium.

Preabdomen

The most interesting part of the holotype is the preabdomen, but
only because of the misinterpretation and attendant misconceptions
that it has occasioned. In order to understand the morphology of this
fossil it is important to keep in mind that it is highly shattered and

KJELLESVIG-WAERING: SCORPIONIDA

181

Fig. 98. Another fragment of the integument taken from the base of the pre-
femur of Mazonia woodiana Meek and Worthen. Note dark round spot (see fig. 99)
and canal and cellular structure. X 75.

that, in the preabdomen alone, at least five distinct and separate
parts have been moved enough to produce the erroneous interpreta-
tions that have led to wrong conclusions of major taxonomic impor-
tance. In fairness to previous writers, it must be admitted that the
fossil is quite misleading, inasmuch as the various sections have been
displaced in such a manner as to cause the miscount of eight preab-
dominal tergites.

The tergites of Mazonia woodiana are characterized by an un-
usually prominent anterior transverse ridge such as is well known in
present-day scorpions, e.g., Tityus, Broteochactas, Hadrurus and Ve-
jovis. In Mazonia this transverse ridge is highly developed, much as
in such Eurypterida as Eurypterus, Erieopterus and Buffalopterus.
It is present in an equally exaggerated state in the Silurian Proscorp-
ius, but is not developed in the Silurian Archaeophonus or Palaeo-
phonus. Similarly, in Carboniferous scorpions the anterior ridge is
developed in Buthiscorpius and Mazoniscorpio, but not in many others.

The first tergite of the holotype of Mazonia woodiana is preserved
so that most of the central part and a fragment of the extreme right
edge are present. This tergite may have been moved, possibly dur-
ing ecdysis, so that the anterior ridge, if present on this tergite, was
pushed under the carapace. It could well be, however, that the first

182 FIELDIANA: GEOLOGY, VOLUME 12

tergite does not have an anterior transverse ridge, a condition known
in many eurypterids that have the ridges developed on the other
tergites. I subscribe to the latter possibility. The ridge that appears
to be the anterior transverse ridge of the tergite is actually the rounded
basal ridge of the carapace.

The anterior part of the right half of the second tergite is pre-
served attached to the first. Both of these tergites preserve the exte-
rior surface, but neither reveals any ornamentation. There is a
jagged break between the second tergite and the next unit that fol-
lows. This is composed of parts of the central and right portion of
the third and fourth tergites and the anterior ridge of the fifth, all
retaining the external surface. The entire unit has been displaced
slightly, but not significantly, to the left of the cephalic axis, as shown
by the groups of small tubercles which undoubtedly occurred along
the central axis.

In line with the anterior transverse ridge of the fifth tergite, is a
fragment of the extreme right side of the tergite, preserved as an im-
pression of the inner surface. This piece is completely isolated from
the unit that retains the rest of the anterior ridge of this tergite.

Also isolated, but apparently not greatly displaced from the pre-
ceding tergite, is the extreme right side of the sixth tergite. A veiy
steep side is present at the edge. This portion is preserved as an im-
pression of the ventral or inner side of the tergite.

The last unit comprises parts of the sixth and seventh tergites,
diagonally displaced from the central axis considerably to the pos-
terior and right. The two "sternites" preserved, which will be de-
scribed below, show this same diagonal displacement. The unit ac-
tually is composed of most of the sixth and seventh tergites, but it
also includes a small fragment that occurs to the right of the main
fragments. The main fragment preserves the dorsal side of the ter-
gites, whereas the isolated piece of the sixth tergite on the right side
is an impression of the ventral surface.

The sixth tergite is preserved so that the extreme left side is re-
vealed and most of the central part. A narrow longitudinal ridge is
present at midsection, although it does not reveal any of the central
tubercles noted on the third and fourth tergites. The entire unit has
not only been displaced diagonally, but partly rolled over, as attested
by the incurved and steep side of the isolated fragment of the sixth
tergite on the right side. This displacement and the accompanying
rolling over are also attested by the exposure of the left side edges of
the very prominent anterior ridge of the last preabdominal (7) tergite.

