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HARVARD   UNIVERSITY 


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OF  THE 

MUSEUM   OF  COMPARATIVE  ZOOLOGY 


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MDCCCXLVI. 


THE 


ORGANIZATION  OF  TRILOBITES, 


DEDUCED  FROM  THEIR  LIVING  AFFINITIES; 


^pstcmatic  l\e\)iclo  of  tijc  ^ptcttö  l)tt|)crto  ticöcriljcti. 


HERMANN  BURMEISTER,  M.D.  PH.D. 

OEDINARY  PBOFESSOR  OF  ZOOLOGY,  AND  DIKECTOK  OF  THE  ZOOLOGICAL  MUSEUII  IN  THE  UNITED  IIUEDKICIIS  UNIVEHSITY 

OF  HALLE-WITTE>BERG  ;    COllRESPONUING  MEMBER  OF  TttE  ROY'AL  ACADEMY  OP  TURIN  ;    MEMBER  OF  TUE  IMPERIAL 

ACADEMY  NATUR.E  CURIOSORUM  ;    OP  THE  ROYAL  RUSSIAN  SOCIETY  OP  NATURALISTS  OF  MOSCOW  ;    OF  TUE 

PHYSICO-MEDICAL  SOCIETY  OF  ERLANGEN  ;    OF  THE  NATURAL  HISTORY  SOCIETIES  OF  BERLIN,  HALLE, 

ALTENBURG,  HAMBURGH,  AND  THE  HARTZ  ;    OF  THE  ENTOMOLOGICAL  SOCIETIES  OF  LONDON, 

PARIS,  STETTIN,  PENNSYLVANIA,  ETC.  ETC. 


EDITED  FROM  THE  GERMAN, 


PROFESSOR  BELL,  F.R.S. 


PROFESSOR  E.  FORBES,  F.R.S. 


LONDON : 

PRINTED  FOR  THE  RAY  SOCIETY. 


UDCCCXLTI. 


PRINTED  BV  C.  AND  J.  ADLARD,  BARTHOLOMEW  CLOSE. 


'/ 


o 


The  Treatise  on  the  Organization  and  Classification  of  Triloljites,  1)y  Professor 
BuRMEiSTER,  HOW  presented  to  the  members  of  the  Ray  Society,  is  not  merely  a  translation 
of  the  orij^final  German  edition  published  at  Berlin  in  1843,  but  a  new  edition,  revised, 
augmented,  and  in  part  rewritten  by  the  distinguished  Author  himself,  who  has  most 
kindly  endeavoured  to  render  the  Ray  version  as  complete  as  possible  by  embodying  all 
the  information  which  had  accumulated  since  the  publication  of  the  German  edition. 
Through  the  aid  of  Professor  Burmeistcr  the  Society  has  been  enabled  to  procure  impressions 
from  the  original  and  very  beautifid  plates.  These  have  also  been  revised  by  the  Author, 
and  several  important  figures  added. 

The  translation  has  been  executed,  under  the  superintendence  of  the  Editors,  by 
Dr.  Hermann  MLx.  In  the  revision  of  the  first  section  of  the  work,  they  have  been  kindly 
assisted  by  Professor  Ansted. 

The  translation,  especially  of  the  systematic  part,  is  nearly  a  literal  one ;  such  being, 
in  the  opinion  of  the  Editors,  most  likely  to  convey  the  sense  of  the  Author,  although 
elegance  of  expression  may  occasionally  have  thereby  been  sacrificed.  They  have  carefully 
abstained  from  altering  any  expression  of  the  Author's  meaning,  and  even  where  they 
might  dissent  from  his  Aaews,  have  preferred  silence  to  the  intrusion  of  their  own  opinions. 
The  notes  they  have  added  are  all  of  an  explanatory  or  supplementary  nature,  and  especially 
such  as  may  prove  useful  to  the  English  reader. 

The  Editors  feel  that  they  need  not  dwell  on  the  great  importance  of  the  volume 
which  has  been  committed  to  their  charge.  As  a  dissertation  on  a  most-  diflicult  tribe 
of  fossil  Articidata  by  an  eminent  Zoologist,  deeply  versed  in  the  organization  of  the  great 
class  to  which  it  belongs,  the  work  assumes  an  importance  which  can  rarely  be  accorded 
to  palffiontological  essays  treating  of  the  remains  of  Invertebrate  Animals. 

THOMAS  BELL, 
EDWARD  FORBES. 
London:  December  18-16. 


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pag.  90,  Ed.  alt.,  O.von.  1760,  8vo. 
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1709. Tractatus  de  Origine  Lapidum  Figuratorum.     Lucern.  -!to. 

