A revision of the families and genera of the Stylonuracea (Eurypterida)

GEOLOGY

UNIVERSITY OF
/LLINOfS LIBRARY

ATURBANA-CHAMPA/GM
GEOLOGY

6,S "^''"S/

FIELDIANA . GEOLOGY

Published by
CHICAGO NATURAL HISTORY MUSEUM

Volume 14 January 27, 1966 No. 9

A Revision of the Families and Genera
of the Stylonuracea (Eurypterida)

Erik N. Kjellesvig-Waering

Research Associate, Department op Geology

The genus Stylonurus was first made known by Page in 1855 in a
report to the British Association. In the first edition of his famed
Advanced Text-Book of Geology (1856, p. 135, fig, 2), he figured and
named the single specimen as Stylonurus powriensis, a name which
he altered to Stylonurus powriei in the second edition of his Text-Book
(1859, p. 181, fig. 3). If the genus Stylonurus is to date from 1856
when Page first proposed it with S. powriensis as obvious type spe-
cies by monotypy, then the original name of the species must be used,
since the genus could not have been proposed without a type
species. The nearly whole specimen came from the Lower Devonian
Old Red Sandstone of Scotland, and revealed long, slender legs with-
out the characteristic paddles which characterized the hitherto known
eurypterids. In the later publication, Page described another Stylo-
nurus as S. spinipes (1859, p. 181, fig. 1) from the Silurian of Scot-
land. It is curious, and not entirely understandable, that the specific
name Stylonurus powriensis Page {S. powriei) became established in
the literature, but Stylonurus spinipes Page did not, although it was
redescribed on the basis of the same specimen by Woodward (1866-
78 [1872], pp. 129-131, pi. XXIV, fig. 1) as Stylonurus logani Wood-
ward. There is no question that Page's Stylonurus spinipes 1859 has
clear priority over Stylonurus logani Woodward, 1872. It would be
inconsistent to accept the name Stylonurus powriensis Page (S. pow-
riei) and not Stylonurus spinipes Page when both were equally well
figured and "described." The type of the latter is an important
specimen and the species became in fact better known than the geno-
type. Since Stylonurus spinipes Page will be referred to repeatedly
below, I wish to emphasize its validity.

Library of Congress Catalog Card Number: 66-17 It67 -»r llR^|l(.^1 3^ '^'^
" 169

No. 1001 169 ^^r1

170 FIELDIANA: GEOLOGY, VOLUME 14

Further species of what we consider Stylonuracea today were es-
tablished in 1859, both in Huxley and Salter's great monograph and
in Hall's equally important work. Laurie, in 1892, added the new
genus Drepanopterus from a large suite of stylonuroids from the Silu-
rian Gala-Tarranon beds of Scotland. It was not until the celebrated
monograph of Clarke and Ruedemann in 1912 that a serious attempt
was made to subdivide the "stylonurids" into several generic and sub-
generic categories. Dolichopterus was recognized as a genus and the
"true stylonurids" (those without paddles) were divided into four
definite groups, which were considered subgenera: (1) Stylonurus
(Stylonurus) , (2) Stylonurus (Tarsopterus), (3) Stylonurus {Ctenop-
terus), (4) Stylonurus (Drepanopterus) and a fifth group which they
considered "Indeterminate species."

Clarke and Ruedemann, however, still considered Dolichopterus
and Stylonurus as part of the family Eurypteridae. Diener in 1924
recognized the obvious and major differences between Stylonurus and
its subgenera on the one hand and members of the family Eurypteri-
dae on the other, and erected the new family Stylonuridae Diener.

In 1951 St0rmer, in an important paper, established the family
Rhenopteridae on the significant basis of the ventral shield of the
carapace and the form of the metastoma. In all outward appearance
— that is, dorsally — the Rhenopteridae could well have been mistaken
for Stylonuridae were it not for the very different underside. As in
scorpions, considerable and increasing evidence is being accumulated,
indicating that the major morphological differences of taxonomic im-
portance are to be found on the ventral surface. This applies not
only to higher taxa but to species and subspecies.

Several other families were added to what became known as the
superfamily Stylonuracea Diener, 1924 (nom. transl. St0rmer, 1951
[ex Stylonidae, 1924) ] . St0rmer gave new names to some of Clarke and
Ruedemann's 1912 genera which were junior homonyms, among them
changing Tarsopterus to Tarsopterella. Later, other families were
added to the Stylonuracea, namely, Dolichopteridae Kjellesvig-
Waering and St0rmer, 1952; Hibbertopteridae Kjellesvig-Waering,
1959 and Woodwardopteridae Kjellesvig-Waering, 1959.

I have for many years considered that the family Stylonuridae,
and in particular the genus Stylonurus, was a catch-all for practi-
cally anything that had stylonuroid legs: that is, legs in which the
last pair lacked the flat paddle so characteristic of the other euryp-
terids. In using the ventral shield and the metastoma as the main
distinction between families, as St0rmer did with respect to the

KJELLESVIG-WAERING: STYLONURACEA

171

cT^..^

10

12

13

14

15

16

Fig. 95. Schematic diagrams of the carapaces of the genera of the families
Stylonuridae, Pageidae, Drepanopteridae, Kokomopteridae, Rhenopteridae and
Laurieipteridae. 1, Stylonurus; 2, Parastylonurus; 3, Stylonuroides; 4, Stylonu-
rella; 5, Brachyopterus; 6, Brachyopterella; 7, Clarkeipterus; 8, Melbournopterus;
9, Kokomopterus; 10, Pagea; 11, Drepanopterus; 12, Rhenopterus; 13, Laurieipterus;
14, Ctenopterus; 15, Hallipterus; 16, Mazonipterus.

Rhenopteridae, it is obvious that many of the species presently
placed in the family Stylonuridae differ widely and show so little
affinity that continued grouping under a single family (or mainly, a
single genus) is not consistent, judicious or desirable. In the Scorpi-
onida, the sternum, the structure homologous with the eurypterid
metastoma, is of great phylogenetic and taxonomic importance for
the separation of families (see Petrunkevitch, 1916, pp. 600-608).
We have in the past used the ventral shield and metastoma as essen-

172

FIELDIANA: GEOLOGY, VOLUME 14

Fig. 96. Diagrammatic outlines of the metastomas of most of the families of
the Stylonuracea (excluding Carboniferous and Permian families): 1, Dolichop-
teridae; 2, Stylonuridae; 3, Drepanopteridae; 4, Pageidae; 5, Kokomopteridae;
6, Rhenopteridae; 7, Laurieipteridae.

tial characters for the separation of families in the other non-stylonu-
roid eurypterids. St0rmer was the first to apply this criterion for
separation of the Rhenopteridae from the Stylonuridae — a step that is
correct, progressive and a definite contribution to a better taxonomy.
With this thought in mind, it becomes obvious that the family
Stylonuridae needs radical revision on a world-wide basis, necessi-
tating the description of new families and genera. In general, there-
fore, I shall use the structure of the prosomal ventral shield and the
shape of the metastoma as criteria for the separation of families.
Genera are based on the shape of the carapace, shape and position of
the eyes, the type of opisthosoma and the size, shape and count of the
podomeres. Unfortunately, for some unknown reason the opercula
of the Stylonuracea are little known, and knowledge of these in the
future will be of considerable importance toward a better classification.

