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HARVARD UNIVERSITY

‘e
Library of the
Museum of

Comparative Zoology

“MAR

VERSITY

Review of selected North American

mitrate stylophorans (Homalozoa: Echinodermata)

by

Ronald L. Parsley

Paleontological Research Institution
1259 Trumansburg Road
Ithaca, New York, 14850 U.S.A.

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VOLUME 100, NUMBER 336 JANUARY 15, 1991

Review of selected North American

mitrate stylophorans (Homalozoa: Echinodermata)

by

Ronald L. Parsley

Paleontological Research Institution
1259 Trumansburg Road
Ithaca, New York, 14850 U.S.A.

ORS Sig Ba Oe nt ey

Library of Congress Card Number: 90-63453

Printed in the United States of America
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CONTENTS

PANES TTA VM eters cae aera en Sara cme Sune sae tee ah Str HST aue TE Co Poriodeh aaa em ate anata suche taboteanaptoea nana ecanehe aavck ana ouch enige ea apenas Gaemeu sol sania eee
THERON VLG EL OTN year ters clr cde ors pe ores oe eV LaT Sek s vo EIOLCL a) oeVOPRTG VOPR GLCES ce re POL ous CTeMeNate eh kava sie eke ea loi Asker Searatehchoraayecerslcleyelabet icisichs erefetoneeel nate
OvenvicwLOMRecumbentsECHIMOGERMS) c.veccs svc cvseg.ceuseeashel sae enererese Susice ore tas) susyereetchtresesreteietavaqs nie, Wvayavereseinevers consterevarete eievovccererartusya ©] ebsieveraiters
Reviews lathe: SUDpHYyUMMELOIMAlOZOA Ne cpsser tale store cote caceevs ra cous teTele ye bo lets vet ehete eters ofoheseini Fos serens¥evsfeaenovets yatta] rete lay sieboreteee sus) Vanes aueyatere tm cVeranels
PSHE LSlASSH EL OMIOSTC LEA efie mrcronerk hava tercrs care eve ieraie (aegene ences fre/oxate Lat cucysveueue jelisters cerehansve Grete ene uewe levahetesevete stots paveuctaietevere vette svare (oheveretalone kegs esers
Miher@lass;@tenOcystoldeaiay. pier crea yaa iene ratercia recs sie Syston Tea weeps cat eesete t ectanel me cere lane scr mronamorenen srs atsestateh Reicher nue erecta tansy skecoetens
MTEL GlaSSMELOmOLOStEL eae «are spavares eae te Sansa cos yar ceo paveh eta evan es choses ave Sucicvors a1 ssa} el aVevopsy Sav aenevey oy 8 eh eben ctedat ni cite ce foratevel op si cleneevere foretelay siecace, aie
Thee Chas Saullo ogasconmgocsunenceadaooundD dos souedsnaceeeeooognucuoud eonobponccounh sugbeUDo UN aoonpnoO CUD egdenE
MMA X OTLOMIRIC HE OSH Oc sev Scyeucas cee yer ok sassy eI Siero GM tees ons N OTC aG= us oye le Es Ha OSU faye Sea es ereUe Veale Fe SyESLCks US CayeVois cays eA ens ieucyeeseve suf hci oh Veeenerer avers
Morphology, Functional Morphology, and Life Habits
(OUARETAUEAAVGy cL NS RO ose et oe Gide i eo Oe Renn aire ee nee eerie CRC TcnOeee TeET O ee Oe Ree cae aU Onto.
Morphology
TONG) \ «SE otra teens Seco g Hic oe BEES Oc RC ORC Oi oO REL Ea eT aan odo Rian ree nena er clon aon Meee mene Otter oes oi
/NTIETsoy eli yG yaaa anne San eee acc Seca es own oases oto mee a eae tots a annem mao pe eaeranoeeaonicood seas oe
Mnigmsyanduehylogenyviotthe Mitratan are cer yessierstesctepee seis ous eves eles ie eucse es ekta cde bao tere a ese tey= each ol sh stokene elses ategrioreretersyepsgeveniciens
AGMORARCEDNGO see son cen ont ago LOC Teron oe arn On acre caster Mena DE oe anE omen omOat one Ane oUL ond Ts Comer on poco sgeguakc
Systematic Paleontology
LIER OGG LYST ey Spey eS ear Ba ene eco Petia ene eee ie esha are cam A emo anin CIA DeraoS on OL oo ne Douce ono ce bee nas
AbbreviationsOfRepOSitOry ENStitwthONs: <2 oe s2 ese, c ase sdce,o, «seein, oi:0i sheer tue © are tasevetovs ie osese)s © oyoyaie lov apo ei seoseia sys exsfene spe ssvssysicpstetsy shsisi susie islets
Systematics
Class Stylophora
Order Mitrata
SubordersAnomial ocystitidars 5 2cc'cccusccteccssstiscpesorsisesscseueusserah eyoFay cues ac eeelte stoi exes sr creebaye oye fone eyetieysy every susveyetsl ceGeasvsveuet | t= vekeIunyaonctekeps
ami lyANOMAalOGyStith dae sc eykc ps says roccyess bole Sresces oer Vee Te NG, ces Toe xev aye Negocio SF eerele (eV ie seaee Pepe ey ue ue shop oeegeVe re cet -ccy Tass one tepeteteyeteten ors
Subfamily;Anomalocystitinae ) s:-io8,s.2. certs. caecteweens sue itees ee eyczeicte ea ee se ese ceed ToC) Ue one NETS ees Sep oyateTCLe Nao ACT gexec enae Stef h ONS
(GENUS PATO TIE OCVSTILEST verti: Wako ire soa eeeo Feud ALE Sete seh ea N SS ole eres ne nenay eT Ree eae eect tig ene ee ey onc anya eeeRatGerel atte
VA NO IMALOGYSUILCSICOMIIULEUS TEL ANN vs cessor erate eee LSAT sees EI LTRS TP OTN ATT ICO OCP oeeee reels
(GenussA1erOCVStis mes BOM ares sscerar tye here vers ede ey eee ER eT PaCS TELE Seo PEI pete Con SEE epee Re Mtoe ererste wh ancysttersaehs
I SARA UAT RES SC Os amo counendenbog bb tan sco tes sabe oues deme rosademnes ooabidacd Gaurd pooMdotaredpT
SubfamilygEnoplOurimacy yrs cps sesses ye aera eee asa cher eet oe chenene gap ecen ties eae shee ete anare reson adage covey aieteln cusieesteyeveney Wels Weroteisicacte
Genusrenoploura Wetherby cecccs casicdecaceox teen Roe Nis Stovec een reer Meer eure ete oN Tee eRe ey aU See ey SNe eo Tob oy RTETEP cay Lee eC as cue soNEPE a
IENODIOUNANDUNCIALANBRASSIET SSP cle epee h acs hale yee Sete ee i SU Eee eee eae oad Re eA eV ee shoo o oe TOR as io oA Me Mek Pevoysie) eae onces eterey Meese
Enoploura balanoidess(Meek) tac. ads oo iorscops oe TOTS eT Reo hoo Coed She Go) 20 aE Spe VeHCU OIE AEE TELE cus RSE
Enoplouract i balanoidess(Meek))= rr cscteqa tes erstents ote vesse hNSCs UP one IS Soe TTS aoe PTO FURS TT RES eee abe Srey eRe
FE ODIOUTASPOD EL CASTCL! A. seeterer rete Pon eee R eae ICS SION ETE NEEL Shore ONCE E POPSSO OE OE SEE TO Eee Te
Proploural ct Npopel' Casters | Asisy. fossa eeoretsesocenrtecs c Pei ere Pe Te Ne COTTA OTC. See Case ean ee
Family Placocystitidae
SubfamilyaPlacocystitinaes sac ses cays cysts tose e cree a ey cccasyeet eee aie rete bole ee Oe Pero here ee otc P pa tevoeie olseerek erin
GENUS IRON fiGystis eves OMe ie ae aI Lao sees ES aes TS eo ea are La rar hse depen aetna serene fewses
IKODAGYSUISCRIPKSIOIAISINS!SP 5 gsc sucn ees eset eM Fou AILS SPN NRE sf re STEIN NSI OLN Tis ETSI RHE TTS ace poe ree
GenuszAteleocystitessBillings: sysisrecevsrot a 2. sso8 fact act senaae Seabed tee ee eibsee ha oa iress oo age dR Tae TEM SIE Seyece ge PT eee
AteleacystiteswnuxleyieBillingsin sete eee ean Seisene Glee OnE RE oes nie ET EOE ee OC EOC EGET:
rAteleocystites;chrAsnuxleyieBillingse eases cin eter. Sem eee cere ere eee ee STS ee rere ere aT a cries iets
Suborder Peltocystiti damier. o1t be tetere testes eect aso AN SneT ect ais ons notes Leveneeseccrsiete Parent rela cei ealede Pareueberey seeker vane ie ieerarspe rescore:
Jha by) Sho Corn ialsk: |e ot ene Rana Dae n atts Eee Reesor ccmooroagTdbcncommaCodan me umoendotebcn cars
GenusvAnatiferocystisi©@ bay ely eee hycctrceeriaasac Sites teres Seeded Cae aes Toe eee eae EES eR CA TLE eT RCT EEE eee ats
PAN GICrOCYSTISiDADINALGA BASSIED) lun ety are aren enc foe.e ere oe One See ee eee
ANpendixr Collecting Weocalities) cstescrarsccc.cr.ccsvspecre ctcrelatsveye sca en cue ven ays Tes ctevaye a) iavavevesaeiat Maelo c1Cy-FSTRIn ECLTOES GREE PeeTec oc ene YaST ere
IREfETENGESIC1tEG Ns rer areata ree os eras en I TS eins ce NCL, Ba Sesto Sidlavaro aaah sual oils Sates aie tshe iat eye etel See ltats) PROTEST E OTe Eee

U
&
MCOINIDDUAUNYG

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eee
nhOO

a
co oO

LIST OF ILLUSTRATIONS

Text-figure Page
12 Reconstruction (of-E noploura\ pope? iniatsidistressed orientation: ....22.- «--4-222-seeeees = seen esos cee eee eee eee eee 9
2, Reconstruction of Enoploura'popei in its normal feeding orientation: «2 d..c2222< 0.2 csien a2 cle cee oes eeeiele ieee eee 11
3. An oblique view of the proximal aulacophore, styloid, and a portion of the distal aulacophore of Enoploura popei .............. 12
4° Phylogenetic/chart of the:Anomalocystitida. “55 <2 )asies cee winnees © ossae saveleim ad eetele cis ee-o¥ 21essle me ysieie eke BOS ae eee eee ee Een 16
59 Carapace detailiofiAnormalocystites!COWMULUS, aac (as a2 eo 2 eases (oes ausese rele eine ise eee cee sie evar ee secre foldout inside back cover
6a)Plastron detailiofdnomalocystites\COMmuUlusy ise: eis oee nie eno cle eee cece Cee ieee ee eee ea eee foldout inside back cover
(peateraliview) Of AnOmalocyStilesiCOTMULUS se psca<jcters fe aie cictes Pas, «Verve sia iexa aye sfolebe cto ise ees a Seen eit foldout inside back cover
Suslnternaliplastronisurtace of Aromalocystiles;COMMUlUss =. \cis\sisislaie sais 2 cies eis « satel eielala akevayere eiaisrereienstecistekeeiericke foldout inside back cover
9: | Carapace Of -KierocystisiinSertus BON. TMSPs 2.7.2) s sos sce ain 5 2 aim cis |e © 1S Fee Ia See SSS HS EISS. HE ISIC nNOS + 6 POTTS Tee 22

110: *Garapacesandsplastron: Ofc E MOplOUrAiDODEL ~ 55) s5cco,2eeo =: 1a) sas see 37a soncrs wie'a (aba etarare cl unaus este pene cookers eaaca hie ane there ee 24

11. Articulating spines and articulating surface on M4/M’5 of Enoploura popei ..... 2... 6.0.6 ce eee ee eee eee 24

1}2Internaltfeatures:OfE roplourd: Opel, te... asisre.s eyes Sat sieve ove sue 0,5 0:5 60 S182 -asb (afar wie Wala saisiOLe wl aioe SS Tio ole eee SIOe ee Ee eee 25

Se) Detailtofiuthe:styloid\ofEnoplouraspopel sa acnnss = eerie is oe = ere ep ei ais) aos hee aren dee ohare ete ea eee eens BREE eee ee 27

4: Transverse cross-sections of the distal styloid blade of Enoploura popel .......<.... occ. 000 0002.00 o/0je wneieie oo 0 0.2.02 eee eee 28

IS! Carapace Of EOplOUura DUNCIALA® 6 ocs:xia-< ie sisioe aro su(e i558 S161 BIN 4 (6 Sibi Bs) Bre Tw Sinoy el 8 WS a vo raANEIRTS) oil oe foxsitshaleve elt je OVAL ise NOLO 31

UGaPlastromiof:E nOplOura punctate occ spo scczsaneraste sv synior aso, e pa) sy S354 Guaa eke) ianateta alarm, 31s oR SPAN eu epeEE able eats eaeha aT Ee 31

17. Partial reconstructions of internal surface of the carapace of Enoploura popéi ........ 2.2... c cece ccc cc cece een eens 33

US2\ Carapace: ofKopficyStisvAarkficldr N:BEMs, To: SP sale) <1o,</<-cseteiacereaiasaraiesd ela nfs ela ara \aie WIS stoeeimelo ae ape is eye eee Trea Se ee 35

9S Garapacejand! plastroniof AnatiferOcystis|PADiNAta) reresss «ws siciapes a osisiejsisjale steve sisee © aiere(oe aie =| store. sisieie feelers eee eee eee 39

20:3Plastronsof-Anatiferocystis\papillatas <. crocsiocsie.aystzse aie Gs cto 4 ais iets, vie Shits, a12. vale Sais OS EersI# 8 TO OSES RRL CE EEE Ee 40

LIST OF TABLES

Table Page

2 Explanations'of plate abbreviations|usediain' this paper) oy. smic.c sss iraeicle oi ice os sie teats otek foldout inside back cover

REVIEW OF SELECTED NORTH AMERICAN
MITRATE STYLOPHORANS (HOMALOZOA: ECHINODERMATA)

by
RONALD L. PARSLEY

Department of Geology
Tulane University
New Orleans, Louisiana 70118

ABSTRACT

This paper reviews most of the North American mitrate stylophoran genera and species that are assigned to two suborders,
the Anomalocystitida and the Peltocystida. The Anomalocystitida is herein divided into two long-ranging families, the Anom-
alocystitidae and the Placocystitidae. The Anomalocystitidae contains mostly North American species (Middle Ordovician—Early
Devonian) that are characterized by the proximal carapace margin having three plates, and only very rarely a placocystitid plate.
North American species include, within the new subfamily Anomalocystitinae, Wil/manocystis denticulatus Kolata and Jollie,
1982 (Middle Ordovician), Kierocystis insertus, n. gen. and sp. (Middle Ordovician), Anomalocystites cornutus Hall, 1859 [= A.
disparilis Hall, 1859], (Early Devonian); and within the subfamily Enoplourinae, Enoploura punctata Bassler, 1932 (Middle
Ordovician), Enoploura balanoides (Meek, 1872) [= E. crustacea (Haeckel, 1896) = E. wetherbyi Caster, 1952 = E. meeki Caster,
1952] and Enoploura popei Caster, 1952 (Late Ordovician). Species assignable to the Placocystitidae are found in North America,
Europe, and Australia. They are characterized by the proximal carapace having only two plates in contact with the aulacophore,
the MA plate consistently excluded, and the placocystitid plate rarely missing. North American forms discussed herein include,
within the subfamily Placocystitinae, Ate/eocystites huxleyi Billings, 1858 (Middle Ordovician), and Kopficystis kirkfieldi, n. gen.
and sp. (Middle Ordovician). It seems likely that the Southern Hemisphere subfamily Allanicytidiinae branched off from the
placocystitids some time in the Early Silurian and persisted until the Early Devonian. The North American representative of
the Peltocystida, the kirkocystid Anatiferocystis spinosa Ubaghs, 1979 [= Kirkocystis papillata (Bassler, 1932)] from the Middle
Ordovician of Oklahoma, is represented in Bohemia as well. This genus has a greatly reduced number of plates. The disposition
and growth of these plates are discussed herein.

The feeding strategies of mitrates are seen to be different than previously reported. In mitrates, the aulacophore faced into the
prevailing current, convex upward, and food was conveyed to the food groove under the dorsally-fused cover plates through the
arcuate to chevron-shaped openings between the overlapping set of cover plate pairs. The width of these openings was controlled
by the degree of distal aulacophore convexity. Previous representations of feeding figured the distal aulacophore concavely curved
over the proximal aulacophore and proximal theca. I see this as a closing mechanism, used under extreme conditions, that
resulted in jamming together of the overlapping fused cover plate pairs (the configuration commonly preserved in the fossil
record).

Onigin of the Anomalocystitida derives from Reticulocarpos-like cornutans. It is suggested that the distal marginal plate elements
of the theca in the cornute ancestral stock have been lost. Only M1—M4 thecal marginals are homologous between cornutes and
anomalocystitids.

INTRODUCTION

In the years since Caster’s seminal 1952 paper on
Enoploura Wetherby, 1879, which included the first
major review of many of the known North American
mitrate echinoderms, a great deal of new material and
knowledge of stylophorans has come to light. Many
new ideas have been presented concerning their clas-
sification and how they functioned as animals. Ubaghs
(1961 and subsequent publications) pointed out that
the tail-like appendage in stylophorans was a feeding
organ (aulacophore) and thereby reversed the orien-
tation commonly assumed for these creatures. Haude
(1980) modified Ubaghs’ aulacophore model in the
mitrates by proposing that they pipetted nutrients off
the sea floor through an opening in the distal end of
the aulacophore. Abundant examples of closed ter-
minal ends of mitrate aulacophores show that view to

be untenable. This work supports Ubaghs, with some
minor modifications in interpretation of the deploy-
ment of the aulacophore as a feeding organ.

Ubaghs’ opinion on the location of the mouth and
function of the aulacophore is by no means universally
accepted. Philip (1979, pp. 458-460), for example, sug-
gests that the distal opening in all homalozoans is the
site of both mouth and anus, the gut being U-shaped.
Philip reflects the traditional view held by authors prior
to Ubaghs’ work of 1961. More recent adherents to
this model are Kolata and Jollie (1982) and Kolata
(1984). In the latter work, Kolata postulates a shallow
burrowing habit with the distal (abaulacophoral) end
protruding from the substrate along with the articu-
lating distal spines.

Jefferies (1967, 1968a, and subsequent papers) has
proposed that the Stylophora are not echinoderms at
all, but are more properly placed in the chordates under

6 BULLETIN 336

the subphylum Calcichordata Jefferies, 1967. His views
have met with a storm of rebuttal (Jefferies, 1968b,
Ubaghs, 1975, Philip, 1979, Chauvel, 1981, Kolata
and Jollie, 1982, and Jollie, 1982), in which I concur.
Various aspects of stylophoran evolution are also
under debate. I support Ubaghs’ view that homalo-
zoans are polyphyletic and that their primary sym-
metry is nearly, but not truly bilateral. Caster (1968,
1983), on the other hand, strongly suggests that hom-
alozoans are monophyletic and that the ancestral echi-
nodermal radical was triradiate. Using cladistic meth-
ods, Paul and Smith (1984, pp. 461—462) would derive
the carpoid homalozoans from an Early Cambrian
asymmetric solute radical, and by virtue of their meth-
odology argue that the group is monophyletic.

OVERVIEW OF RECUMBENT ECHINODERMS

In this brief introductory look at the homalozoans
and other recumbent echinoderm groups (i.e., pleu-
rocystitids and rhipidocystians), I suggest that the over-
all morphologic similarity displayed by all of these
groups is due to convergence brought on by adaptation
to similar bottom-living habits. Generally all of these
forms have a high degree of thecal streamlining and
bilaterality (but rarely are they truly bilateral). In most,
a rim of substantial marginal plates surrounds flexible
polyplated central surfaces on both inferior and su-
perior surfaces. In some, one or both somatic surfaces
are also regularized into rigid surfaces. Ventral or in-
ferior surfaces are commonly concave, with the mar-
ginals serving as runners or skids to minimize adhesion
to the bottom. In many forms, appendages such as
columns, steles, and aulacophores were adapted to serve
locomotor functions. These recumbent forms not only
exploited a similar food source, but in doing so exer-
cised some degree of vagility in moving from place to
place using their elongated appendage, or, minimally,
were sufficiently vagile to favorably orient themselves
on the sea floor relative to nutrient-bearing currents.

Most of these forms are found in low-energy envi-
ronments where lime muds to limy shales were de-
posited, although higher energy environments (i.e., in
calcarenites and fine-grained sandstones) are associ-
ated with a number of genera. These low-energy en-
vironments suggest that stylophorans fed at or very
near the water—sediment interface, where nutrients ac-
cumulated. Perhaps these organisms are best described
as concentrate suspension feeders, utilizing the rich
organic concentrates and associated microbiota pres-
ent in slow current regimes in the first few mm above
the water—sediment interface. None of the mentioned
recumbent echinoderms appears to have been a true
suspension feeder in the “upper” water column. The
total range of these recumbent feeders is from Middle
Cambrian to Early Pennsylvanian. The greatest diver-

sity, if all recumbent echinoderms are considered to-
gether, is in the Middle and Late Ordovician. It should
be noted that articulate brachiopods and nestling clams,
which derived their food from the same part of the
water column, also enjoyed considerable diversity in
the Middle and Late Ordovician.

I can only speculate why homalozoans and recum-
bent blastozoans did not persist higher in the geologic
column. They were probably supplanted by more ef-
ficient forms or eliminated by durophagous predators
(Signor and Brett, 1984), because there is little reason
to believe that the physical aspects of this ecologic
niche have significantly changed since the Early Pa-
leozoic.

REVIEW OF THE SUBPHYLUM HOMALOZOA

The subphylum Homalozoa Whitehouse, 1941, is
an artificial grouping of four morphologically similar
classes that ecologically exploited the nutrient-rich lay-
er at and near the water—sediment interface, and per-
haps the smaller elements of the closely-adjacent mei-
ofauna. Homalozoans range from the Middle Cambrian
to Early Pennsylvanian and manifest their greatest
abundance and diversity in Middle and Late Ordo-
vician, at which time recumbent bottom-living echi-
noderms of the subphylum Blastozoa are also at the
acme of their abundance and diversity.

The class Homostelea Gill and Caster, 1960, is made
up of a single order, the Cincta Jaekel, 1918, and is
limited to the Middle Cambrian of Europe and North
Africa.

The class Ctenocystoidea Robison and Sprinkle,
1969, is also limited to the Middle Cambrian of North
America, Europe (France and Bohemia), and North
Africa, and is the only “carpoid’”’ group without an
appendage.

The class Homoiostelea Gill and Caster, 1960, rang-
es from the Late Cambrian to the Middle Devonian
of Europe and North America. Because of their eco-
logical convergence, members of this class show re-
markable similarities to some stylophoran genera and
to several of the pleurocystitid rhombiferans, such as
Amecystis Ulrich and Kirk, 1921, and Pleurocystites
Billings, 1854 (see, e.g., Dehm, 1934).

The class Stylophora Gill and Caster, 1960, ranges
from the Middle Cambrian to Early Pennsylvanian and
is geographically the most widely-distributed class, be-
ing found in North America, Europe, South America,
Africa, and Australia. To date, no stylophorans have
been reported from the several continental plates that
make up Asia. Stylophorans have a long feeding organ,
the aulacophore, that in some is strongly homeo-
morphic with the stem or stele of homoiosteles. This
homeomorphy, as discussed below, is probably in part
due to the convergence in locomotor function.

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 7

THE CLASS HOMOSTELEA

Homosteleans, which are restricted to the Middle
Cambrian, are characterized by a thecal margin of large
plates, and slightly convex superior and inferior sur-
faces of smaller plates, presumably forming flexible
surfaces. Antipodal to the single appendage, two jux-
taposed openings, the mouth and anus, argue for the
presence of a U-shaped gut in the living animal. Der-
stler (written commun., 1986) and Paul (written com-
mun., 1986) have reported that a small structure like
an anal pyramid is located near the operculum (over
the ?anal opening) in the field of small flexible platelets
on the superior surface. The function and frequency
of occurrence of this structure is unknown. The short
and probably relatively inflexible stele appears to be
dimerous; the large dimeres are interpreted to be ex-
tensions of the thecal marginal plates. Dorsal and ven-
tral intercalates give the structure a superficially te-
tramerous appearance. The intercalates along the length
of the stele may be homologous with the thecal cen-
tralia. Nowhere among recumbent echinoderms is the
derivation of the major appendage (stele, column, or
aulacophore) from the theca as clear as it is in the
Homostelea. The smooth transition from marginal
plates to stele plates is reminiscent of some early eocri-
noids (see Sprinkle, 1973, pp. 36-40), where the col-
umn appears to be differentiated from existing aboral
thecal plates (see Ubaghs, 1968b, p. S576).

The primitive deployment of transverse epithecal
food grooves on the marginal plates, coupled with the
closely positioned mouth and anal openings, suggest
an ancestral stemmed form that derived its food from
the water column and secondarily became recumbent
on the sea bottom, presumably to exploit a richer food
source. Only the homosteleans and homoiosteleans of-
fer strong evidence for once having been attached “‘pel-
matozoans”’ (Ubaghs and Robison, 1985), and as such,
free-standing, suspension-feeding echinoderms.

The juxtaposition of the mouth and anus, which is
good evidence for a U-shaped gut, and the theca-stele
transition are both characteristics of homosteleans that
clearly make them different from all other homalo-
zoans. On philosophical grounds, it might be more
sensible to place the homosteleans in the Blastozoa
Sprinkle, 1973, where transverse ambulacra, (?)anal or
(?)gonopore pyramids, transitional plating between
theca and column, and essentially undifferentiated col-
umns are more common. However, the lack of ex-
othecal or true epithecal brachioles makes such a reas-
signment on sound morphological grounds impossible.

THE CLASS CTENOCYSTOIDEA

The Ctenocystoidea are unusual homalozoans that
are devoid of any sort of appendage, and their marginal
plates do not extend from top to bottom surfaces. Rath-

er, they are laterally sutured, in roughly opposed top
and bottom series. Their top and bottom polyplated
somatic surfaces are similar, however, to those of other
polyplated homalozoans and recumbent blastozoans.
The anterior ctenoid structures are unique, but later-
ally, grooves impressed into the marginals are remi-
niscent of the lateral food grooves of the Homostelea.

Ubaghs (1975, p. 84) has suggested that this class is
closer to the Stylophora than any other class. However,
on morphological grounds, there is little evidence for
this. One might argue with equal persuasion for phy-
logenetic closeness to the Homalozoa (both groups have
similar lateral food grooves on the marginals) or the
rhipidiocystian eocrinoids (both groups have a similar
thecal shape, and ctenoid organs may be homologous
with brachiole bases); all this, of course, is speculation.
Horns on the posterior left side of the marginals may
suggest a remnant insert area of a lost appendage.
Sprinkle and Robison (1978) have detailed what is
known of this group. At this time, ctenocystoids cannot
be allied with any other class and their inclusion in the
Homalozoa is one of convenience.

Although this class was known until recently only
from the Middle Cambrian of North America (Utah
and Idaho, Glossopleura Zone), it is now known from
North Africa (Sprinkle, oral commun., 1985), the Jince
Formation of Bohemia (Fatka and Kordule, 1985),
Montagne Noire, France (Ubaghs, 1987), and the
Coonigan Formation of New South Wales, Australia
(Jell, Barrett, and Banks, 1985).

THE CLASS HOMOIOSTELEA

Homoiosteleans commonly bear strong resemblance
to the stylophorans because of the similarity of their
main appendage and, in some, thecal morphology. In
the homoiosteleans the proxistele is fundamentally and
commonly an imbricating tetramerous structure that
grades into a trimerous or dimerous medial section,
the mesistele, which in turn grades into a long dististele
that commonly is dimerous, but by intercalation may
be superficially trimerous. The close similarity of the
homoiostelean stele to the stylophoran aulacophore is
probably due to the similarity in locomotor function
(i.e., in the wriggling or swimming of the animal, with
the appendage posterior). In the homoiosteleans, the
stele is a stem: in stylophorans, the aulacophore, a
stem-like structure, is also the feeding organ. Juvenile
specimens of Castericystis vali Ubaghs and Robison,
1985, from the Middle Cambrian of Utah, further sug-
gest this appendage is a stem: they were attached to
the substrate at the distal end of the stele. More mature
specimens broke loose and then used the stele as a
locomotor organ. Despite the numerous superficial
similarities between homoiosteleans and stylophorans,
nothing suggests that the appendages or the thecal plates

8 BULLETIN 336

can be homologized!. The single, anterior, undiffer-
entiated, biserial feeding appendage in homoiosteleans
is a true arm, a skeletal extension of the body cavity
(Caster, 1968, p. S586); all other recumbent bottom-
feeding echinoderms with biserial feeding appendages
(e.g., pleurocystitids, rhipidocystians) have brachioles,
and with rare exceptions have two or more. Some Or-
dovician homoiosteleans from North America (e.g.,
Iowacystis Thomas and Ladd, 1926, and Belemnocys-
tites Miller and Gurley, 1894) have well-developed
marginal and infracentral plates and bear superficial
similarities to some mitrate stylophorans and to some
pleurocystitid rhombiferans.