1711.     L.  I).  Heirmaun,  Maslographia,  Brigfe,  4to,  p.  214,  No.  .50,  Tab.  IX,  Figs.  .00,  11,41,  12,  31. 
1718.     J.  J.  Scheuehzer,  Oryctographia.     Turici,  4to,  p.  316. 
*1729.     M.  V.  Bromell,  Lithographia  Suecana,  in  the  Actis  Liter.  Suecife,  Upsal,  vol.  ii,  4to,  p.  408  scq. ;  a  separate 

edition  of  it.     Holm,  and  Lips.,  1740,  8vo,  p.  76. 
*1732.     Fr.  E.  Briichmmi,  Centur.  Epist.  Itinerar.     Wolfenh.  4to;  Epist.  23,  Tab.  II,  Figs.   1-7  (1732);    and 
Epist.  64,  Tab.  Ill,  Fig.  5  (1737). 
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1747. Wästgötha  Resa.     Stockh.  8vo. 

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17Ö3.     E.  Mende:  Da  Costa,  in  the  same,  vol.  .xlviii,  pt.  I,  p.  286,  No.  42. 

* Linneeus,  Museum  Tessiniauum.     Holm.,  fol.,  p.  123,  Tab.  XII. 

*17.i4.     3V.  J.  Torrubia,  Apparato  para  la  Historia  Natural  Espanola.  torn,  i,  iMadr.,  fol.,  p.  83,  §  XIII,  No.  96,  4to. 

* ■ ■  translated  into  German  by  Ch.  G.  v.  Murr.     Halle,  1773,  4to,  p.  91,  §"XCVI,  10.5.  4to. 

*  17.56.     J.  G.  Lehmann,  Versuch  einer  Geschichte  von  Flötzgebirgen.    Berhn,  8vo,  p.  73,  Tab.  I,  Figs.  A  B. 
17.57.     Linnteus,  Skanska  Resa.    Stockh.  8vo,  p.  121. 

* Guettard,  Memou'.  sur  les  Ardoises  d' Angers,  in  the  Histoir.  de  I'Acad,  des  Scienc,  Ann.  1757,  nouv.  cent. 

Tab.  XV,  p.  82  seq. 

(I  made  use  of  the  reprint,  Amsterdam,  1768,  8vo,  p.  76-128,  Tab.  VII-IX.) 

Gen:mar,  Beschreibung  einer  Versteinerten  Muschel    mit  dreifachem  Rücken.      In  den  Arbeiten   einer 

vereinigten  Gesellsch.  in  der  Ober-Lausitz  von  den  Geschichten  der  Gelahrtheit.     (Description  of  a 
petrified  shell  with  a  treble  ridge.     In  the  Transactions  of  a  Society  in  the  Upper  Lausitz.)     Lobau, 
8vo,  pt.  II,  p.  785,  III,  p.  185,  Figs.  17-21. 
1759.     Liniuevs,  PetriÄcatet  Entomol.  Parodoxus,  etc.  etc.,  copied  in  the  Act.  Reg.  Acad.  Scient.     Holmiens,  8vo, 

p.  19,  Tab.  I,  Figs.  1-4. 
1763.     Joh.  With.  Ballmer,  Naturgeschichte  des  Mineralreiches.     (Natural  History  of  the  Mineral  Kingdom.) 
*1766.     D.J.  G.  Lehmann,  De  Entrochis  et  Asteriis,  m  the  Nov.  Comm.  Acad.  Scient.  Imper.  Petropolit,  torn,  x, 
(for  1764,)  p.  429  .seq.  §  XU,  Tab.  XH,  Figs.  8-10. 
1767.     Darila,  Catalogue  Systematique  et  Raisonne  des  Curiosites  de  la  Nature.     Paris,  8vo,  Fig.  vols,  i-iii. 

* Neues  Hamburger  Magazin,  II  Stück.  S.  410.     (New  Hamburgh  Magazine,  pt.  II,  p.  410.) 