KJELLESVIG-WAERING: STYLONURACEA 173

Descriptions of all families and genera of the Stylonuracea are in-
cluded here, as well as lists of the species referred to each genus. The
families included are: Dolichopteridae, Stylonuridae, Pageidae, Drep-
anopteridae, Kokomopteridae, Rhenopteridae, Laurieipteridae, Wood-
wardopteridae, and Hibbertopteridae.

SYSTEMATICS

Order Eurypterida Burmeister, 1845

Suborder Eurypterida Burmeister, 1845

Superfamily Stylonuracea Diener, 1924

Family Dolichopteridae Kjellesvig-Waering and St0rmer, 1952

* Genus Dolichopterus Hall, 1859

Dmgfwosis.— Dolichopteridae of medium size; test apparently
smooth except for circular scales on certain appendages; prosoma
subquadrate; lateral eyes situated close to anterolateral angles; ocelli
centrally located; ventral doublure unknown; chelicera unknown,
probably small, simple; second to fourth paired appendages stout,
increasing in length posteriorly, spinous; fifth and sixth paired ap-
pendages with supplementary flat lobes on distal joints, ultimate
joint forming a large claw in the fifth, and a broad, greatly enlarged
lobe (paddle) in the sixth appendage, lateral margin of paddle slightly
serrate; metastoma narrow, cordate anteriorly, truncated at base;
male median appendage very long, two-jointed; female appendage
very small, not well known; no appreciable contraction of meta-
soma; posterior tergites produced into wing-like epimera; telson spike-
like (Kjellesvig-Waering and St0rmer, 1952, p. 660),

Type species. — Eurypteriis (Dolichopterus) macrocheirus Hall, 1859.

Distribution. — New York, Pennsylvania, Ohio, Saaremaa (Oesel),
U.S.S.R., and England.

Stratigraphic range. — Ordovician to Devonian.
The following species are recognized for this genus:

Dolichopterus antiquus Ruedemann, 1942 Ordovician New York

Dolichopterus asperatus Kjellesvig-Waering, Devonian Ohio

1961

Siluro-Devonian

England

Silurian

New York

Silurian

New York

Devonian

U.S.S.R.

Silurian

New York

Silurian

New York

174 FIELDIANA: GEOLOGY, VOLUME 14

Dolichopterus bulbosus Kjellesvig-Waering,
1961

Dolichopterus herkimerensis Caster and
Kjellesvig-Waering, 1956

Dolichopterus jewetti Caster and Kjellesvig-
Waering, 1956

Dolichopterus lancmani (Delle), 1936

Dolichopterus macrocheirus Hall, 1859

Dolichopterus siluriceps Clarke and Ruede-
mann, 1912

Dolichopterus st0rmeri Caster and Kjelles- Silurian Oesel

vig-Waering, 1956

Genus Strobilopterus Ruedemann, 1935

Diagnosis. — Dolichopteridae of medium size; test covered with
pustules and semi-lunar scales; prosoma semiovate; compound eyes
submarginal; ocelli unknown; ventral doublure unknown; sixth ap-
pendages with movable, supplementary flat lobes on distal joints,
ultimate joint forming large, flat lobe; distal joints and lobes forming
paddle with strongly serrate margin; metastoma very narrow, cor-
date at anterior end; base unknown; male median appendage very
long, consisting of one undivided joint; metasoma contracted past
first tergite; telson unknown (Kjellesvig-Waering and St0rmer, 1952,
p. 660).

Type species. — Pterygotus princetonii Ruedemann, 1934.

Distribution. — Wyoming.

Stratigraphic range. — Lower Devonian.

Remarks. — Strobilopterus princetonii (Ruedemann) remains as the
only known species.

Genus Ruedetnannipterus, new genus

Diagnosis. — Dolichopteridae of small size; distinctly stylonuroid
in general aspect; carapace longer than wide; considerably wider in
front than behind, making base of carapace narrowest part; eyes large,
with narrow arcuate visual area, and large palpebral lobes located an-
teriorly and intramarginally on the carapace; axes of eyes parallel;
ocelli located midway between, or grouped with the lateral eyes; pro-
somal appendages unknown except the sixth which are greatly elon-
gated, subcylindrical legs having the last three joints flattened into
numerous, narrow, leaf-like supplementary lobes; mesosoma very
narrow; integument mainly smooth.

KJELLESVIG-WAERING: STYLONURACEA 175

Type species. — Dolichopterus stylonuroides Clarke and Ruede-
mann, 1912.

Derivation of name. — Named in honor of Rudolf Ruedemann whose
many contributions to our knowledge of the Chelicerata are basic and
well known to all who work in this group.

Distribution. — Eastern New York.

Stratigraphic range.- — Ordovician.

Remarks. — Ruedemannipterus seems to be an interesting connect-
ing genus between the Dolichopteridae and Stylonuridae. The dis-
tinctly elongated carapace and narrow mesosoma, as well as the
narrow sixth leg, resemble features of some of the Stylonuridae. How-
ever, the development of a paddle, although narrow, with numerous
supplementary lobes, probably should designate this genus as one of
the Dolichopteridae. As it is obviously a connecting genus, good
arguments for it being a stylonurid can also be advanced. Brachy-
opterus St0rmer, 1951, has a carapace which in general shape resem-
bles Ruedemannipterus, although the position of the eyes and the
stylonurid type of legs make further comparison unnecessary.

A number of other eurypterids which have aroused uncertainty as
to their generic affinities can now be referred to the genus Ruedeman-
nipterus. These include Dolichopterus latifrons Clarke and Ruede-
mann, 1912, from the Ordovician Schenectady shales of Schenectady,
New York, and Dolichopterus breviceps Clarke and Ruedemann, 1912,
from the Ordovician Normanskill shale of Catskill, New York.

Genus Tarsopterella St0rmer, 1951

Diagnosis. — Medium- to-large dolichopterids, outer surface with
strongly developed knobs and scales; prosoma broadly subrectangu-
lar, slightly concave in front; lateral eyes small; opisthosoma with
pronounced epimers; prosomal legs unknown, except fragments of
last leg which indicate presence of a wide paddle, possibly dolichop-
teroid (diagnosis modified from St0rmer, 1955, pp. 38-39).

Type species. — Stylonurus scoticus Woodward, 1864.

Distribution. — Scotland and Germany.

Stratigraphic range. — Devonian.

Remarks. — The two podomeres preserved on the left side of the
holotype are flat structures indicating the presence of a paddle. On
the other hand, St0rmer (1955, p. 39) believes that the legs were
probably stylonuroid. The overall aspect of the eurypterid could in-

176 FIELDIANA: GEOLOGY, VOLUME 14

dicate that it is either a dolichopterid or one of the stylonuroids. The
ornamentation is more typical of such stylonuroids as Hallipterus.
Nevertheless, the flattened podomeres indicate that if Tarsopterella
is a stylonuracean, it should probably be referred to the Dolichop-
teridae. This is done here with considerable misgivings until the
ventral side is known or some more prosomal appendages are found
of this highly spectacular eurypterid. It is not precluded that Tar-
sopterella may not belong among the Eurypteracea.