THE CLAsSs STYLOPHORA

The Stylophora, as previously indicated, have an
appendage somewhat similar to the stele of the hom-
oiosteleans. Proximally it is tetramerous, abruptly giv-
ing way to a basically uniserial cone-shaped section
(stylocone) or a section that has flanges (styloids), which
in turn grades into an elongate uniserial “‘tail-like”
section. Both the styloid/stylocone and distal section
have covering plates. On the styloid/stylocone they are
small: on the distal section, they are large, commonly
firmly articulated with the basal ossicle, and almost
always tightly sutured to each other. In the Stylophora,
the appendage is the aulacophore and serves as the
feeding structure. The aulacophore (Gr. = groove bear-
er) is named for the food groove on the superior surface
of the ossicles (Ubaghs, 1968a, p. S532). The structure
and organization of the aulacophore, while somewhat
similar to that of the homoiostelean stele, is unique.
No class other than the Stylophora has an exothecal
subvective structure with proximodistally tripartite or-
ganization, attachment devices for temporary anchor-
ing (spines and flanges on styloids), and a functional
mouth located in the structure itself (between the prox-
imal aulacophore and the styloid/stylocone), and that
serves as a locomotor organ. Not all authors agree with
the functional aspects of this interpretation. Indeed,
the subvective nature of the aulacophore is questioned
on several fronts (Jefferies, 1967, 1968b; Philip, 1979;
Kolata and Jollie, 1982). These authors opt to place
the mouth at the opposite end of the theca.

Stylophora have “‘suffered”’ more than any other re-
cumbent echinoderm group from interpretation and
reinterpretation. This work is no exception, and a re-
vised morphological analysis of the aulacophore, and
an overall discussion of the modus operandi of the
mitrates is presented herein.

' For a dissenting opinion concerning the appendage, see Caster,
1968, p. S582.

Taxonomic Position

Homalozoans are among the most enigmatic of fos-
sils. No homalozoan group has been more variously
interpreted than the Stylophora. Because of different
interpretations concerning the aulacophore, position
of mouth and anus, and identity of superior and in-
ferior surfaces of the theca, many different sets of mor-
phological terms, orientations, and indeed zoological
affinities are rooted in the literature. In this paper, I
will discuss why I believe the orientation and general
functional morphology presented by Ubaghs (1961) are
correct. I am especially concerned with the rationale
for viewing the multisegmented appendage or aula-
cophore as subvective and anterior. However, I will
modify Ubaghs’ views on modes of feeding and lo-
comotion.

Other basic organizational interpretations have fall-
en into two categories: (1) The mouth and anus are
located at the distal opening of the theca, perhaps with
an introvert tucked inside and extruded for feeding
(Kolata and Jollie, 1982). An extension of this reason-
ing is that the animal is presumed to have a U-shaped
gut (Philip, 1979). (2) These animals are not echino-
derms, and should be placed in a subphylum of the
Chordata, the Calcichordata (Jefferies: 1967; 1968a;
and subsequent papers). In Jefferies’ scheme the Mi-
trates are commonly inverted, relative to “‘echino-
derm”’ orientation; instead of the aulacophore extend-
ing into the substrate as a digging and/or locomotor
organ, the flanges on the styloid, in his orientation, are
directed away from the substrate, and locomotion is
effected by sapping movements of the aulacophore (Jef-
feries, 1984). Numerous aspects of mitrate morphology
indicate, in my opinion, that the convex thecal surface
is uppermost and the aulacophore did not “grub” in
the substrate. Cornutes in Jefferies’ scheme are main-
tained in their usual top—bottom orientation: the oral
end of the animal is opposite (distal) to the appendage
(aulacophore). I believe that Jefferies’ position has been
adequately refuted in the literature by others (Ubaghs,
1975: Philip, 1979; Jollie, 1982; Kolata and Jollie,
1982), and in this paper I will treat stylophorans as
echinoderms.

Stylophora must be regarded as Echinodermata be-
cause of many of the traits of that phylum which they
variously manifest. All have unicrystalline calcium
carbonate plates that are infused with stromal cavities.
Carlson and Fisher (1981) have shown that in the mi-
trate Enoploura Wetherby, 1879, stereom to which
muscles and ligaments were attached is discernible in
the articulations of the aulacophore. Also, other fea-
tures together characteristic of echinoderms in the Sty-
lophora are anal pyramids, sutural pores, articulated

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 9

spines, and differentiated marginal and somatic plates.
Syzygial sutures have been observed in the styloids of
Enoploura, and pillar structures, similar to those in
sand dollars, have been observed on both sides of the
distal thecal opening in Afeleocystites Billings, 1858
(Kolata and Jollie, 1982) and in Anomalocystites Hall,
1858 (herein). Evidence for a water-vascular system in
the Stylophora is good. The best evidence is seen in
the aulacophore of Phyllocystis Thoral, 1935 in the
form of parallel grooves and transverse grooves con-
necting to the main food groove (Ubaghs, 1968a, p.
S529; Ubaghs, 1969, pp. 32-36). Similar structures,
less well defined, are seen in the aulacophore of Mi-
trocystites Barrande, 1887 (Ubaghs, 1968a, p. $531).
In both cases shallow pits at the ends of the transverse
grooves would have been sites of the ampullae for the
podia. Structures such as cothurnopores and ctenoid
organs have been variously interpreted but are prob-
ably respiratory. Jn toto, the combination of charac-
teristic echinoderm features seems sufficient to place
stylophorans in the Echinodermata.

Morphology, Functional Morphology,
and Life Habits

Orientation

The two major morphological parts of a stylophoran
are the theca and the aulacophore (Text-fig. 1). The
mitrate theca commonly has single or paired movable
spines at the opposite end of the theca from the au-
lacophore. The proximal ends of the theca and of the
aulacophore are at their junction: it should be noted
that the aulacophore is often inset several segments
into the theca. The terms ora/ and aboral are not syn-
onymous with proximal and distal, respectively, with
regard to the theca, because the oral opening appears
to be at the distal end of the proximal aulacophore.
Thus, either on the theca or on the aulacophore, distal
should be interpreted as away from where the theca
and aulacophore join. In this sense it is similar to the
proximal plane of “‘pelmatozoans” except here it is
used with a feeding appendage and not with a columnar
appendage. The terms proximal and distal will be used

Text-figure 1.—Reconstruction of Enoploura popei in its distressed orientation, with the distal aulacophore reflexed over the proximal
aulacophore and proximal end of the theca. This figure is based on UCM 25993 (PI. 6, figs. 1-3). In this orientation, the cover plates are
tightly closed. In many cases, this is the curved condition in which the aulacophore is found in the fossil record. The moveable distal paired
spines help buttress the theca and, along with styloid blades, aid in stabilizing the organism in the current, which in this figure moves from
lower right to upper left.

10 BULLETIN 336

herein to avoid confusion. The terms superior and in-
ferior or dorsal and ventral are used relative to per-
ceived habitus orientation, and in the strict morpho-
logical sense may not be correct.

The theca in most mitrates is convexo-concave or
convexoplane: the convex face is invariably superior
or dorsal. This orientation is suggested not only by
hydrodynamic considerations but because the ventro-
lateral margins are commonly produced into runners
or skids, apparently to minimize adhesion to the sub-
strate. Spines or flanges on the styloid and distal au-
lacophore for purchase in the substrate always face
downward relative to the convex thecal face: thus the
food groove faces away from the substrate. The single
or paired distal articulating spines helped buttress the
animal and served as sensory-tactile structures, anal-
ogous to a cat’s whisker, when the animal was at rest.

In living and feeding mitrates, the distal aulacophore
was bowed upward from the styloid; the distalmost
end rested against or was close to the substrate (Parsley
and Caster, 1982; Parsley, 1988). Many mitrate spec-
imens have been found with the aulacophore preserved
with a concave-upward curvature. This probably was
an extreme distress position that was preserved in death.
Cornutes, on the other hand, deployed the entire au-
lacophore parallel to the sea floor (Parsley, 1988).

Morphology
Theca

Almost all mitrates and some cornutes have an es-
sentially bilateral streamlined theca (sagittate outlines
are seen in some cornutans [e.g., Phyllocystis Thoral,
1935, Amygdalotheca Ubaghs, 1969]), but true bilat-
eral plating is rare. Some Silurian (Tasmanicytidium
Caster, 1983, and Notocarpos Philip, 1981) and De-
vonian (Allanicytidium Caster and Gill in Ubaghs,
1968a) genera appear bilaterally symmetrical in their
plating, but these are rare and restricted to the present-
day Southern Hemisphere (the mid-Paleozoic Malvi-
nokaffric Realm). The proximal end of theca is the
thickest and most convexly-rounded part of the dorsal
theca. Distally the theca thins and the superior surface
is flattened. Commonly the greatest width is just distal
to the proximal end of the theca. Distal tapering is
slight in most mitrates, except for sagittate forms, and
most genera have a blunted distal end. The distal ap-
erture includes the anal opening. In some (e.g., Eno-
ploura Wetherby, 1879, and Ateleocystites Billings,
1858), a distinct lip extends distally from the ventral
distal marginals and is commonly cantilevered slightly
above the concave ventral surface. In Anomalocystites
Hall, 1858, the lip is folded back on itself to raise the
threshold of the distal opening higher above the sub-
strate.

Some cornutes also have irregularly-shaped thecae
(which are commonly outlined by well-defined mar-
ginals) that are commonly likened to a medieval boot
or shoe. In these cornutes, the marginals have prom-
inent ventral knobs that contact the sea bottom. Gen-
era such as Cothurnocystis Bather, 1913, and Galliae-
cystis Ubaghs, 1969, which manifest these features, are
considered to have been essentially sessile (Parsley,
1988).

Aulacophore

Ubaghs (1961, 1968a) clearly demonstrated (to the
satisfaction of most workers) that the distal end of the
appendage in the Mitrata and Cornuta was the primary
feeding organ. He renamed the entire appendage the
aulacophore and re-oriented it by rotating it 180° (con-
trary to the orientation of previous authors), to place
it at the anterior end of the animal, in normal, bila-
terian mouth-anterior fashion. Several features of the
distal aulacophore indicate that it was posterior during
locomotion, but its feeding orientation is not as ob-
vious and is open to some speculation. In all stylo-
phorans, the aulacophore is basically the same struc-
ture and remains conservatively unchanged in each of
the two major orders, the Cornuta and the Mitrata. In
each order, a tetramerous proximal aulacophore dis-
tally (after six or more segments) abruptly gives way
to a stylocone (in cornutes and in a few mitrates) or
styloid (in most mitrates), which is made up of fused
uniserial ossicles. The styloid/stylocone is derived from
the distal aulacophore by fusion of at least three of its
most proximal uniserial ossicles. In the mitrate Eno-
ploura Wetherby, 1879, the two styloid flanges are lat-
eral extentions of ossicles on either side of the syzy-
gially-fused sutures (Text-figs. 10 and 13), and represent
an extreme in styloid development. Each styloid/styl-
ocone ossicle has a pair of small cover plates. The
styloid/stylocone grades distally into the distal aula-
cophore, which is made up of large, articulating, uni-
serial ossicles. Each ossicle is covered by large paired,
distally-overlapping covering plates (Text-fig. 2). The
distal aulacophore may be one-and-one-half to two
times the length of the theca.

Generally, feeding appendages are considered to be
uniserial (in stylophorans, crinoids, and paracrinoids)
or biserial (in some advanced crinoids and almost all
blastozoans), their covering plates being incidental be-
cause of their small size. In the uniserial mitrates, where
the cover plates are much larger and do not seem to
be erectile, they are instead tightly sutured along the
dorsal sagittal axis. Here the distal aulacophore is at
least functionally a triserial appendage. The cover plates
roof over a well-defined food groove that terminates
at the junction of the styloid and the proximal aula-

NoOrTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 11

cophore. The feeding mechanics of the mitrate aula-
cophore, through the intersegmental arcuate openings
made by the overlapping cover plates, is discussed be-
low. Earlier suggestions by Parsley (1980) that the cov-
er plates may have rotated outwards to expose the food
groove do not, in light of newer data on the nature of
cover plate suturing, seem to be viable as a feeding
mechanism. In cornutes, the cover plates open to ex-
pose the food groove. This is especially manifest in
irregular or asymmetrical forms, which appear to have
been sessile (Parsley, 1988).

The stylophoran aulacophore and the homoiostelean
stele are very similar. In both, the proximal part of the
appendage is tetramerous. In some of the dendrocys-
titid homiosteleans, the tetrameres secondarily break
up into multiplated rings and smaller annulations of
platelets (see Caster, 1968, pp. S594— $598). Distally,
the stele grades into a dimerous distal stele, commonly
through an intermediate area, the mesistele, that necks
down and twists. In some genera, large intercalates
make this area trimerous. The function of the mesistele
seems to have been one of stiffening, to impart more
leverage to the flexible dististele. This leverage pre-
sumably made locomotion more efficient.

The mesistele—stylocone/styloid and distal stele—dis-
tal aulacophore, while they are commonly superficially
similar, are basically different structures, and their
shared homeomorphy is apparently due to functional
convergence.

The adthecal part of the aulacophore structure, the
proximal aulacophore, has a very large internal lumen
which is continuous with the interior of the theca. The
proximal aulacophore extends through, not out from

the surface of the marginals as, for example, in most
blastozoans, and might best be viewed as a proboscis
with the mouth opening at the distal end. The only
other bilateral echinoderms with a feeding proboscis
that extends through an opening in a rigid theca are
the psolid holothurians. Only very rarely [e.g., in Kier-
ocystis, n. gen., and possibly in Allanicytidium Caster
and Gill in Ubaghs, 1968a] do superior proximalmost
tetrameres of the proximal aulacophore abut against
the external surfaces of the marginals, rather than being
significantly inset and resting against the apophyses.

The aulacophore apophyses in most stylophorans
invariably considerably restrict the openness between
theca and aulacophore. The apophyses serve for mus-
cle attachment, and against them the proximalmost
platelets of the proximal aulacophore abutted.

The mouth is located at the juncture of the stylocone/
styloid and the alimentary canal, which in turn is lo-
cated at the distal end of the proximal aulacophore.
This is suggested by the deeply-incised food groove on
the superior face of the styloid, which is closely jux-
taposed to the distal elements of the proximal aula-
cophore. Ingested food was passed under the plating
of the proximal aulacophore and into the theca. None
of the many specimens, belonging to diverse genera,
that have been examined show evidence that the food
groove passed over the proximal aulacophore and en-
tered the theca at the juncture with proximal aulacop-
hore.

Extensions of the ambulacra away from the mouth
onto exothecal extensions are quite common in the
Echinodermata and have occurred independently a
number of times. In some, these ambulacral extensions

Text-figure 2.—Reconstruction of Enoploura popei in its normal feeding orientation. This figure is based on UCM 25993 (PI. 6, figs. 1-3).
While the styloid and proximalmost distal aulacophore segments bite into the sediment for stability, with additional buttressing from the
distal spines, the distal aulacophore curves convexly over the substrate to feed. The openings thus formed between the fused cover plates are
chevron-shaped to narrowly hemi-elliptical, but are large enough to admit food particles to the food groove. Current direction is from right

to left.

12 BULLETIN 336

include evaginations of the coelomic tissues as, for
example, in crinoids. These are primarily uniserial
structures and bear pinnules. Others do not seem to
have coelomic evaginations in the exothecal extensions
and are biserial (brachioles) and are only rarely “pin-
nulate’’. Brachioles are manifest in blastozoans such
as rhombiferans, diploporids, and eocrinoids. Rarely,
brachioles may be triserial, as seen in the diploporid
Eumorphocystis Branson and Peck, 1940 (see Parsley,
1982).

The unidirectional extension of the ambulacrum
away from the mouth in stylophorans is very primitive
and apparently was never part of a more complex ar-
rangement. Indeed this would be nearly impossible,
since the mouth opening is on the aulacophore itself,
located between the proximal aulacophore and the sty-
loid/stylocone. Recent authors have championed ideas
of early primary symmetry in echinoderms; Caster
(1968, 1983), Paul and Smith (1984), and Smith (1988)
for a triradiate system; Parsley and Mintz (1975), and
Parsley (1982) for a transverse—bilateral system. Nei-
ther can apply to the Stylophora.

The exothecal extension of coelomic tissue in the
Stylophora would have extended into the proximal
aulacophore and the proximal end of the stylocone/
styloid. The distal aulacophore is a true uniserial struc-
ture like the arms of crinoids and paracrinoids, but
without evaginations of the coelomic linings extending
through the ossicles. Coelomic tissue, including the
water-vascular system, may have been developed on
the superior surface of the ossicles, where it would have
been closely associated with the food groove.

With the overall similarity of the distal aulacophore
to other echinoderm feeding appendages, it is hard to
imagine that it is anything else. The maintenance in
mitrates of a large grooved area on the upper surface
of the ventral ossicles, especially in conjunction with
the large space formed by roofing over the food groove
with very tightly sutured or possibly even fused cover
plates suggests primary and continued use of the struc-
ture in a subvective role.

I suggest that if the aulacophore were not a feeding
structure, selective pressures to enhance locomotion
would have reduced the hollowed-out aspect of the
structure and in other ways would have modified it for
greater strength and flexibility. Rather, it seems that a
balance of feeding and locomotor selective pressures
was responsible for the conservative morphology of
the aulacophore exhibited in both cornutes and mi-
trates.

Actual function of the distal aulacophore differs
somewhat between the Mitrata and the Cornuta. In the
cornutes, Ubaghs (1961, 1968a) has conclusively shown
that the cover plates opened (apparently in succession
from the proximal to the distal end, because of distal

overlap) to expose the food groove. Feeding was ap-
parently carried out by the distal aulacophore in the
nutrient-rich layer just above the water—sediment in-
terface. The cornute aulacophore, especially as seen in
the genus Phyllocystis Thoral, 1935, may have had a
water-vascular system. Lateral depressions on either
side of the food groove are connected to it by short
transverse grooves, one set per segment. The geometry
of this interconnected groove system is strongly sug-
gestive of a water-vascular system. Ubaghs (1968a)
suggested that the lateral depressions were for ampul-
lae, with podia extending from them for feeding pur-
poses. Similar structures suggestive of a water-vascular
system have been observed in other cornutes (e.g., Cer-
atocystis Jaekel, 1901), but have been observed only
in a single mitrate (Mitrocystites Barrande, 1887).
Distal aulacophores in mitrates are commonly seg-
mentally intact, strongly suggesting that the dorsal (sag-
ittal) cover plate suture was very tight, as are the sutures
between the cover plates and the ventral ossicle. In
conjunction, the distal aulacophore abuts the styloid
at a narrow angle to the perpendicular: this angled
articulation kept the aulacophore away from the sea
floor. Parsley (1980), Parsley and Caster (1982), Sprin-
kle (1976), Ubaghs (1979), and Carlson and Fisher
(1981) have interpreted this, and the concave upper
surface of the distal aulacophores that are commonly
preserved, to mean that the distal aulacophore was held
straight up or curved above the proximal aulacophore
and possibly over the proximal theca (“‘scorpion” con-
figuration). Thus the ossicles would face into the cur-
rent like the arms of rheophobic crinoids, and feeding
would occur in back eddies in the lee of the ossicles.
Kolata and Jollie (1982) have pointed out that, indeed,
the cover plates could not open and in the concave-
upward configuration, the cover plates are too tightly

Text-figure 3.—An oblique view of the proximal aulacophore,
styloid, and a portion of the distal aulacophore of Enoploura popei.
By convexly arching the aulacophore ossicles, the fused plate pairs
are distally prized open to admit food-laden currents [arrows]. Food
moved to the mouth, at the junction of the proximal aulacophore
and styloid, via ciliary action along the longitudinal food groove.

NorTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 13

pinched together to expose the food groove. This seems
be the “‘distressed’”’ pre-mortality position, and that
most commonly preserved (Text-fig. 1). This config-
uration is especially prevalent in Cincinnatian age
specimens of Enoploura, and is common in other Or-
dovician mitrates as well. Devonian genera such as
Rhenocystis Dehm, 1932 (pl. 1, figs. 4-9), Paranacystis
Caster, 1954a (text-fig. 2; pl. 1, figs. 2, 3, 7, 8; pl. 3,
fig. 1) and Anomalocystites Hall, 1858 (pl. 1, figs. 6,
7), are also good examples. Suspension feeding by hold-
ing the aulacophore aloft in the water column, also
would have rendered the animal hydrodynamically un-
stable. Preliminary results from testing 1:1 scale mod-
els of Enoploura-like mitrates in a flume clearly suggest
that the aulacophore-aloft ““scorpion” configuration was
stable only when the animal was facing directly into
the current. Cross currents, even under 10 cm/sec,
would topple the model: by direct inference this con-
figuration seems unlikely in living animals.

Examination of more than a dozen distal aulacop-
hores also shows that the ventral ossicles are com-
monly strongly denticulate: the proximal ventral os-
sicles of this series are similar to those of the styloid.
These denticulations are curved toward the theca and
could have provided additional purchase on the sea
bottom. The recurved or undercut flanges allow the
aulacophore to bow convexly upward from the styloid
to the tip. In doing so, the cover plates were prized
open, forcing the distal ends of the cover plate pairs
upward, thereby exposing the food groove by creating
narrow, arcuate to chevron-shaped openings. By al-
tering the degree of curvature, the openings could be
enlarged or diminished. The distal edges of the cover
plates served as small scoops directing nutrient-rich
waters toward the food groove (Text-figs. 2 and 3).
Presumably only small particulate matter would be
able to reach the food groove, minimizing clogging
problems in this roofed-over system. An analogous
scheme of narrow openings allowing size-sorted par-
ticles to enter the food conduit area is used by articulate
brachiopods.

Feeding close to the water—sediment interface placed
the mitrates in the same niche as other recumbent
homalozoans and blastozoans. The length of the food
groove on the aulacophore, in proportion to thecal size,
indicates that the relative size of the feeding area is
small. Since these animals are presumed to have been
active and would have had moderately high energy-
input requirements, the relatively small feeding area
of the aulacophore clearly suggests not only that it was
efficient, but also that it exploited a nutrient-rich en-
vironment. The most available high-nutrient food
source would be in the concentrated organic layer just
above the water—sediment interface. Feeding, with the
aulacophore held in a shallow convex arc would have

been far more stable than holding it aloft, directed into
the prevailing current. Cornutes also would have fed
in the nutrient-rich bottom layer. The erectile cover
plates in cornutes suggest that a wider range of size of
food particles could be utilized. This seemingly more
primitive scheme had the advantage of allowing less
selective but more efficient feeding in asymmetrical,
essentially sessile cornutes, but they may have lacked
the sorting ability to allow continuous feeding in turbid
waters. Cornutes may have had to close their cover
plates under very turbid conditions, while mitrates
would have been able to continue feeding by virtue of
the sieving ability of their non-erectile plates.

In mitrates, the very narrow slit in the styloid near
the end of the food groove suggests food was probably
finely particulate. Fine particulate food was probably
more readily digestible and more easily transported
down the food groove. If Ubaghs (1961) and Parsley
(1988) are correct about the presence of a well-devel-
oped water-vascular system in the cornute aulacop-
hore, the sorting and rejection of food particles could
have been carried out by action of the podia.

The aulacophore was fully extended during loco-
motion. The distal overlap of cover plates and their
tight sutures on the top and sides of the aulacophore
also made it a stronger and more efficient locomotor
appendage.

Among most recumbent-—vagile Early Paleozoic
echinoderms, the theca commonly has one or both
thecal faces flexibly polyplated, presumably for respi-
ratory pumping. Parsley (1982; 1988) has suggested
that in some forms pumping may also have aided in
feeding. In mitrates that have rigid thecae (e.g., Eno-
ploura and Ateleocystites), the supracentralia have what
appear to be muscle scars on their inner faces. These
scars are presumed to be part of a muscular system
that compressed either or both the gut and surrounding
body cavity, to propel water through it (Text-figs. 12,
17). In mitrates, gut pumping may have induced a
current inside the roofed-over aulacophore. The pres-
sure differential along the food groove would have cre-
ated incurrents through the narrow arcuate openings
made by the cover plates, and ingestion through the
narrow openings may have been a more dynamic pro-
cess than would one simply powered by ciliary cur-
rents.

Parsley (1981, p. K2) has also shown that in life
Enoploura may have taken refuge under brachiopod
shells (e.g., Rafinesquina Hall and Clarke, 1892). Sev-
eral specimens from the Middle Ordovician Lexington
Limestone of Kentucky suggest that the theca was un-
der the shell and the aulacophore extended out from
beneath it.

The common occurrence of mitrates in fine-grained
sandstones and limy shales would indicate that they

14 BULLETIN 336

were not efficient swimmers and/or feeders in higher
energy environments. In lower energy environments,
more nutrients would accumulate at the water—sedi-
ment interface, and aulacophore feeding would be more
efficient. Most mitrates and solutes, for that matter,
were little more than wrigglers, and were not capable
of swift or sustained movement. Lateral overlapping
in the inferior, or both superior and inferior, sutures
of the proximal aulacophore or stele would permit lim-
ited lateral movements in this probably well-muscled
area. These lateral movements, translated distally,
would have set up propulsive, undulating waves.

Movement and orientation of mitrates can be sum-
marized as follows: (1) The aulacophore was both a
feeding and a locomotor organ. (2) While the animal
was being propelled by the aulacophore, the distal end
of the theca acted as the prow of the animal. The ar-
ticulated spines may have aided in maneuvering. (3)
The styloid blades were primarily for anchoring the
animal, and were not the primary locomotor struc-
tures. (4) The animal displayed a rheotaxial orienta-
tion.

Lastly, it must be stressed that the orientations used
herein are functional and perhaps only partly mor-
phological. As is stated elsewhere, it is unwise to at-
tempt to postulate orientation on the basis of inferred
larval type [cf. Caster’s (1952, p. 10, fn. 4) discussion
of the basic orientation suggested by Bather (1900),
which is primarily based on the embryology of the
comatulid crinoid Antedon Freminville, 1811]. Mor-
phologically, aulacophore-bearing carpoids can be ori-
ented aulacophore = anterior; aboral theca = posterior.
Whether or not the carapace and plastron should be
morphologically ‘“‘dorsal—ventral” or “‘right—left’’ is
largely speculative.

ORIGINS AND PHYLOGENY OF THE MITRATA

Most of the evidence that mitrates are derived from
cornutes is based on homologous elements and on
morphological trends. The two groups share a homol-
ogous aulacophore and several homologous thecal el-
ements; primarily, the marginal plates. Mitrates appear
simpler than their cornute ancestors, with reduced
numbers of marginals, fewer centralia, and reduced
anal structures. Mitrates show a higher degree of bi-
laterality (including loss of the cornute zygal or strut),
which seems to be related to adaptation for greater
mobility.

Since the publication of the Treatise on Invertebrate
Paleontology, Part S (Ubaghs, 1968a), several new cor-
nute and mitrate genera have been described, and it is
now possible to construct a reasonable scenario show-
ing in generalized terms the evolution of some of the
early mitrates (anomalocystitids and mitrocystitids)
from symmetrical cornutes (Parsley, 1988). The evi-

dence is still too sketchy for meaningful cladistic anal-
ysis: a viewpoint that runs counter to that of Jefferies
(1981, 1986) and of Jefferies and Lewis (1978). Deri-
vation of an early mitrate from a symmetrical cornute
stock involved a number of evolutionary steps. Major
changes included relative shortening of the theca, by
means of a reduction in the number of distal marginal
plates. While there are commonly no more than four
paired marginals in a mitrate (possibly up to six pairs
in mitrocystitids), there may be up to seven pairs in a
symmetrical cornute such as Amygdalotheca Ubaghs,
1969. While relative thecal shortening occurs in all
mitrates, the mode and manifestation varies with the
suborder. In mitrocystitids, marginal plate loss is min-
imal to none; the distalmost marginals symmetrically
move toward and impinge on the anal apparatus. An-
omalocystitids commonly have four marginals, the anal
apparatus having retreated proximally between the
nearly parallel distal marginals. Marginals in lagyno-
cystids are not only reduced in number but are asym-
metrically and azygously arranged. The theca in this
suborder is also diagonally compressed distally, which
is partly responsible for the loss of marginals and cen-
tralia. Peltocystids manifest the greatest reduction in
marginals and centralia. While not so asymmetrical as
lagynocystids, peltocystids also show evidence of distal
diagonal compression, and homology of the distal mar-
ginals in this suborder is quite problematical.