*1768.     C.F.  rr(i/c/i-ens),  Nachricht  von  seltenen  Versteinerungen,  in  3  Sendschreiben,  etc.  Stralsundisches  Magazin, 
vol.  i,  p.  267,  8to. 
(Information  on  Rare  Petrifactions,  in  three  letters.   Stralsund  Magazine,  vol.  i,  p.  267.  8  ;  also  separately 
reprinted  under  the  above  title,  1769,  8vo.) 
1769.     Zeno,  Von  den  Seeversteineningen  und  Fossilen  bei  Prag,  in  dessen  neuen  Physikalischen  Belustigungen, 
Prag.  1769,  8vo.    (On  Slariue  Petrifactions  and  Fossils  near  Prague,  in  his  new  Physical  Entertaniments, 
Prague,  1769,  8vo.) 
*I770.     J.  Th.  Klein,  Specimen  descript.  petrefact.  Gedanens.    Nuremberg,  fol..  Tab.  XV,  Figs.  3-7. 
*1771.     Joh.    Imm.   Tf'alch,  Naturgeschichte  der  Versteinerungen,  zur  Erläuterung  der  Knorr'schen  Sammlung. 
Niirnb.  fol.  Theil  II,  S.  95  (1768),  and  Thcü  III,  S.  120  (1771). 
(Natural  Historv  of  Petrifactions,  to  illustrate  Knorrs  Collection.    Nuremb.  fol.  pt.  II,  p.  95 — 1768,  and 
pt.  Ill,  p.  120-1771). 

(The  part  published  by  Knorr,  1755,  contains  no  Trilobites.) 

*  The  works  indicated  by  *  I  have  consulted  myself. — .\eTHOR. 


viii  BIBLIOGRAPHY. 

*17"3.     Joh.  Beckmann,  De  Reductione   Rerum   Fossilium   ad    Genera  Naturalia   Prototyporum.      In    tlie   Nov. 

Comment.  Soc.  Reg.  Scient.  Götting.  vol.  iii,  p.  2,  p.  100  seq. 
*1775.     Gr.  V.  K{inshj),  Schreiben  an  J.  Edl.  v.  Born,  in  den  Abhandl.  einer  PrivatgeseUsch.   in  Böhmen.  I  Bd. 

S.  243,  seq.  mit.  Abbildungen,  8vo. 
(Letter  to  J.  Edl.  v.  Born,  in  the  Transactions  of  a  Private  Society  in  Bohemia,  vol.  i,  p.  243  seq.  with 

illustrations.) 
*1781.     3/.  T.  Briinnich,  Beskrivelse  over  Trilobiten.     In  den  Nya  Sanding  af  det  Kong.  Danske  Widensk.  Skrifter. 

Kiobeuh.  4to,  i,  p.  384. 
*178j.     A.   Modeer,  Anmerk.   über  Märkische  Versteinerungen.     In  den   Schrift,  der  Berl.   Gesellschaft   natnrf. 

Freunde,  6r  Bd.  S.  247,  Tab.  II,  Figs.  1-12.  8. 
(Remarks  on  Fossils  from  the  Mark.  In  the  Transactions  of  the  Berlin  Society  of  Naturalists,  vol.  vi,  p.  247, 

Tab.  II,  Figs.  1-12.  8.) 
*1793.     J.  C.  Gehler,  De  quibusdam  rarioribus  Agri  Lipsiensis  Petrificatis,  spec.  I.     Lips.  4to. 

1807.     Jul.  de  Tristan,  in  the  Journal  des  Mines,  vol.  xxiii.  No.  133,  p.  21. 
*1810.     Fr.   Blumenhach,  Abbildungen  Naturhistorischcr  Gegenstände.      (Figures  of  objects  of  Natural  History, 

I  Cent.  Tab.  L.  Gottingen,  8vo.) 
* F.  Fr.  V.  Schlotheim,  über  Tril.   Cornigerus,  in  Leonliard' s   Taschenbuch  für  die  gcsammte  Jlineralogie, 

vol.  iv,  p.  1.     Frankfort,  8vo. 
*181 1 .     Jam.  Parkihson,  Organic  Remains  of  a  Former  World,  vol.  iii,  p.  263,  pi.  XVII,  Figs.  1 1-19.    London,  4to. 
*1820.     E.  Fr.  t\   Sehlotheim,  Die  Petrefaktenkunde  auf  ihrem  jetzigen  Standpunkte,  etc.     (Paleontology  in  its 

Present  State,  etc.     Gotha,  Svo,  p.  39.) 
*I821.     P.  A.  Latreille,  Affinites  des  Trilobites.  Mem.  du  Mus.  d'Hist.  Natur.,  torn,  vii,  p.  22,  4to,  and  Annal.  des 

Seienc.  Phys.  deBruxelles,  torn,  vi,  350,  seq. 
* r.  Aiidoiiin,    Recherches   sur  les   Rapports  Natureis    qui  existent    entre  les  Trilobites  et    les  Animaux 

Articules.     Annal.  des  Seienc.   Physiq.  de  Bruxelles,  tom.  viii,  p.  233,  1821  ;    Isis,    1822,  I,  87-104, 

Table  I. 
* TTahlenliert/,  Petrificata  TeUuris  SuecanEe.     Nova  Acta  Reg.  Soc.  Scient.    Upsal,  tom.  viii,  4to,  p.  18  seq. 