The following species are recognized :

Tarsopterella scoticum (Woodward), 1865 Devonian Scotland

Tarsopterella laticeps St0rmer, 1936 Devonian Germany

Family Stylonuridae Diener, 1924

Diagnosis. — Ventral shield and metastoma unknown ; eyes located
in posterior half of carapace, opisthosoma undifferentiated, triloba-
tion present; last two legs very long.

The above family diagnosis is based on the type species of Stylo-
nurus as restricted here. However, if genera such as Stylonuroides,
Stylonurella, Parastylonurus, Brachyopterus and Brachyopterella are
used in the diagnosis, then a much better and more complete diag-
nosis can be made. I suspect, however, that some of these genera
will be found eventually to have no significant affinities with the type
genus. It is almost certain that further revisions in the diagnosis of
the family will be forthcoming with discovery of additional material.
With these reservations in mind, the diagnosis of the family may
further include:

Diagnosis. — Ventral shield with epistoma; metastoma very nar-
row, with deep triangular notch or deeply cordate anteriorly, and
with base truncated.

It should be noted that when the underside of Stylonurus powri-
ensis Page, the genotype, is known, genera such as Parastylonurus,
Stylonuroides, Stylonurella, Brachyopterus, Brachyopterella, and others
here included in the Stylonuridae, may well be found to belong to
other and distinct families.

The following genera are recognized for this family:

Stylonurus Page, 1856
Stylonurella, new genus
Stylonuroides, new genus
Parastylonurus, new genus

KJELLESVIG-WAERING: STYLONURACEA 177

Brachyopterus, St0rmer, 1951

Brachyopterella, new genus

Clarkeipterus, new genus

Melbournopterus, Caster and Kjellesvig-Waering, 1953

(?) Dorfopterus, Kjellesvig-Waering, 1955

Genus Stylonurus Page, 1856, emended

Diagnosis. — Stylonuridae of medium size, prosoma subquadrate,
lateral margins slightly rounded outward to reach greatest width at
midsection, anterolateral angles rounded; eyes arcuate, located in
posterior half of prosoma; podomere-count unknown, but the last
two legs are greatly elongated, the last one extending to at least the
twelfth tergite; opisthosoma wide, short, trilobated, and without dif-
ferentiation into a pre- and post-abdomen; metasoma grades into the
long telson without diff erentation ; underside unknown.

Type species.- — Stylonurus powriensis Page, 1856.

Distribution. — Scotland, Pennsylvania (?) and New York (?).

Stratigraphic range. — Devonian.

Remarks. — The above diagnosis is an emendation, but based only
on the type species. However, it is necessary because Stylonurus, as
was the case with the genus Eurypterus (Kjellesvig-Waering, 1948,
p. 4; 1958, p. 1107), has become a convenient entity to which to refer
practically any eurypterid with stylonuroid legs. Species have been
referred to this genus on the basis of characters conforming to those
of the type species in only the most general way, serving to place
them in the superfamily Stylonuracea. This criticism is not aimed
at any particular worker in the eurypterids, and it includes myself as
much as anyone else.

Page, in his original description (1856, p. 135), described the geno-
type as "quaint-looking," and indeed it is, remaining as unique and
enigmatic today as it did over one hundred years ago. The charac-
ters distinguishing Stylonurus from other stylonurids are not only the
position of the eyes in the rear of the carapace, and the shape of
the carapace, but more importantly the distinct trilobation, not only
of the mesosoma as in some other eurypterids (Megalograptus, Mixop-
terus) , but also of the metasoma, a feature not found elsewhere except
in the recently described Pagea of Waterston (1962), and the Wood-
wardopteridae, both considerably different eurypterids. Even with-
out the presence of trilobation, the short, wide opisthosoma, without
the slightest trace of differentiation, is a significant feature. The

178 FIELDIANA: GEOLOGY, VOLUME 14

underside of the genotype would likely be of great interest and per-
haps as surprising as the dorsal.

Basing the generic differences on the carapace, position of the eyes
and type of opisthosoma, I recognize several genera which previously
had been included in the genus Stylonurus. These are Brachyopte-
rella, Parastylonurus, Stylonuroides and Stylonurella. Unfortunately,
the genus Stylonurus remains with only one species, the genotype.
Other fragmentary specimens are questionably assigned.

It is significant to recall that Clarke and Ruedemann, in their divi-
sion of the stylonuroids in 1912, recognized the dilemma of the holo-
type and wrote, "Only a single specimen, not very favorably preserved
in sandstone, has been recorded and although Page's not very correct
figure and explanation have been followed by Woodward's elaborate
description and careful illustration, this genotype is still incompletely
known. Indeed, when the investigation of a considerable number of
species revealed to us the presence of divisions of undoubted sub-
generic rank, it remained doubtful with which of these the genotype
belongs and which of the divisions therefore represents Stylonurus
sensu stricto." (1912, p. 278). The divisions given here should help
to alleviate this confusion, although problems still remain.

The species recognized for this genus are:

Stylonurus ? ensiformis Woodward, 1864
Stylonurus powriensis Page, 1856
Stylonurus ? shaffneri Willard, 1933
Stylonurus ? wrightianus Dawson, 1881

Genus Stylonuroides, new genus

Diagnosis. — Stylonuridae of small size; carapace elongated-para-
bolic, longer than wide, surrounded by conspicuous wide marginal
rim; eyes elongated-reniform, with axes parallel, and located so that
their posterior borders are in the anterior half of the carapace; ocelli
situated approximately midway between the eyes; third walking leg
(IV) short, and with single opposable spines; fourth and fifth walking
legs (V, VI) devoid of spines, except at the terminal end of the last leg
which has either two flat spines or structures that might be interpreted
as narrow supplementary lobes; podomere-count: ?-?-?-8-?-9.

Type species.- — Stylonurus dolichopteroides St0rmer, 1934.

Distribution. — Norway and New York.

Stratigraphic range. — Ordovician and Siluro-Devonian.

Devonian

Scotland

Devonian

Scotland

Devonian

Pennsylvania

Devonian

New York

KJELLESVIG-WAERING: STYLONURACEA 179

Remarks. — Stylonuroides can easily be distinguished from all other
stylonurids by the very long carapace and reniform eyes, as well as
the details of the termination of the last walking leg. It is, as the
species name of the genotype indicates, and as St0rmer (1934, p. 103)
has pointed out, another link between the Dolichopteridae and the
Stylonuridae, a further step in the transition from species such as
Ruedemannipterus stylonuroides (Clarke and Ruedemann) . However,
the long carapace and reniform eyes, a considerable departure from
the usual greatly arcuate eyes of the stylonurids, may well reveal
some affinities with the family Rhenopteridae.