KJELLESVIG-WAERING: SCORPIONIDA

183

Another good indication of the various differential displacements
that the preabdomen has suffered can be seen by the isolated line at
the left of the abdomen. This actually represents the extreme edge

Fig. 99. This represents the dark round spot on the piece of integument shown
in Figure 98, which reveals a socket for a tactile hair (trichobothrium?). The raised
marginal lip of the socket as well as the stump (dark area) of the seta can be clearly
defined. X600.

of the anterior left side of the preabdomen. This line probably repre-
sents the original edges of the underside in cross-section and is at-
tached to the unit containing the carapace. I suspect that the an-
terior sternites and other ventral structures are therefore embedded
inside of the concretion. The original outline of the left side may be
reconstructed by following the dotted line (see fig. 92) . A similar line
starting at the extreme right fragment of the first tergite gives the
proportions of this interesting scorpion and will reveal in a striking
manner the great displacements that have occurred. The reconstruc-
tion (fig. 93) is based on these proportions, and reveals a very robust
scorpion.

The seventh tergite is the most interesting of all because of its
very distinct and unusual ornamentation. It is noteworthy also be-
cause of the unusually thick and wide anterior transverse ridge, which
may best be seen at the left side of the tergite. The entire tergite
appears normal, that is, it probably was subconical in shape. Scat-

184 FIELDIANA: GEOLOGY, VOLUME 12

tered pustules occur, but at least two indistinct, though nevertheless
quite noticeable, rows of punctae are present. A very large solitary
pustule occurs at the left rear part and probably is duplicated on the

Fig. 100. Trichobothrium of the living scorpion Tityus trinitatis Pocock from
Trinidad, from the basal part of the prefemur, showing cup-shaped area, tactile
seta, and raised marginal rim, not greatly unlike that in the Pennsylvanian Ma-
zonia woodiana Meek and Worthen. X75.

right, but that side has been rolled over, I believe that there are
three rows of punctae or perhaps four, as postulated by Petrunke-
vitch in his restoration. Either way, this again emphasizes the great
displacement of these last two tergites. However, I disagree with
Petrunkevitch that the caudal tergites, or postabdomen, must have
been slender as in Dolichophonus. I should surmise from the heavy
construction of this scorpion (see restoration, fig. 93) that the caudal
segments were also stoutly developed. There is no correlation how-
ever in modern scorpions regarding the stoutness of the appendages
in comparison to the proportions of the opisthosoma.

Between the main body of the sixth and the fourth tergites are two
ventral abdominal plates, or "sternites." Meek and Worthen (1868)
show these in their figure but do not describe them. Petrunkevitch
(1913, 1949, 1953, 1955) neither figures nor describes these important
structures and therefore it must be assumed that these authors either
did not recognize these as the "sternites" or else assumed that they

KJELLESVIG-WAERING: SCORPIONIDA 185

were dorsal structures. The two "stemites" are shaded in Figure 92,
and may be seen on the photographs in Figure 91. Neither shows any
trace of ornamentation or stigmata, although these would certainly
have been preserved if they had occurred. The anterior diagonal
"stemite" is nearly complete and clearly divided into two halves.
The lower half (on a diagonal) is partly covered at the inner part, but
the other part reveals a distinct, rounded, inner edge (see A on fig. 92) .
This is positive evidence of the split, lobostern, abdominal plates.
The plate posterior to the two broken ones described shows the much
greater length that is characteristic of these long, overlapping lobo-
stern plates.

Measurements of the tergites of the abdomen of this specimen are
difficult because of their fragmentary condition, and the telescoping
of some. Nevertheless some measurements are possible, but should
be accepted with considerable reservations. I suspect that the great-
est width of the preabdomen occurs at the central part of the fourth
tergite. With these reservations, the following measurements are
given as approximately correct (those in italics represent actual di-
mensions; the rest are reconstructed) :

(in mm.)