Tab.  1  and  II. 
*1822.     A.  Broyniart,  Histoire  Naturelle  des  Crustaees  Fossiles.    Paris,  4to. 

Ch.  Stokes,  in  the  Transactions  of  the  Geol.  Soc.  of  London.     First  Series,  vol.  viii,  p.  208,  pi.  XXVII. 

*1823.     E.  F.  V.  Sehlotheim,  Nachträge  zur  Petrefaetenkunde,  part  II,  p.  1.     Gotha,  8vo. 

1824.  J.    W.    Dahnann,    in   the  Kongl.   Swenska  Academ.   nya   Handling,   (for    1824,)    p.  370.      Entomostr. 

Actinurus,  Tab.  IV,  Figs.  1-4. 

(Has  also  been  published  in  a  separate  form.) 
* Bckay,  in  the  Annals  of  the  Lyceum  of  Nat.  History  of  New  York,  vol.  i,  p.  174.     (An  extract  from  it 

appeared  in  the  Isis,   1832,  p.   1072);    and  also  in  the  Isis,  vol.  i,  p.  375,  1825;    on  Eurypterus, 

(Isis,  1832,  p.  564,  Tab.  IX.) 
* F.  W.  Honinffhaus,  on  Calym.  Macrophthalma.   Isis,  vol.  i,  pp.  464,  534,  and  986. 

1825.  Koniff,  Icones  Sectiles,  etc.  London,  4to. 

H.  Bronn,    in    Leorihard's    Taschenbuch,    No.   4,  p.   317,    Tab.  II.      (The    author    here   distinguishes 

Cal.  latifrons  and  Cal.  Schlotheimii.) 
— - —      Graf.  V.  Sternberg,  Verhandlungen  d.  Gesellschaft  d.  vaterländischen  Museums  zu  Prag.     (Transactions  of 

the  Society  of  the  National  Museum  at  Prague,  3  vols.  Tab.   I,   Fig.  3.     Uebersicbt  der  in  Böhmen 

bisher  aufgefundenen  Trilobiten.     (Synopsis  of  the  Trilobites  hitherto  discovered  in  Bohemia.) 
* E.  Eichwald,  Observationes  Geognostico-Zoologicae  per  Ingriam  Marisque  Baltici  Provincias,  nee  non  de 

Trdobitis.  Casani,  1825,  4to.     (Noticed  in  Leonhard's  Taschenbuch,  1828,  104.) 
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Audouiu  and  A.  Brogniart,  vol.  viii,  p.  186  seq.  pi.  XXVIII  and  XXIX. 
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•      Ch.  Boek,  Notitser  til  laeren  ora  Trilobitern,  in  the  Mag.  for  Nat.  Science ,  fiirst  Series,  vol.  i,  part  I. 

Noticed  by  Count  Sternberg  in  the  Trans,  of  the  Soc.  of  the  National  Museum,  at  Prague,  1833,  p.  45. 
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(Journal    for   New  Discoveries  in    Physiology,    Chemisti-y,    Natural    History,   and   Technology).     St. 

Petersburg.  Nos.  I  and  2,  (in  the  Russian  language.) 

1828.  Ueber  Boek's  Untersuchungen,  Auszug  von  Bronn,  in  Leonhard's  Zeitschrift.     Jahrg.  1828.     (On  Boek's 

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Natur,  etc.  tom.  xv,  p.  83,  8vo,  pi.  II. 
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BIBLIOGRAPHY.  ix 

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p.  ;«i. 
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Trilobites.)   Isis,  1830,  JUi,  Table  V,  Fig.  1-3. 
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and  Isis,  1831,  p.  341). 
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Journal,  1833,  G2-1. 

* II.  V.  Meyer,  on  Calymene  requalis,  in  Nova  Act.  Phys.  Med.  a.  C.  L.  C.  n.  c.  XV,  2,  100. 

M832.     Jac.  Green,  a  Monograph  of  the  TrUobites  of  North  America.  Phil.  Svo,  (published  by  James  Brano,  see  also 

Leonh.  Journ.  1836,  p.  451). 
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World.     Jena  (Mauke),  4  to,  c.  Fig. 
* Gr.  i\  Sternberg,  in  the  Verhandlungen  der  Gesellschaft  des  vaterländischen  Museums  zu  Prag.  S.  45. 