The following species are recognized for the genus:

Stylonuroides dilichopieroides (St0rmer), 1934 Siluro-Devonian Norway

Stylonuroides limbatus (Clarke and Ruede- Ordovician New York

mann), 1912

Genus Stylonurella, new genus

Diagnosis. — Stylonuridae of small size; subquadrate prosoma, ap-
proximately as long as wide, slightly constricted at midsection; eyes
parallel, arcuate, anteriorly located, intramarginally, about midway
in the anterior half of the carapace; ventral shield with epistoma, but
metastoma unknown; first two appendages also unknown, third and
fourth prosomal legs very short, last two walking legs very long;
podomere-count: ?-?-7?-8-9-9?; metasoma very narrow, non-tri-
lobed, tapering.

Type species. — Stylonurus spinipes Page, 1859 (^Stylonurus lo-
gani Woodward) .

Distribution. — Scotland, Norway, New York and Pennsylvania.

Stratigraphic range. — Ordovician, Silurian and Devonian.

Remarks. — Although this was one of the earliest described stylo-
nuroids, made known not long after the description of the genotype
of Stylonurus, it bears no close (generic) affinities to that genus. The
differences between this genus and Stylonurus are numerous and out-
standing. Stylonurus has eyes placed on the posterior half of the
carapace whereas Stylonurella has them anteriorly located. Perhaps
of even greater importance is the wide opisthosoma with trilobation
of stylonurus as against the narrow terete mesosoma without any
trace of trilobation in Stylonurella. The differences of Parastylonurus
also are numerous and obvious. The quadrate form of the carapace

180

FIELDIANA: GEOLOGY, VOLUME 14

of Stylonurella differs greatly from the subrounded, wider than long,
carapace of Parastylonurus.

In the shape of the carapace and position of the eyes, Stylonurella
has a resemblance to Kokomopterus, however the altogether different
type of prosomal appendages is a difference that precludes the neces-
sity for further comparison.

Recognized species for this genus are:

Stylonurella arnoldi (Ehlers), 1935

Stylonurella modestus (Clarke and Ruede-
mann), 1912

Stylonurella otisius (Clarke), 1907

Stylonurella ruedemanni (St0rmer), 1934

Stylonurella spinipes (Page), 1859

Upper Devonian

Pennsylvania

Ordovician

New York

Silurian

New York

Siluro-Devonian

Norway-

Silurian

Scotland

Genus Parastylonurus, new genus

Diagnosis.- — Stylonuridae of small to medium size; prosoma
rounded-quadrate; wider than long, with lateral eyes, arcuate and
located on anterior half of the carapace; metastoma very long, with
deep triangular notch or deeply cordate and with base truncated;
first three walking legs very short with single opposable spines on
each joint; last two walking legs very long, reaching to the last ter-
gite; podomere-count: ?-?-7?-8-9-9; ornamentation consists of scales;
opisthosoma narrow, undifferentiated; telson spike-like.

Type species. — Stylonurus ornatus Laurie, 1892.

Distribution. — Scotland, England, New York and Pennsylvania.

Stratigraphic range. — Ordovician, Silurian and Devonian.

Remarks.- — Parastylonurus includes more forms previously in-
cluded in the genus Stylonurus than do the other genera described
here. However, in my opinion, the development of distinct triloba-
tion in the genus Stylonurus sets that genus irrevocably apart from
the species that are here referred to Parastylonurus. The position of
the eyes is also a major generic difference.

The following species are recognized :

Parastylonurus ? beecheri (Hall), 1884 Devonian

Parastylonurus macrophthalmus (Laurie), 1895 Silurian

Parastylonurus 1 megalops (Salter), 1859 Siluro-Devonian

Parastylonurus myops (Clarke), 1907 Silurian

Pennsylvania

Scotland

England

New York,
Pennsylvania

KJELLESVIG-WAERING: STYLONURACEA 181

Parastylonurus ornatus (Laurie), 1895 Silurian Scotland

Parastylonurtis rusti(RuedeTn3inn), 1926 Ordovician New York

Genus Brachyopterus St0rmer, 1951

Diagnosis. — Stylonuridae of small size; prosoma with greatest
width anteriorly, length equivalent to greatest width, base narrower
than anterior, rounded anteriorly; eyes elongated -reniform, with axes
slightly converging; first leg developed as grasping organ, all other
legs very stout, with few spines, stylonuroid but not excessively de-
veloped; opisthosoma short, relatively broad, undifferentiated; meta-
soma tapering into clavate, spike-like telson. (Modified from St0rmer,
1951, p. 416.)

Type species. — Brachyopterus stuhblefieldi St0rmer, 1951.

Distribution. — Wales.

Stratigraphic range. — Ordovician.

Remarks. — There is no other genus known that warrants compari-
son, or, indeed at our present state of knowledge, reveals any close
affinities with this very unusual genus; but see Remarks following the
discussion of Brachyopterella.

Genus Brachyopterella, new genus

Diagnosis. — Stylonuridae of small size; carapace pentagonal, with
little or no marginal rim and with concave base; eyes oblique, close-
set, placed anteriorly on the carapace, very long, banana-shaped, and
with axes converging and crossing a short distance in front of the
eyes; ocelli placed well forward between the eyes; epistoma well de-
veloped; legs increasing gradually, the first three with short opposable
spines at the end of each joint, the last two walking legs longer but
without spines; podomere-count: 3?-7-8-8-9-?; metastoma unknown;
ornamentation smooth on carapace, legs partly covered with granu-
lations.

Type species. — Stylonurus pentagonalis St0rmer, 1934.

Distribution. — Norway.

Stratigraphic range. — Ordovician (?), Siluro-Devonian.

Remarks. — The genotype has been included in the Middle Ordo-
vician genus Brachyopterus. However, the differences are much too
great to include the Norwegian form with the latter. The shape of
the carapace, and the altogether different type of eyes, as well as their

182 FIELDIANA: GEOLOGY, VOLUME 14

location, preclude the need for any comparison. There are no other
stylonuroids with the characteristics of Brachyopterella.

The species that are referred to this genus are:

Brachyopterella ? magna (Clarke and Ruede- Ordovician New York

mann), 1912

Brachyopterella pentagonalis (St0rmer), 1934 Siluro-Devonian Norway

Genus Clarkeipterus, new genus

Diagnosis. — Stylonuridae of small size; carapace longer than wide,
suboval, pointed anteriorly, with the base considerably narrower than
the greatest width, which is at midsection, base concave; eyes cres-
centric, large, located slightly in front of the middle of the carapace,
axes of eyes slightly convergent anteriorly, palpebral lobes very large
and circular, attached by narrow bridge to the carapace at the inner
part of the eyes; ocelli midway between the eyes; marginal rim either
not present or very narrow; ventral shield mostly unknown but bor-
dered by an unsutured marginal rim; no ornamentation present.

Type species. — Dolichopterus ? testudineus Clarke and Ruedemann,
1912.

Derivation of generic name.- — Named in honor of John M. Clarke
for his many contributions to our knowledge of the Eurypterida.

Distribution. — Scotland (?), New York.

Stratigraphic range. — Silurian.