A development concomitant with distal loss of mar-
ginals is that instead of the distalmost single (in pel-
tocystids and lagnocystids) or paired (in anomalocys-
titids) marginals being lost, a flexible articulation was
developed between them (or it) and the adjacent mar-
ginal(s), and the distalmost marginal(s) functioned as
distal spines. This morphologic deviation was first sug-
gested by Kirk (1911, p. 25).

In the Mitrocystitidae, there are no articulating
spines, and marginals M5/M’'5 and M6/M’'6 may be
homologous with M5/M'5 and M6/M’6 of Amygdal-
otheca Ubaghs, 1969. Distal marginal M7 may be an
intercalate from the infracentralia. If this marginal plate
homology is correct, it probably precludes the mitro-
cystitids from being ancestral to the anomalocystitids,
and suggests that they are an independent lineage
(Ubaghs, 1968a, p. S545).

Regularization of the centralia seems to have pro-
ceeded more rapidly on the inferior than on the su-
perior surface in all mitrates. On the inferior surface
in anomalocystitids, for example, a large central plate
is partly surrounded by smaller infracentrals (including
the anomalocystitid plate). The smaller plates com-
monly are concentrated along the distal margin. In
anomalocystitids, the distal marginal plates (M5/M’'5
and M6 in the commonly-used numbering system,
equivalent to m5/m’5 and m6, herein) do not resemble

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 15

the proximal and lateral marginals (M1—M4) that com-
monly lie between the superior and inferior surfaces.
Distal marginals m5/m’5 and m6 are taken to be in-
fracentralia that have regularized and filled the open
gap between the distal ends of M4/M’4. Originally
these “‘infracentralia’’ were probably adjacent to the
anal apparatus and retreated with the anus as the an-
cestral stock paedomorphically shortened (see Text-
fig. 4).

The only known exception to this pattern among
anomalocystitids is in the Early Caradocian genus Bar-
randeocarpus Ubaghs, 1979, where the inferior distal
marginals extend distally from M4/M'4 in a manner
suggestive of a continuous marginal series. These plates
are labelled M5/M’'5 and M6 by Ubaghs (1979, pp.
112-119). There are no articulating spines and I as-
sume that they have been lost, or even more likely,
were never present. In Barrandeocarpus, as in more
advanced anomalocystitids, there are three infracen-
tralia including the anomalocystitid plate. I conclude
that the inferior distal marginals m5/m’5 and m6 in
Barrandeocarpus have migrated distally to form a
rounded distal margin and are not homologous with
M5/M'5 and M6 of cornutes or mitrocystitids.

While mitrates do retain anal-valve structures, these
in most cases are considerably reduced in size and
complexity from the condition of their cornute ances-
tors. The degree to which the anal-valve apparatus was
retained appears to be directly related to the degree of
thecal shortening and simplification. Mitrates with the
least anal-valve reduction are the mitrocystitids, which
show the least thecal shortening or reduction of cen-
tralia. This can be contrasted with genera of the pel-
tocystitid family Kirkocystidae (Balanocystites Bar-
rande, 1887, and Anatiferocystis Chauvel, 1941), which
demonstrate the maximum thecal shortening, and re-
duction in plate number, and are without a demon-
strable anal opening. Anomalocystitids show a re-
duced, possibly vestigial anal-valve apparatus in
Ordovician and Silurian genera, and this structure is
lost in Devonian representatives. The only exception
to the correlation of thecal shortening and plate loss
with anal-valve simplification, is in Lagynocystis Jae-
kel, 1918, in which the size of the anal apparatus,
relative to thecal size is considerably greater. Why the-
cal shortening and simplification of the theca should
be related to anal size and complexity is conjectural.
If shortening and simplification was a neotenic process
then possible reduction of the anal-valve elements may
have been involved: but whatever the reason, the phe-
nomenon is clearly present.

The mitrate aulacophore has the same elements as
does that of the cornute. Mitrate aulacophores are lat-
erally compressed, and the ventral ossicles of the distal
aulacophore are pointed and undercut (especially at

the proximal end) for arching and for purchase on the
bottom. The ancestral cornute stylocone was modified
to form the styloid — a stylocone with spines or flanges
for embedment in the substrate.

To construct a scenario for evolving mitrates from
symmetrical cornutes requires morphological types, as
stated above, that represent a logical or plausible tran-
sition. Ubaghs (1968a) noted that this was difficult
because some of the then earliest known mitrates (Pel-
tocystis Thoral, 1935, and Chinianocarpos Ubaghs,
1961, both from the Early Ordovician) were morpho-
logically more advanced than a number of Middle Or-
dovician genera. Since that time several new genera
have been described that allow a plausible scenario to
be constructed. The most generalized of the symmet-
rical cornutes is the Early Ordovician genus Amyg-
dalotheca Ubaghs, 1969. It has seven marginals, a short
zygal, and an open distal end (the marginals do not
join), which is presumably occupied by the anal-valve
apparatus. In order for the theca to gain greater rigidity,
either the marginals must form a distal closure, forcing
the anal apparatus to the distalmost end of the superior
surface (a condition seen in the symmetrical cornute
Phyllocystis Thoral, 1935), or inferior distal centralia
must fuse in order to form a cross-bracing series at the
distal margin.

It seems most likely, in light of observed morpho-
logical patterns, that all mitrates evolved from a dis-
tally ““open”’ symmetrical cornute, even though some
early mitrates show distal marginals converging toward
the anal-valve. An excellent case in point is the mi-
trocystitids. These show only slight thecal shortening
(six marginals), but distally they impinge on the well-
developed anal-valve. The anal-valve is partially
floored by the distalmost thecal plate (M7 of Ubaghs,
1968a) which is a marginal infracentral (a condition
well illustrated by Aspidocarpus Ubaghs, 1979). Mi-
trocystitids do not have distal movable spines. The
marginals, which are equivalent to spines in anomal-
ocystitids and other suborders, are conservatively
maintained as marginals. Mitrocystitids appear to be
an early mitrate lineage that probably did not give rise
to any other mitrate group.

A genus critical to the understanding of the evolution
from symmetrical cornutes to mitrates is Reticulocar-
pos Jefferies and Prokop, 1972, from the Early Ordo-
vician of Bohemia. In many ways, it is intermediate
between symmetrical cornutes and anomalocystitids.
Reticulocarpos is probably best considered the most
advanced cornute. In Reticulocarpos, the zygal is dis-
tally shortened and does not attach to a lateral mar-
ginal. Respiratory pore structures are greatly reduced
and are not arranged in the usual arcuate pattern. Cen-
tralia on both faces are enlarged in size and reduced
in number. As in Amygdalotheca Ubaghs, 1969, the

16 BULLETIN 336

distal end is not continuous with marginals (as in Phyl-
locystis Thoral, 1935), but is open and occupied by
centralia. The distal end of the theca is buttressed by
a bar extending transversely from M4 to M’4 across
the carapace and slightly diagonally at the distal ends
of these two marginals. Distal to the transverse bar are
short marginals M5/M’5, which with superior and in-
ferior distal centralia, form the distal margin.

Continued thecal shortening by distal omission of
centralia (by paedomorphosis) would result in M5/M’5
protruding from the end of the theca in descendant
forms. As descendant shortening continued, protuber-
ent M5/M’5 began to articulate flexibly with M4/M’4
and ultimately they evolved into the articulating spines
(Kirk, 1911, p. 25). The distal ends of M4/M'4 became
the terminal stadium in thecal shortening, uniformly
marking the distal end of the theca in all anomalocys-
titids.

The aulacophore of Reticulocarpos is also mitrate-
like. The styloid and the proximal ossicles of the distal
aulacophore are produced into adthecally-curved
spines. The cover plates on styloid and distal aulacop-
hore are nonerectile.

The other two suborders, the Lagynocystida and Pel-
tocystida, are markedly shortened in the theca and are
laterally and diagonally compressed, thereby elimi-
nating in azygous fashion many marginalia and cen-
tralia. Those elements that are still present are difficult
to homologize. Peltocystids appeared in the Early Or-
dovician, and lagynocystids in the Middle Ordovician.
Derivation and differentiation of the mitrates can rea-
sonably be placed in the Late Cambrian or earliest
Ordovician, and because of the lack of morphological
intermediates, the process was apparently quite rapid.

ACKNOWLEDGEMENTS

Many people have assisted in the preparation of this
work, and their aid is gratefully acknowledged.

Important exchanges of ideas among investigators
of Stylophora, some quite different from mine, were
of great value in writing this work. G. Ubaghs, Uni-
versity of Liége (ret.), Liége, Belgium; K. E. Caster,
University of Cincinnati (ret.), Cincinnati, OH,
U.S. A.; R. P. S. Jefferies, British Museum (Natural
History), London, England, U. K.; D. R. Kolata, Illi-
nois State Geological Survey, Urbana, IL, U. S. A.; and
K. Derstler, University of New Orleans, New Orleans,
LA, U.S. A. were outstanding in this.

This work could not have been undertaken if access
to key collections had not been so generously provided.
K. E. Caster and D. L. Meyer, of the University of
Cincinnati; E. Landing, of the New York State Mu-
seum, Albany, NY, U.S. A.; P. M. Kier and F. Collier,
U. S. National Museum of Natural History, Washing-

Text-figure 4.— Phylogenetic chart of the Anomalocystitida.

(1) The ancestral stock of the anomalocystitids is probably in the
Reticulocarpos-like cornutans. Reticulocarpos Jefferies and Prokop,
1972 has four pairs of marginals proximal to a transverse “bar”
across the carapace that connects M4 and M’4. The distal ends of
M4/M’4 seem to be the distal limit of the theca in most anomalo-
cystitids. Ancestral marginals M5/M’S5 have evolved into the mov-
able distal spines.

(2) Barrandeocarpus Ubaghs, 1979 is clearly a placocystitid, but
this early form has completly lost, or never had, articulating spines.
Distal plastron marginals m5, m6, m’5 (M5, M6, M’5 of Ubaghs,
1979, p. 114) extend distally to lengthen the theca.

(3) The basic dichotomy of the families Placocystitidae and An-
omalocystitidae apparently occurred by the end of the Early Ordo-
vician, and they retained their characteristic features well into the
Early Devonian. In the Anomalocystitidae, all three of the carapace
adaulacophorals make up the proximal margin of the carapace. With
rare exceptions, taxa within this family lack a placocystitid plate. In
taxa within the Placocystitidae, the median aulacophoral (MA) plate
is invariably excluded from the proximal margin, in some specimens
very narrowly. A placocystitid plate is almost always present.

(4) Placocystitid traits are well established in Middle Ordovician
genera, but the placocystitid plate is missing in Kopficystis, n. gen.

(5) The Allanicytidiinae have a nearly bilaterally symmetrical the-
ca, and while lacking a placocystitid plate, most seem to exclude the
MA plate from the proximal margin. The assignment of this sub-
family to the Placocystitidae is admittedly speculative. All of the
representatives of the Allanicytidiinae are restricted to the Malvi-
nokaffric Realm (Australia, Tasmania, and New Zealand). Two pos-
sible species, Placocystis africanus Reed, 1925 and Placocystella ca-
pensis Rennie, 1936 are omitted because of the incomplete knowledge
of their plate arrangements. Both are from the Early Devonian of
South Africa. [see Caster, 1954b]

(6) Allanicytidium Caster and Gill in Ubaghs, 1968a seems to have
its MA plate nearly in contact with the proximal margin, but ex-
cluded from the proximal aulacophore by apparent incorporation of
a pair of upper tetrameres. Details of this area are indistinct, as
indicated by photos of Caster’s latex casts and his drawings (see
Caster, 1983, p. 327).

(7) Victoriacystis Gill and Caster, 1960 is a placocystitid occurring
in the Late Silunan of Victoria, Australia. The presence of undoubted
placocystitids in the Malvinokaffric Realm may strengthen the ar-
gument for the postulated close relationship of Victoriacystis to the
Allanicytidiinae.

(8) The Anomalocystitidae and the subfamily Anomalocystitinae
are present in the Middle Ordovician. The family group remains as
a remarkably conservative taxon until extinction in the Early De-
vonian. In the Anomalocystitinae, the carapace has at least five
arcuate rows of supracentrals.

(9) The Enoplourinae, consisting of the single genus Enoploura
Wetherby, 1879, ranges from the Middle Ordovician to nearly the
end of the Ordovician. In this subfamily, the carapace has undergone
considerable reduction in the number of rows and in the number of
supracentrals. The MA plate dominates the proximal end of the
carapace.

(10) The Australocystinae is represented by the single South Af-
rican genus Australocystis Caster, 1954b. Its assignment to the An-
omalocystitidae is tentative because the carapace is unknown. The
plastron, however, suggests a close relationship with this family. As
with the Allanicytidiinae, this Malvinokaffric genus has an enhanced
bilateral thecal plate arrangement.

For explanations of plate abbreviations, see Table | (foldout inside
back cover).

EARLY
DEVONIAN

SILURIAN

ORDOVICIAN | ORDOVICIAN

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY

Anomalocystites

Australocystis
Rhenocystis

Australocystinae

Allanicytidium :
Victoriacystis

Allanicystidinae

Anomalocystitidae
Anomalocystitinae

S
=
as)
SS
&
c
D
5
S

Enoploura

Enoplourinae

Placocystitidae

Ateleocystites

Barrandeocarpus

~<S

<2 ew ee ee

1 :
Reticulocarpos - like
Anomalocystitid ancestral stock

18 BULLETIN 336

ton, DC, U.S. A., were unstinting in making the nec-
essary specimens available.

Informal communications, both written and oral,
have improved the accuracy of this work. Special thanks
go to: T. Broadhead, University of Tennessee, Knox-
ville, TN, U.S. A.; K. Derstler, University of New
Orleans, New Orleans, LA, U.S. A.; T. Guensburg,
Southern Illinois University, Edwardsville, IL, U. S. A.;
D. Kolata, Illinois Geological Survey, Urbana, IL,
U.S. A.; C. R. C. Paul, University of Liverpool, Liv-
erpool, England, U. K.; and J. Sprinkle, University of
Texas, Austin, TX, U.S.A.

Critical review of the manuscript by T. Broadhead,
University of Tennessee, Knoxville, TN, U. S. A.; D. R.
Kolata, and T. E. Guensburg, Southern Illinois Uni-
versity, Edwardsville, IL, U. S. A., is greatly appreci-
ated. Their efforts greatly improved the clarity of the
manuscript.

A. Arnold and E. R. Dalvé ably executed the line
drawings, reconstructions, and chart. The quality of
their work speaks for itself. Some of the cost of pub-
lication was borne by the Committee on Research of
the Graduate School, Tulane University, New Orleans,
LA, U.S.A.

Finally, the manuscript was typed in numerous ver-
sions by S. Sonnier. My thanks to her for suffering
through my scrawly handwriting.

SYSTEMATIC PALEONTOLOGY
INTRODUCTION

With various and conflicting terminologies used for
thecal plates and structures [e.g., Ubaghs, 1968a; Jef-
feries, 1967 and subsequent papers; Kolata and Guens-
burg, 1979; and Philip, 1979], it is easy to become
confused. I have modified the terminology used by
Ubaghs, which stresses the echinodermal affinities of
the mitrate stylophorans. While Iam in agreement with
Ubaghs’ (1968a) numbering of most of the marginalia
and centralia, I will introduce some new terminology
for the centralia, distal inferior (plastron) marginals,
and distal superior (carapace) marginals (Text-figs. 5—
My:

This study includes all of the North American Mi-
trata (Middle Ordovician to Early Devonian) with the
exception of Ate/eocystites Billings, 1858 (redescribed
by Kolata and Jollie, 1982), Diamphidiocystis Kolata
and Guensburg, 1979, and Willmanocystis Kolata and
Jollie, 1982. I will, however, comment on Ateleocys-
tites in the discussions of other forms. While some of
my terminology and interpretation of life modes differs
from that used by Kolata and Guensburg (1979) and
Kolata and Jollie (1982), Iam in complete agreement
with the systematics used therein.

Synonymies used herein tend to be comprehensive

and chronicle the taxonomic concept of the genus or
species. Listings in various editions of paleontological
or stratigraphical treatises are commonly omitted un-
less the listing has systematic importance.

ABBREVIATIONS OF REPOSITORY INSTITUTIONS

All specimens studied are housed in the following
specimen repositories.

AMNH: American Museum of Natural History, New
Works NYaWaS2Ac

GSC: Geological Survey of Canada, Ottawa, Ontario,
Canada.

MCZ: Museum of Comparative Zoology, Harvard
University, Cambridge, MA, U.S. A.

NYSM: New York State Museum, Albany, NY,
We SvA:

UCB: University of Calfornia, Museum of Paleontol-
ogy, Berkeley, CA, U.S. A.

UCM: University of Cincinnati, Cincinnati, OH,
We SsvAc

USNM: U. S. National Museum of Natural History,
Washington, DC, U.S. A.

SYSTEMATICS

Class STYLOPHORA Gill and Caster, 1960?
Order MITRATA Jaekel, 1918
Suborder ANOMALOCYSTITIDA Caster, 19523

Diagnosis.—Convexo-concave (or planar) mitrates
with rigid bilaterally symmetrical thecae and nearly
bilaterally symmetrical plating. Two adaulacophoral
marginals, three lateral marginals with paired articu-
lating spines extending from M4/M’4. Two or three
adaulacophorals on carapace. Aulacophore commonly
with well-developed styloid.

Range.— Middle Ordovician—Early Pennsylvanian.

Discussion. —Caster (in Gill and Caster, 1960, p. 43,
fn. 6; p. 44, fn. 10), calls attention to the fact that he
separated the Anomalocystida [sic] from the Placo-
cystida [sic] on the basis of Schuchert’s (1904, p. 206,
pl. 40, fig. 5) description of Anomalocystites cornutus
Hall, 1859, in which he described the arms as flexible
structures made up of “‘about 20 pieces in each col-
umn.” Schuchert was probably influenced by the fan-
tastic reconstruction of Placocystis crustacea Haeckel,
1896 (p. 40, figs. 1, 2) [= Enoploura balanoides (Meek,
1872)], in which Haeckel depicted the arms as being
flexible and bearing short pinnulations. Examination
of the type material of A. cornutus, subsequent to ex-
acting preparation by Caster, has led me to conclude
that the so-called segmented arm is a fortuitously

2 =Subphylum Calcichordata Jefferies, 1967, a subphylum of the
Chordata.
3 nom. correct. Ubaghs, 1968a (pro Anomalocystida Caster, 1952).

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 19

placed, detached distal end of an aulacophore. No ev-
idence of a flexible distal arm as conceived by Haeckel
or by Schuchert is present in this or any other mitrate.
Inasmuch as the Anomalocystitida are differentiated
from the Placocystitida only on the basis of the sup-
posed presence of flexible arms, it follows that the two
suborders are synonymous, as has already been sug-
gested by Caster (in Gill and Caster, 1960, p. 44, fn.
10). The subordinal name Anomalocystitida is re-
tained herein, as it is by Ubaghs (1968a).

As emended by Ubaghs (1968a), the Anomalocys-
titidae Bassler, 1938, includes all North American gen-
era currently assigned to the Anomalocystitida (see
Caster, 1952) and all genera formerly placed in the
Placocystitida by Caster (1952), and Gill and Caster
(1960). The latter group is herein recognized as a fam-
ily. The subfamily Australocystinae Caster, 1954b,
raised to family rank by Ubaghs (1968a, p. S561), in-
cludes nearly symmetrical forms from the Malvino-
kaffric Realm that lack anomalocystitid plates. It is
retained herein as a subfamily of the Anomalocysti-
tidae. The anomalocystitid family Allanicytidiidae
Caster and Gill (in Ubaghs, 1968a, pp. S561-S564),
revised by Caster (1983), was originally erected for the
nearly perfectly bilaterally symmetrical genus Allani-
cytidium Caster and Gill in Ubaghs, 1968a, from the
Early Devonian of Australia. Two recently described
genera, Notocarpos Philip, 1981 from the Silurian of
Victoria, Australia, and Tasmanicytidium Caster, 1983
from the Early Silurian of Tasmania have been added
to the Allanicytidiidae. This family has been reduced
herein to subfamily rank and included within the Pla-
cocystitidae. Taxa within the Allanicytidiinae have
considerably reduced numbers of thecal plates; the me-
dian adaulacophoral does not contact the proximal
margin; the anomalocystitid plate (Z plate of Philip in
Notocarpos) is either present or absent, and commonly
there is a well-developed laterally-extended flange on
the styloid.

Kolata and Guensburg (1979) erected a new sub-
order Diamphidiocystida and new family Diamphi-
diocystidae for the unusual mitrate Diamphidiocystis
Kolata and Guensburg, 1979, in which the theca is
turned into a lateral U shape in plan view, with a single
long articulating spine that superfically resembles a
cornute thecal spine.

Family ANOMALOCYSTITIDAE Bassler, 1938

Diagnosis.— Diagnosis of the family is the same as
that of the suborder.

Discussion.— As discussed above, the cornute genus
Reticulocarpos Jefferies and Prokop, 1972, shows many
features intermediate between symmetrical cornutes
and anomalocystitids. In Reticulocarpos, a transverse
bar made up of lateral extensions of M4/M’4 crosses

the superior face near the distal margin. The distalmost
marginal plates (M5/M'5) extend distally from the
joined M4/M'4 marginals. These distalmost marginal
plates are unequal in size and show no sign of movable
articulation, and appear to be solidly sutured. How-
ever, in my view, they are homologous to the articu-
lating spines in anomalocystitids. In this scheme, the
number and disposition of marginal plates in Reticu-
locarpos is consistent with that of the Anomalocysti-
tida.

Subfamily ANOMALOCYSTITINAE Bassler, 1938

Diagnosis.—Anomalocystitids with three adaula-
cophoral plates, two infracentrals (some may have
three) including the anomalocystitid plate. Placocys-
titid plate rarely present. Supracentrals arranged in two
or more rows between adaulacophorals and distal mar-
ginals.

Range.— Middle Ordovician to Early Devonian.

Discussion.— This subfamily retains what appears to
be a primitively large number of supracentrals, but at
the same time shows morphologic innovations in other
parts of the organism (discussed below). This subfam-
ily probably best exemplifies mosaic evolution within
the mitrates. Genera included in this subfamily are
Willmanocystis Kolata and Jollie, 1982, Kierocystis, n.
gen., and Anomalocystites Hall, 1858.

Genus ANOMALOCYSTITES Hall, 1858

Anomalocystites Hall, 1858, p. 279; Hall, 1859, vol. 3, pp. 122, 131;
Hall, 1861, pl. 7A, figs. 5—7, pl. 8B, figs. 1-4; Miller, 1889, p. 224
[pars]; Bather, 1900, p. 51; Jaekel, 1901, p. 668; Schuchert, 1904,
pp. 204-206; Kirk, 1911, pp. 22-26, pl. 3, figs. 9-11; Springer,
1913, pp. 150-151 [pars]; Caster, 1952, pp. 20-23; Caster in
Ubaghs, 1968a, pp. S556—S557, S559; Derstler and Price, 1975,
pp. 7-9; Derstler, 1979, p. 102.

Ateleocystites Billings. Woodward, 1871, pp. 71-73 [pars]; Wood-
ward, 1880, pp. 194-201 [pars].

Anomocystis Hall. Haeckel, 1896, p. 40.

Anomalocystis Hall. Bather, 1889, p. 266 [non Anomalocystis Hall.
Barrande, 1887, p. 89].

Basslerocystis Caster, 1952, pp. 22-26; Caster in Ubaghs, 1968a, pp.
$559, S560.

Type Species.—Anomalocystites cornutus Hall, 1859.

Diagnosis.4— Anomalocystitid with theca subovoid
in outline, carapace and lateral surfaces strongly con-
vex, plastron concave with marked lateral runners;
proximal and distal carapace margins transversely con-
cave, proximal plastron margin deeply concave. Prox-
imal carapace margin with three adaulacophoral plates,
distally followed by four rows of four, five, six, and
four plates, respectively; lateral margins comprised of
four paired marginals (M1—M4), three inferior distal
marginals (m5, m6, m’5), and two infracentrals, a large

* This diagnosis is based on that of Caster (in Ubaghs, 1968a, pp.
$556-S557).

20 BULLETIN 336

central plate, and an anomalocystitid plate. Two small
articulating spines on M4/M'4. Proximal aulacophore
wide, eight or nine segments that imbricate axially on
inferior surface; distal aulacophore long and narrow.

Occurrence.—Early Devonian of Maryland, New
York, and Pennsylvania.

Discussion.— The two previously-recognized species
A. cornutus and A. disparilis Hall, 1859, are preserved
quite differently; the former as moderately complete
to partial specimens of original carbonate material.
Evidence of some disarticulation by compression is
common. Specimens of the latter are only complete to
partial thecae that are replaced by silica. Most of the
surface detail has been lost and many of the interior
features are not distinct. Commonly, specimens rec-
ognized as A. disparilis are three to four times larger
than those recognized as A. cornutus.

On the basis of this restudy of the type and other
material, there is little reason to separate the two spe-
cies. Their plate patterns are nearly identical and their
minor differences in patterns of the supracentral plates
are easily attributable to growth (i.e., size differences).

While these putative species are found in different
formations, they are narrowly separated stratigraphi-
cally (probably less than 10 m) and given the strong
tendency for stasis in the family, I maintain that the
two are conspecific and the genus therefore is mono-
typic.

Although several features of this genus are unique
and highly distinctive, it appears to be the end member
ofa very conservative lineage. The overall proportions
of theca to aulacophore, general makeup of the theca
and aulacophore, and nature of most of the features
on the internal plastron are little changed from Middle
Ordovician genera (e.g., Enoploura Wetherby, 1879 or
Ateleocystites).

The distal end of the theca is certainly distinct from
that of its forerunners. The two lateral distal carapace
marginals fold over to restrict the lateral ends of the
distal (anal) opening. Likewise the lip on the inferior
distal marginals is folded inwards, moving the inferior
threshold higher off the substrate than in earlier genera
(e.g., Enoploura, [P1. 2, figs. 3, 7, 14, Pl. 3, figs. 5, 14]).
There is no evidence of the small wedge-shaped (?)ves-
tigial anal pyramid plates that are common in older
mitrate genera.

At the opposite end of the theca the aulacophore
apophyses are perhaps the largest relative to the size
of the proximal aulacophore. The deep embayment in
the theca for the aulacophore results in the apophyses
being deeply curved inferiorly and less so superiorly
where the wall curves towards the proximal superior
margin. The horns of the apophyses, however, appear
to be somewhat reduced (PI. 2, figs. 4, 9, 10, Pl. 3, figs.
13515):

Retention of the multiplated carapace, a primitive
trait when compared to Malvinokaffric Realm Silurian
and Devonian mitrates (e.g., Tasmanicytidium, Allan-
icytidium and Notocarpos), and Ordovician Enoplour-
inae (e.g., Enoploura) reinforces the overall conser-
vative nature of North American Anomalocystitidae.
Malvinokaffric Realm genera (see, e.g., Caster, 1954b,
1968, and 1983, and Philip, 1981) show a definitive
trend toward thecal simplification, especially on the
superior (carapace) surface. But in reference to the whole
animal, including spines and aulacophore, they too
must be considered only moderately different from their
North American relatives.

The presence of a placocystitid plate in this subfam-
ily is unusual, just as is its lack in the new genus Kop-
ficystis in the Placocystitinae. The placocystitid plate,
and the polyplated carapace in Anomalocystites which
superficially shows resemblance to placocystitids,
clearly show the close-knit nature of the Anomalocys-
titida. The advanced aspects of the distal aperture mor-
phology and the cover plate apparatus of the distal
aulacophore are examples of mosaic evolution.

Anomalocystites cornutus Hall, 1859
Plate 1, figures 1-14, Plate 2, figures 1-16,
Plate 3, figures 1-15; Text-figures 5-8
Anomalocystites cornutus Hall, 1859, p. 133; Hall, 1861, pl. 7A, figs.
5-7.
Anomalocystites disparilis Hall, 1859, p. 145; Hall, 1861, pl. 88, figs.
1-4.
Basslerocystis disparilis (Hall). Caster, 1952, pp. 22, 29, figs. 2e, 2f.

Diagnosis.— Because A. cornutus and A. disparilis are
considered conspecific herein, the genus becomes
monotypic. Hence, the diagnoses for genus and species
are the same.

Description.—The theca is subovoid in outline with
a slightly concave distal carapace margin, resulting in
the appearance of having slightly distally directed horns
or excrescences. The proximal plastron margin is more
deeply indented than the proximal carapace margin
(Pl. 2, figs. 12, 16). In profile, the theca is inflated; the
carapace gently convex, gradually tapering distally (PI.
2, figs. 2, 8, 11; Text-fig. 7). The plastron is nearly
planar, but the distal end bends upward into the short,
nearly vertical distal face; proximally the plastron mar-
gin curves gently into the nearly vertical straight prox-
imal margin. In transverse profile, the plastron is cen-
trally planate with the margins sharply curving
vertically to form the lateral, runnerlike, inferolateral
margins (PI. 2, figs. 3, 4, 7, 9, 10, 14).