Ueber   buhmische  Trilobiten.     Angezeigt  in  Leoiih.  Zeitschr.  1835,  S.  727  seq.     (Transactions  of  the 

National  Museum  at  Prague,  p.  45.    On  Bohemian  Trilobites.    Also  in  Leonh.  Journal,  1835,  p.  727  seq.) 

* Esmark,  in  the  Mag.  f.  Natmvidenskab.     Anden  Raekkes,  i,  2,  268,  Table  VII. 

*1834.     J.  V.  Thompson,  Zoological  Researches,  No.  V.    Cork,  8vo,  c.  Fig. 

* K.  V.  Kloden,  die  Versteinerungen  der  Mark  Brandenburg.     (Petrifactions  of  the  Duchy  of  Brandenl)urg. 

Berlin  (Liideriz)  8vo,  p.  104   seq. 

Fr.  Jukes,  in  London  and  Edinb.  Philosoph.  Mag.  iv,  376.     On  a  new  Trilobite  from  Coalbrook-dale. 

* J.  Green.     Descriptions  of  some  new  North  American  Trilobites,   in  Sillimans  Amer.  Jour,  of  Sc.  and 

Arts,  1834,  Jan.  XXV,  2,  324-337.     Also  in  Leonh.  Zeitschr.    1836,  461   seq.     (Cal.   odontocephala. 

As.  astragalotcs.     As.  tetragonocephalus.     Par.  Ilarlani). 
J.  Green,  Description  of  a  new  species  of  Trilobite,  As.  crypturus,  (without  a  head  !),  in  the  Transactions  of 

the  Geolog.  Society  of  Pennsylvania,  1834,  I,  37-39. 
*1835.     H.  G.  Bronn,  Lethaea  geognostica,  etc.     Stuttg.  8vo,  2  vol.  Fig. 
* M.  Sars,  in  the  Isis,  333  seq.  über  einige  neue  oder  unvollständig  bekannte  Trilobiten.     (On  some  new  or 

imperfectly-known  Trilobites,  with  plates.     Table  IX-X.)     Published  in  Leonh.  Jahrb.  1836,  463. 

* HOninghaus,  on  Calymene  arachnoides,  Crefeld,  4to,  Fig. 

* Harlan,  Medical  aiid  Physical  Researches.    Philad.  8vo,  Fig.  p.  400  (new  Trilobite)   and  p.  297,   (Euryp- 

terus)  seq.  (Synops.  of  Tril.  of  North  America.) 
*1836.     W.  Buck-land,  Bridgcwater  Treatise.     London,  vol.  ii,  Svo,  Fig.      Translated  into  German  by  L.  .igassiz. 
*1837.     /?./.  il/i"'cÄ/«o«,  the  Silurian  System.     London,  4to,  vol.  ii.     Plates. 

* ■      Quenstedt,  in  Wicgmann's  Archiv,  vol.  i,  p.  337.     Zahlenverhältnisse  der  Trilobiten.     (Numerical  propor- 
tions of  the  TrUobites).     Pubhshed  in  Leonh.  Journal,  1838,  p.  485. 
* W.  Ilisinger,  LethiEa  suecica,  etc.  Ilolmise,  1837,  4to,  c.  suppl.  i  and  ii,  (1840).     (Extract  from  Dalmanns 

work,  together  with  an  appendix  of  new  species  and  plates.) 
/.  Green,  on   Cryphaeus  in  Sillim.  American  Journal  of  Science    and  Arts,   1837,    xxxii,  345-49.      See 

also,  Leonhard's  N.  Jahrb.   1838,  363. 
On    two   new    Trilobites.     Cal.   phlyctainodes   and   Trinucleus   platypleurus.      In   the  same 

Journal,  p.   167-169  ;  see  also  p.  363. 

Milne  Edwards,  sur  les  Affinites  des  Trilobites.     L'Institut.  p.  254. 

1838.     Chr.  Boeek,  Uebersicht  der  bisher  in  Norwegen  gefundenen  Trilobiten.  (Synopsis  of  the  Tiilobites  hitherto 

discovered  in  Norway.)    Keilhau,  Gaea  Norwegica,  i,  p.   138-145.     Only  known  to  me  from  the  notice  in 

Leonhard's  N.  Jahrb.  1841,  724. 
*1839.     //.  F.  Emmerich,  de  Trilobitis,  dissert,  petrefact.  inaug.  etc.    Berolini,  7,  Fig. 
* J.  Green,  Remarks  on  the  Trilobites,  in  Sillim.  Am.   Journ.  of  Sc.  and  Ai'ts,  vol.  xxxviii,  No.   I,  p.  35, 

Fig.  c.     Extract  from  Buckland's  Geology  and  Mineralogy. 
*1839.     J.  Green,  on  a  new  Trilobite  :  Asaphus  diurus.  In  Sillim.  Amer.  Jour,  of  Sc.  and  Arts,  vol.  xxxviii,  p.  40. 
* G.  Fischer  De  Waldheim,  Notice  sur  I'Eurypterus  de  Podohe,  etc.  Moscow,  4to,  Fig.     Noticed  in  Leonh. 