Remarks.- — Except for the Dolichopteridae, nearly all the Stylonu-
racea are found in argillaceous or sandy sediments, but Clarkeipterus
is one of the few exceptions as it occurred in a calcareous-magnesian
mud. Clarkeipterus is extremely rare; it is known from only one spec-
imen, though a very well preserved one, from the famous Bertie water-
lime (Fiddlers Green dolomite) of Herkimer County, New York. The
genotype has been doubtfully referred to Dolichopterus or Brachyop-
terus by authors, including myself, but it seems preferable now that
the carapace should be relegated to the redefined family Stylonuridae,
because of the crescentic eyes. There is little purpose in comparing
this genus with any others as it is unique.

The following species are recognized :

Clarkeipterus ? knoxae (Lamont), 1955 Silurian Scotland

Clarkeipterus testudineus (Clarke and Ruede- Silurian New York

mann), 1912

KJELLESVIG-WAERING: STYLONURACEA 183

GJenus Melbournopterus Caster and Kjellesvig-Waering, 1953

Diagnosis. — Stylonuridae of small size; prosoma campanulate,
emarginate in front, and fringed with flat movable spines along the
base; lateral eyes subrectangular, oblique, close together, with inter-
posed ocelli in the posterior half of the carapace.

Type species. — Melbournopterus crossotus Caster and Kjellesvig-
Waering, 1953.

Distribution. — Australia.

Stratigraphic range. — Silurian.

Remarks. — Only a single specimen of the type of this strange genus
has been reported. Curiously, it is one of the few stylonuroids which,
like Stylonurus, has the eyes in the posterior part of the carapace.

Genus Dorfopterus Kjellesvig-Waering, 1955

Diagnosis. — Telson very long and styliform, with peculiar reticu-
lated pattern of ornamentation.

Type species. — Dorfopterus angu^ticolis Kjellesvig-Waering, 1955.

Distribution. — Wyoming.

Stratigraphic range. — Early Devonian.

Remarks. — Specimens recently collected by Robert H. Denison
and Eugene S. Richardson, Jr., of Chicago Natural History Museum,
show that this is a gigantic eurypterid and that the reticulated pattern
of ornamentation is clearly developed on the opisthosomal tergites.

Family Pageidae, new family

Diagnosis.— StylonuvsLcea. with ventral shield having well devel-
oped epistoma; metastoma coffin-shaped, truncated at both anterior
and posterior ends.

Type genus. — Pagea Waterston, 1962.

Remarks.- — The Pageidae differ from the other families that retain
an epistoma, namely the Stylonuridae and Laurieipteridae, in the
coffin-shaped metastoma, as against the long, deeply-notched meta-
stoma of the Stylonuridae, and the broadly subrectangular one in the
Laurieipteridae. The trilobation, although considered here a generic
character, may well be of higher taxonomic importance. The family
is monotypic at present.

184 FIELDIANA: GEOLOGY, VOLUME 14

Genus Pagea Waterston, 1962

Diagnosis. — Medium-sized stylonuroid eurypterid; shape of pro-
soma probably subrectangular, lateral eyes arcuate, in the anterior
half of the prosoma, subcentral; anterior margin of prosoma straight;
third and fourth prosomal appendages bearing a double row of numer-
ous flat spines, fifth and sixth prosomal appendages simple, keeled,
tapering, sixth appendage reaching as far as the pretelson; podomere-
count: ?-?-?-7-9-10; abdomen unusually slender with lateral epi-
meres on the postabdominal segments, axial furrows (trilobation)
present on all abdominal segments; telson long, styliform, keeled.
(Modified from Waterston, 1962, pp. 937-938.)

Type species.- — Pagea sturrocki Waterston, 1962.

Distribution.- — Scotland and Wales.

Stratigraphic range. — Devonian, Lower Old Red Sandstone.

Remarks. — This remarkable and unique eurypterid differs so widely
from all others that comparison is superfluous. The unusually nar-
row opisthosoma, with trilobation, is unknown in any of the other
genera of the Stylonuracea. It appears likely that trilobation in a
narrow form such as this may be connected with strengthening the
presumably highly flexible opisthosoma. However, this is not true
of the trilobation in Stylonurus powriensis Page, a species which is
noteworthy for its wide and heavily constructed opisthosoma. The
podomere-count, ?-?-?-? -9-10, is of considerable generic importance
in my opinion, and it differs from those of other Stylonuracea.

Two species are recognized for the genus:

Pagea sturrocki Waterston, 1962 Devonian Scotland

Pagea symondsii (Salter), 1S57 Devonian Wales

Pagea symondsii (Salter) reveals the same shape of carapace, with
eyes located at the same position, as well as having the wide anterior
marginal rim. Although the holotype is a dorsal impression, both
Salter (in Huxley and Salter, 1859, pi. X, fig. 1) and Woodward (1866-
78, pi. XXI, fig. 4) show two diagonal depressions which very likely
are the reflection of the epistomal sutures; thus P. symondsii (Salter)
must have had the same wide epistoma that Waterston found in
P. sturrocki.

Family Drepanopteridae, new family

Dmgrwosw.^Stylonuracea with metastoma ovoid, its anterior cor-
date, and posterior rounded; ventral shield unknown.

KJELLESVIG-WAERING: STYLONURACEA 185

Type genus. — Drepanoptenis Laurie, 1892.

The family Drepanopteridae differs from the Stylonuridae, with
which it has always been associated, in the important feature of the
entirely different-shaped metastoma. In contrast to the elongated,
narrow metastoma of the Stylonuridae, deeply notched anteriorly
and truncated at the posterior end, that of the Drepanopteridae com-
prises an unusual, "Eurypteridae-like" metastoma, namely, ovate and
anteriorly cordate.

At present the family remains monotypic, and definitely known
only from Scotland in Silurian beds, and possibly in the Devonian.
A questionable occurrence has been recorded from the Ordovician of
New York.

Genus Drepanopterus Laurie, 1892

Diagnosis. — Drepanopteridae of small size; prosoma horseshoe
shaped, narrower at base than at the rounded lateral margins; wide
marginal rim; eyes arcuate, located at midsection; prosomal append-
ages stout, increasing gradually in length posteriorly and devoid of
spines except for possible spurs (?) on the ends of central joints of the
posterior (VI) leg; this leg (VI) terminates in a flattened, slightly ex-
panded, falcate joint, and reaches only to the anterior part of the
postabdomen; metastoma ovoid and cordate at the anterior end;
opisthosoma completely undifferentiated, wide and tapering into a
clavate or wedge-shaped telson; opercula not well known; ornamen-
tation comprises scale-like markings and pustules.

Type species.- — Drepanopterus pentlandicus Laurie, 1892.

Distribution. — Scotland and New York (?).

Stratigraphic range. — Ordovician ?; Silurian; Devonian ?

Remarks.- — Drepanopterus reveals characteristics which recall the
Eurypteridae in many respects. This was first suggested by Peach
to Laurie (1892, p. 161). The Drepanopteridae reveal characteris-
tics, such as the ovoid metastoma, which distinguish them from the
rest of the Stylonuracea, but show affinities to the Eurypteridae
through the Dolichopteridae, and such genera as Onychopterella of
the Eurypteridae. However, the development could just as well have
been reversed. These evolutionary trends between the two groups
are important to keep in mind when future discoveries in Ordovician
and Cambrian rocks may possibly resolve the problem of the early
phylogeny of this group.