Marginal plates make up the bulk of the inferior and
inferolateral surfaces (Pl. 1, figs. 3, 7; Text-fig. 6).
Adaulacophoral plates M1/M’1 are deeply excavated
for the reception of the proximal aulacophore, and
together they comprise the entire aulacophore embay-

NoOrTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 21

ment (PI. 1, figs. 3, 7, Pl. 2, fig. 5; Text-fig. 6). Relative
to those of most other mitrates, these plates are smaller
in size, due primarily to their excavate nature. Lateral
to M1/M'1 are M2/M’2, which on the plastron are
subarcuate in outline and unlike M1/M’1, which do
not extend onto the lateral faces, have the greatest
lateral expression of any of the marginals, in lateral
view commonly displaying a subpentagonal outline
(Text-figs. 6, 7). Marginals M3/M’3 are subrectangular
on the plastron and subpentagonal on the lateral faces.
They are nearly as long as the M2/M’2 laterals. On
the distal margins are M4/M'4. These are the smallest
of the marginals and are the most complex in form,
being developed on the distal margin as well as infer-
iorly and laterally. The distal end of each plate is pro-
duced obliquely towards the carapace, and extending
out from this surface are the spine bases. Each spine
base is composed of a rounded ridge that parallels the
distal wall of the carapace. They each truncate near the
distal inferolateral margin and each is surrounded by
a U-shaped muscle pit (Pl. 2, figs. 3, 7, Pl. 3, fig. 5).
The entire articulatory apparatus is located on M4/
M’4, and does not extend onto adjacent plates.

The inferior distal margin is made up of three sub-
rectangular to subpentagonal plates, m5, m6, and m’5,
which vary slightly in outline and relative length from
one specimen to another. Together they form a slightly
convex distal margin of the plastron.

The rest of the plastron is made up of two infracen-
trals that together occupy a roughly pentagonal area
on the distal half of the theca. The larger infracentral
is commonly pentagonal, although irregularly so; the
smaller anomalocystitid plate is located at the distal
left of the pentagonal area, abutting against M’4 and
m’5, and is commonly pentagonal in outline (PI. 1, figs.
3, 7; Text-fig. 6).

On the superior surface, the carapace is made up of
27 plates arranged in distally concave arcuate rows.
The three adaulacophoral plates are relatively small,
compared to earlier mitrates. The central plate is sub-
hexagonal, and the two lateral plates are irregularly
pentagonal (PI. 1, figs. 4, 14; Text-fig. 5).

Distal to the adaulacophorals is the first of four ar-
cuate rows of polygonal supracentrals. This first series
is commonly made up of four plates with the lateral
plates being the largest of all supracentrals. In the sag-
ittal axis of this series most specimens commonly are
weathered, and plate material is commonly missing.
At least one specimen (PI. 1, fig. 14) clearly shows a
placocystitid plate in this position, and since the pla-
cocystitid plate is commonly thin, it probably explains
why this plate is seldom seen (also see Jefferies, 1984,
pp. 310, 311, fig. 9).

The next arcuate row is made up of five slightly
smaller plates with the median and admedian plates

being the largest. The lateral plates, however, are only
slightly reduced. These plates are all irregularly hex-
agonal in outline. The next series is made up of six,
again slightly smaller, but nearly equisized plates. Most
are hexagonal, but tend to be somewhat irregular in
facet length. The final series consists of only four su-
pracentrals that are all of unequal size, and most are
hexagonal.

The distal carapace marginal plates commonly form
a shallow concave margin with the lateralmost plates
projecting distally to form low rounded horns (PI. 2,
figs. 1, 16; Text-fig. 5). These same outer lateral distal
carapace plates are geniculated, folding inward to re-
duce the size of the lateral opening and to define it as
an oval to squared—oval opening. The other three car-
apace marginals are small, nearly equal in size, and
pentagonal. This series extends distally farther than
the inferior lip and as such gives the distal opening the
aspect of being slightly recessed. This feature may be
unique among mitrates, but preservation among some
Devonian Malvinokaffric Realm mitrates precludes a
more definite statement.

With the material at hand, little can be determined
of the inner surfaces of the carapace plates. What can
be seen on the floor of the plastron suggests the overall
structure is very similar to that of Enoploura Weth-
erby, 1879, or Ateleocystites Billings, 1858. A promi-
nent diagonally-trending septum extends from the
proximal left area of the plastron to the distal right
corner, where it terminates at the outer margin of what
appears to be one of a pair of distal muscle pits (Pl. 1,
fig. 2, Pl. 3, figs. 4, 7, 9, 13; Text-fig. 8). The spur (the
pointed peak on the septum) stands quite high and is
located about one-third the length of the large infra-
central, measured from its proximal margin. A prom-
inent triangular field of convexly-curved thickened
stereom (typical of mitrates) extends from the aula-
cophore insert margin to the spur on the transverse
septum.

Prominent pits, probably for muscle attachment, are
located on m5 and m’5 and extend and open onto the
adjacent M4/M'4 marginals. These pits are especially
noticeable due to the thickening of the adjacent plate
material, which is actually the thickened area where
the plates bend slightly to form the up-stepped distal
margin (Text-fig. 8). Ifthe walls of the pits are projected
through the walls of M4/M'4, they coincide with the
muscle pits of the movable spines. The pits are, in part,
diagonally roofed over by pillars (apophyses of Kolata
and Jollie, 1982, pp. 643, 646, fig. 4-A) that extend
from m5/m’5 to the interior surfaces of the geniculated
lateral distal carapace plates. The suture is located near
the middle of the pillars and appears to be similar to
the irregular sutures in the pillars of sand dollars.

Aulacophore apophyses, horns and other elements

DD BULLETIN 336

of the aulacophore articulating apparatus are not well
preserved, but overall appear to differ little from those
structures in earlier mitrates. Perhaps the most signif-
icant difference between Anomalocystites and older an-
omalocystitid genera is the reduction in the number of
segments of the proximal aulacophore to only eight or
nine (Pl. 1, figs. 1-4). Judging from the aulacophore
insert area of the theca, the proximal aulacophore was
greatly inflated, but had a significant taper toward the
styloid (Pl. 1, figs. 7, 8). This tetramerous structure has
sutures in the axial plane and medially along the lateral
faces; all sutures abut smoothly, except on the inferior
surface where they alternately imbricate to give the
structure added flexibility (Pl. 1, fig. 3).

The styloid, like that ofall anomalocystitids, is made
up of three segments. So far as can be determined, the
styloid blades are not greatly extended as in Enoploura,
but are only slightly protuberant, as in Ateleocystites
(see Kolata and Jollie, 1982, p. 642). The nature of the

Text-figure 9.—Carapace of Kierocystis insertus. This figure is based
on USNM 42166 (PI. 4, figs. 10, 12). The paired plates between the
proximal aulacophore and the adorals are the proximal aulacophore
insert plates (PSI).

For explanations of plate abbreviations, see Table | (foldout inside
back cover).

styloid covering plates, the articulation between styloid
and distal aulacophore, and the angle of insertion of
the distal aulacophore into the styloid, are all un-
known.

Distal aulacophores are known from only a few spec-
imens (PI. 1, figs. 2, 5-9, 14). They are virtually the
same as those of earlier anomalocystitids. Several dif-
ferences, however, are worth noting. The inferior spines
are not as pronounced as in earlier forms and thereby
give the inferior faces of the ossicle a more externally-
rounded appearance. The covering plates are not as
extensively overlapped and the portion that overlaps
the adjacent distal plate appears to sit in a recess or
depression. Also, the covering plates are not as large
and produce a lower vault over the food groove than
in Ordovician and Silurian genera. The overall length
of the distal aulacophore appears to be about the same,
relative to thecal length, as that of Enoploura or Ate-
leocystites.

Occurrence.— Manlius Formation, Olney Member,
Saltsburg quarries, Dayville, New York (Localities A
and C); also, from an unknown locality ““Lower Held-
erberg, Litchfield, New York” (Locality B), [A. cor-
nutus]; Ridgely Formation, Cumberland, Maryland
(Locality D), and Ridgely, West Virginia; Shriver For-
mation, Curtin, Pennsylvania: Early Devonian (see
Derstler and Price, 1975, Derstler, 1979).

Types.—Syntypes: AMNH 2288°, Locality A. Hy-
potypes: NYSM 15010, 15011, Locality A. UCB D-
1875, Locality A. UCM 46044, Locality B. USNM
35078°, Locality C. USNM 35079, Locality C. USNM
33661A-33661G, Locality D. AMNH 2720, Locality
D.

Genus KIEROCYSTIS, new genus

Type species.— Kierocystis insertus, n. sp.

Remarks.—Because this genus is monotypic, it fol-
lows that its diagnosis, description, and occurrence will
be the same as for the species.

Kierocystis insertus, new species
Plate 4, figures 10-12; Text-figure 9

Diagnosis.—Anomalocystitids with small, triangu-
lar, proximal aulacophore insert (PSI) plates inserted
between right and left adaulacophorals and median
adaulacophoral plates.

Occurrence.—The single known specimen is from
the Curdsville Limestone Member of the Lexington
Limestone, Middle Ordovician (Trentonian), Curds-
ville, Mercer County, Kentucky (Locality G).

5 four specimens on a small slab. Because each specimen shows
different aspects of the morphology of A. cornutus, it seems advisable
to me not to designate a lectotype.

© four carapace specimens and several aulacophores on a small
slab.

NorTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 23

Type.— Holotype: USNM 42166, Locality G.

Description.—The most striking feature of this new
species, and its principal taxonomic trait, is the pres-
ence of two small, triangular plates inserted into the
proximal margin of the carapace (PI. 4, fig. 12; Text-
fig. 9). These proximal aulacophore insert plates (PSI)
were probably derived from the dorsal meres of the
proximal segment of the proximal aulacophore. The
maximum extension of these plates into the theca oc-
curs at the RA/MA and LA/MA sutures. The PSI
plates abut medially and exclude the MA plate from
the proximal margin. Curvature of the PSI plates lat-
erally exceeds that of RA and LA so that the lateral
ends hang free of the theca and articulate in an ap-
parently normal fashion with the superior meres of the
distally-adjacent, proximal aulacophore segment.

Aside from the incorporation of the PSI plates into
the theca and the slight modification in outline of plates
adjacent to them, especially the MA plate, the shapes
and positions of the rest of the plates seem to be fairly
typical of Anomalocystites Hall, 1858: the median
adaulacophoral plate (MA) is shaped more like that of
Enoploura Wetherby, 1879. There is no evidence of
the infolded distal lip seen in Anomalocystites. Because
of preservation, the number of supracentrals is not
possible to determine, but the number and arrange-
ment appear to be similar to those of Anomalocystites.

Discussion.—Some illustrations of Placocystites de
Koninck, 1869 (Woodward, 1871, p. 72; Haeckel, 1896,
pl. 2, fig. 12) show a pair of PSI-like plates inserted
into the dorsal stele embayment. Woodward (1880, p.
196) called them “‘narrow basals’’. Jefferies (1984) and
Jefferies and Lewis (1978) refer to this area as the pos-
terior surface (‘‘p. sf.’’). The excellent photo illustra-
tions of Placocystites forbesianus de Koninck, 1869, in
Jefferies and Lewis (1978) clearly indicate that PSI-
like plates may also be present, but whether they are
truly inserted plates, or whether it is an area that simply
displays a different ornament pattern, is unknown. The
presence of PSI-like plates in Placocystites demon-
strates possible morphologic convergence with Kiero-
cystis, n. gen. However, the general supracentral plate
pattern of the carapace clearly supports the assignment
of Kierocystis to the Anomalocystitinae.

As is a normal trait for this subfamily, the carapace
embayment for the proximal aulacophore is unusually
pronounced. The proximal end of the carapace also
lacks the usual transverse, ridgelike ornament common
to many species of anomalocystitids.

Aside from the incorporation into the theca of the
dorsal meres of the first proximal segment of the au-
lacophore, the remaining proximal aulacophore seg-
ments are in every way typical of other anomalocys-
titids. The sagittal area of the proximal aulacophore
of the holotype of Kierocystis insertus, n. sp., has been

so fractured that its internal, distally imbricate nature
is exposed. Externally, the meres are distally tightly
telescoped over one another. The styloid and distal
aulacophore are absent in this monotypic genus.

The conservative morphology seen in this subfamily
is striking. Anomalocystites (Early Devonian) and Kier-
ocystis (Middle Ordovician) are very similar overall.

Subfamily ENOPLOURINAE Caster, 1952

Diagnosis’.—Anomalocystitids that have three
adaulacophorals, three infracentrals, and lack a pla-
cocystitid plate. Commonly a single arcuate row of
supracentrals between adaulacophorals and distal car-
apace marginals.

Discussion.—This monotypic subfamily of the An-
omalocystitidae is based on Enoploura, which in thecal
characteristics is distinct from other genera in the fam-
ily because of the decreased rows and numbers of su-
pracentralia. Caster (1952) originally placed Ateleo-
cystites Billings, 1858, in this subfamily, but its clearcut
placocystitid traits place it outside the family group.
Kolata and Jollie (1982), in their emendation of the
subfamily, included Wil/manocystis Kolata and Jollie,
1982 within it. The current definition of the subfamily
suggests Willmanocystis should be placed in the sub-
family Anomalocystitinae, because of its more abun-
dant rows and greater number of supracentralia.

Genus ENOPLOURA Wetherby, 18798

Anomalocystites Hall. Meek, 1872, p. 423, 424 [pars]; Meek, 1873,
pp. 41-44, pl. 3bis, figs. 6a—c [pars]; Miller, 1889, p. 224 [pars];
Springer, 1913, pp. 150-151 [pars]; [non Anomalocystites Hall,
1858].

Enoploura Wetherby, 1879, pp. 162-166, pl. 7, figs. la—g [as a crus-
tacean]; Jaekel, 1901, p. 668; Bather, 1900, p. 51; Caster, 1952,
pp. 9-56, pl. 1-4; Ubaghs, 1968a, p. S560.

Ateleocystites Billings. Woodward, 1880, pp. 193-201 [pars]; Bassler,
1915, p. 88 [pars] [non Ateleocystites Billings, 1858].

Placocystis [sic] de Koninck. Haeckel, 1896, pp. 39, 40 [pars] [non
Placocystites de Koninck, 1869].

Type species.—Anomalocystites (Ateleocystites?) bal-
anoides Meek, 1872.

Diagnosis.—Theca subrectangular in outline, de-
pressed, gently convexo-concave. Superior surface
(carpace) with three large adaulacophorals; six smaller,
arcuately-arranged supracentrals; five distal carapace
marginals, the central three bearing distally-directed
fixed spines. Inferior face (plastron) with three infra-
centrals; three distal plastron marginals that together
form an up-stepped, distally-produced, arcuate lip. Ar-
ticulated spines about one-half length of theca long;
spines articulate on a well-defined mamelon in vertical
groove on distal ends of M4/M'4. Proximal aulacop-

7 modified from Kolata and Jollie, 1982, p. 649.
8 emended.

24 BULLETIN 336

hore with about 1 1 segments; styloid robust, some spe-
cies with extended rounded flanges; distal aulacophore
with from 20 to more than 40 segments, and proximal
segments markedly spinose.

Occurrence.—Middle Ordovician: Trentonian of
Tennessee and Kentucky. Late Ordovician: Edenian
of Tennessee; Cincinnatian of Ohio, Kentucky, and
Indiana.

Discussion. —Caster’s (1952) extensive paper on this
genus eliminates the need for detailed description of
the thecal plating (see Text-fig. 10). However, since
that work, new aspects of the morphology have become
known. I will concentrate on these new findings in the

Text-figure 10.—Carapace (A) and plastron (B) of Enoploura po-
pei. This figure is based on UCM 25993 (PI. 6, figs. 1, 3). On the
aulacophore: pa = proximal aulacophore; s = styloid.

For explanations of other plate abbreviations, see Table | (foldout
inside back cover).

Text-figure 11.—Articulating spines and articulating surface on
M4/M'5 of Enoploura popei. Scale bar in all figures is 1 mm long.
A, B, adsagittal (inside) side of a right spine. Note the articulating
socket which abuts the mamelon and the bounding arcuate muscle
ridge (Text-fig. 11F); C, D, absagittal views of a left spine, showing
muscle ridge and pit. Presumably these pits were for attachment of
muscles antagonistic to those on the opposite lateral surface. Muscles
attached on this side would pull the spine laterally outward: those
on the opposite surface would pull the spines laterally toward the
sagittal plane; E, top view of a spine. The thickened end is the top
side of the articulating area. Note how it would cover much of the
articulating area; F, articulating area on an M4 plate. The raised
boss is the mamelon. The spine would articulate between the ma-
melon and the left margin of the slightly-depressed articulating area
(as viewed). All photos were taken on an Amray 1700 S.E.M. at a
power setting of 30 kv.

For explanations of plate abbreviations, see Table | (foldout inside
back cover).

NortH AMERICAN MITRATE STYLOPHORANS: PARSLEY 25

following detailed discussion on the morphology of the
genus.

The new information comes from: (1) restudy of the
hitherto poorly-known Edenian forms; (2) new artic-
ulated Cincinnatian specimens; and (3) several thou-
sand disarticulated plates of Enoploura now in the Uni-
versity of Cincinnati Museum.

Theca.—Several important aspects of thecal mor-
phology have hitherto been unknown or have not been
discussed in the literature. The distal margin of many
mitrates, including Enoploura, is commonly not pre-
served, or is badly crushed and incomplete. With the
exception of several Edenian specimens [figured by
Bassler (1932, pl. 18, fig. 9), but the distal margins not
discussed], all specimens previously illustrated in the
literature fail to show the lower, distally-protuding,
rounded lip of the distal marginals m5, m6, m’5. The
lip extends from the upper portion of the transverse
ridge, so that when one of these plates is viewed lat-
erally, the lip is cantilevered above and out from the
plastron surface. On m6, the lip portion of the plate is
not as wide as the thecal portion at the transverse ridge,
thereby creating slight gaps between m6 and m5/m’S.
The lateral edges of the lip portion are slightly in-
dented, but are parallel to the sagittal plane.

The adjacent marginals m5 and m’5 are also divided
into thecal and lip portions, but not as distinctly, due
to the lateral reduction in height and width of the trans-
verse ridge. The shorter lip portion is angled toward
the m6 lip and apparently in some individuals not only
fills the indented portion of m6, but slightly underlies
it as well (Text-figs. 10, 12C).

The serrate transverse ridge developed on the inter-
nal faces of the inferior distal marginals (PI. 5, figs. 1,
3, 10) is matched by a similar serrate ridge developed
on the interior of at least three distal carapace marginal
plates: CM2, CM3, CM’2. These opposed ridges form
a transverse wall across the central portion of the distal
aperture, but apparently it is not complete laterally. It
is not known whether the serrations mesh, forming a
solid wall, or are opposed, and result in a perforated
structure. The latter case seems more likely when the
venations discussed below are considered.

The serrations on the transverse ridges appear to be
the remnants of the anal pyramid system. These ser-
rations appear to be platelets of the ancestral anal pyr-
amid, which are clearly seen in earlier mitrates (see
Mitrocystites Barrande, 1887, or Mitrocystella Jaekel,
1901, where the anal pyramid is frequently preserved
more or less intact). These platelets appear to be fused
to the adjacent thecal plate(s) and show little tendency
to be displaced. The degree to which these triangular
platelets function in Enoploura is unknown, but the
redeployment of these anal platelets along transverse

ridges, rather than in an anal pyramid configuration,
may be concomitant with the development of some
sort of cloacal arrangement situated proximal to them.

In disarticulated Cincinnatian specimens of Eno-
ploura, the lip is traversed by a fine, diverging “vein”
or groove system that originates at the serrate trans-
verse ridge (wall), each trunk or groove in line with a
depression or serration on the top of the ridge (Text-
fig. 12C). The venations are more prominent on the
m6 lip than on the adjacent m5 and m’5 marginals,
where the serrations on the transverse ridge are cor-
respondingly less developed. The serrate ridge on the
inner face of the CM3 plate may be homologous or

A

y GGss

Text-figure 12.—Internal features of Enoploura popei. A, B, in-
ternal markings on the median adaulacophoral (MA) plate. These
markings are, putatively, scars of muscles used in anal—cloacal pump-
ing, which served primarily for respiration; C, partial reconstruction
of lateral marginal plates and distal marginal plates (m5, m6, m’S5) .
Note the veinlike pattern on the lip extending out from, and included
on the transverse ridge marking the end of the distal body cavity.
The internal ridges on the distalmost marginals (M4—M'4) are of
uncertain function. It is suggested that they are muscle attachment
ridges to impart control on the opening and closing of the presumed
distal anal—cloacal structure.

For explanations of plate abbreviations, see Table | (foldout inside
back cover).

26 BULLETIN 336

analogous with the internal foldings of this plate in
Mitrocystites (see Pl. 5, figs. 1, 7, 8).

The distal ends of the marginals M4 and M’4 are
flared along their outside lateral and ventral edges into
rounded ridges and produce an expanded articulatory
area for the movable spines (Text-fig. 11F). These two
ridges meet at nearly a right angle in the inferolateral
portion of the M4/M’4 distal face, and both ridges are
in contact with a third diagonally-sloping ridge that
completes the enclosure of the triangular articulatory
area. The boss or mamelon, on which the spines ar-
ticulate, is part of this sloping ridge, and is located
halfway between the superior and inferior thecal faces.
The outside lateral wall or ridge of the articulatory area
seems to serve as a “bumper” to limit the range of
lateral movement of the spines. It probably functioned
as a seat of muscle attachment for the spines as well.
When articulated specimens are viewed dorsally, the
spines seem to articulate in a simple groove. The ma-
melon is slightly indented into the articulatory area
from the diagonal ridge. In outline, the mamelon is
elongate oval, with the long axis parallel to the adjacent
sloping ridge. In profile, its articulatory surface is even-
ly rounded.

Articulatory surfaces on the spines are considerably
more complex than those on the marginals. The spines
are differentiable into right and left on the basis of
these surfaces. Each process has a pair of lateral, in-
feroproximal hollows, the greater indentation being the
acetabulum, which articulates against the outer—lateral
surface of the mamelon. The outside and smaller in-
feroproximal embayment is probably a seat of attach-
ment for muscles that extended from the embayment
to the raised wall of the articulatory area (Text-figs.
11A-D). Between the two embayments at the extreme
proximal end of the spine is a suboval pit with its long
axis parallel to the extensiplane. It seems likely that it
was filled with cartilage or flesh, which ensured smooth
movement against the rounded embayment of the the-
cal articulatory groove. The detail of this articulatory
area has been observed only on recently-discovered
disarticulated specimens of Cincinnatian age.

Spines of Enoploura distal to the proximal articu-
latory area show a consistent morphology. In profile,
they are slightly bowed ventrally (Text-fig. 11C). Dis-
tally they are compressed and somewhat bladelike;
proximally, adjacent to the articulatory area, the shaft
is nearly terete (Text-fig. 11E). The upper surface of
the most proximal part of the shaft is broad and round-
ed, effectively concealing the complex articulatory ap-
paratus in the few known specimens that preserve the
spine in place. The length of a spine is roughly half
that of the theca to which it is attached (Pl. 5, fig. 9).
Ornament consists of very fine reticulate ridges that
are parallel or subparallel to the length of the spine.

Commonly the ornament is hidden by fine-grained
sediment or is altered to a fine, pustulose texture due
to impressions from the matrix.

The marginals M4 and M’4 are externally evenly
paired, but on the interior inferior surfaces they are
curiously unpaired (Text-fig. 12C). On the floor of the
right marginal M4 is an elevated, subquadrate area
that is bounded on the outside-lateral and distal sides
by sharply elevated ridges. The outside-lateral ridge is
higher, commonly with two cusps. In some specimens,
the cusps are slightly bent over the raised area. Com-
monly this area is bisected by a third ridge that extends
diagonally toward the distal margin, from the juncture
of the two previously-mentioned ridges to the M4—m5
suture. Marginal M’4 does not have an elevated area,
but the same general area is differentiated by a low
ridge (Text-fig. 12C). The function of these areas is not
completely understood, but they were at least partially
for muscle attachment.

Sagittally adjacent to the spine articulatory areas is
a sharply-incised, squared embayment that receives a
squared boss or peg located on the outside angled edge
of m5 and m’5 (Text-fig. 12C). This peg is located on
the edge of the thecal portion of the plate and does not
extend onto the lip. This angular articulation greatly
strengthens the distal edge of the theca, and the portion
of the peg protruding out of the squared embayment
may also serve for muscle attachment. Pegs on m5 and
m’5 seem to be equal in size.

Protruding from the distal carapace marginal plates
CM2, CM’2, and CM3 are distally-directed, short
spines that extend out over the lip (PI. 5, fig. 9; Text-
fig. 17B) on the inferior surface. These spines are fre-
quently broken off: in life they would have helped pro-
tect the distal, anal opening. On the proximal margin
of the theca, Caster (1952, p. 12) described small, tri-
angular “‘interbasal plates” (ib) intercalating between
the M1/M’'1 and M2/M'2 marginals. These so-called
ib plates are now seen to be simply prosopon features
defined by ridges on the M1/M'1 marginals.

Internally the M1 marginals are greatly modified.
Extending from the inner margin of the aulacophore
embayment is an internal wall, the aulacophore apoph-
yses, which slopes distally from the plastron and abuts,
but does not fuse with the inner surface of the carapace
(i.e., against the RA, MA, and LA plates). In their
overall appearance, the aulacophore apophyses seem
similar to those of Anomalocystites disparilis Hall, 1859
(see Kirk, 1911, pl. 3, fig. 11), Placocystites forbesianus
de Koninck, 1869 (see Ubaghs, 1968a, p. 522, fig. 4),
and Ateleocystites guttenbergensis Kolata and Jollie,
1982 (pl. 2, figs. 11, 13). Commonly this partition is
only slightly thinner than the normal plate thickness.
The apophyses are equal in size and are divided by the
common suture between the marginals M1/M'1. Near

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 27

the carapace there is a horizontally-directed, sagittally-
centered, oval foramen in the apophyses. This is ap-
parantly the only avenue of communication between
the aulacophore and the theca. Most of the outer pe-
riphery of the apophyses is bordered by a sharply de-
fined ridge. It is just inside this ridge and against the
apophyseal wall that the first elements of the proximal
aulacophore abut. The ridge probably served as an
anchoring collar between the aulacophore and theca.

Aulacophore.—As in all Stylophora, the aulacophore
of Enoploura is divisible into three basic parts: (1) a

tetramerous proximal aulacophore, the ossicles of which
dovetail inferosagittally, more or less evenly abut su-
perosagittally, and evenly abut in the plane of exten-
sion; (2) an intermediate zone, the styloid, made up of
three uniserial segments, and produced into the two
blades or flanges for purchase into the substrate; (3) a
multisegmented, uniserial, distal aulacophore, which
consists of sharply-keeled ossicles, each with a large,
evenly paired set of covering plates (PI. 6, figs. 4, 5;
Text-figs. 1-3).

Enoploura has about 11 complete segments in the

D Pb

Text-figure 13.— Detail of the styloid of Enoploura popei. These figures are based on UCM 46049 (PI. 6, figs. 6, 8, 11, and 9, respectively).
A, B, distal views with distal aulacophore insert area; C, proximal view, showing the proximal aulacophore insert area; D, lateral view of the
styloid. db = distal blade of the styloid; fg = food groove; im = insert margin; m = muscle pit; pb = proximal blade of the styloid; pp =
proximal pit; si = styloid insert area (part of the styloid that displaces ventral tetrameres of the proximal aulacophores).

For explanations of other plate abbreviations, see Table | (foldout inside back cover).

28 BULLETIN 336

proximal aulacophore. Adjacent to the styloid there
are several segments that do not meet inferosagittally;
they are pushed aside by the proximal process of the
styloid (Pl. 6, fig. 2). Overlap of the inferior meres in
each segment at the sagittal plane is slight. This is in
contrast to the tetramerous solutan proxistele where
the overlapping, both superior and inferior, is more
extensive. The lateral sutures in Enoploura are very
tightly ankylosed, as is the dorsal sagittal suture, but
in the latter case the suture is recessed in a shallow
groove (PI. 6, fig. 12). In adult specimens, the cross-
sectional outline of the proximal aulacophore is a
slightly depressed oval, while in juveniles it tends to
be circular.

Distal to the proximal stele is the three-segment sty-
loid, which has flanges paralleling the inner sutures
between the first and second, and between the second

Text-figure 14.—Transverse cross-sections of the distal styloid blade
of Enoploura popei. Both figures are mirror-image reconstructions
generated by duplicating a single half-image in reverse. Note the
“canal” systems in the syzygial suture system.

and third ossicles. Flanges show definite specific vari-
ations. In the Cincinnatian species E. popei Caster,
1952, they are broadly-rounded transversely and in-
feriorly (Pl. 6, figs. 9, 11; Text-figs. 13A—D), but in
other Cincinnatian species and in Trentonian and Ed-
enian forms, they are less transversely-expanded and
more acuminate inferiorly (Pl. 4, fig. 6, Pl. 5, figs. 1,
5, Pl. 6, figs. 10, 13). The styloid also includes two
pairs of covering plates that convexly arch over the
longitudinally-short superior extremity of the distal
blade (PI. 4, fig. 6, Pl. 6, fig. 1).