N.  Jahrb.  1840,  736. 
*1840.     L.  r.  Buch,  Beiträge  zur  Bestimmung  der  Gebirgsformationen  in  Russland,  in  Karsten  s  Archiv  für  Mine- 
ralogie, etc.  Bd.  XV.  Beriin,  8vo,  127.  (Contributions  to  the  History  of  the  Geology  of  Russia,  in  Karsten  s 

Archiv  for  Mineralogy,  etc.  vol.  xv,  Berlin,  8vo.     Noticed  iu  Leonh.  N.  Jahrb.  1840,  127. 

* Milne  Edwards,  Histoire  Naturelle  des  Crustaees.     Paris,  8vo,  vol.  iii,  p.  285  seq. 

* G.    Gr.    zu   Münster,  Beiträge  zur   Petrefactenkunde.     (Contributions  to   Paleontology.)  Bayreuth,    4to, 

vol.  iii,  p.  34  seq.     Noticed  in  Leonh.  N.  Jahrb.  1840,  135. 

*1842.  Vol,  V,  p.  112  seq. 

*1840.     //.    G.   Bronn,  über  die  mit  Homalonotus  verwandten  Trilobiten-Genera.     (On  the  genera  of  Trilobites 

related  to  Homalonotus.)     Noticed  in  Leonh.  Journal,  1840,  445. 
*1841.     A.   Goldfuss,   Beiträge  zur  Petrefactenkunde.     (Contributions  to  Paleontology,  in <Nova  Acta  Phys.  Med. 

Soc.  Leop.  Cur.  n.  s.  vol.  six,  pi.  I,  p.  327  seq.      Four  new  genera  :  Bostrichopus  (.'),  Arges,  Harpes, 

Brontes,  Illcenus.     Noticed  in  Leonh.  N.  Jahrb.  1841,  820. 
* L.  de  Koninck,  Memoire  sur  les  Crustaees  fossiles  de  Belgique,  in  Mem.  de  TAcad.  Roy.  de  Bruxelles,. 

tom.  XV. 


X  BIBLIOGRAPHY. 

*1842.     /.  Locke,  on  Isoteles  megistos,  in  Sillim.  Amer.  Jour.,  vol.  xlii.  No.  2,  p.  3GG. 
Laporte  de  Castelnau,  on  the  feet  of  the  Trilobites,  in  L'Institut,  18-11.',  p.  74.   Extract  from  it  in  Leoiili. 

and  Bronn,  n.  Jahrb.  1843,  p.  504. 

E.  Ekhwahl,  die  Urwelt,  Russlands,  II  Hft.  S.  60,  1842-4  (Metopias,  Lichas.) 

*1843.     /.  Locke,  on  Ceraurus  Crosotus,  in    Sillhn.  Am.  Journ.  of  Sc.  and  Arts,  vol.  .\liv.  No.  2,  p.  346. 

* F.  A  Römer,  die  Versteinerungen  des  Harzgebirges.     (The  fossils  of  the  Harz.)  Hannover,  1843-4. 

* Gohlfiiss,  systematische  Uebersicht   der  Trilobiten,  und  Beschreibung  einiger  neuen  Arten.     (Systematic 

review  of  Trilobites,  and  description  of  some  new  species,  in  Leonh.  and  Bronn  s   n.   Jarhb.    1843, 

p.  537.  seq.  Table  IV-VI. 

L.  de  Castelnau,  Essai  sur  le  Systeme  Silurien  de  I'Ameriquc  Septentrionale.      1843. 

* J.  E.  Portlock,  Report  on  the  Geology  of  the  county  of  Londonderry,  &c.     Dublin,  1843,  8vo,  with  Plates 

and  Map,  p.  234-312,  pi.  I-XI. 
*1844.     S.   L.   Luven,   on  Cali/mene   clavifrons   and   Cahjmene  ovata,  Dalmann ;   in  Ofvers  of   Kongl.   Vel-Akad. 

Forhandl.  1844,  p.  63. 
* L.  de Koninck,  Description  des  Animaux  Fossiles,  qui  se  trouvent  dans  le  terrains  Carbonifere  de  Belgique. 