Devonian

Scotland

Silurian

Scotland

Silurian

Scotland

Silurian

Scotland

Ordovician

New York

186 FIELDIANA: GEOLOGY, VOLUME 14

The following species are recognized for the genus:

Drepanopterus (?) abonensis Simpson, 1951

Drepanoptrus bembicoides Laurie, 1899

Drepanopterus lobatus Laurie, 1899

Drepanopterus pentlandicus Laurie, 1895

Drepanopterus ? ruedemanni (O'Connell), 1916 Ordovician

Family Kokomopteridae, new family

Diagnosis. — Stylonuracea with band-like ventral shield of the pro-
soma, without epistoma; metastoma broadly pyriform, very wide
posteriorly and notched anteriorly and with a broad emargination at
the posterior end.

Type genus. — Kokomopterus new genus.

The differences between this family and others are significant. It
resembles the Rhenopteridae in the band-like ventral shield and lack
of epistoma. However, the totally different metastomas are sufficient
for separation, and further comparison with that family as well as
the other Stylonuracea is considered superfluous. At present the
family is monotypic and is known only from the Silurian of Indiana.

In comparison with the Drepanopteridae, the difference lies in the
ovate, anteriorly cordate metastoma as against the altogether differ-
ent-shaped structure described above for the Kokomopteridae. Pre-
viously, the type species of Kokomopterus (K. longicaudatus [Clarke
and Ruedemann]) had been mistaken for a Drepanopterus.

Genus Kokomopterus, new genus

Diagnosis. — Kokomopteridae of small size; carapace subquadrate,
slightly wider than long, lateral margins parallel; eyes arcuate, with
axes parallel, and located in the anterior half of the carapace, consid-
erably apart from one another; ventral shield probably consisting of
an undivided plate, with narrow marginal rim; prosomal legs stylo-
nuroid, but increasing posteriorly in a gradual manner; podomere-
count: ?-?-?-8-9-9; the second to fifth legs armed with single, un-
equal, opposable spines; last leg without spines and reaching to the
eleventh opisthosomal tergite; all legs terminate in single spine; meta-
stoma broadly pyriform, with narrow notch at anterior end and
broadly but slightly emarginate at the posterior; opisthosoma differ-
entiated into a preabdomen of seven tergites and a much narrower
postabdomen of five, of which the twelfth tergite is long, rectangular

KJELLESVIG-WAERING: STYLONURACEA

187

and with sides nearly parallel ; male operculum unknown ; female oper-
culum short, composed of one undivided joint with slightly rounded
margins that comprises most of the appendage, and a short triangular
termination that is divided into two parts, each of which forms a
narrow triangular prong (see fig. 97) ; telson very narrow, spike-like,
forming a conspicuous attenuation in comparison to the metasoma;
ornamentation consists of fine to coarse scales and mucrones.

Type species.- — Stylonurus {Drepanopterus) longicaudatiis Clarke
and Ruedemann, 1912.

Derivation of name. — Named from the area of Kokomo, Indiana
which has furnished the famous Kokomo eurypterid fauna.

Distribution. — Indiana.

Stratigraphic range. — Upper Silurian.

Remarks. — The genus Kokomopterus differs from Drepanopterus
in having a subquadrate carapace with anteriorly located eyes as
against a horseshoe shaped carapace with eyes located at midsection.
The opisthosoma of Kokomopterus has a clearly differentiated pre-
abdomen as contrasted with the opisthosoma of Drepanopterus, which

Fig. 97. Female (Type B) operculum of Kokomopterus longicaudatus (Clarke
and Ruedemann) from the Silurian Kokomo dolomite of Kokomo, Indiana. The
mid-line represents the transverse suture. There were no deltoid plates developed.
The inner part of the opercular plates and the median organ were covered with
setae.

188 FIELDIANA: GEOLOGY, VOLUME 14

is entirely undifferentiated. In the latter the tergites of the meta-
soma are very wide and conical and almost grade into the wide (an-
teriorly), wedge-shaped or clavate telson. A very important difference
lies in the presence of spines in the fourth walking leg of Kokomop-
terus as compared to the non-spinous character of the same leg in
Drepanopterus. The last podomere of the fifth or last walking leg in
all species of Drepanopterus terminates in a falcate, and presumably
flattened, slightly expanded spine as against the narrow conical shape
of the corresponding leg in Kokomopterus. The metastomas, of course,
are entirely different.

One species is recognized for the genus:

Kokomopterus longicaudatus

(Clarke and Ruedemann) 1912 Silurian Indiana

Part of the generic description and the basis for family separation
are derived from new data. A specimen from the Silurian Kokomo
dolomite, at Yeoman Quarry, Kokomo, Indiana, which was collected
by W. P. Leutze in 1959 and kindly presented to me (No. 74 tem-
porarily in my collection) , reveals many details of considerable taxo-

FiG. 98. Metastoma of Kokomopterus longi-
caudatus (Clarke and Ruedemann) from the Silur-
ian Kokomo dolomite of Kokomo, Indiana.

nomic importance. The overall length of the specimen is estimated
at 11 cm. The most interesting feature is the shape of the metastoma,
which is roughly oval, with a narrow notch at the anterior and a
broad base which is slightly cordate or emarginate (see fig. 98). It
measures 8.1 mm. in length and 7.2 mm. in greatest width (see fig. 95).
The female, or Type B (see fig. 97), operculum is well preserved,
showing even such details as the setae. The appendage is small,
about one-third the length of the operculum, and consists of an un-

KJELLESVIG-WAERING: STYLONURACEA 189

divided, rather broad lanceolate joint, with two triangular joints at
the distal end. A transverse suture occurs at the midsection of the
opercular flaps. The lanceolate joint, as well as the surrounding parts
of the operculum, are very hirsute, being covered with dark brown
tactile setae. The fine punctation that occurs on the triangular points
likely represents sites where the setae had broken away. The cara-
pace measures 19.4 mm. in length with an estimated width of 26.0
mm. The ventral shield apparently comprises an undivided, or non-
sutured, plate of 6 mm. in width at the anterior part. There is no
trace of an epistoma, or of sutures, although the preservation of this
part does not allow complete confidence. The prosomal appendages
of this specimen are too poorly preserved for description. The dorsal
side of the specimen, however, retains the original coloration as is
common with the eurypterids of the Kokomo assemblage. The speci-
men is shiny, fairly dark brown; but curiously it reveals a narrow,
very dark brown line, over one millimeter wide, that runs through
the center of the dorsal length of the opisthosoma. This is not to be
mistaken for a suture as it is definitely a color distinction. This is
the first instance of a purely colored ornamentational pattern known
in the stylonuroids. The dorsal side is covered with scales, most of
which are semi-lunar in shape; others become rather pointed. The
doublures of the tergites are heavily hirsute.