In E. popei, the morphology of the styloid blades is
easily observed (PI. 6, figs. 1-3, 6-9, 11; Text-fig. 13).
In this species, the styloid blades are dissimilar in size
and outline. The distal blade is larger, hemispherical
in outline, and dorsally capped by the covering plates.
The smaller proximal blade is situated in a more in-
ferior position and is quadrate in outline. This blade
underlies that portion of the styloid that protrudes into
the inferior distal portion of the proximal aulacophore
and is without covering plates. On both blades the
distal faces are generally gently convex. The proximal
face of the distal blade is slightly concave to moderately
convex, while the proximal face of the proximal blade
is planar to markedly convex. The differences in cur-
vature on both blades is a function of size; smaller
specimens have blades with more surface curvature,
but as they grow they tend to become flatter on both
surfaces. Subradial ridges composed of pustules are
present, especially near the periphery of the proximal
faces of both blades. Similar ornament is present on
the distal faces, except the ridges are commonly less
distinct and the pustulose ridges tend to anastomose.

The three segments that comprise the styloid are
markedly unequal in length; the proximal and medial
segments comprise most of the total length, while the
distal segment is restricted to the distal portions of the
distal blade and the distal aulacophore insert area. Only
two pairs of covering plates have been detected and
they are supra-oral in position, belonging to the medial
and distal segments. They seem to be non-erectile and
are greatly reduced in length. The pair for the proximal
segment is apparently lost due to insertion into the
proximal aulacophore.

In the planes of the sutures in E. popei is a radiate
“canal” system that underlies the radiate prosopon
(Text-fig. 14). These ‘‘canals” are commonly seen as
lines of greenish-black pyrite, which commonly weath-
ers into red ferric compounds near the periphery of the
blade. There are 40 to 60 of them in the distal blade
and about half as many in the proximal blade. Their
function is unknown; perhaps they were sensory in
nature. Connection between this system and the in-
ternal cavities (i.e., in the aulacophore insert area or
in the protruding portion that extends into the prox-

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 29

imal aulacophore) has not been observed, but it does
seem likely. This system, when viewed between the
thecal plates by serial sectioning, appears to be similar
to syzygial suturing, although this condition has in-
dependently evolved within the mitrates. On the distal
face of the distal blade is the indented insert area for
the distal aulacophore. This area is subogival in outline
and is bordered by a low ridge (PI. 6, figs. 6-8; Text-
figs. 13A, B). Medially, in the insert area, is a flat-sided
cavity that extends ventrally into a well-rounded mus-
cle pit. Superior to this cavity are the two, stepwise-
arranged, flat-topped, paired seats for the remnant cov-
ering plates.

The proximal end of the insert area is defined by a
pair of muscle pits on elevated column-like bases, sep-
arated along the sagittal axis by a very thin septum (PI.
6, figs. 6-8; Text-figs. 13A, B). The septum ends near
the superior margin and the medial indentation prob-
ably marks the course of the food groove. Each muscle
pit is transversely ovoid. The distal walls of the pits
are lower and concave, while the proximal walls are
considerably elevated and convex.

The dorsal muscle pits are situated on pier-like bases
that have migrated upward during ontogeny due to
peripheral growth, and in larger specimens the bases
are, as expected, more highly developed. The dorsal
muscle pits are located in the second or middle of the
three segments. Between the bases of the muscle pits
and the distal end of the distal aulacophore insert area
are paired “‘septa’”’ that extend parallel to the suture
toward the midline. These “septa’’ appear to be part
of the distalmost segment and probably served as abut-
ments for the proximalmost ossicle of the distal au-
lacophore. The upper parts of these abutment plates
may also have provided muscle attachment to the dis-
tal aulacophore.

The two distal styloid segments also share the ventral
muscle pit that occupies the bottom of the distal au-
lacophore insert area. This deep rounded pit allowed
the distal aulacophore to move up and down in the
medial plane. Muscle(s) extending from the inferior pit
would have probably attached close to the top of the
ossicle and the contraction of this and the two superior
muscles would have elevated the aulacophore with the
lower parts of the abutment plates serving as the ful-
crum.

Proximal to the proximal wall of the insert area, the
inferior styloid section slopes toward the midline and
comprises that part of the styloid which inserts into
the proximal aulacophore. In profile, this portion of
the styloid is concave superiorly and gently convex
inferiorly (PI. 6, fig. 9; Text-fig. 13D). On the superior
margin of this spoonlike protrusion is the narrow me-
dial slit which, as indicated above, is probably for the
passage of the food groove. Most of the large hollow

space enclosed by the spoonlike protrusion was prob-
ably for muscle attachments and enclosure of other
organ systems associated with feeding (/.e., (?) water-
vascular, nervous, and associated coelomic cavities)
(Pl. 6, fig. 11; Text-fig. 13C). No trace of water-vascular
apparatus is found in the styloid interior or on the distal
aulacophore of this genus.

The two non-erectile covering plates situated over
the distal styloid blade are supra-oral. The mouth was
situated at the termination of the food groove, which
was located between the superior muscle pits. In the
proximal insert area of the styloid, the food conduit is
internal and extends under the superior meres of the
proximal aulacophore and into the theca. Speculation
by some authors that the mouth, or orifice to the in-
terior, lay between the theca and superior meres of the
proximal aulacophore is not tenable in Enoploura or
any other observed genus. The very tight suturing in
this area precludes the possibility of such an orifice in
this position. In all known specimens, the length of the
distal aulacophore exceeds that of the theca. It tapers
very gently to an acute and apparently very flexible
terminus. Throughout its length, it is consistently uni-
serial. Ossicle and cover plates present a teardrop-
shaped cross-section. The V-shaped or keeled ossicle,
like those in other mitrates and in the Cornuta, lacks
an internal lumen.

The transverse sutures between the ossicles bisect
the sutural flanges that extend inferiorly and infero-
laterally. These flanges are developed to a much lesser
degree than in the styloid. Especially prominent are
proximally-directed sutural cusps, which are best de-
veloped on the ossicles adjacent to the styloid.

Evenly paired over each ventral ossicle is a pair of
covering plates that are nearly as tall as the underlying
ossicle and distally overlap the covering plates on the
adjacent distal segment. The gently concave articula-
tory bases fit evenly along the correspondingly convex
dorsal surfaces of the ossicles.

The distally-overlapping cover plates meet in a
straight, very tight suture along the superior midline.
The tightness of the suturing is attested to by the fact
that in known specimens, cover plates are rarely sep-
arated from their opposed basal ossicles. There is no
evidence that the cover plates were erectile or capable
of rotation.

Most specimens have between 30 and 40 segments
(Pl. 6, figs. 4, 5, 10) in the distal aulacophore. In spec-
imens of Cincinnatian age, the distal aulacophore of
Enoploura inserts into the specialized insert area of the
styloid at an angle of approximately 55° to the hori-
zontal. The nature of the articulatory surfaces indi-
cates, however, that the distal aulacophore could be
straightened in this location. Trentonian and Edenian
forms do not seem to have this initial insertion angle

30 BULLETIN 336

with the distal segment of the styloid, and probably
this lack of insert angularity is a more primitive con-
dition.

Functional considerations.— While much of this sec-
tion applies to many other mitrates as well, the detailed
knowledge of the nature of the styloid and spine artic-
ulation in Enoploura makes this the appropriate place
for this discussion.

The three segments of the styloid are joined by coarse
syzygial sutures between the middle and end members.
The sutural portions of these segments are produced
into the flanges that anchor into the substrate. The
stromal openings in the sutures are large enough to
make up, in effect, a radiating “canal”? system. The
ends of these “‘canals”’ appear slightly bulbous and the
tissue in them may have served as sediment chemo-
receptors and/or as an orientating sensory device. The
canals terminate internally near the food groove, and
it is assumed connected with axial nerve trunks.

The principal direction of active locomotion was
with the distal end of the theca foremost. The prow-
like character of the protruding, cantilevered lip, the
ventrally-arched runnerlike articulating spines, and the
distally-directed spines on the CM3 plate all point to
this interpretation. The hydrofoil profile of Enoploura
would have acted as a laminar-flow wing and would
have provided lift while the animal was swimming or
sculling along. Lift would also be generated while the
animal was at rest: water flowed over the theca in the
opposite direction (/.e., proximally to distally while the
animal faced into the current). While this might induce
less stability due to hydrodynamic lift, it may, in part,
indicate the selective value of the counteracting large
styloid blades. The animal may have ratcheted for short
distances across the sea floor using the styloid (cf: Cast-
er, 1952, pl. 42) and the large spines on the proximal
ossicles of the distal aulacophore, to adjust its orien-
tation relative to currents.

Orientation of the mamelon and acetabulum on the
spine strongly suggests that the thecal spines moved
parallel or nearly parallel to the substrate. Movement
probably extended from an outward position of ap-
proximately 30° to the sagittal plane to an inward and
slightly upward (as evidenced by the inclined articu-
latory boss) position of the same magnitude, and to-
taling about 60° of movement. These must be consid-
ered as maximum values; movement was, most likely,
commonly through a smaller angular distance. Inward
swing probably extended only slightly inside the lateral
marginal plane and total outward movement was prob-
ably not more than 20°. Some authors have speculated
that the spines may have served as struts to hold the
theca off the sea floor (see, e.g., Caster, Dalvé, and
Pope, 1955). Dehm (1934, p. 29), on the other hand,
postulated that the fine spines of the mitrate Rheno-

cystis Dehm, 1932, were too delicate and attenuate to
serve as struts to elevate the animal above the sub-
strate. The articulatory apparatus of the spines on En-
oploura strongly indicates that vertical movement that
would lift the animal off the substrate was improbable.
Considering the general similarity of all anomalocys-
titid spines in size, shape, and area of articulation, these
structures most likely all had a similar horizontal mode
of movement and served as buttresses to hold the an-
imal stable while feeding.

Enoploura punctata Bassler, 1932
Plate 4, figures 5-9, Plate 5, figures 1-5, 8, 10,
Plate 6, figures 10, 13; Text-figures 15, 16

Enopleura [sic] punctata Bassler, 1932, p. 218, pl. 18. fig. 9; Bassler,
1935, p. 406.
Enoploura punctata (Bassler) [sic]. Bassler, 1943, p. 157.

Diagnosis.—Theca commonly, but not invariably,
relatively wider than Late Ordovician species; carapace
ornament scaly punctate; distal lip thick, spines thick,
apparently straight, terete. Styloid blades not greatly
expanded.

Occurrence.—Trentonian, Cannon Limestone,
known from a single locality 0.5 mi north-northeast
of Pulaski, Tennessee. Guensburg (oral commun., 1987)
feels certain that the material is from the base of the
Catheys Limestone, Costellaria beds (Edenian), at the
same geographical locality, and is not from the Cannon
Limestone as originally described (Locality F).

Types.—Syntypes?: USNM 91854, Locality F. Top-
otypes/hypotypes: USNM 91854!°, Locality F.

Morphological discussion.—The dorsal theca differs
little in plate configuration from younger Cincinnatian
age species except that the plates commonly are wider
and result in a relatively broader theca. Ornament on
the carapace is made up of deep punctae uniformly
spread across the plates. This pattern, as the species
name implies, is characteristic of the species. Most
specimens are so weathered that coarser stromal pat-
terns in the punctae can be seen. As is typical in most
mitrates, a band of small, transverse, aborally-over-
lapping ridges extends across the distal end of the car-
apace (see Caster, 1952, p. 13).

The plastron is known from a single specimen (PI.
5, fig. 8), which does not significantly differ from that
of other species of Enoploura (Text-fig. 16).

The arcuate lip on the distal end of the theca is

° The four syntypes consist of three variously preserved carapaces
and a laterally crushed proximal aulacophore, styloid, and proximal
segments of a distal aulacophore, all on a small slab. It seems in-
advisable to me to select a lectotype.

‘0 nine specimens collected at the same time and place by Bassler;
mostly carapaces, but one plastron and fragments of the aulacophore
are also preserved. All specimens are USNM 91854.

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 31

thicker than that found on E. popei Caster, 1952, from
the Cincinnatian, which probably accounts for its pres-
ervation, and in E. punctata, the radiating venation
system on the lip has not been observed (PI. 4, fig. 5;
Text-fig. 15).

Proximal to the distal margin of the lip, the trans-
verse serrate marginal ridge is well-developed on sev-
eral specimens. Its greatest elevation is medial on the
median marginal plate m6 and slopes laterally to the
floor of the theca on marginal plates m5 and m’5. On
marginals m5 and m’5, there is a shallow depression
between the end of the transverse marginal ridge and
the distal-lateral corner of M4—M'4, where the spine
articulation is located. Probably there was a pair of
aboral openings on either side of the transverse ridge,
as indicated by the depressions that served as avenues

Text-figure 15.—Carapace of Enoploura punctata. This figure is
based on USNM 91856 (PI. 4, fig. 5). Note that the spines are more
massive and terete than the thinner, blade-like spines of Enoploura
popei. Also, note that the distal lip is more robust than that in
Enoploura popei.

For explanations of plate abbreviations, see Table | (foldout inside
back cover).

for muscles between the thecal interior and the spines,
as well as serving as the anal opening of the gut. That
the anus probably opened through the right aperture
is suggested by the fact that the diagonal ridge, or sep-
tum (Ubaghs, 1968a, p. S528) (Pl. 4, fig. 5, Pl. 5, fig.
4), a probable secretion of the gut-support mesentery,
extends directly to it.

Spine sockets are not so well defined as in some
younger species, but there seems to be little difference
in their basic configuration. Spines are apparently te-
rete throughout and show little, if any, of the distal
compression seen in Cincinnatian species. Total rela-
tive length of the spines is not known; there is no
assurance that the distal ends of any of the preserved
spines are present. Those that are preserved appear to
be unusually short (PI. 4, figs. 5, 8, 9, Pl. 5, figs. 1, 3,
Pl. 6, fig. 10).

The proximal aulacophore is made up of about 10
or 11 segments, of which three or four are hidden by
the carapace, but their inferior tetrameres are exposed
in the plastron embayment. The proximal aulacophore

Text-figure 16.—Plastron of Enoploura punctata. This figure is
based on USNM 91854 (PI. 5, fig. 8). Morphologic details of the
external distal end of the plastron are poorly known.

For explanations of plate abbreviations, see Table | (foldout inside
back cover).

32 BULLETIN 336

is completely typical of the genus (see Caster, 1952, p.
14). The styloid of E. punctata is similar to that of E.
balanoides (Meek, 1872). The blades do not extend out
as far, nor are they as rounded as those in E. popei.
They are more acutely rounded inferiorly, resulting in
a plowshare-like outline (Pl. 4, figs. 7, 8, Pl. 5, fig. 1).

Two pairs of covering plates above the distal styloid
blade are larger than those in E. popei and less con-
stricted dorsally, due to the flatter insertion angle of
the distal aulacophore into the styloid (PI. 4, fig. 7). In
E. popei, the angle of insertion is such that the proximal
pair of covering plates on the distal aulacophore is
almost in contact with the superior meres of the distal
proximal aulacophore segment; the superior ends of
the covering plates are nearly crowded out.

Preservation of the styloid of E. punctata shows none
of the syzygial suturing that is present between the
styloid elements in disarticulated specimens of EF. po-
pel.

The distal aulacophore, as in other species of Eno-
ploura, consists of a keel-shaped basal series with a
pair of covering plates over each ossicle. Narrow su-
tural flanges on the proximal end of the distal aula-
cophore are especially prominent.

Covering plates on the distal aulacophore are rela-
tively larger than those of E. popei, and tend to display
a greater degree of distal overlapping. Raised muscle
ridges on the distal margins of these plates tend to be
larger than on Cincinnatian species (PI. 4, fig. 6).

The total number of segments in FE. punctata is un-
known; no example of a complete distal aulacophore
is extant. When one compares a nearly complete au-
lacophore of EF. punctata (P1. 5, fig. 5, Pl. 6, fig. 10) to
that of specifically indeterminate Cincinnatian age
specimens of the same genus (PI. 6, figs. 4, 5), the total
number of segments in both cases is commonly 30 to
40 and may be as high as 50. Species of Enoploura of
Cincinnatian age have a thicker, more robust, distal
aulacophore.

Discussion. — Bassler (1932), p. 218, 219) briefly de-
scribed and figured this species, “which is distin-
guished from other members of this genus by its punc-
tate surface.” Bassler (1935, pp. 403, 406) briefly
redescribed the species, explaining that this was nec-
essary under the new, post-1930 rules of zoological
nomenclature, in order to validate this and other taxa
proposed as new in his 1932 publication. The original
description was minimally adequate, and the 1935
publication did little to improve it: E. punctata was
described as follows:

“This well marked cystid is distinguished from the
genotype, E. balanoides (Meek), by its flattened theca
and specially by its highly punctate surface.”

In both descriptions, Bassler misspelled the generic
name, introducing the nomen imperfectum, Enopleura.

The flattened theca is partly due to preservation,
although these relatively broad specimens probably did
have a flatter carapace than most of the Cincinnatian
species.

Enoploura balanoides (Meek, 1872)
Plate 4, figures 1-4

Anomalocystites (Ateleocystites?) balanoides Meek, 1872, pp. 423,

424; Meek, 1873, p. 41-44, pl. 3bis, figs. 6a—-c.

Enoploura balanoides (Meek). Wetherby, 1879, pt. 1, p. 163; pt. 2,
pl. 7, figs. 1d—g; Bather, 1900, p. 51; Bassler and Moodey, 1943,
p. 157; Caster, 1952, pp. 28, 30, pl. 2, figs. 7-9.

Ateleocystites balanoides (Meek). Woodward, 1880, p. 198, pl. 6 figs.
6-15; Bassler, 1915, p. 88.

Anomalocystites balanoides (Meek). Miller, 1889, p. 224, fig. 247.

Placocystis crustacea Haeckel, 1896, pp. 39, 40, pl. 2, figs. 5, 6, 7,
text-figs. 1, 2,

Enoploura crustacea (Haeckel). Bather, 1900, p. 51; Caster, 1952,
pp. 30-32, pl. 2, figs. 1-6.

Enoploura wetherbyi Caster, 1952, pp. 32-33, pl. 2, figs. 10- 12.

Enoploura meeki Caster, 1952, p. 39. pl. 4, figs. 1-3.

Diagnosis.—Enoploura with smooth carapace ex-
cept for cuesta-like ridges on adaulacophoral carapace
plates and marginals, styloid blades plowshare-shaped.

Occurrence.—Maysvillian and Cincinnatian: Cin-
cinnati, Ohio and vicinity (Localities E and Q [Locality
Q, identified by Caster (1952) is that of the holotype
of Enoploura balanoides, which is presumed lost]).

Types''.—Holotype: The holotype specimen of En-
oploura balanoides (Meek, 1872), is presumed lost. It
is from the Fairview Formation, Cincinnati, Ohio (see
Caster, 1952, pp. 28, 30). UCM 37296 [holotype of E.
crustacea (Haeckel, 1896)], Locality E. UCM 31309,
Locality L.

Description.—The type species varies from other
species by surface markings and by the paired plow-
share-like blades rather than a rounded pair of styloid
blades (e.g., as in E. popei). In all other respects the
description under the generic heading holds for this
species.

Discussion.—The genus Enoploura was based on in-
complete specimens of E. balanoides, which consist of
the proximal half of the theca, with or without an
attached partial to complete proximal aulacophore. In
one specimen the styloid appears to be intact and is of
a size and configuration similar to that of Ate/eocystites
Billings, 1858, or Anomalocystites Hall, 1858 (see
Wetherby, 1879, pl. 7, figs. la—g).

The holotype specimen of Enoploura crustacea
(Haeckel) was lost for many years; in the 1960’s, it was
located and is now in the collections of the University
of Cincinnati. This original specimen of Wetherby was
given a new species name by Haeckel and placed in

‘| E. meeki Caster, 1952, and E. wetherbyi Caster, 1952, are re-
garded as synonyms of E. bal/anoides: each is represented by a single
incomplete specimen (see Caster, 1952).

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 33

the genus Placocystis [sic]. Haeckel felt it was sufh-
ciently different from Meek’s holotype (which is only
a proximal end of a theca) to warrant a new species
assignment. Caster (1952) removed a second specimen
illustrated by Wetherby (1879, pl. 7, figs. 1, la, 1b)
and established Enoploura wetherbyi. This specimen
with the styloid and several segments of the distal au-
lacophore intact and attached to a distally incomplete
theca was originally placed in the Crustacea by Weth-
erby. This mistaken assignment brought disparaging
remarks by Woodward (1880) [see Caster, 1952, p. 33].

Enoploura crustacea, Enoploura wetherbyi, and En-
oploura meeki, each of which is known only by a partial
(proximal) theca with few or no aulacophore segments
attached, are all late Richmondian in age and are herein
considered conspecific with E. balanoides. Enoploura
balanoides is also probably Maysvillian in age, al-
though the data on the stratigraphic placement of the
holotype are obscure (see Caster, 1952, p. 30).

Other than the priority established by E. balanoides,
the validity of any of these synonymized species is
questionable. Together, all of them easily fit within the
range of variability now known for the clearly-recog-
nizable species E. punctata (Edenian) or E. popei (Cin-
cinnatian). E. balanoides is coeval with E. popei, but
with the synonymized forms extends farther up the
section. In the Cincinnatian, two species of Enoploura
are now recognized: E. popei, with large, rounded sty-
loid flanges (Maysvillian), and E. balanoides, with plow-
share-like flanges (Maysvillian and Richmondian).

Enoploura cf. E. balanoides (Meek, 1872)
Plate 5, figures 6, 7, Plate 6, figure 12

Occurrence.—Maysvillian: Cincinnati, Ohio (Local-
ity Q) and Camden, Ohio (Locality L).

Types.—UCM 46045, 46046 (Locality Q); UCM
31309 (Locality L).

Discussion.—The proximal aulacophore of E. bal-
anoides, with its plowshare-like styloid, is usually nar-
rower, rounder, and more tapered than the proximal
aulacophore of E. popei. The incomplete specimens
included under Enoploura cf. E. balanoides are ten-
tatively placed here due to the nature of their proximal
aulacophores. Because the proximal aulacophore is
easily deformed, this method of assigning specimens
to species is tenuous and not reliable as a taxobasis.

Enoploura popei Caster, 1952
Plate 6, figures 1-3, 6-9, 11;
Text-figures 1-3, 10-14, 17

Enoploura popei Caster, 1952, pp. 34-39, pl. 1, figs. 1-6, pl. 3, figs.
1-6, pl. 4, figs. 4-8, text-fig. 1.

Diagnosis.—Enoploura with large rounded styloid

Text-figure 17.—A, B, partial reconstructions of the internal sur-
face of the carapace of Enoploura popei, using disarticulated plates.
Markings on these plates are highly variable and presumably rep-
resent muscle and tissue attachment sites. The large ridges on the
LA and RA plates probably served for proximal aulacophore an-
choring, and/or muscle attachments. Note the well-developed, dis-
tally-directed spines on the carapace marginals (CM2, CM3, CM’2).

For explanations of plate abbreviations, see Table | (foldout inside
back cover).

34 BULLETIN 336

blades, distal marginal carapace plates with punctate
prosopon.

Occurrence. — Late Ordovician (Maysvillian), vicin-
ity of Cincinnati, Ohio (Localities I and K).

Types.— Holotype: UCM 25993, Locality I. Hypo-
types: UCM 46049, Locality K.

Discussion.— The general aspects of this species have
been described above under the generic heading. The
distinguishing characters of the species are given in the
diagnosis.

In addition to the known articulated specimens,
which include complete thecae, spines, and nearly
complete aulacophores, thousands of disarticulated
plates and spines are known. These come from Bou-
dinot Avenue in Cincinnati, and were collected by J.
Stocker and W. Deak, amateur paleontologists. Their
collections of these plates are now in the collections of
the University of Cincinnati. Also in the University
collections are similar, but commonly less well-pre-
served plates from St. Marys, Indiana. The plates from
the latter locality appear to be from about the same
horizon as those from Boudinot Avenue. These give
us a good picture of the internal plate anatomy of this
genus, which is quite similar to that of other anom-
alocystitids. The most important variable appears to
be the branching pattern on the internal surface of the
MA plate (Text-figs. 12A, 12B, 17A, 17B).

Enoploura cf. E. popei Caster, 1952
Plate 5, figures 9, 11

cf. Enoploura popei Caster, 1952, pp. 34-39, pl. 1, figs. 1-6, pl. 3,
figs. 1-6, pl. 4, figs. 4-8, text-fig. 1.

Occurrence.— Late Ordovician Whitewater Forma-
tion (Locality H) and Waynesville Formation (Locality
P), southern Indiana.

Discussion.— Proximal aulacophores of E. popei tend
to be broader, and more oval than circular in cross-
section, and are less tapered than those of FE. balan-
oides. This more robust nature is probably due to the
larger and more rounded styloid blades. The poorly
preserved specimens included under Enoploura cf. E.
popei appear to have remnants of FE. popei-like prox-
imal aulacophores. As with E. balanoides, this method
of assigning specimens to this species is very tentative
due to the deformable nature of the proximal aula-
cophore.

Family PLACOCYSTITIDAE Caster, 1952!
Subfamily PLACOCYSTITINAE Caster, 1952!3

Diagnosis.—Anomalocystitids with one to three in-
fracentrals, four or five rows of more or less symmet-

'2 =Placocystidae Caster, 1952 (nom. correct. Gill and Caster, 1960).
'3 =Placocystinae Caster, 1952 (nom. correct. Gill and Caster, 1960).

rically-arranged supracentralia, median adaulacophor-
al (MA) plate does not reach superior proximal margin,
sagittally-placed placocystitid plate commonly pres-
ent, rarely missing.

Discussion.— Caster (1952, p. 27) defined this sub-
family, in part, as having one or two somatic plates on
the plastron, a symmetrically-arranged carapace with
four or five rows of centralia, and a sagittally-placed
placocystitid plate.

Kolata and Jollie (1982) modified the definition to
include Ateleocystites Billings, 1858 (Caradocian—
Trentonian of eastern North America) and Barran-
deocarpus Ubaghs, 1979 (Early Caradocian of Bohe-
mia), each of which have three infracentrals. More
importantly, they recognized the subfamilial charac-
teristic that only two superior (left and right) adaula-
cophoral plates form the proximal margin. The median
adaulacophoral plate is excluded, in some specimens
quite narrowly, from contact with the proximal aula-
cophore. This characteristic, which might seem to be
a minor morphological variable, is nevertheless con-
sistent throughout the range of the subfamily (Middle
Ordovician—Early Devonian).

In Placocystites forbesianus de Koninck, 1869, the
P or placocystitid plate (Caster, 1952) or the xi plate
(Jefferies, 1984) has been observed in juveniles to be
large and variable-telative to the size of the carapace.
As Jefferies (1984) observed, while the location of the
plate center remains relatively the same, the adjacent
lateral somatics gradually surround it and it becomes
relatively reduced in size. In more mature specimens,
the greatly-reduced plate, in terms of the area exposed
to the interior of the theca, evenly flares out (as seen
in its broad funnel-shaped cross-section) over the ad-
jacent plates and results in a rounded plate outline on
the outer surface. Because the plate overrides the ad-
jacent centralia and thins considerably near its periph-
ery, a relatively minor amount of surface erosion and/
or solution can significantly reduce the size of this plate.
The shape of the P plate is apparently determined nei-
ther by abutting against adjacent plates, nor by forming
at a triple junction (Jefferies 1984, pp. 308-311; text-
figs. 9, 10). Rather, the mode of emplacement is either
by reduction through resorption and surrounding by
adjacent centralia, or possibly by secondary resorption
and subsequent redeposition. Neither case has been
observed. However, Jefferies’ evidence for the former
case is highly compelling.

The closely-related new genus, Kopficystis, does not
show signs of this ontogenetic sequence (i.e., the P plate
is apparently missing, which could be due to juvenile
resorption). The area of the carapace where the P plate
occurs appears to be a zone of considerable stereom
secretion/?resorption activity in mitrates, even in non-
placocystitids, because a small placocystitid-like plate

NorTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 35

has been observed in some specimens of Anomalocys-
tites.

The genera Placocystites de Koninck, 1869, Rhen-
ocystis Dehm, 1932, Barrandeocarpus Ubaghs, 1979,
and Ateleocystites Billings 1858, easily fit into this sub-
family. Kopficystis, n. gen., very closely resembles
Rhenocystis in its general outline, number of plate se-
ries on the carapace, and configuration of the superior
proximal theca. It differs in that no placocystitid plate
is present in this monotypic genus. As previously in-
dicated, it seems advisable to slightly expand the def-
inition of this subfamily rather than to create a new
one to receive this single genus. Inclusion of Ateleo-
cystites, Barrandeocarpus, and Kopficystis in the Pla-
cocystitinae extends the range of the subfamily from
Late Silurian—Early Devonian downward to the Middle
Ordovician.