Liege,  1842-44,  4to,  p.  595,  pi.  LIII. 

C.T.  Römer,  das  Rhesnische  Uebergangs-gebirge.     Hannover,  4to,  1844. 

*1845.     H.    T.   Emmerich,    über   die  TrUobiten,  Leonh.   and   Bronn.   Neues  Jalirbuch.   für  Jlineral.  &c.,   S.    18. 

(Translated  in  Taylor's  Scientific  Memoirs,  part  6th.) 

* S.  L.  Loveti,  über  Swedische  Trilobiten  in  Ofvers.  K.  V.  Swed.  Forh.  1845,  p.  46,  and  104,  plates  I  and  11. 

* E  Beyrich,  liber  einige  Böhmische  Ti-ilobiten.     Berlin,  1845,  4to. 

[To  the  above  may  be  added : 

J.  PÄ«7/(/M,  Geology  of  Yorkshire.     4to,  1830. 

Figures  and  Descriptions  of  the  Palaeozoic  Fossils  of  Cornwall,  Devon,  and  West  Somerset. 

London,  8vo,  1841. 
Vanuxem,  Geology  of  New  York.     4to,  Albany,  1842. 

E.  Emmons,  Geology  of  New  York.     4to,  1842. 
Hall,  Geology  of  New  York.     4to,  1843. 

Many  of  the  figures  of  Trilobites  in  the  New  York  Geological  Reports  are  copied  in  the  seventh  volimie 
of  Sil/imans  Journal,  1846. 

F.  3rCo>/,  A  Synopsis  of  the  Characters  of  the  Carboniferous  Fossils  of  Ireland.     Dublin,  4to,  1844. 

R.  I.  Mxrehison,  E.  de  Verneuil,  and  A.  de  Keyserling,  Geology  of  Russia,  vol.  ii,  Paleontology,  p.  376, 

plate  XXVII.  (One  new  species,  Phillijasia  Ouralica,  is  described.)  1845. 
R.  Griffith  and  F.  MCoy,  A  Synopsis  of  the  Silurian  Fossils  of  Ireland,  4to,  1846.     Dublin,  1846. 
J.  Barrande,  Notice  preliminaire  sur  le  Systeme  Silurien  et  les  Trilobites  de  Bohemie,  8vo,  1846. 
T.  Oldham,  on  Griffithides  glohiceps,  in  Proceedings  of  the  Dublin  Geological  Society  for  1846,  and  Plate.] 


CONTENTS. 


PAGE 

Preface    ........  ] 

Introduction  .......  3 


CHAPTER  I. 

On  the  Visible  Structure  of  the  Body  of  the  Trilobites  .  .  13 

CHAPTER  II. 

Affinity  of  the  Trilobites  to  the  Existing  Articulata  .  .  .31 

CHAPTER  III. 

Systematic  Arrangement  of  the  Species       ....  53 


Appendix     .               .               .               .               .               .              .  .112 

Supplementary  Appendix  by  the  Editors      ....  121 

Description  of  the  Plates         .               .               .               .               .  .129 

Index  of  Genera  and  Species  enumerated  by  the  Author        .               .  133 


PREFACE. 


Having  given  a  sketch  of  the  plan  of  my  present  work  in  the  subsequent  introduction, 
it  will  be  superfluous  to  enlarge  further  upon  it  here.  My  treatment  of  this  subject  in  a 
merely  zoological  point  of  view  is  partly  owing  to  the  very  natural  consideration  that  these 
most  ancient  remains  of  the  animal  world  not  only  admit  of  such  a  mode  of  contemplation, 
but,  indeed,  demand  it,  if  the  subject  is  to  be  thoroughly  worked  out ;  but  partly  also  no 
doubt  it  is  to  be  attributed  to  the  entirely  zoological  direction  of  my  studies.  Works  on 
fossils  are  undoubtedly  the  more  profound,  the  more  the  autlior  has  penetrated  into  the 
study  both  of  Geology  and  Zoology ;  but  who,  excepting  Cuvier,  can  boast  of  such  a 
universality  ?  I  therefore  preferred  to  relinquish  the  geological  investigation  of  the  subject 
entirely,  and  not  enlarge  on  the  various  strata  containing  Trilobites,  and  I  would  also 
request  the  reader  not  to  lay  any  great  weight  on  the  geological  observations  he  will 
occasionally  meet  with  in  the  course  of  the  work ;  for  they  may  sometimes  have  been  based 
on  the  views  of  others  imperfectly  understood,  and  for  this  and  other  reasons  they  must 
be  considered  as  not  to  be  implicitly  relied  on.  On  the  other  hand,  I  would  venture  to 
hope,  that  my  zoological  system  of  arranging  the  various  groups  may  meet  with  the  appro- 
bation of  my  readers,  and  that  I  may  have  succeeded  in  my  endeavours  to  lay  the  foun- 
dation of  a  single  and  correct  view  of  the  subject,  which  may  supersede  the  many  fluctu- 
ating ones  hitherto  prevailing.  My  object  indeed  included  both  these  departments  of  the 
subject,  but  I  cannot  answer  for  the  correct  designation  of  many  specimens  supposed  to  be 
of  identical  species,  but  frequently  no  doubt  imperfectly  determined,  or  of  others  presumed 
to  be  new,  the  originals  of  which  I  was  not  permitted  to  examine.  I  have  indeed  received 
much  assistance  from  German  authors,  but  have  often  not  been  so  fortunate  with  regard  to 
those  whose  species  appeared  to  me  the  most  questionable,  and  in  such  cases  the 
determination  was  frequently  left  to  the  view  I  took  of  them  on  my  own  personal  inspection. 
I  have  seen  everything  connected  with  my  object  contained  in  the  collections  of  Berlin 
and  Halle,  and  I  have  also  received  valuable  contributions  from  Mr.  Bocksch  in  Silesia, 
from  Captain   von  Charpentier,   and   from    Mr.   Honinghaus   at   Crefeld.      On    the   other 