Tergite

Length

No. 1

3.5

No. 2

3.8

No. 3

4.0

No. 4

4.1

No. 5

4.3

No. 6

U

No. 7

8.0

Summation

The preabdomen of the holotype has caused considerable con-
fusion, and led Meek and Worthen in 1868 (p. 563) to suspect that
it retained eight tergites, because there was "space enough between
the anterior, or seventh one seen, and the cephalothorax, for an
eighth one."

Petrunkevitch (1913, p. 36), after reviewing the holotype, con-
cluded that eight tergites composed the preabdomen and therefore
he keyed out the genus Mazonia as follows: "Seventh abdominal ter-
gite similar to the preceding ones, eighth similar to the seventh of
recent scorpions." In the same publication (p. 55) he speculated on
the number of caudal segments inasmuch as he accepted the count of
eight for the preabdomen. However, on page 26 he expressed some
doubt as to Mazonia being a true scorpion. In 1953 (p. 13), after
another examination of the holotype, any doubts that Petrunkevitch

186 FIELDIANA: GEOLOGY, VOLUME 12

Fig. 101. Base of the trichobothrium from the base of the prefemur of Tityus
trinitatis Pocock, viewed from the side to show the base of the seta and marginal
rim of socket. X600.

may have had concerning his earlier interpretation of the presence of
eight preabdominal tergites were dispelled; he asserted (italics by
Petrunkevitch) : "On the other hand patient further development of
the specimen revealed additional features in the structure of the cara-
pace and definitely confirmed the presence of eight preabdominal ter-
gites." The incorrect interpretation later led to the establishment of
a suborder (Petrunkevitch, 1949, p. 127) and lesser taxa. Later
St0rmer (1963, p. 116, text-fig. 44), following Petrunkevitch's asser-
tive but erroneous analysis, applied it to an otherwise excellent com-
parison between the Scorpionida and Eurypterida. There is no ques-
tion concerning the pregenital or prenatal tergite; however, there is
no certainty that this (first) tergite will be found in the adult scorp-
ions (see below) except possibly in the pre-scorpionid progenitors.

The preabdomen of Mazonia comprises seven tergites, precisely
the same number present in all scorpions known, whether fossil or
living. Although the holotype is fragmentary, the parts preserved
are very well preserved, and unless one understands and takes into
consideration that the specimen is in a highly fragmentary state, pre-
served in at least five major separate sections, mistakes are bound
to occur.

It is not the purpose of this short note to propose significant
changes in the systematics of the Scorpionida. I am at present en-

KJELLESVIG-WAERING: SCORPIONIDA 187

gaged in a study of several Lower Paleozoic scorpions which reveal
considerable new data, and would prefer to await conclusion of that
study before proposing certain necessary changes. Obviously, the
suborder Protoscorpionina Petrunkevitch, 1949, is at least ill-con-
ceived, and perhaps other groups based in part on the eight-segmented
preabdomen or the "hidden tergite" are also illusory.

In this respect, I think it is well to quote Wills (1960, p. 321)
concerning his essentially correct discussion of Mazonia woodiana
made from a rubber cast (Wills, however, suspected that the first
tergite might have been intersegmental tissue). "If the extra tergite
should prove to be fictional, another of Petrunkevitch's (1955, p. P70)
superfamilies and families would disappear. Also his whole suborder
Protoscorpionina is based on the Carboniferous Mazonia woodiana
and on the Silurian genera Palaeophonus, Dolichophonus and Pro-
scorpius, which three, he states, have the first tergite (of the supposed
seven characterizing his suborder) concealed under the carapace.
None, however, of the published figures of these three forms shows
more than six mesosomatic tergites, and the transverse mark across
the hinder part of the carapace, which is the sole evidence for his
statement about the concealed tergite, can be matched in many Re-
cent scorpions and probably in Carboniferous ones also (p. 285). I
therefore regard as ill-founded his 1955 diagnosis of the family Palae-
ophonidae 'First abdominal tergite concealed under carapace, its an-
terior edge indicated by a transverse furrow.' "