Genus KOPFICYSTIS, new genus

Type species.—Kopficystis kirkfieldi, n. sp.

Remarks.—Since this genus is monotypic, it follows
that diagnosis, description, and occurrence of this new
genus are the same as those for the species.

Kopficystis kirkfieldi, new species
Plate 7, figure 10; Text-figure 18

Diagnosis.—Placocystitid with median adaulaco-
phoral plate exserted from adoral margin; no P plate;
at least five transverse series of supracentralia.

Occurrence.— Middle Ordovician (Trentonian),
Kirkfield, Ontario (Locality O).

Type.— Holotype: USNM 116408, Locality O.

Description.—What is known of this new taxon is
derived from a single specimen that shows the nearly
complete but distally weathered superior surface (car-
apace) of the theca. Thecal sockets for the articulating
distal spines are present, but the spines themselves are
missing. A poorly-preserved portion of an apparently
typical mitrate proximal aulacophore is present.

In outline and general plate arrangement, Kopficystis
kirkfieldi, n. sp., bears a strong resemblance to the De-
vonian genus Rhenocystis Dehm, 1932. There is no
evidence of any transverse ornament ridges, especially
on the adaulacophorals, that are so common on taxa
included in the Anomalocystitida; instead, the surface
is covered with even, fine-grained, pustules.

The aulacophore embayment is broad, as in Eno-
ploura, but the median adaulacophoral (MA) plate is
narrowly excluded from the margin, which is wholly
made up of right and left adaulacophoral plates (RA
and LA). Both the right and left adaulacophoral plates
are broad at the expense of the quadrangular median
adaulacophoral plate (Pl. 7, fig. 10; Text-fig. 18).

Distal to the adaulacophoral series are four subequal
median supracentrals (a—d) in a transverse series across

the theca: their disposition is typical within the Pla-
cocystitinae.

Distal to this transverse series of supracentrals is a
pair of large, subpentagonal supracentral plates (e, i)
that extend almost to the middle of the theca. These
subpentagonal plates are most atypical of anomalo-
cystitids, and their size and shape must be regarded as
generic characters. The marginal positions of these
plates correspond to the area covered by supracentrals
e and i of Anomalocystites . Whether there is any ho-
mology between these two genera which are in different
families, with respect to these plates, is conjectural.
Discussion and identification of the supracentralia in
Kopficystis is, however, compared to the position of
supracentralia in Anomalocystites.

avy, Pp A'‘CM1 : ;

pana «Ke
selec eM SGRIN GSE «ee ere?

Text-figure 18.—Carapace of Kopficystis kirkfieldi, n. gen. and sp.
This figure is based on USNM 116408 (PI. 7, fig. 10). The MA plate
is slightly excluded from the aulacophoral margin. Plates covering
the distal half of the carapace either represent composites of smaller
plates or are enlarged plates that have crowded out adjacent supra-
central plates. For example, plate gl occupies the same space as plates
g and 1 in Anomalocystites cornutus.

For explanations of plate abbreviations, see Table 1 (foldout inside
back cover).

36 BULLETIN 336

Distal to e and i are two marginal supracentrals, j
and o, which are irregularly-square in outline. The left
plate, j, is poorly preserved and largely missing. Be-
tween e/j and i/o is a large pentagonal “‘central-dorsal”
(gl) plate that extends from a sutured contact with b
distally beyond j and o to contact the distal carapace
marginal series. The “‘central—dorsal”’ plate is so named
because it occupies the space of the midplates of the
second and third rows of supracentrals in Anomalo-
cystites.

Partial remains of the right distal carapace marginal
(CM1) indicate a similar outline to that of the adjacent
o plate. The rest of the distal carapace marginals are
not preserved.

Anal valve platelets are visible at the distal end of
the carapace: normally they would be covered by the
distal carapace marginals. They appear to be better
developed than in either Enoploura Wetherby, 1879,
or Ateleocystites Billings, 1858.

Articulatory sockets for spines located on the aboral
ends M4 and M’4 are similar to those of Enoploura.

Discussion.— Despite the incompleteness of the ho-
lotype of the type and only known species, there is
enough to see the striking resemblance to the placo-
cystitid carapace (cf. Rhenocystis or Placocystites de
Koninck, 1869) in the number and arrangement of the
plates. Kopficystis lacks the typical placocystitid (P)
plate, which is diagnostic of the placocystitids.

It also appears, but with no great degree of certainty,
that the carapace distal margin consists of three plates.
This number is typical in the Placocystitinae (except
in Ateleocystites, which apparently has four), while in
the Enoplourinae this margin is composed of five plates.

Genus ATELEOCYSTITES Billings, 1858

Ateleocystites Billings, 1858, pp. 72-73, fig. 4; Zittel, 1879, p. 413(pars);
Woodward, 1880, pp. 194-201, pl. 6(pars); Kirk, 1911, pp. 22-
23; Bassler, 1915, p. 88; Jaekel, 1918, p. 122; Wilson, 1946, pp.
7, 8, pl. 2, figs. 1-4; Caster, 1952, pp. 17— 21, 27-29, figs. 2A, 2B;
Gill and Caster, 1960, pp. 44, 45; Regnéll, 1960, pp. 166, 167;
Kolata and Jollie, 1982, pp. 640- 649, pl. 1, figs. 1-16, pl. 2, text-
figs. 3-9.

non Placocystites de Koninck, 1869. Woodward and Billings in
Woodward, 1871, pp. 71, 72.

non Anomalocystites (Ateleocystites?) Meek, 1872, pp. 423, 424; Meek,
1873, pp. 41-44, pl. 3bis, figs. 6a—c [= Enoploura balanoides (Meek).
Caster, 1952, p. 28].

Anomalocystites Hall. Miller, 1889, pp. 224, 226(pars); Springer,
1913, p. 150(pars).

non Atelocystites Haeckel, 1896, pp. 41-43, pl. 2, figs. 10-12. [=
Placocystites, fide Regneéll, 1945, p. 197.]

Atelecystis Billings. Bather, 1900, p. 51.

[2] Ateleocystites Lindstrém, non Billings. Regnell, 1945, pp. 196—
197. [= Placocystites fide Regnéll, 1945, p. 197, fn. 7]

Type species.—Ateleocystites huxleyi Billings, 1858.
Diagnosis.—Placocystitinae with well developed

transverse distally pseudo-imbricating ornament ridg-
es on M1/M'1 and M2/M’2; placocystitid plate prom-
inent, MA plate excluded from adaulacophoral mar-
gin.

Occurrence.—Type species known from three Tren-
tonian age localities: ?Hull Beds, Ottawa Limestone,
Brigham Quarry, near Hull, Quebec (Locality R); Ot-
tawa Limestone, Hull Beds, locality unknown (Locality
S); and Martinsburg Formation, Swatara Gap, Leba-
non County, Pennsylvania (Locality T). One and pos-
sibly two other species are known from the Glens Falls
Formation, Trenton Falls, New York (Locality M), and
from the Guttenberg Formation, upper Mississippi
River Valley: Middle Ordovician.

Discussion.—Kolata and Jollie (1982) clearly dem-
onstrated that Ate/eocystites is properly included in the
anomalocystitid subfamily Placocystitinae. The two
features diagnostic of the subfamily, the exclusion of
the MA plate from the adaulacophore margin, and the
presence of a placocystitid plate are both present in
this genus.

Most of the type specimens of 4. huxleyi Billings,
1858, from Quebec are plastrons, and only a single
specimen displays a poorly-preserved proximal cara-
pace. Previous to this report, the complete carapace of
Ateleocystites was known only in 4. guttenbergensis
Kolata and Jollie, 1982. Fortuitous preservation of
specimens of Afeleocystites from the Glens Falls Lime-
stone locality at Trenton Falls, New York, has resulted
in mostly plastrons being represented. For years it was
thought these undescribed specimens were referable to
Enoploura. Recent discovery of several carapaces in
the collections of the MCZ unquestionably places these
specimens in Ateleocystites: they are referred, with some
degree of certainty, to the type species, A. huxleyi.

Specimens collected in Swatara Gap, in the upper-
most Martinsburg Formation (Climacograptus spini-

ferus Zone), Lebanon County, Pennsylvania, are mor-

phologically very close if not identical to the type
species, A. huxleyi, and may even be conspecific with
A. guttenbergensis (Derstler, written commun., 1984).
Kolata and Jollie (1982, p. 648) point out, however,
that there is an extra supracentral, directly distal to the
P plate in the specimen from Swatara Gap. In A. gut-
tenbergensis, the spines of the styloid and adjacent os-
sicles of the distal aulacophore are especially promi-
nent. Kolata (written commun., 1987) reports that in
subsequent finds of A. guttenbergensis, the theca may
reach lengths of 2.5 cm, certainly the largest size yet
reported for this genus. The degree to which the ob-
served differences between A. huxleyi and A. gutten-
bergensis represent intra- or interspecies variability is
open to question, and the specimens from the Glens
Falls Limestone are of little help in this matter. There

NorTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 37

is no need to redescribe this genus: Kolata and Jollie
(1982) have given an excellent picture of its charac-
teristics. I will, however, illustrate herein new speci-
mens of A. cf. A. huxleyi from the Glens Falls Lime-
stone, Trenton Falls, New York.

Ateleocystites huxleyi Billings, 1858

Ateleocystites huxleyi Billings, 1858, pp. 72-74, fig. 4; Woodward,
1871, pp. 71-73; Woodward, 1880, pp. 193-201, pl. 6, fig. 1;
Bassler, 1915, p. 88; Wilson, 1946, pp. 7, 8, pl. 2, figs. 1-4; Caster,
1952, p. 29, fig. 29, figs. 2A, 2B; Kolata and Jollie, 1982, pp. 640,
648; [non Lindstrém, 1888 (ref. Regnéll, 1945, pp. 196, 197 [=
Placocystites aff. forbesianus fide Gislén in Regnéll, 1945, fn. 7, p.
197))].

Anomalocystites huxleyi (Billings). Miller, 1889, pp. 224, 226.

Ateleocystis huxleyi (Billings). Haeckel, 1896, p. 41.

Atelecystis huxleyi (Billings). Bather, 1900, p. 51.

Diagnosis.—Ateleocystites with well developed
transverse distally pseudo-imbricating ornament ridg-
es on M1/M’1 and M2/M’2; placocystitid plate well
developed.

Occurrence.—Hull Beds, Ottawa Limestone, Brig-
ham Quarry, near Hull, Quebec (Locality R); an un-
known locality, Hull Beds, presumably close to the
former site (Locality S); and Martinsburg Formation,
Swatara Gap, Lebanon County, Pennsylvania: Middle
Ordovician (Locality T).

Types.— Holotype: GSC 1392, paratypes GSC 1392
a-h, Brigham Quarry, Hull Beds, Ottawa Limestone,
near Hull, Quebec (Locality R). Hypotypes: MCZ 1063,
MCZ 2064, USNM 93348 and USNM 401499, Lo-
cality M.

Discussion.—The type species A. huxleyi, and A. gut-
tenbergensis may be conspecific. The question will be
settled by obtaining topotypes of A. hux/eyi with the
carapace intact. Until then, the excellent descriptions
of A. guttenbergensis by Kolata and Jollie will for prac-
tical purposes more than suffice for a detailed expla-
nation of morphology.

In describing the type material, Billings (1858, pp.
72, 73, fig. 4) originally figured a comb-like structure
traversing the aboral end of the theca, which he sug-
gested to be “the marginal ambulacral ossicula of the
ordinary Cystitidae.”” On further examination of Bill-
ings’ lectotype, Wilson (1946, p. 7) noted that this
structure is ‘‘a piece of plate half buried in the matrix”’,
and it is recognized herein as internal corrugations
related to the transverse ridge of the distal carapace
marginals. Wilson added that “another specimen .. .
shows another and perhaps truer branching arrange-
ment of the pinnules.”’ This paralectotype specimen
displays a bundle of spicular material aboral to the m6
marginal. It seems to be nothing more than extraneous
organic carbonate material and is not like any structure
known in the mitrates.

Ateleocystites cf. A. huxleyi Billings, 1858
Plate 7, figures 1-4

Occurrence.—Glens Falls Formation, Trenton Falls,
New York: Middle Ordovician (Locality M).

Types.— The four specimens figured are MCZ 1063,
MCZ 2064, USNM 93348, and USNM 401499.

Discussion.— For a number of years, specimens la-
beled Enoploura in the USNM and other collections
have been known, but were unfigured in earlier works
because of their incomplete nature and because of some
uncertainty as to their correct generic assignment. Re-
cently, incomplete specimens with well-preserved car-
apaces were discovered in the collections of the MCZ.
The presence of a placocystitid plate, the exclusion of
the MA plate from the proximal carapace margin, and
the distinctive ornament on the adaulacophoral plates
demonstrate that these specimens are truly assignable
to Ateleocystites. They seem to be quite close to the
type species, 4. huxleyi.

Several specimens show rather complete aulacop-
hores. They are long, fully extended, and not reflexed
back toward the theca as is typical with anomalocys-
titids, especially specimens preserved in younger stra-
ta. Also, the number of distal aulacophore segments
in these specimens is estimated at between 25 and 30.
In A. guttenbergensis, Kolata and Jollie estimate there
are 35 to 40 segments in the distal aulacophore. In
both species, counts were estimated on nearly complete
distal aulacophores. However, the thecal size in the
illustrated examples of A. guttenbergensis appears to
be about one-half that of A. cf. A. huxleyi. As in En-
oploura, the number of distal aulacophore segments
seems variable, and the number of segments alone
probably is not of taxonomic significance.

Suborder PELTOCYSTIDA Jefferies and Lewis, 1978

Diagnosis.—Mitrates with an asymmetrical theca,
number of thecal plates reduced, two especially large
adaulacophorals, these in some genera considerably
overlapped along superior sagittal axis: single tapering,
slightly sigmoidal articulating spine on right distal end
of theca: aulacophore long, ossicles of proximal seg-
ments of distal aulacophore especially spinose.

Discussion. —Jefferies and Lewis (1978, p. 422) re-
moved the superficially-similar peltocystids from the
Lagynocystida because of the lack of common mor-
phological traits. Lagynocystis Jaekel, 1918, has a hol-
low articulating spine on left side of the theca and three
adaulacophorals on the superior surface. The proximal
aulacophore is quite different from that of the Pelto-
cystida, and the styloid is considerably more dentic-
ulate (see Jefferies and Lewis, 1978, p. 422). The Pel-
tocystida do not have internal ctenoid organs, which

38 BULLETIN 336

are a diagnostic feature of Lagynocystis, and the prox-
imal plates on the superior surface of peltocystids are
large and paired.

This suborder is now divided into two families, the
Peltocystidae and the Kirkocystidae. The Peltocystidae
is characterized by the single genus Pe/tocystis Thoral,
1935 from the Early Ordovician of France. Asymmetry
in the marginals and intracentrals is marked in Pel-
tocystis, and reversal of the basic asymmetrical plate
order (see Ubaghs, 1968a, p. SS00; Ubaghs, 1969, p.
82) is also evident. The single sigmoidal articulating
spine, large adaulacophorals, and similar aulacophore
seem sufficient to demonstrate close relationship to the
other peltocystid family, the Kirkocystidae.

The Kirkocystidae, with two genera, represents the
end-point in the reduction in number of thecal plates
in the Mitrata. In Anatiferocystis Chauvel, 1941, adau-
lacophorals are the dominant plates and make up most
of the theca. Marginals M1/M'1 are extremely asym-
metrical and are completely restricted to the inferior
surface. A large distal marginal flap on the infradistal
end completes the theca, except for a narrowly-exposed
infraplate (probably an ingressed marginal), adjacent
to the right adaulacophoral, which bears the single,
articulating, sigmoidal spine. Balanocystites Barrande,
1887 is quite similar to Anatiferocystis, but does vary
slightly (see Ubaghs, 1968a, pp. S555, S557; Jefferies,
1981, p. 374).

Family KIRKOCYSTIDAE Caster, 1952

Diagnosis.‘4—Theca convexoplanar, asymmetrical,
composed of only two adaulacophorals, two marginals
(M1, M’1), one subanal, and in some an internal mar-
ginal (?7M5 or ?M’4) with articulating distal spine;
adaulacophorals convex, elongate, subequal, very large,
covering entire superior face and large part of inferior
face; M1 and M’1 reduced, M1 smaller than M’'1, M’1
extends distally to subanal, which is inserted between
distal lateral inferior margins of adaulacophorals;
proximal region of aulacophore composed of four te-
tramerous segments; styloid and following distal au-
lacophore ossicles inferiorly spinose.

Occurrence.—Kirkocystids are found in the Middle
Ordovician of North America (Oklahoma) and Europe
(Bohemia). Recently a probable kirkocystid of Mor-
rowan (Pennsylvanian) age was uncovered in the Gene
Autry Shale Member of the Golf Course Formation in
southern Oklahoma. This specimen is the youngest
known mitrate and extends the upper range of this
group by about 70 million years (Frest, Kolata, and
Mapes, 1985).

Discussion.—The Kirkocystidae are probably de-
rived from the Early Ordovician genus Peltocystis

'* modified from Ubaghs, 1968a, S555.

Thoral, 1935, or a Peltocystis-like ancestor. Features
such as the very similar aulacophores, sinuous single
articulated aboral spine, large paired adaulacophorals,
and distally-extended M’1 on the inferior surface all
suggest close affinities. The probability that the spine-
bearing plate in Anatiferocystis is an ingressed marginal
in contact with M’1 further supports this close rela-
tionship.

Marginal plates present in a Peltocystis-like ancestor,
other than M1 and M’1, may also be fused within the
adaulacophoral plates along the inferolateral ridges,
but their presence is doubtful. Both superior and in-
ferior centralia, probably present in the ancestral stock,
have been lost in the Kirkocystidae, nor are they added
during ontogeny. The greatly reduced number of thecal
plates, and the ingression of M’4 or MS suggests a
paedomorphic mode in the derivation of the kirko-
cystid from the peltocystid theca (/.e., many distal plates
present in ancestral stock are omitted, just as they are,
but to a lesser degree, in the evolution of the anom-
alocystitids). The streamlining and reduced size of the
kirkocystid theca, the powerfully-constructed proxi-
mal aulacophore, and the long distal aulacophore in-
dicate adaptation to a more mobile mode of life.

Genus ANATIFEROCYSTIS Chauvel, 1941

Lagynocystis Jaekel. Chauvel, 1937 [pars], p. 3.

Anatiferocystis Chauvel, 1941, pp. 206-210; Ubaghs, 1968a, S555;
Ubaghs, 1979, pp. 107-111, fig. 4.

Enoploura? Wetherby. Bassler, 1943 [pars], p. 695, pl. 1, figs. 3-5.

Kirkocystis Bassler, 1950, p. 277, p. 275, figs. 15, 16.

Type species.—Anatiferocystis barrandei Chauvel,
1941.

Diagnosis.‘*5—Theca convexoplanar, asymmetrical,
tapering distally, made up of six plates: two adaula-
cophorals, two marginals (M1, M’1); distal marginal
(M'4 or M5) with spine articulation, plate almost com-
pletely internal except for narrow exposure adjacent to
subanal, and inclined, distally situated subanal; sutures
between adaulacophorals commonly overlapped.

Discussion.—The study of European species of An-
atiferocystis, A. barrandei (the type species), and A.
spinosa, has been primarily by use of latex rubber molds
and casts. Principal details of the thecae in both seem
much the same as in the North American species A.
papillata (Bassler, 1943), which is preserved as original
calcite material. A. spinosa Ubaghs, 1979, preserves
considerable aulacophore detail and some detail of the
articulating spine. Spines with their articulating sur-
faces are now known in A. papillata. Careful compar-
ison of the external features of A. papillata and A.
spinosa indicate that the two species, which appear to
be coeval, are also conspecific.

'S modified from Ubaghs, 1979, p. 107.

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 39

Anatiferocystis papillata (Bassler, 1943)
Plate 7, figures 5-9, 11-13, Plate 8, figures 1-11;
Text-figures 19, 20

Enopleura? [sic] papillata Bassler, 1943, p. 695, pl. 1, figs. 3-5.

Kirkocystis papillata (Bassler). Bassler, 1950, p. 277, figs. 15, 16.

Anatiferocystis papillata (Bassler). Ubaghs, 1968a, p. S555; Parsley,
1982, p. 323.

Anatiferocystis spinosa Ubaghs, 1979, pp. 107-111, fig. 4.

Diagnosis.'°— Anatiferocystis with theca covered with
numerous posteriorly-inclined small triangular spines.

Occurrence.—Letna Formation (Early Caradocian),
Haj near Zahorany, Bohemia, Czechoslovakia; Poole-
ville Member, Bromide Formation (Blackriveran),
Criner Hills, Oklahoma (see Parsley, 1982, p. 323)
[Locality N], Benbolt Formation (Blackriveran), east-
ern Tennessee (Broadhead, written commun., 1986).

Types.—Hypotypes: UCM 46036-46043, USNM
401450-401451, Locality N.

Description.—The superior surface (carapace) of the
theca is convex, and the inferior surface (plastron) is
slightly concave to planar (PI. 7, figs. 5, 6, 9, 11, 12;
Pl. 8, figs. 1-8, 11). The sides and carapace gently taper
distally to the asymmetrically-blunted end (PI. 7, figs.
7, 8; Text-fig. 19C). The theca is almost entirely made
up of the paired adaulacophoral plates. Both adaula-
cophorals are reflexed into an inferolateral ridge at the
proximal end of theca, which becomes diagonally lat-
eral distally (Pl. 7, figs. 6, 12, Pl. 8, figs. 3, 7, 11). The
suture between the adaulacophorals is considerably

‘© translated from Ubaghs, 1979, p. 108.

overlapped on the carapace; commonly the right adau-
lacophoral overlaps the left at a ratio of about 2:1.
There is little thinning of the plates along this suture.
Hence, the suture is marked by a step on the carapace
surface (Pl. 7, figs. 9, 11; Pl. 8, figs. 1, 2, 4, 6).

On the plastron, marginals M1, M’1 form the in-
ferior proximal margin. M1 is small, rectangular, and
is developed only as part of the marginal rim. M’1
extends distally as a narrow band between adaulaco-
phorals to the subanal (Text-fig. 19); and the adaula-
cophorals may overlap the lateral surfaces of M’1 so
that the plate seems inset into the plastron surface.

Between the right adaulacophoral and the subanal
is a narrow, slightly arcuate plate that commonly ap-
pears to be set slightly on edge. This is the external
exposure of a larger ingressed marginal plate that ex-
tends from the right distal margin, proximally to the
midline of the theca, where it terminates against the
distal extremity of M’1. At the distal margin of this
plate is a short peglike extension with a terminal ar-
ticulatory surface for a moveable spine (PI. 7, fig. 7,
Pl. 8, figs. 7, 11). For reasons given below, this plate
is presumed to be homologous with M’4 or MS. (Text-
figs. 19, 20).

Serial sectioning shows that the septum extends from
the apophyses, across the interior of the right adam-
bulacral to its termination, apparently under the spine
boss on M’4 or M’S. :

Proximally the variably-shaped subanal is hinged
against the left adaulacophoral, M’1 and M’4 or MS.
The plate seems tightly sutured but probably could

Text-figure 19.—Carapace and plastron of Anatiferocystis papillata (Bassler). This figure is based on UCM 46036 (PI. 7, figs. 5-7). A, superior
(carapace) surface; B, inferior surface (plastron); C, right lateral view. S = subanal plate; sa = spine attachment base.
For explanations of other plate abbreviations, see Table | (foldout inside back cover).

40 BULLETIN 336

open sufficiently to allow for passage of fecal material
(Pl. 7, fig. 6; Pl. 8, fig. 7; Text-figs. 19, 20). The distal
edge of the subanal is denticulate (seen only in well-
preserved specimens).

The lateral and inferior aulacophoral rim is equipped
with ridges and shallow pits, which probably served
for muscle attachment. Adaulacophorals have a raised
triangular area on the outer inferolateral corner of the
theca. The central part of this area is roundly excavated
with the deepest part adjacent to the juxtaposed mar-
ginals. Marginals M1/M’1 are similarly raised in nar-
row rectangular fields adjacent to the aulacophore in-

Text-figure 20.—Anatiferocystis papillata (Bassler). S.E.M. pho-
tographs of plastrons, showing the nature of 7M’4 and its spine base.
A, Undisturbed plastron showing plate sutures. UCM 46047. B,
Plastron with subanal displaced to an on-edge position. ?M’4 is more
clearly seen as being ingressed at a low angle into the theca. UCM
46048. Photos taken on an Amray 1700 S.E.M. at a power setting
of 30 kv.

For explanations of plate abbreviations, see Table | (foldout inside
back cover).

sert area and are similarly roundly excavated (PI. 7,
figs. 12, 13, Pl. 8, figs. 3, 7). These depressed areas
superficially resemble scutelae (normally internal
structures), and probably served a similar function (i.e.,
aulacophore muscle attachment). A broad low ridge
on the proximal ends of the adaulacophorals may also
have served for muscle attachment.

The surfaces of the superior and lateral faces are
covered with short, distally-inclined, triangular den-
ticles (see Ubaghs, 1979, pp. 108-110, fig. 4e). They
are concentrated along the proximal-—lateral margins
where the distal cant is especially prominent, but are
otherwise evenly distributed over the superior surface.
Denticles are present on the plastron but are restricted
to the adaulacophoral plates, especially the left. They
are more symmetrical than those on the carapace and
without distal cant. The epistereom is quite thin on all
of the plates and slight surface erosion exposes the
coarser stroma in the interior of the plates.

The aulacophore insertion area is large and encom-
passes nearly the total width and height of the theca.
Into this cavity the proximal aulacophore is tightly
inserted (Pl. 8, fig. 9). Apophyses have not been ob-
served. The proximal aulacophore is made up of four
tetramerous segments that sharply taper toward the
styloid. In cross-section, it is an inflated oval; the lat-
eral margins are sharply angled, the superior and in-
ferior faces flatly and evenly curved. The edges of the
segments are slightly thickened and fluted. The styloid
is poorly known, but is significantly narrower than the
proximal aulacophore. There appear to be two infer-
iorly-directed spines, connected by a narrow septum
on the inferior surface.

Distal aulacophores, known only from Bohemian
specimens, are made up of from 40 to more than 45
segments. Each segment consists of an ossicle with
paired dorsal covering plates. Covering plates overlap
the proximal part of each distal cover plate pair. The
proximal ossicles are produced into sharp styloid-like
flanges, presumably to grip the substrate.

Total length of the aulacophore exceeds three times
that of the theca and in terms of the ratio of length of
aulacophore to length of theca, is the longest aulacop-
hore known in the Mitrata (see Ubaghs, 1979, pp. 109,
figs. 4a—d, f, g, 110).

The distal articulating spine is thin, slightly curved,
and gently tapering from its thickened basal area. It is
about one-half the length of the theca and is apparently
curved toward the sagittal axis (PI. 8, fig. 10).

Discussion.— Derivation of these unusual kirkocys-
tid genera (Anatiferocystis Chauvel, 1941, and Bal-
anocystites Barrande, 1887), is clearly the result of re-
duction in the number of thecal plates from a more
abundantly-plated ancestor. The large paired adaula-
cophorals on the superior thecal surface are distinctive

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 41

in all genera in this suborder. In kirkocystids, distal
centralia in ancestral forms have been eliminated by
the distal extension of this large plate pair. Similarly
the lack of marginal plates, almost certainly present in
the ancestral stock, is difficult to explain. They have
either been excluded, with the exception of M1, M’l,
and the ingressed marginal M’4 or MS, or they may
be fused into the theca (primarily on the lateral and
inferior faces of the theca). This fusion, if true, would
have occurred along with the development of the re-
flexed lateral—ventral ridge, which in some specimens
appears to be a very tightly ankylosed suture. If ho-
mologies with Pe/tocystis Thoral, 1935, are valid, M2,
M3, and M4 on the right side, and M’2 and M’3 on
the left may be retained in the theca, fused to their
adjacent adaulacophorals or, perhaps, some of the el-
ements may be incorporated, and others omitted.
However, I suspect that with the exception of M1, M’1,
and the ingressed marginal, all of the marginals have
been excluded in the phylogeny of the kirkocystid lin-
eage. Discovery of intermediate forms would probably
throw light on this matter.

The ingressed marginal is called M’4 or M5 because
it has the spine base and is tentatively assumed to be
homologous with the spine base-bearing M’4 or M5
plate in Peltocystis. M4/M'4 plates are commonly the
moveable spine-bearing plates among mitrates. If M5
of Peltocystis (as designated by Ubaghs, 1969, p. 82)
is in reality M’4, then the relationship of marginal plate
to articulated spine remains constant. The markedly
asymmetric nature of the marginal thecal plates in Pe/-
tocystis suggests this interpretation is correct. Whether
or not the ingressed spine-bearing marginal in Anati-
ferocystis is homologous to M'4 or to M5 of Peltocystis
is speculative.