Family Rhenopteridae St0rmer, 1951

Diagnosis. — Stylonuracea with ventral shield having median suture,
but no epistoma; metastoma pyriform, slightly concave anteriorly,
broadly rounded posteriorly.

The family remains monotypic and is known only from the De-
vonian of Germany and possibly New York.

Genus Rhenopterus St0rmer, 1951

Diagnosis. — Carapace longer than wide, rounded anteriorly, and
with lateral eyes reniform, located slightly in front of midsection;
first two (or three) pairs of walking legs with spines, last two pairs
without spines; male appendage short, with two distal spurs; podo-
mere-count: ?-7 -8-8-9-9.

Type species.— Rhenopterus diensti St^rmer, 1951.

Distribution. — Germany and New York (?).

190 FIELDIANA: GEOLOGY, VOLUME 14

The following species are recognized for this genus:

Rhenopterus diensti St^rmer, 1936 Devonian Germany

Rhenopterus latus St^rmer, 1936 Devonian Germany

Rhenopterus ? maccarthyi (Kjellesvig-Waer- Devonian New York

ing), 1934

Rhenopterus tuberculatus St0rmer, 1936 Devonian Germany

Family Laurieipteridae, new family

Diagnosis. — Stylonuracea with ventral shield having well devel-
oped epistoma; metastoma broadly sub-rectangular, slightly emargi-
nate anteriorly and posteriorly.

Type genus. — Laurieipterus, new genus.

Remarks. — The Laurieipteridae is composed of the genera Laurie-
ipterus, Ctenopterus, Hallipterus and Mazonipterus, all of which are
characterized by unusually long carapaces, and were generally
grouped together, more or less, under the genus Ctenopterus. Laurie,
however, as early as 1899 (pi. 2, fig. 3), had revealed the unusual rec-
tangular metastoma, and this was verified by Waterston (1962, p. 145,
text-fig. 3) who also worked out the details of the ventral shield.

The family Laurieipteridae is easily separated from all the other
families of the Stylonuracea. In comparison with those families which
have a developed epistoma, namely, the Stylonuridae and Pageidae,
the greatest dissimilarity lies in the altogether different metastomas.
That of the Stylonuridae is very narrow and deeply notched anteri-
orly, whereas in the Pageidae it is "coffin-shaped," or elongated, with
the anterior wider, and both anterior and posterior ends truncated.
This is in sharp contrast to the broad sub-rectangular metastoma of
the Laurieipteridae.

Genus Laurieipterus, new genus

Diagnosis. — Laurieipteridae of medium-size, carapace enormously
elongated, very narrow at the base but with the lateral margins greatly
expanded at midsection; anterior rounded with ornamentation of cren-
ulations; lateral eyes small and arcuate, anteriorly located and well
apart; ocelli located in front of the lateral eyes; legs powerful and not
excessively long; podomere-count: ?-?-? -8-8-8; spines developed on
all but last two walking legs, which are completely bare, the spines
increasing in length along the posterior side of each joint; ventral
shield with well developed epistoma and with triangular transverse

KJELLESVIG-WAERING: STYLONURACEA 191

line clearly separating the anterior rostral area from the inclined rear
of the shield; opisthosoma is unknown except as fragments.
Type species. — Stylonurus elegans Laurie, 1899.

Derivation of generic name. — Named in honor of Malcolm Laurie
for his many original contributions to our knowledge of Eurypterida
and Scorpionida.

Distribution. — Scotland .

Stratigraphic range. — Silurian, Gala-Tarannon.

Remarks. — Laurieipterus differs greatly from the other genera of
the Laurieipteridae, and comparison is needed only with Ctenopterus,
the genus under which this strange eurypterid had been included
since the Clarke and Ruedemann monograph of 1912. Firstly, the
carapaces are very different; that of Laurieipterus is highly bulbous
at midsection with an extremely narrow base, as against the anteri-
orly converging carapace of Ctenopterus with its wide base and un-
usual cheek pouches. The latter has a greatly different arrangement
of the spines of the anterior legs, and has one podomere more on the
last two legs. There are numerous other differences not necessary to
detail here (see Clarke and Ruedemann, 1912, p. 286; Laurie, 1899,
p. 580, and Waterston, 1962, p. 143).

Genus Ctenopterus Clarke and Ruedemann, 1912

Diagnosis. — Laurieipteridae of small size; carapace elongated oval,
longer than wide, and with widest part in posterior fourth, narrowing
anteriorly to less than half the width, anterior margin prominent and
ornamented with fringe of spines; lateral eyes elongated arcuate, with
median ocelli approximately midway between; two oval cheek-like
ridges are on each side of the carapace; first and second appendages
unknown, third and fourth very long and armed with slender, paired
spines of even length, the last two walking legs extremely long, the
sixth reaching to the twelfth tergite, these two legs terete and bare of
spines, all legs terminating in a pointed, conical joint; podomere-
count: ?-?-8-8-9-9; metastoma unknown; preabdomen slender, but
well differentiated from the postabdomen ; opercula not well known ;
telson presumably a long spike; ornamentation highly variable, con-
sisting of pustules and scales.

Type species. — Stylonurus cestrotus Clarke, 1907.
Distribution. — New York.
Stratigraphic range. — Silurian.

192 FIELDIANA: GEOLOGY, VOLUME 14

Remarks. — The differences between Ctenopterus and Laurieipterus
have been described above in discussion of the latter genus. In com-
parison with Hallipterus and Mazonipterus the differences lie in the
position and characteristics of the eyes and the altogether different
ornamentation.

Only one species is recognized for the genus Ctenopterus:
Ctenopterus cestrotus (Clarke), 1907 Silurian New York

Genus Hallipterus Kjellesvig-Waering, 1963

Diagnosis. — Laurieipteridae of large size; carapace subelliptical,
longer than wide, truncated at the base and surrounded by a promi-
nent but unornamented marginal rim; lateral eyes very small, arcu-
ate, close-set and centrally located on the carapace and separated by
a prominent median ridge with large ocelU located at the posterior
extremity; conspicuous orbital ridges surround the lateral eyes ante-
riorly and laterally ; the ornamentation comprises coarse elongate and
confluent pustules arranged in concentric lines particularly prominent
on the anterior of the carapace; chelicera simple, elongated; first
walking leg with fiat movable spines; rest of appendages and opistho-
soma unknown.

Type species. — Stylonurus excelsior Hall, 1883.

Distribution.- — New York and Pennsylvania.

Stratigraphic range.- — Upper Devonian.

Remarks. — This genus of gigantic eurypterids is composed of two
famous species, Hallipterus excelsior (Hall) of New York and H. la-
coanus (Claypole) of Pennsylvania, and is well known through the
famous restorations of Beecher, and later of Clarke and Ruedemann.
Unfortunately, these well known restorations, except for the carapace
and first legs, were based mainly on the opisthosoma and appendages
of other Stylonuracea. Differences between this genus and Laurieip-
terus or Ctenopterus have been discussed under the Remarks on
those genera.