Genera other than Mazonia included by Petrunkevitch (1955)
under the suborder Protoscorpionina, "Scorpions with first abdom-
inal segment persisting in the adult and abdomen with eight ter-
gites," are Dolichophonus, Palaeophonus and Proscorpius, although
in each it is clear that only seven tergites compose the preabdomen.
In the case of Proscorpius, the posterior band-like swelling (see Kjel-
lesvig-Waering, 1964, pi. 2, fig. 3) may be a reflection of the posterior
doublure of the carapace, or merely a raised posterior area of the
carapace, among other possibilities. A similar basal doublure is found
in all eurypterids, and it is present in a reduced state in living or ter-
restrial scorpions. As Wills (1960, p. 321) has stated, the swelling at
the base of the carapace is known in both Carboniferous and Recent
scorpions. The same conclusion seems to apply where Petrunkevitch
(1953, p. 11, fig. 7) illustrates a band-like part at the base of the cara-
pace of Dolichophonus loudonensis (Laurie) . This indeed seems to be
the case, as Petrunkevitch (1953, p. 8, fig. 8) clearly restores Palae-
ophonus caledonicus Hunter correctly as a form with the usual seven

188 FIELDIANA: GEOLOGY, VOLUME 12

preabdominal tergites, though he includes it in the suborder Proto-
scorpionina. Therefore, the main support for the presence of the
extra tergite in fossil forms is based on the highly shattered holotype
of Mazonia woodiana and this has been shown here to have a pre-
abdomen that consists of the usual seven tergites. Mazonia woodiana
Meek and Worthen should be considered a typical member of the
Lobosterni, and should possibly be grouped together with genera such
as Lichnophthalmus, Typhloscorpius and Benniescorpio. In my opin-
ion, Alloscorpius wordingleyi (Woodward) is a Mazonia.

If, as Petrunkevitch claims, the covered, and therefore invisible,
pregenital tergite lies hidden under the carapace in early Paleozoic
scorpions, there is no reason, other than geological age, to claim that
all adult scorpions in the Paleozoic also retained this elusive and
imaginary tergite. This reasoning could be applied not merely to
Palaeophonus, Dolichophonus or Proscorpius, but to all fossil scorp-
ions. However, it is known that all Paleozoic scorpions clearly re-
tain the usual seven tergites in the preabdomen and nowhere is there
evidence of eight tergites in the adult, or in neonatal, scorpions. The
theory as pertains to the adult scorpions, if at all valid, as well as the
classification proposed by Petrunkevitch for these early forms, must
necessarily await phylogenetic evidence in the form of undoubted
fossil specimens that may furnish the necessary morphological data.
That evidence cannot be furnished by Mazonia woodiana Meek and
Worthen or any known fossil scorpion.

The fact that some embryonic scorpions (all?) have been found
to retain a pregenital tergite is insufficient reason to expect that any
of the older fossil scorpions, that is, animals that have reached the
state of evolution in which they are recognized as Scorpionida La-
treille 1817, would have a preabdomen of eight tergites followed by
a postabdomen of the usual five tergites. Certainly, in the closely
related Eurypterida, neonates consistently reveal a much smaller
number of tergites than later stadia and early scorpions may well
have had a similar development. Because the known Paleozoic
scorpions, whether from the Silurian, Devonian or Carboniferous,
had by that time established the definite characteristics that persist
to the present, it would be surprising if these fossil scorpions did not
also have a rather similar ontogeny; therefore, the pregenital tergite
should be expected in the embryo, and not in the adults of these
Paleozoic scorpions. In short, inasmuch as the macroevolution of the
scorpions had already been established in the Silurian, it should fol-
low that similar advancement had also progressed in the embryonic

KJELLESVIG-WAERING: SCORPIONIDA 189

development. The pregenital tergite in modern scorpions may more
properly represent a remnant of the pre-scorpion ancestor, rather
than an eighth preabdominal tergite of the ancestral adult scorpions.
The question, therefore, is: when in scorpion evolution was the pre-
genital tergite present in the adult? To date the fossil evidence does
not answer the question, as all scorpions so far known retain a seven-
segmented preabdomen.