The subanal is commonly oblique to the sagittal axis
and at best was capable of limited opening, enough to
allow for the passage of fecal material. Similar subanal
plates in Balanocystites and Chinianocarpos Ubaghs,
1961, also appear to be tightly sutured, and at best
were capable of limited movement. This would seem
to refute Philip’s (1979, p. 468) opinion that mitrates
possessed U-shaped guts, with mouth opening and anus
at the distal end of the theca. Feeding at this end of
theca, involving movements of the subanal plate in
these genera, would appear to have been difficult and
unlikely. In Chinianocarpos, mouth and anus would
have had to open into the substrate. There is no evi-
dence that mitrates were ever deposit feeders.

Overlap of the adaulacophorals on the superior sur-
face is considerable, with the right adaulacophoral
overlapping the left with a ratio of about 2:1 (Pl. 8,
figs. 2, 6). There may be a tendency in this suborder
toward minor reversals in right—-left thecal symmetry,
which may be related to asymmetry of infracentral

plastron plates seen in Peltocystis (see Ubaghs, 1968a,
p. S500; Ubaghs, 1969, pp. 82-84). No apparent reason
or cause for the reversal of overlap in Anatiferocystis
seems apparent. The consistent overlap ratio seen in
specimens from various localities does suggest, how-
ever, uniform genetic control.

Life habits of Anatiferocystis probably differ slightly
from those of the anomalocystitids and most of the
other mitrates as well. The small, compact, streamlined
theca and unusually long aulacophore suggest a more
mobile organism. Undulations of the aulacophore
probably originated in the proximal aulacophore and
were translated through the styloid to the laterally-
compressed distal aulacophore. Several simultaneous
waves may have been possible, thus allowing the an-
imal to swim with a minimum of thecal yawing. Un-
dulations would have propelled the animal, theca end
first, in tadpole fashion above the bottom. The stream-
lined hydrofoil shape of the theca would provide lift
and the diagonal lateral ridges would have served as
hydrofoils to keep the distal end horizontal or facing
slightly upward while the aulacophore was sculling.
Likewise, the single articulating spine may have in part
had a hydrofoil function, as well as serving as a buttress
while the animal was at rest.

The sharp ventral spines on the distal aulacophore
(see Ubaghs, 1979, p. 109, figs. 4b, d, f) would seem
to indicate that the aulacophore stretched out along
the bottom, taking in nutrients just above the water—
sediment interface. If the aulacophore faced into a cur-
rent, as the moveable spine and curvature of the au-
lacophore ossicle spines suggests that it did, then the
slightly-arched aulacophore would have effectively
trapped food particles moving just off the bottom: the
method of feeding suggested for all other Mitrata.

APPENDIX
Collecting Localities

A.—“‘Jerusalum Hill”!’. Manlius Formation, Olney Member,
Saltsburg quarries, Dayville, New York.

B.— Unknown locality, Lower Helderberg, Litchfield, New York'®.

C.— Manlius Formation, Olney Member, Saltsburg quarries, Days
Corner, Herkimer Co., New York.

D.—Ridgely Formation, Cumberland, Maryland’’.

E.— Whitewater or Saluda formations, Richmondian, Oxford, Ohio.

F.—Cannon Limestone, 0.5 mi*° north-north-east of Pulaski, Ten-
nessee [label reads 1.5 miles], Bassler, 1932. Guensburg (written
commun., 1987) feels certain that this material is from the lower
part of the Catheys Formation (Edenian).

'’ this locality may no longer be extant.

'8 information from museum label.

'? see Derstler and Price (1975), Derstler (1979).

20 label reads 1.5 miles; Guensburg (written commun., 1987) feels
certain that this material is from the lower part of the Catheys For-
mation (Edenian).

42 BULLETIN 336

G.—Curdsville Member, Lexington Limestone, Curdsville, Mer-
cer Co., Kentucky?!.
H.— Whitewater Formation, in road cut south of Liberty, Indiana.
I.—Grant Lake Formation, Corryville Member, Stonelick Creek,
Clermont Co., Ohio.
J.—Grand Lake Formation, Warren Co., Ohio.
K.—Bull Fork Formation, Boudinot Ave, Cincinnati, Ohio.
L.—Elkhorn or Whitewater formations, one mile northeast of
Camden, Ohio, on Seven Mile Creek, parallel to main highway~*
M.—Glens Falls Limestone, Trenton Falls, New York.
N.— Upper Pooleville Member, Bromide Formation, Criner Hills,

2! information from museum label.
22 information from museum label.

Carter Co., Oklahoma. All specimens are from Rock Crossing (Sprin-
kle, 1982).

O.—Kirkfield Limestone, Kirkfield, Ontario.

P.— Waynesville Formation, along railroad cut number 13, lower
3, SEY, Sec. 8, T. 6 N., R. 2 W., Suman 712’ Quadrangle. near Weis-
berg, Indiana.

Q.—Fairview Formation?, Cincinnati, Ohio’.

R.—Hull Beds, Ottawa Limestone, Brigham Quarry, near Hull,
Quebec.

S.— Unknown locality, Hull Beds, Ottawa Limestone, presumably
close to Brigham Quarry, near Hull, Quebec.

T.—Martinsburg Formation, Swatara Gap, Lebanon County,
Pennsylvania: Middle Ordovician.

23 information from museum label.

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46

Figure

BULLETIN 336

EXPLANATION OF PLATE 1

1=1'4% AnomalocystitesicornutusiElallon neice aioe ae ees etsierisincie elicit eee ise tec ei eto eter eeeee

1-4.

ANMH 2288 [syntypes], Locality A. 1, disturbed specimen, mostly the carapace and proximal aulacophore, 2.5; 2,
eroded specimen showing interior of the plastron [Note the transverse ridge, part of one movable spine attached, proximal
aulacophore, and part of the distal aulacophore-covering plates.], x 2.5; 3, plastron with proximal aulacophore and attached
eroded styloid, x 3.0; 4, carapace with proximal aulacophore and part of distal aulacophore attached, x 3.0.

. NYSM 15010, partial carapace with most of aulacophore intact and attached, x 2.5, Locality A.
. USNM 35079, poorly-preserved theca with proximal and distal aulacophore attached, x 3.0, Locality C.
. UCM 46044, plastron with proximal aulacophore, x 2.0, Locality B.

NYSM 15011, plastron with proximal and most of the ventral distal aulacophore exposed, x 2.5, Locality A.
USNM 35078, lateral view of the styloid and adjacent distal aulacophore segments [Other aulacophore segments are in
the upper part of the figure.], x 0.5, Locality C.

. UCB D-1875, eroded specimen, (mostly) interior of plastron exposed, distal marginals of carapace are intact, x 3.0, Locality

A.

. USNM 35078, 11, carapace with eroded proximal aulacophore, x 3.0; 12, incomplete carapace with proximal aulacophore

and twisted styloid attached, x 4.0; 13, eroded and distorted carapace [Note the displaced distal end of the distal aulacophore
resting on the specimen.], 4.0; 14, proximal end of carapace with distorted proximal aulacophore and twisted distal
aulacophore attached [Note the rarely-preserved placocystitid plate.], x 3.0, Locality C.

PLATE |

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 100

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 100 PLATE 2

Figure

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY

EXPLANATION OF PLATE 2

Nl Gem A MOMMAIOCY SELLCSICOPRULUS ELAM 525 0 oc5 cs jes aoete econ cae eee ae ak redeem eee che = le Se ste cael cy oth Sethe oad a yelepegetere are eee Eva CORREIA
All specimens from Locality D.

1-5.
6-9.

HOM 135 15:

12, 14, 16.

USNM 33661A, carapace, left lateral, distal, proximal, and plastron views of a nearly complete theca, x 2.0.
USNM 33661B, plastron, distal, proximal, and right lateral views of a nearly complete theca [Note the well-
developed “runners” or skids and the beveled lip at the distal end of the theca in figure 6; the well-preserved spine
bases and inset anal opening in figure 7; and the attachment area for the proximal aulacophore in figure 9.], x 2.0.
USNM 33661D, proximal, right lateral, carapace, and plastron views of a theca damaged in the proximal carapace
area, x 2.0.

USNM 33661C, plastron, distal, and carapace views of a proximally incomplete theca [Note the rectangular inset
anal opening in figure 14.], x 2.0.

47

48 BULLETIN 336

EXPLANATION OF PLATE 3

Figure Page
1=152 Anomalocystites\cornutus TRA o-s.ye.cs- © isis oie «eter es rete cree ra intent meses eoeiolenoiel oheh revels el she efatetetenst sists eketel teckel eee 20
All specimens from Locality D.
1, 3. USNM 33661E, carapace and plastron views of a nearly complete theca (except for the proximal area of the carapace)
[Theca is slightly skewed.], x 2.0.
2. USNM 3366C, left lateral view of a carapace, x 2.0.
4-7. USNM 33661F, (mostly) internal plastron, distal, external plastron, and oblique internal plastron views of an incomplete
theca [Note in figures 4 and 7, the transverse ridge, muscle pits, and aboral platform, and in figure 7, the fractured
echinoid-like pillars adjacent to the anal opening.], x 2.0.
8, 10. USNM 33661G, carapace and plastron views of a nearly complete but skewed theca, x 2.0.
9, 11-15. AMNH 2720, (mostly) internal plastron, left lateral, right lateral, proximal to distal oblique view of the internal plastron,
distal, and proximal views of an incomplete theca with most of the carapace missing [Note the well-developed transverse
ridge and echinoid-like pillars adjacent to the muscle pits and distal aperture.], x 2.0.

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 100 PLATE 3

Hdl fee T

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 100 PLATE 4

Figure

1-4. Enoploura balanoides (Meek)

5-9.

10-12.

NorTH AMERICAN MITRATE STYLOPHORANS: PARSLEY

EXPLANATION OF PLATE 4

UCM 37296. Holotype of Enoploura crustacea Haeckel, 1896, carapace, right lateral, left lateral, and plastron views of a nearly
complete theca with attached proximal aulacophore, x 2.25, Locality E.

Enoploura punctata Bassler

All specimens are syntypes (USNM 91856), from Locality F.

5.

6.
Te
8.

9.

Kierocystis insertus, new genus and species

Carapace with articulating spines and distorted proximal aulacophore attached [Note the transverse ridge on the internal
surface of the plastron exposed by erosion of the carapace plates.], x 3.0.

Lateral view of a deformed proximal aulacophore, eroded styloid, and proximal segments of the distal aulacophore, 5.0.
Nearly complete carapace with the attached poorly-preserved proximal aulacophore and part of the distal aulacophore, x 2.75.
Carapace with the internal surface exposed; the distorted proximal aulacophore is also exposed [Part of the right articulated
spine is also present.], x 3.5.

Slightly distorted carapace with the movable spines articulated; proximal aulacophore incomplete and distorted [This specimen
has been considerably prepared since its first illustration by Bassler (1932, p. 18, figure 9, lowermost specimen).], x 3.5.

USNM 42166 (holotype), from Locality G.

10.
Wyte

12.

Carapace with incomplete proximal aulacophore and discontinuous distal aulacophore, ~ 3.0.

Poorly-preserved and incomplete plastron with proximal aulacophore, eroded styloid, and several segments of the distal
aulacophore attached, x 3.0.

Proximal area showing the proximalmost upper tetrameres of the proximal aulacophore inserted into the carapace, x 5.0.

49

22

50 BULLETIN 336

EXPLANATION OF PLATE 5

Figure
1=5:'8\ 10: Enoploura punctata Bassler. ..:../- 22%: 5)2,0 cc's) 2m =ravsictercsel ove sieters sievous)sisievel= sieteve o eropeleleVaiere oe, Sisislcl skoxe) <i et Ree eee eee eae
1-5. All specimens from Locality F. 1, USNM 91854, theca with (mostly) internal surface of the plastron exposed, proximal
aulacophore, styloid, and short section of distal aulacophore attached and deformed, x 4.0; 2, USNM 91854, deformed
theca, carapace exposed, proximal aulacophore attached, and deformed, x 3.5; 3, USNM 91854 (syntype: see Bassler,
1932, p. 18, figure 9, specimen on upper right), weathered carapace with part of the internal surface of the plastron
exposed, x 3.5; 4, USNM 91854, eroded carapace showing part of the tranverse ridge on the internal surface of the
plastron, proximal aulacophore, and several segments of the distal aulacophore attached, x4.0; 5, USNM 91854,
deformed proximal aulacophore, eroded styloid, and nearly complete ventral distal aulacophore, x 3.0.
8. USNM 91854, plastron and attached proximal aulacophore, x 4.0, Locality F.
10. USNM 91854, distal end of plastron (lip) with denticulate platelets which are probably functional or vestigial anal-
pyramid plates [Note adjacent proximal part of the articulated spine with stereom structure preserved.], x 7.5, Locality
FE:
6;.7, Enoploura'cf. E: balanoides\(MeeK)) << ..2.2-</0:<:<cccos «015, sac, «jes nse ain 4101 o elo rere ale ote ske olay) Sees aisia. s]noie 2 Re eteioieel ets ee eee
Both specimens x 3.0, from Locality Q.
6. UCM 46045, proximal carapace with proximal aulacophore and several segments of the distal aulacophore attached.
7. UCM 46046, eroded plastron with proximal aulacophore, eroded styloid, and several distal aulacophore ossicles attached.
9-1. Enoploura:chE: poppet! Caster, cx jis -s 000 << jenn sapere o 0s alas a) oser ny yaa coe see Tene od Xr N ey VTS We eee TOTS Tee
9. UCM 43378, eroded carapace with paired spines nearly articulated [Note spines on distal marginal plates of carapace.
Stereom structures are visible on most of the plates. This specimen is unusually large for a mitrate.], x 2.0, Locality H.
11. USNM 145586, carapace with attached poorly-preserved proximal aulacophore and part of the distal aulacophore,

x 2.5, Locality P.

33

34

PLATE 5

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 100

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 100 PLATE 6

Figure

1-3, 6-9, 11.

. Enoploura species

NoOrTH AMERICAN MITRATE STYLOPHORANS: PARSLEY

EXPLANATION OF PLATE 6

ENOplouraipOopel Caster ree cece ei oe ee eee Te ee Se Aid EAE Se aes NE ENG TE SS LE Dale lataIe BLS alee wise mars, Siete Says elke

1-3. UCM 25993 (holotype), carapace, left lateral, and plastron views [Theca is slightly distorted with the proximal part
of the right spine proximal aulacophore, well-defined styloid, and several proximal elements of the distal aulacophore
attached.], x 2.0, Locality I.

6-8. UCM 46049, distal ends of distalmost styloid blades [Note the deep muscle pits and narrow slit for the food groove.],
x 3.0, Locality K.

9. UCM 46049, lateral view of a styloid that is composed of three fused ossicles, x 6.0, Locality K.
11. UCM 46049, proximal end of styloid blade [The deep pit is continuous with the lumen of the proximal aulacophore.],

x 3.0, Locality K.

USNM 40704, lateral and ventral views of a nearly complete aulacophore [Distal aulacophore appears to be preserved in

the feeding position.], x 3.0, Locality J.

EE RODLOUTASPUNCLALANDASSIEL Se rie ye eee oes as were Te ee BORO STE et eTe eT) HeLa cfapee nave rote eran sicha elarsteastetetes here syerers

Both specimens are USNM 91854, x 3.0, Locality F.

10. Incomplete carapace with a spine and most of the aulacophore attached.

13. Eroded carapace with eroded proximal aulacophore and eroded proximal segments of distal aulacophore.
EnoplouraictE- ‘balanoidesi(NUeek)) mys creraretc ave: ave isve scares 5 yous el nya at avaie a Sten eer aoe etece ns slenad slater 20 'e-artte Stee teers chevataneie treveeeveiera tere
UCM 31309, proximal aulacophore with partal styloid blade and poorly-preserved distal aulacophore segments attached,
x 3.0, Locality L.

Si

32

30

33

52

Figure

1-4. Ateleocystites cf. A. huxleyi Billings

Ile

Bry

4.

5-9, 11-13. Anatiferocystis papillata (Bassler)

5-7.

OMS:

AE 2:

10. Kopficystis kirkfieldi, new genus and species

BULLETIN 336

EXPLANATION OF PLATE 7

MCZ 1063, incomplete and eroded carapace with an attached distorted proximal aulacophore and the proximal
half, or so, of the distal aulacophore, x 4.0, Locality M.

MCZ 2064, proximal carapace with the proximal aulacophore and several poorly-preserved distal aulacophore
segments attached [Note the well-preserved placocystitid plate.], x 4.0, Locality M.

. USNM 93348, incomplete plastron with poorly-preserved proximal aulacophore and styloid; distal aulacophore

essentially complete, x 2.5, Locality M.

USNM 401499, distally-incomplete plastron, proximal aulacophore, weathered styloid, and part of the distal au-
lacophore, x 2.0, Locality M.

UCM 46036, carapace, plastron, and right lateral views of a theca with distorted and displaced proximal aulacophore
[Note the spine base for the single articulating spine in figure 6.], x 4.5, Locality N.

UCM 46037, right lateral view of a theca, 4.5.

UCM 46039, carapace and incomplete plastron views of a theca with an incomplete proximal aulacophore attached,
x 4.5, Locality N.

UCM 46038, carapace and plastron views of a theca [Note the axial displacements of the plates of the plastron.],
x 5.0, Locality N.

USNM 116408 (holotype), slightly distorted carapace with an incomplete distal aulacophore attached [Note the anal-pyramid
platelets at the distal end of the theca exposed by erosion of the overlying CM series.], x 4.5, Locality O.

39

35

PLATE 7

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 100

PLATE 8

BULLETINS OF AMERICAN PALEONTOLOGY, VOLUME 100

NORTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 53

EXPLANATION OF PLATE 8

Figure Page
MeN MMPA TALIS CrOCY STIS} PAPEL Ata: (EXASSIEN) fe casysscb e551) S502 ses REESE 8 ie STENTS SE UDI SH 08 SPERSP ONS vate Sin Vos lone aa or ata eres Seas oy eusisKoeeeehonetee 39
1, 3. UCM 46037, carapace and disturbed plastron of a theca with remnants of the proximal aulacophore attached, x 4.5, Locality
N

2. UCM 46040, carapace of a theca, x5, Locality N.
4,5. UCM 46041, carapace and plastron of a distally-incomplete theca [The incomplete distorted proximal aulacophore is
attached.], x 4.5, Locality N.
6, 7. USNM 401450, well-preserved carapace and plastron of a theca [Note the protruded subanal plate and spine base.], x 4.5,
Locality N.
8, 11. USNM 401451, carapace and plastron of a theca [Note the well-defined spine base at end of plastron.], x 5.0, Locality N.
9. UCM 46042, proximal view of a theca with attached distorted proximal aulacophore, x 6.0, Locality N.
10. UCM 46043, theca with articulated spine lying across it [Note the stereom structure of the spine.], x 5.0, Locality N.

54 BULLETIN 336

INDEX

Note: Page numbers are in light face; plate numbers are in bold face type; the page numbers on which principal discussions occur are in italics;

B indicates the foldout inside the back cover.

DOr alGisCUSSE ep aaesces coe stes orees oh sent acsseasiseneccsssecaeaceszccess 9
PANTO be Sone eC OGEE ECE COEEEE DOCSEGEEE EEC EEE CRETE RECT ERC EEE REE EE scepconesoca 6
IN OME Sees oe seers aes cee taee dc ossacariesdibineaasssasevaveeversses 6,7
SOU th igrercc coos cesccn see sc cee ce creole ws ses ob acstuser se dsseuesveccatesceseee= 16
africanus, Placocystis 16
Allanicytidiidae Caster and Gill in Ubaghs, 1968a ............ 17,19
Allanicytidtinae cere cssrrcer ce eo sncre cs weer ca enone sel aeseceersss 5,16,17,19
Allanicytidium Caster and Gill in Ubaghs, 1968a ..............-......-.
Ba SES EEE EE aCSOSSEB RECEP OCC AS EI SECCOSCES eRe EEE Eee 10,11,16,17,19,20
AmecystisiUlnchvand Karke 920) © coin. cescdecse-sesconceecsostecesessss 6
AMNH [American Museum of Natural History, New York, NY,
WES PAG ress concceescoxteet vests oos te sevececscvetdeseexsutes 18,22,46,48
AmygaalothecalUibaghs: 1969) nc.c-c.-csese--=-20ceassecessccesee 10,14,15
Anatiferocystis Chauvel, 1941 ... 15,38,40,41
barranden@nauveledl GA lierces.s0.<ccesccnsecosesseeecsssereete sco stee ee 38
papillata (Bassler, 1943) .................. 38,39,40,52,53
SDIMOSQAO DASHS a liOi1. 9) name cenaes asec scddacss cessed tccscasccscesseeses 5,39
Anomalocystida Caster, 1952 18
ANOMGIOCYSTISHEAAM re cncas sestone ce s8 acco seten eee se eeeeenoeneeaeccnse eens 19
Anomalocystites Hall, 1858 ...... 9,10,13,17,79,20,22,23,32,35,36
DATANOIGeSi(INICOK) soe core snes od ox soees eases eae een neat neato 32
cornutus Hall, 1859 .......... bp ee} Bae 5,18,20,22,35,46-48,B
GISDAFIIISHEAA 85 9 eesecccer scene cescuce eee cesesecereencensseaees 5,20,26
huxleyi (Billings) 37
Anomalocystites (Ateleocystites?) Meek, 1872 ..................2...- 36
DAlANOIdeSWNICEK IS 12 ie cerew cc. coe Fare oreo ce eon nee 23,32
Anomalocystitida Caster, 1952 ...................000 5,16,18,19,20,35
Anomalocystitidae Bassler, 1938 ..................... 5,16,17,19,20,23
Anomalocystitinae Bassler, 1938 $16, 07519:23
ANOMOCYStiS all! oocc2scccccoscs occ ccecccasccssctecacceceesecescsseseccetoes 19
Antedonikreminvilles 18! coe. .c.-ceccescescceccececccacnescecsescceceeees 14
ANITIOLA ARS vas sons Boeee can can teens sda deauesteeet bases wetsvedesieeSeeWeteerstexs 18
Asia 6
ASDIAOCATPUSIU BARNS. wl 97.9 Wese.cacecscucees scesccneazesccsceconetareeesee 15
Atelecystisi Billings |i. .cceec.csscsssseesssessecsceevecovscs osscsseeseseneeeoeres 36
hnuxleyit(Billimgs) ic cccccceccaseecce-seeceescssscoees teens: oonee weret tees 37
PALCICOGYSTISINUXI CVU (BIULINGS) hececes: nce. ceetes scerecsecaneorseensenceees 37
Ateleocystites Billings, 1858 .......... 9,10,13,17-23,32,34,35,36,37
balanoides) (Meek) fee cx2cccccees <0 = 2 ce 2e<0-<ccrd sone anes -eeteeee eee 32
guttenbergensis Kolata and Jollie, 1982 .................... 26,36,37
huxleyi pilings 8S 82 --scc---<-2--00cccceseoees>
cf. A. huxleyi Billings, 1858 .................
Ateleocystites Lindstrém, non Billings
Atelocystites/Haeckel;s 896) cere .<-.ce-seecencscasnesss sos evcdececetecvesves
Australia sre vac cceese cee coeeeeseh voices ov'ee dea ves scuasceccessieterseess

Australocystinae’ Caster, 1954b) <..........<1csccses<c-vssevcscece 16,17,19
AustralocystisiGasters VWO54D ie. cssencseccrse coe ccecceseece seer were 16,17
Balanocystites'Barrande:; 1887) ..:...:<.......0.csc-s22eee 15,38,40,41
balanoides,
ANOMALOCYSUILES sci sacotessassaces de duscasewscoccestesoceeesneetoee rete 32
Anomalocystites (AteleOcystites?) .........csccccceecenccneceeeeees 23,32
ALCLCOCYSUILES so ccvsdvcsccswuses sanndevneavatodeadete satecnecneseieeeeete 32
Enoploura ...... 4 §,18,32,33,34,36,49
balanoides (cf.), Enoploura .................0.-.06++ 5.0) cece: 33,50,51
Barrande: (887) mesectsscsccssecescescomaceeseeecerees 9,12,15,19,25,38,40

barrandei; AnatifeErOGySliS. ...c..ceeeesenee ete 38
Barrandeocarpus Ubaghs, 1979 .............022.c0cec00eeeee 15-17,34,35
Bassler (U9) \ sce. 22st trees cceeec 23,32,36,37

Bassler (1932) ....
Bassler (1935) .......
Bassler (1938) .2.cscc..cescexssccsessssesecacstssstavescuecnveseeseeeeeeeeeeeet
Bassler(1:943)) « /ecccecevsseco00ce.vs-5 tere
Bassler (1950) heses.cce-cseoses secs
Bassler and Moodey (1943) .....
Basslerocystis Caster, 1952 ... oe Pe
disparilis: (Halll) ............-.c0..02-cee0ees steerer ee
Bather! (1899) )\ sccscccd.cccsccescosccesescoscvoscssseoseeree ee Ee
Bather (1900)
Bather (1913)
Belemnocystites Miller and Gurley, 1894 ...
Benbolt Formation. .....-....2+..0....s<.csssssectsesesescasce nee eee
Billings’ (854) ) << sc0s sen ovccccevecacss0sossescesacsseeeese cone ee TREE
Billings (1858) 5,9,10,18,21,23,32,34-36,37

5,25,30,32,41,49,50

Blastozoa‘ Sprinkles 1973: 2..ccsccsos0-cesccscesceceeee eee tne eee 6,7
BORG Ma aes orcs treat ee eae ec ons ee §-7,15,34,38,40
Haj) near. Zahorany. «.:....2.<2<5..6..sc.ss-0s-<s2-s500eenecateereeeneneetee 39
Branson’ and Peck (1940) secs... .. cccenescssseee terete eee Eee 12
British Museum (Natural History), London, England, U.K. ... 16
Broadheads. Te csciccc.cucccocsceevevesssavssostou carcveeeec eee eee eee 18,39
Bromide Formation, Pooleville Member ........................- 39,42
Bull Fork Formation) 222. 20.22 <0. 00 see ccaceenctasesscseene sense eeenees 42
Calcichordata Jeffermess W967) 22.0... sccessesescoeecestecaee ten taeneete 6,8,18
Cannon’ Limestone’ <. 2. <::2s<c.c.ccc0cesaconcctecsoneee cnet entero 30,41
Capensis; PlacOCystella cc .ssvccssescevessossseasstusccsceseeeeceeseeeneneen 16
@arlson(and) Fisher: (19811) <<. 5....c. aces nvccceessecees secceeseeee ere 8,12
@asteri(i952) vcs ccc cercsscescesses 5,14,18-20,23,24,28,30-34,36-38
Caster'(1954a)) .c.cc.0c.cscsescscccsevesnececvenncccess doe tesen eater Coe EEE eEEe 13
Caster (1954b) 16,19,20
Gasteri(GG8) eemsc ccs sceustsscscecbes con nete cease es sece eee 6,8,11,12,20
@asteri (MOSS) Ftecccseccseescns cossreeseseneeeeee .... 6,10,12,16,19,20
Gasters Dalveéesand Popes (1955))<.cccc---ce-ceeeceseenete
Easter Ke, Ee siciescenesseccsdscessestecssssetens nee
Castericystis vali Ubaghs and Robison, 1985. ...............0..000000+
Catheys Limestone Formation
Ceratocystis Jaekel, 1901 ...................