Genus Mazonipterus Kjellesvig-Waering, 1963

Diagnosis.- — Stylonuridae of medium size; carapace very elon-
gated, with lateral eyes arcuate and placed anteriorly on the cara-
pace; greatest width of carapace occurs midway; palpebral lobe at-
tached to carapace by a narrow bridge on outer-posterior part of lobe;

KJELLESVIG-WAERING: STYLONURACEA 193

marginal rim very narrow, simple, not ornamented; ornamentation
smooth; no other parts known.

Type species. — Mazonipterus cyclophthalmus Kjellesvig-Waering,
1963.

Distribution. — Illinois and Czechoslovakia (?).

Stratigraphic range. — Middle Pennsylvanian (Illinois); Lower
Carboniferous? (Czechoslovakia.)

Remarks. — There is a marked resemblance of this form to Laurie-
ipterus and Ctenopterus, but the very different type of eyes precludes
further comparison. It should be noted that in the holotype, the
ventral shield had been reflected through, although preservation did
not permit detailed description; it is important to record that the tri-
angular transverse line, marking off the anterior rostral area from the
inclined posterior part, as in Limulus, and in Brachyopterella, Laurie-
ipterus, and other Stylonuracea as well, was discernible. It might
therefore be rather safe to speculate that this genus retained an
epistoma.

The genus comprises one species, with another doubtfully included :

Mazonipterus cyclophthalmus Kjellesvig- Pennsylvanian Illinois

Waering, 1963

Mazonipterus (?) ostraviensis (Augusta and Lower Czecho-

Pfibyl), 1951 Carboniferous Slovakia

Family Woodwardopteridae Kjellesvig-Waering, 1959

Diagnosis. — Stylonuracea of medium size; outer surface covered
with coarse scales and tubercles; prosoma campanulate, with stylo-
nuroid appendages increasing in size posteriorly; first and second
tergites greatly developed, the others normal in length.

Type genus. — Woodwardopterus Kjellesvig-Waering, 1959.

The family is considered to include two genera, Borchgrevinkium
and Woodwardopterus.

Genus Borchgrevinkium Novojilov, 1959

Dmgwos«s.— Carapace elongated-parabolic; eyes unknown; legs
mainly unknown, except basal (?) joints, which are highly spinous,
undifferentiated; mesosoma with first two tergites longer than the
rest of the mesosomal tergites; opisthosoma undifferentiated, with
trilobation, caused by two ridges, present from the third to the tenth
tergites; pretelson with dorsal forked area and telson short and styli-

194 FIELDIANA: GEOLOGY, VOLUME 14

form; underside practically unknown; ornamentation is composed of
squamous sculpturing.

Type species. — Borchgrevinkium taimyrense Novojilov, 1959.

Stratigraphic range. — Lower Devonian (Upper Silurian ?).

Distribution. — Southwest Taimyr, Siberia, U.S.S.R.

Recognized species. — Borchgrevinkium taimyrense Novojilov.

Remarks. — The five walking legs preserved, regardless of whether
they represent the basal, middle or distal podomeres, clearly desig-
nate this very peculiar and interesting eurypterid as a stylonuracean,
and thus with affinities with the Woodwardopteridae rather than the
Mycteropidae, which are considered a family of the Mixopteracea.

Genus Woodwardopterus Kjellesvig-Waering, 1959

Diagnosis. — Woodwardopteridae of medium size, outer surface
covered by coarse scales and tubercles; prosoma campanulate; eyes
and ocelli unknown; prosomal appendages without spines but with
supplementary lobes developed on anterior legs; first and second
tergites greatly developed; opisthosoma trilobate in posterior part;
telson unknown.

Type species. — Eurypterus scabrosus Woodward, 1887.

Stratigraphic range. — Lower Carboniferous.

Distribution.- — Scotland .

Recognized species. — Woodwardopterus scabrosus (Woodward), 1887.

Family Hibbertopteridae Kjellesvig-Waering, 1959

Diagnosis. — Ventral shield of two plates, joined anteriorly by
suture, no epistoma; metastoma trapezoidal, cordate anteriorly with
median posterior suture and narrowing anteriorly.

The family includes the two genera Hibbertopterus and Campy-
locephalus.

Genus Hibbertopterus Kjellesvig-Waering, 1959

Diagnosis. — Hibbertopteridae with broad semi-circular prosoma
and with centrally located arcuate eyes with narrow visual area and
surrounded by annular cuticular thickening (orbital ridges) .

Type species. — Eurypterus scouleri Hibbert.

Distribution. — Scotland, Ireland (?), Pennsylvania (?), Czecho-
slovakia (?) and South Africa (?).

KJELLESVIG-WAERING: STYLONURACEA

195

Stratigraphic range. — Lower Carboniferous; Upper Devonian (?).

The following species are recognized :

Hibbertopterus ? hibernicus (Baily), 1872
Hibbertopterus ? minutisculptus (Peach), 1907

Hibbertopterus 1 potens (Hall), 1884
Hibbertopterus 1 salmi (Stur), 1877

Hibbertopterus scouleri (Hibbert), 1836

Hibbertopterus ? sewardi (Strand), 1926

Hibbertopterus ? stevensoni (Etheridge, Jr.),
1876

Devonian

Ireland

Lower
Carboniferous

Scotland

Pennsylvanian

Pennsylvania

Lower
Carboniferous

Czecho-
slovakia

Lower
Carboniferous

Scotland

Carboniferous

South Africa

Lower
Carboniferous

Scotland

Genus Campylocephalus Eichwald, 1860

Diagnosis. — Hibbertopteridae with subelliptical prosoma, narrow
at base and broadest at midsection; compound eyes reniform, without
annular cuticular thickening, located in posterior half of prosoma.

Type species. — Limulus oculatus Kutorga, 1838.

Distribution. — Urals, U.S.S.R.

Stratigraphic range. — Upper Carboniferous-Permian.

Recognized species for this genus:
Campylocephalus oculatus (Kutorga) Permian (?) U.S.S.R.

REFERENCES

Baily, W. H.

1866-72 in Woodward, H. Monograph of the British Fossil Crustacea, etc.,
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1953. Melbournopterus, A New Silurian Eurypterid from Australia. Jour. Pal.,
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Clarke, J. M.

1907. The Eurypterus shales of Shawangunk Mountains in eastern New York.
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Clarke, J. M., and R. Ruedemann

1912. The Eurypterida of New York. New York State Mus., Memoir 14,
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Etheridge, R., Jr.

1877. On the Remains of a Large Crustacean, probably indicative of a New
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196 FIELDIANA: GEOLOGY, VOLUME 14

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1859. On the anatomy and affinities of the Genus Pterygotus (Huxley) and
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1838. Beitrag zur Kenntnis der organischen Uberreste des Kupfersandsteins
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1948. The Mazon Creek Eurypterid. A Revision of the Genus Lepidoderma.

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Laurie, M.

1892. On some Eurypterid Remains from the Upper Silurian Rocks of the Pent-
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NovoJiLOV, N.

1958. Polystomurum st^rmeri new genus and species of Eurypterida from the
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Petrunkevitch, a.

1916. The shape of the sternum in Scorpions as a systematic and a phylogenetic
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ST0RMER, L.

1934. Merostomata from the Downtonian Sandstone of Ringerike, Norway.
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