REFERENCES

Dubinin, W.
1962. Handbook of the Paleontology and Geology of the U.S.S.R., 9, part
Scorpionida, pp. 423-433, figs. 1220-1260.

Grabau, a. W. and H. W. Shimer

1910. North American Index Fossils. 2 vols., 909 pp., 1937 figs.

Kjellesvig-Waering, E. N.

1966. Silurian Scorpions of New York. Jour. Paleont., 40, pp. 359-375. Pis.
42-44; 18 text-figs.

Meek, F. B, and A. H. Worthen

1868. Illinois Geol. Surv. Rept., 3, Paleontology, Genus Mazonia, pp. 563-565,
4 figs.

Miller, S. A.
1877. Palaeozoic Fossils: A Catalogue of the Genera and Species, etc. 253 pp.,

Cincinnati, Ohio. Privately published.
1892a. North American Geology and Palaeontology. 664 pp., 1194 figs.
1892b. First Appendix, pp. 665-718, figs. 1195-1265. Cincinnati, Ohio. Pri-
vately published.

Peach, B. N.

1883. On some new species of fossil Scorpions from the carboniferous rocks of
Scotland. Trans. Roy. Soc, Edinburgh, 30, pp. 397-412, pis. 22-23.

Petrunkevitch, a.

1913. A Monograph of the Terrestrial Palaeozoic Arachnida of North America.

Conn. Acad. Arts Sci., Trans. 18, pp. 1-137, pis. I-XIII, text-figs. 1-88.
1949. A Study of Palaeozoic Arachnida. Conn. Acad. Arts Sci., Trans., 37,

315 pp., 83 pis.
1953. Paleozoic and Mesozoic Arachnida of Europe. Geol. Soc. America,

Mem. 53, 128 pp., 58 pis.
1955. Treatise on Invertebrate Paleontology, pt. P, Arthropoda 2, Arachnida,

pp. P44-P162, figs. 31-116.

Scudder, S. H.

1885. Arachnoidea in Zittel's Handbuch der Palaeontologie, I Abth., Bd. 2.
1895. Notes upon myriapods and arachnids found in sigillarian stumps in the
Nova Scotia coal field. Canad. Geol. Surv., Contrib. Paleont., 2, pt. I,
art. 3, pp. 57-66, pis. IV-V.
190 0. Zittel's Textbook of Paleontology, translation by Eastman. London.

190 FIELDIANA: GEOLOGY, VOLUME 12

Shimer, H. W. and R. R. Shrock

1944. Index Fossils of North America, 837 pp., 303 pis., John Wiley & Sons,
New York. Part on Scorpionida, p. 709, pi. 300, figs. 6-11.

ST0RMER, L.

1963. Gigantoscorpio willsi, A new scorpion from the Lower Carboniferous of
Scotland and its associated preying microorganisms. Skr. Norske Vid.-Akad.,
Oslo; Mat.-Naturv. Kl., Ny Ser., No. 8, 171 pp., 22 pis., 45 text-figs.

Wills, L. J.

1959. The External Anatomy of some Carboniferous "Scorpions," Part 1.
Palaeontology, 1, pt. 4, pp. 261-282, pis. 49-50.

1960. The External Anatomy of some Carboniferous "Scorpions," Part 2.
Palaeontology, 3, pt. 3, pp. 276-332, pis. 46-57

Publications 1065, 1066, 1067, and 1068