Chauvel (1937)
Chauvel (1941)
Chauvel (1981)
Chinianocarpos Ubaghs, 1961

Chordata
G@inctaJackeli918) cs.c2 5. foc. c. eaves cesta seen
Climacograptus spiniferus Zone
Colliers Fe. cece fics. cece. os coveusexcavcccosdedeensstecseesce sovsoenseuse wteeeee 16
Coonigan’ Formation ........;.c2:.5..0sccsteasscecesctascesscnse sta oneee ones 7
Cornutal 22h. 2 sieis cies siastacceeecs oie eeA eee eco ee eee 10,12,29
cornutus, Anomalocystites ..... 123 §,18,20,22,35,46—-48,B
GCOSste ANIA DEAS re. «fea sccedeecvscesdescaecstensevwes eon oee herent 30
GothurnocystisiBather 193) me.sc-ccc cece sceeteseecetee ne seen ere ameeeeeee 10
crustacea,

Enoploura

Placocystis ...
Ctenocystoidea Robison and Sprinkle, 1969 ....................... 6,7

GCystitidae oo. sc0ccsccsc teccceces deatsuvecouesscacsdoes sonst erwercerscreceeerecs 37

NorTH AMERICAN MITRATE STYLOPHORANS: PARSLEY 55

PO7ECHOSIOV AKITA aren. cesne one snetietececsmee ste esincssel selceiorinaiamicouciceelsi' ort 39
BIR, TEL TR, secansoacoono see bot eee RSH So: BESECHOOE HEE RE BBB OO DOC RE ToCo CUS EBS a 18
iBreallc, (WY. ocoscascoseconsbnoboss0ek Bec aseaeceas0can 000d 9un ce sEOpoGeEEsoeradcocsson 34
Dehm (1932) ............ ws
Brolin (OB) eccsaconececasscece enc cosacaaces eneo ade sueuqeoscasoencoco0ccG
FICPILICUIALUS: WIILINANOCYSTIS, ....0.2-2c000eoceca2csanancarsvosuseesceeeesease 5
WMETStLETT (GIO) enace seseeescetes cosecee reece eeeweacetacesccsedesstcors 19,22,41
Merstlerniandverice (97D)! xs. <ssesse--- coe sce --seaceeeeeesencven= 19,22,41
METS eta meee ea can cst saeco ccece conc cqosc-c2acecssnesesstncncunesenecs 7,18,36
Diamphidiocystida Kolata and Guensburg, 1979 ...............0. 19
Diamphidiocystidae Kolata and Guensburg, 1979 ................ 19
Diamphidiocystis Kolata and Guensburg, 1979 ................. 18,19
disparilis,

VAN ONAL OGY SULCS Pesaran scene Seceee sate seee de canons sonasieses:oneeese 5,20,26

IBEISS ET OCVSILS pe mec essence tee eee wecees sn onastcce-accemssansseesecesse==== 20
FUIST TI ACASCUSSEC eee raetecen secs cn esc ates cee cs snacscascdseccssensnesasseace seeeee 9
dlargall, GYRETERER) jaca cannsosasponacdecse Soe Ee SB EEEaaocob dc Bua EaRDOe Rao og aaSeS 10
Benimodenmatayeccescssscecscaseescactorescavat ras seonereceeceasenaces essai 8,9
BU KhornWhOnmatlOmine se sacra secs so scsscxessotsesics'scececviogs oxdeeeeectinc eyes 42

Enopleura Bassler, 1932 32
punctata Bassler, 1932 30
Enopleura? papillata Bassler, 1943. .............2cc0eeceeeeeeeeeeeeeee 39
FEO IOUFGANWVELNEI DY; H1S11.9 fez 2e22e-Ja0-seess- se 200s cecesone>s-cacucseeseestees
J GHSERDSCEC CREE EEO ES 5,8-10,13,16,17,20—22,23,25,27,30-33,36,37
balanoides (Meek, 1872) ............ Awe 5,18,32,33,34,36,49
cf. E. balanoides (Meek, 1872) 5:6) -2.s 33,50,51
Crustacea (HaccKels, 1896) |: cescec-se-cosscasceascsseeceser-ccens 5,33,49
PRICCK I CASTELL OSD) thera sive cceesscecsds case's ceeeocssecsecesteecsee 55335511
Ope Casters 9S 2 cee: cous cocsccece- scores sersencaecenscuesssseesere=-e= seo
ACCC EETES 6 ...... 5,9,11,12,24,25,27,28,31,32,33,34,51
Chee a popel Caster W952) cc cceccsenvascceaceecesacceest=s St pats 34,50
punctata Bassler, 1932 ............. 4560... 5,30,31-33,49-51
SDM rea oe scence ra secadieccapcsstAicedasesedtaseacsvesseseess (Siaeeerce 51
WELNETDY I CASterg ODD sersccarstes sesccec vente necensescesssees sosenaes 5,32
EXIOPLOUTA TA CLUE DY fecseece oi ceson eon. one sueavecotccsonsonmacecassast es 33,38
Enoplourinae Caster, 1952 .................ceeceeeeee es 5,16,17,20,23,36
Eumorphocystis Branson and Peck, 1940 ..................00.00200 08+ 2.
TELLS ]SS nochoosesdad ene cEes BIL cer eCoea aE EcBO SARS ae AC ASSnE Dep eEnccodmnonects 5,6,38
AMV IC WAL ONMAUONE-cer=seersesse sees sansa e-sec soc eee els
Fatka and Kordule (1985)
ONDESTQNUS PE ACOCYSLLCS mere ece = sesertnsecccsesece esses sesanesser 23,26,34
MOLDESTANUS (all) PIACOCYSLILCS eos. o0des00sco<essetecsacseecescee eases: -2- 36
BANCO Meso sec cots ccewscsavacseacotesbescteuesseness

Montagne Noire
Freminville (1811)
iprestulkolatasand) Mapes (1985)! < 12.22. ...-2---..-2-<-<s2-c-essesen=2=0 38

GalliaecystisiW@ bagns; 1969) co.cc... ..---.2--22-ccescaeveusetevsenessseer 10
Gill and Caster (1960) ees
Glens Falls Limestone Formation ....

37,42

MGI OSSODICUFAPLONC teeetectse ese eor a ec eee eter cc secs sooner daw oewe seaeaneneaes 7
Golf Course Formation, Gene Autry Shale Member ............. 38
Grandileake; HOLM AtiOM).-2-----o-ceecen- socue nse sc lene scccdes Sacer corer es 42
Grant Lake Formation, Corryville Member ..................-..5+++ 42
GSC [Geological Survey of Canada, Ottawa, Ontario, Canada] .....
Ee ee ney cea ae eae et ae Cosne notee NE esoceMacdieeene teas 18,37
BSUIENS DUNE pol Eal eacscccseneescorsec ssc eccsecesreseoresocectesssienss 18,30,41

Guttenberg Formation
guttenbergensis, Ateleocystites

PAcCKelll (18 96))cc.s.0ssessece--cscsco=stoseeneseceseess 5,18,19,23,32,36,37
HAATIN((S 58) feevscccesseces-ssccss-coc-assaesencsseseacesece-=- 9,10; 13519523;32
“ERAT (1835) ce casconagsancecnereaccecadaceJeocuncocar meee poTnacescaans 5,18,20,26

FALLS 61) Wewocesencccesscscvescsedceserscerscte=curauscuceceqceconesedsys
Haliand! @larke (892) iteersce. a tectee- tere. cat cacecsvenscsencesecereeces
Hauder(980)itecscsscccesse-secccneces
Helderberg, Lower .................2++-
Homalozoa Whitehouse, 1941 et i
Homoiostelea Gill and Caster, 1960 ................2.-.cescoeceereees 6,7
Homostelea‘Gilliand!Gaster 19602209. Seen sen-sccssossersereces== 6,7
huxleyi,
ANOMAIOCYSLILES sank sk asco eteweree conse aenon eo ees a etne weavaaseadeestes 37
ALELECY SIS) < ccssscec esse tances ssoee seen ote sc aad as oe xe ea aces aausdetiweseoes 37
VATEICOCY SUIS cox. sate esac teetenne toads done case santo etenedessceoseecseeh ease 37
ALEICOCYSLILCS scenes. sccdevenesscosesdeetece: 5,36,37
huxleyi (cf.), Ateleocystites 37,52
Td ah osc 3csis cedecie ek cnet s cesteetssvase stds od duvoueseahie<t spec (oneseedeeetuene se i
Illinois State Geological Survey, Urbana, IL, U.S.A. ... 16

UnGianal’..c3: 3. cos. sccnsceaseccsccacancsesoccnccesteceensveees

St. Marys
Weisberg, railroad cut 13, lower 2, SE 4, Sec. 8, T. 6 N., R. 2

W., Suman 7!’ quadrangle [Locality P] 34,42,50
EIPETIOTAGISCUSSEG vesveseeccteseesepasstoasecasate see neoce-seeneaseanseseeceee 10
EISEN LUS PRIET OGY SUS Goose s0=- sence scneoecscaescatececees 5,22,23,49
Towacystis:sDhomasjandadd> 1926) cc s-.2c0-2. <2 sen ecce eo: -oscessoneoeses 8
Jackel((MOON) etessccccecscsesceseecscen tee s-2oe-sewccescerese ses 12,19,23,25
Jaekell((1 98)! ceive. ccwsweessceeecees 6,15,18,36,37
Jefferies (1967) rave sseanoi sme svoposeoiewete 5,8,18
Jefteriest(l96S8a)inecs. secre coeeco core otearesecsaceseasecsecerancseseeeeeet as 5,8
Jefferies (US 68D) socce-oees coc sccce sz tees eceeetecec sence -wepesctecscesensacete 6,8
Jefferies (1981)

Jefferies (1984)
Jefferies (1986)
Jefferies and Lewis (1978) ...........::ccceeeeeeeeeeeeeeceeeeeeeees 14,23,37
Jefferies and Prokop (1972) ................655 [esoreadescseedeeese 15,16,19
Jefferies RPA Se ccccscesessecesssteecctecce ane eeesesss 16
Vell Barrett; and) Banks) (985) )e- sees ceece-cee= ses cc--c---ceccensenesescens 7
JincesROnmationipe ce: ssc seeeece ec ae cen ences case eseeee es teeoeeeteersaaes 1
Ollie (O82) ke covcccesecenccescecescet ceretereteccn tease ovecnccnanewarceesener=s 6,8
Keen tuck ys iccceecccacssmcvaesessere ce veces sdotesneseacsecseneceseonseseee etree 13,24
Mercer Co., Curdsville [Locality G] iEesabecct 22542:49
Kalen PAM a 5: S28 ncae coccenc sect csi cwasceecesns se scothr souk ct isetaceseeete 16
IRTETOCYSLISS TIS GEN, covers ccecccs cosec sseccvecte renssonees 11,17,19,22,23
LTISENLUSTLGSD. esos sores seen ota eae cane eee Bows: 5,22,23,49
IKairk(G UM) erecoccesteccesecs coeee ee ccoenee 14,16,19,26,36
Rirkhield Ubimestome a oe-seecectroseasaccu-sccrecs cate ose osteecs cowsctansenal 42
Kirkfield SROpICyStis' see. sesscaccecee-vssadedoccasseneesces! 9 tece=== 5535,52
Kairkocystidae) Caster; 195222... .5.21.2.-ssscs+s--<cssecessesacaors 15,38
KirkocystispBassler sl 950) serssrsssseescoe cer srnca se cnencenc soose seeaeen anes
papillata (Bassler, 1932) =
Koolata(1984)) ic. .cccccccosactsosceecstess ssadeusdgee csncvces see teaendtctsweevase
Kolata and Guensburg (1979) .............2.::escsseeeeeeeeeeeeeeeees 18,19
Kolata and Jollie (1982) .......... 6,8,9,12,18,19,21-23,26,34,36,37
Kolata dD Rivy 2. vere cveccnoesone Sooran a cera sonar an eee Taare 16,18,36
de Koninck (1869) 23,26,35,36
IROpfiGyStis ns SEM cessee sees oeesedaces seer eecee see raee 16,17,20,34,35,36
KeirkfieldiS ie Spiess cossoseseaxsveveteecwsseusasevcoesses Vf feesses 5535552
Magynocystida; ...c0c.cc<sss+scrasesess- coo 16,37
Lagynocystis Jaekel, 1918 15,37,38
Banding Bi cosic ss cacectre ae sane soon ae Tee aw Sw Oana aan OT BOT OE 16
BetnayHOrmationy oecoscesceere cco reese ce eee ae ore oan anak dn cstea ee
Mexingtoncimestone ..ccssoccesnessccscesteseeereesosscresacese

Curdsville Limestone Member
Lindstrém (1888)

56 BULLETIN 336

Localities:
A: New York, Dayville, Saltsburg quarries, “Jerusalem Hill” ....
SNe ee Rca RU ee ESE ect os SAE SENS LO ot Seen weiasuste 22,41,46
B: New York, Litchfield, unknown locality ............... 22,41,46
C: New York, Herkimer Co., Days Corer, Saltsburg quarries ...
RE COR EEOC CE ohare ea acento Tee eorcas 22,41,46
D: Maryland, Cumberland Rn DLATEAT IOS
IE Ohio;! Oxford). «25220. .02 <-secnasesssesasesssesesessacesesesesacs- 32,41,49
F: Tennessee, 0.5 mi north-northeast of Pulaski ... 30,4/,49-51
G: Kentucky, Mercer Co., Curdsville .................. 22,23,42,49
H: Indiana, in road cut south of Liberty ................... 34,42,50
I: Ohio, Clermont Co., Stonelick Creek .................... 34,42,51
Jer@hios Warren! Cob. cos sc ec sovecee seeees seco tc es Hoe eeee ede scaeees 42,51
K: Ohio, Cincinnati, Boudinot Avenue .................... 34,42,51
L: Ohio, one mile northeast of Camden, on Seven Mile Creek,
parallelito;mainihighwayeecese-2--7-<-steeceeeeeeee sees 32,33,42,51
IM:iNewsYork, Trenton? Falls) 222.2220. 2-0-2 -2- <2 2-2 = 36,37,42,52
N: Oklahoma, Carter Co., Criner Hills, Rock Crossing .............
Seiaee sete eoek owen ve eetetaxaelecatta tasewaredereie beetatdad 39,42,52,53
Ox Ontario. Kirkfiel disse AF. te eecee cscs. ert oor e ee et acae 35,42,52
P: Indiana, Weisberg, railroad cut 13, lower 12, SE 4, Sec. 8, T. 6
N., R. 2 W., Suman 7'2’ quadrangle ..................... 34,42,50
@Ohios Gincinnatier eeesaees cece econo see eee eee 32,33,42,50
R: Quebec, near Hull, Brigham Quarry .................... 36,37,42
S: Quebec, near Hull, presumably close to Bigham Quarry ......
oS cab coc aC SOARED SO OOO IOOLSOE 36,37,42
T: Pennsylvania, Lebanon Co., Swatara Gap ............ 36,37,42
Malvinokafinici Realms. sc.sss<s0ss2e-esreneesere--a-a-=s-e=>= 10,16,19-21
Manlius Formation, Olney Member .....................2.2200-+- 22,41
MartinsburpROrnmatiOnyscesrccc career -seasese toe ane see seenae ... 36,37,42
Maryland esc stececan nc one ssaa sna c cas tarecencentasae sen stsscnaseees tanceenes 19
Cumberland! [WocalityD|\\c2-.2cc2-c2.se2--eene-sceeseere 22,41,47,48
MCZ [Museum of Comparative Zoology, Harvard University, Cam-
bridges MAS USA] | cscccsteveccces cesseesee cootteesees 18,36,37,52
Meek (1872) 5,18,23,31-33,36
IMeeki(1'8773) kivc-vec-c-nccccosces naveve coscdecevect sovetwatacssestressee 23,32,36
TMCEKE EP NODIOUT A vic xacascc cate coer ee testes oaunc=sacesosscusoenbeaveesnsess 5,33
Meyer. Die cicacccavccssestovcvecesvscccstscuca tues cues ssovcedacsensesoseccher 16
Miller (889) pence caencesesccess 19,23,32,36,37
Millerrand! Gurley, ((1894)) 22 -siccc. cases. scs0cccceccncuctecvceceseeeseensere
Mississippi River Valley
Mitratanlackel sOWS i iccsescecccrcersss-occesseeecrenes
Mitrocystella Jaekel, 1901
WMitrocystites(BarranGes 1 SSi/) cc. sns-ce see see ce setecease aces creas 9,12,26
ING W? YOLK San coccstosec ce cosues aden cecectscvsiarchescasessntbenstenereeercsenece 19
Dayville, Saltsburg quarries, “Jerusalem Hill” [Locality A] .......
Do shoe ce aacnce Seen daa 5c SOS aca stn Sea REs Sica Netces eea eet ws Sates 22,41,46
Herkimer Co., Days Corner, Saltsburg quarries [Locality C] ......
FEO REECE REE EERE On oc eo eoe ace eneacreaeecre 22,41,46
Litchfield, unknown locality [Locality B] .................. 22,41,46
MrentoniFalls:[WocalityiMl] (e-css-csessce see es sees eee ecesers sex 37,42,52
INew Zealand 6x ies ccs cocccecn cosas se sees tenccnccncctatocses sc tact aneesecetavaes 16
NotocarposiPhilips li9 8). crscc. cence ceccecnsesseencessonceese 10,17,19,20
NYSM [New York State Museum, Albany, NY, U.S. A.] ............
EM iT Re D6 i360 os ce Bi eabhacuetan ava caedauasse eee eees 16,18,22,46
OIG es rei Sass sa tees de enon wha de oc Galea eu see ec Sac ea ee vaa eu Tounaenaoones 24
Cincinnati [Locality Q] ses to 22935342550
Boudinot Avenue [Locality K] .....................0eceeeee 33,42,51
Clermont Co., Stonelick Creek [Locality I] ............... 33,42,51

one mile northeast of Camden, on Seven Mile Creek, parallel to

main highway [Locality L] ... 32,33,42,51
@xford | [Mocality:E]) <=. <.2---2<.+- 32,41,49
Warren’ Co: [eocalitys J] <<.<.2--.--<ssss<:s--ss0se-sescerecence sense 42,51

Oklahomas.: .-<. 25220. 2 ccseesncecscnsases esau senses cscose soeessseteete erence 5,38
Carter Co., Criner Hills, Rock Crossing [Locality N] ...............-
sea Rares Saat ee OREO Ee eve von eae nan oC Omen cee een 39,42,52,53
SOUTHEMN. 5.12.20. 2250 cceekecsocsece ssc cee sedendexeesaceosenssecacstese eeeeereee 38
Ontario, Kirkfield [Locality O] - 35,4252.
Oral GiSCUSSEM | 2...se soc Secee-es aw awsesaeeeeee|ot does deed eeatec eee eee eee 9
Ottawa Limestone, Hull Beds 36,37,42
papillata,
JNPOTIVARDENOIR, sbossangenosaccenwococeocenanes WS vice 38,39,40,52,53
FEfnopleura? ...5ccsc2ccsecewccnvk eee oeee esos eo 39
KirkKOCyStis: occ... osc dacc0sk ae canst ase ooh ore 5,39
Paranacystis'Gaster; U954a\ 2.222 2ec.ccce-nccncccsceseese sence eee 13
Parsley (1980) «sere ccsecccoctct scesedaene cecsree-cseosenet ee Coe

Parsley (1981) ...
Parsley (1982) 12,13,39
Parsleyi(U988) wcs.ci ins sccveccesccccscestaccvaeeseucecess soso 10,11,13,14
Parsley and Caster (1982) .... 10,12

Parsley and Mintz (1975) .... Saver ge
Paul and Smith (1984) ...... de eo OMleD)
Paull: Ci sRaiGs seessccecdcecassasewoecesovekacaxceactee soe saeeC eee 7,18
Peltocystida Jefferies and Lewis, 1978 S637,
Peltocystidae .cccocisc0scececes csccsesavaesavane cc acse seuss: coeeoe eee O oe ReReEe 38
Peltocystis Thoral, 1935 .... ... 15,37,38,40,41
Pennsylvania) cic... c..seceescasesescocevsessscsecuccsescec0e seteeoeseCoN OER 19

GUE occ Foc ens corcaecctna ds saan sutton cas tueeeet ooo ges ee eee ee 22

Lebanon Co., Swatara Gap [Locality T] ................... 36,37,42
Philip (1979) 5,6,8,18,41
Philip) (1981) cccee cs .cecesdesseceacssescecscosnoece cocoee teem 10,19,20
Phylloeystis Thorals 1935) \.2.... scsosereensedes cece tees 9,10,12,16

Placocystella capensis Rennie, 1936 ....
Rlacocystidalpeeess-ese-o- screens
Placocystidae Caster, 1952 e
Placocystinae Caster; 1952) <i... :..cccsccsscoetus-cescaeseece ston eaeeee
Placocystis de Koninck

africanus Reed, 1925

crustacea Haeckel, 1896
Placocystites de Koninck, 1869

18,32

forbesianus de Koninck, 1869 23,26,34

Aff: fOLDESIANUS:....605 ccovees0sesdneceonesscicesaseecese estes see tee eeee eee 36
Placocystitida
Placocystitidae(Gaster, 1952). .c.2 cnacewccuccoceessconeeser 5,16,17,19,34
Placocystitinae; Caster, W952). c-navecsoeeceeceese-eseeet 5,20,34,35,36
Pleurocystites Billings, 1854. :..5..s...c-ce..0.ccssceecostoveesseeseo toes 6
popei, Enoploura .. 6 ...... 5,9,11,12,24,25,27,28,31,32,33,34,51
DPOpell (GE), EMODIOUTG ecssnn ce scssesteowa exe teeeee eee Si arose 34,50
proximal: GiScuSS€G. ......:.0% 00: ««csaeesedssecewwesscesases tedeete eee eee 9
punctata,

ENOPICUIG o.050.scvecsuscscaesvaussncvseusees set sect eter CeO a TO 30

IE NODIOUT Ge eee xc oeoeaceet eee 45:6. 2-2— 5,30,31-33,49-51
QUEDEC:) .iccc dee doeseksssvectessccesccscusss totes ceisecteues Conon nee ee eee eee 36

near Hull, Brigham Quarry [Locality R] ................... 36,37,42

presumably close to Brigham Quarry [Locality S] ... 36,37,42

Rafinesquina Hall and Clarke, 1892 13
Reed! (925) assasenivse = ever eeeee a6)
Repnéll\(1945) Mises eee S| SS 37
Repnéll: (1960) .cc. oss cocce ccb ccd deeb ec seas hoe ete ee 36
Rennie'(U936)) a...ccccsssdawes csoesccseavccvespiseeocecosanes baer oo aee een 16
Reticulocarpos Jefferies and Prokop, 1972 5,15-17,19
Rhenoeystis Dehm. 1932 \2s.cesc. =e ee 17,30,35,36
Ridgely Formation 22,41
Robison: and Sprinkle |(1969)) 2... cc1-.s0c.ccceseocecccscscseeece ten sence 6
Saluda Formation: iscsi s cases focsseceuascoveesesecseceenncs. qeeseeee eee 41

NorTH AMERICAN MITRATE STYLOPHORANS: PARSLEY SyI/

Mehucherti(1904) jesse teccossececesee ce -cseseasesnoseasssesestineracseenss
ini ershOLMAtlONy esceeceracecceceee-s-ctecesnovesieresslensess
Signor and Brett (1984) .... ae
Shanti (QE). a sesccnasdocsesssocahoacoonc0 bases ba5 goo bo Ip soca CoO SE CUOARaEoe
SORTER, BL ccasbocsosgcua conn noon aE eoageO CSU SHEC EE HsE Sec ARCO SOO EOS oEIE ORS er 18
SouthyAMeniGal s..5-.2------c--e+eea0oes
Southern Hemisphere
Southern Illinois University, Edwardsville, IL, U.S.A. ......... 18
UE TIODIOUNE we hs sscccsess-.c- secs vascceennseererecenneesessessn~ (Werrcecs 51
spinosa, Anatiferocystis 3539
Springer (1913) .......-....... 19,23,36
prinkley(G/S) ieee as-ceeee--222s-secescess2-assccceccesseceeenctenseccecn-sssres= 7
Sprinkle (1976) ............ 12
RSPR EI (O82) eeesteressasscsssssnnacccecceesessecersree-ccccceccescare===== 42
Sprinkle and Robison (1978) ...............s0es-esseeceeeeeeeeeceneeeeseres 7
Somtelas Ub scecesoandeononcescseoceddes
SLOGKEIM Seat tec tesseehicccczccvassuenseesess =
Stylophora Gill and Caster, 1960 ...............
NUEDENLOMAGISGUSSEG. 2.20.2 2ccceedeosecesiascccacovesecerscesenctarnermsseessse
Masmanicytidium Caster, 1983) ...........-...0-se00--0+-0e=-
Tennessee
0.5 mi north-northeast of Pulaski [Locality F] ...... 30,41,49-S1
PASTOR ne nes cee ae ae ener ce ce secceacsccedccaiaessensaeeneresess- 39
Bho MmasianGs leadGi('92.6)\ esse cece oe caceacceese-caceocaranccclmmecesessnoce 8
Thinermll (NOES) keacssnossnoccseaceonaeaaceessoacaooced 9,10,12,16,37,38,40
Tulane University, New Orleans, LA, U. S. A., [Committee of Re-
search of the Graduate School] ..................---02ceeceeeeeeees 18
(Uoereing (SKS) Reconedenecaoncs se ccoecasbecsseceassooseea= 5,8,10,12,13,15,41
Ubaghs (1968a) ............ 8-12, 14—16,18,19,23,26,31,37,38,39,41
MU bagphsy(WUO6Sb) easssseocees ceeet cen -e--caacescseesesececesscorceq-asrancens ===" 7
Ubaghs (1969) 9,10,14,15,37,38,41

Ubaghs (1975) 6,7,8
AOaghsi(979))\o.-- -c.c--cow-cooecosecoecczseoses-aee 5,12,15,16,35,39-41

Wibaghs' (9877) esessce-casescemccasrecsneseceueens-csssssanccaewsesrereceanereses= 7
WihaghsiandsRobisoni (1985) ieeretsers-csscesnen=ceseacesantesssseaenccncsese 1
Wibaghs iGabesrce-tacccecnsretece secectecarersesasconsteccsosescsaancaes 16,18
UCB [University of California, Berkeley, CA, U.S. A.] ...............
Dero dc dea voseanee ssSeas Sooo nen er oan ceases Dtiuestssecsccceseeaseaesceees 18,22,46
UCM [University of Cincinnati, Cincinnati, OH, U.S. A.] ..........
wate acescdoneenete ss 9,11,16,18,22,24,27,32,33,34,39,40,45,48-52
Wlrichtand Kairks(192'1)) ee -ececc cece sevtnressscacnasecastssessscescscceres 6
University of Liverpool, Liverpool, England, U.K. .............. 18
University of Liége, Liége, Belgium: ......................-.scsssssesee» 16
University of New Orleans, New Orleans, LA, U.S.A. ......... 16
University of Tennessee, Knoxville, TN, U.S. A. ...............5. 18
University of Texas; Austin, DX W.S.As .22-222.2...2.2.0...20c0e00 18
USNM [U. S. National Museum of Natural History, Washington,
DCSE. SHAW ieceeetecccsteees 16,/8,22,30,31,35,37,39,46-53,B
MU ital 6 = secacesseesasces ce eros saeans Secnunices deteee sucsaseecsccustoecesseereee 1
VaAliss GASLENICVSEISE wecenccetuensses eoceeenateen teocesecc rer oenenmanatsacnennces 7
WEEP GISCUSSEG Nene cec eect ear tncsosseancee tae orcesiassaeranesenseasarae 10
Victoriacystis Gill and Caster, 1960 .............:::sseeeeeeeeeeeees 16,17
Waynesville Bormationy ----..2s0..-020:.a:scs--2u-¢ecceessececeeveress- 34,42
Wests Virginia, Ridgelyisi...ce-ce.csecesecpese-sse2:2 sca -cnsscsese=seeeenenne 22
Wetherby) (1'877/9)) <-------e-c2s-csessssceee 5,8,10,16,20,21,23,32,33,36
WELRErD YL LEMOD IOUT sence teeneneconcenerssesneecnaasecesesesec=seeace= 33,38
Wihitehouse (19 4)l) esrcossecececte seco terete soe cocce ee reces-cseastrseeanes
Whitewater Formations o2---cse-c2cece-.co-c2reas == saetansecees=oesenens
Willmanocystis Kolata and Jollie, 1982 ...................5++
denticulatus Kolata and Jollie, 1982 ..............
WialSoni(194'6)) ceeveccsececeeceosssne core cececnecee ss sereeseniasecemreclmtone
Woodward\(li87il) 2 :c.c.cc-csectesessessecscccs-nccsesssossceasssosee
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Text-figure 5.—Carapace detail of Anomalocystites cornutus. This
figure is based on USNM 33661A (PI. 2, fig. 1).

Carapace

Text-figure 6.—Plastron detail of Anomalocystites cornutus. This
figure is based on USNM 33661A (PI. 2, fig. 5).

Text-figure 7.—Lateral view of Anomalocystites cornutus. This figure is based on USNM 33661A (PI. 2, fig. 2).

/
m’5 m6 m5

Text-figure 8.—Internal plastron surface of Anomalocystites cor-
nutus. This figure is a composite based on USNM 33661F and AMNH
2720 (PI. 3, figs. 4, 7, 9, 13). Extending from M’1 to the muscle pit
in M4 is the diagonally-transverse septum. Triangular area devel-
oped mostly on M’1-M1 is the raised (thickened) oral field. The
triangular area developed on m’5, m6, m5, A, and CS is the thickened
distal field. Between M’4—-m'5 and M4-mS are the muscle pits. These
pits probably contained muscles that moved the spines toward the
sagittal plane and (probably) muscles that were part of the anal
sphincter system. Overlayering of plate material to form the walls
and deepen the muscle pits has obscured the plate sutures. Narrow
inner marginal grooves run the length of the theca from the muscle
pits to the extremities of M2-M’2.

Table 1.—Explanations of plate abbreviations used in this paper.

A: anomalocystitid plate

a-s: supracentral plates

CM1-CM2: carapace marginal plates (right side)
CM'1-CM’2: carapace marginal plates (left side)
CM3, CM’3: carapace marginal plate (sagittal)

cs: central infracentral plate

DS: distal infracentral plate

LA: left adaulacophoral plate

MA: median adaulacophoral plate

M1-MS5: marginal plates (right side)

M'1-M'S5: marginal plates (left side)

m5: plastron distal—marginal plate (right side)
m5: plastron distal—marginal plate (left side)
m6, m'6: plastron distal—marginal plate (sagittal)
RA: right adaulacophoral plate

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