1 


2  PREFACE. 

hand,  I  have  had  but  few  opportunities  of  examining  original  specimens  from  England 
and  America.  My  present  work  therefore  certainly  ought  not  to  be  considered  as  complete ; 
it  will  unquestionably  admit  of  much  improvement,  and  for  this  purpose  I  should  gratefully 
receive  any  assistance,  especially  of  original  specimens  of  species  hitherto  unknown  to  me, 
even  if  it  were  only  for  temporary  inspection.  Indeed  I  should  be  satisfied  with  good 
figures  of  such  specimens,  provided  they  were  accompanied  by  explanatory  descriptions. 
Such  illustrations  being  rare,  I  have  made  it  my  principal  object  to  render  the  plates  contained 
in  this  work  as  perfect  as  possible.  I  have  had  the  good  fortune  to  meet  with  an  artist 
in  the  person  of  Mr.  A.  Andorif,  of  Berlin,  whose  talents  and  whose  execution  of  the 
engravings  are  such,  that  I  can,  without  the  slightest  hesitation,  recommend  the  plates,  which 
were  executed  by  him,  as  patterns  for  imitation  to  all  artists.  Every  person  acquainted 
with  the  subject  will  undoubtedly  agree  with  me,  that  better  and  more  beautiful  representa- 
tions of  Trilobites,  or  figures  more  true  to  nature  in  every  respect,  are  not  in  existence. 


Halle;  May  ^th,  1843. 


INTRODUCTION. 


SECTION  I. 


Researches  on  organic  bodies  of  former  ages  are  equally  interesting  and  necessary 
to  the  Zoologist  and  Geologist,  although  their  respective  objects  in  pursuing  such  studies 
are  different.  For  whilst  the  Geologist  is  generally  satisfied  with  establishing  the  difference 
or  identity  of  the  species  found  in  the  several  strata,  the  Zoologist  insists  rather  on  a 
perfect  knowledge  of  the  animal  in  question,  to  enable  him  thereby  to  determine  the  modi- 
fications which  the  entire  animal  organization  has  experienced  in  the  successive  periods  of 
the  earth's  formation. 

These  entirely  different  interests  of  the  observers  explain  in  some  measure  why  the 
knowledge  of  extinct  animals  necessarily  remained  in  a  defective  and  imperfect  state  so  long  as 
no  competent  Zoologist  occupied  himself  with  the  subject,  and  indeed,  even  a  Zoologist  who  is 
so  qualified  can  only  give  satisfactory  information  if  perfectly  acquainted  ^ath  the  organization 
of  the  living  allies  of  such  animals,  and  that  in  most  minute  detail.  This  indeed  is  sufficiently 
proved  by  Cuvier's  great  researches  in  the  department  of  Palfeozoology,  and  the  example 
of  this  great  man  has  led  modern  Geologists  who  study  fossils  to  the  conviction  of  the  neces- 
sity of  profound  zoological  studies,  and  has  convinced  them  that  an  investigation,  at  least 
of  the  higher  animals,  cannot  be  instituted  without  accurate  zoological  knowledge.  The 
truth  of  this  principle  has,  however,  been  less  acknowledged  with  regard  to  the  lower  animals, 
and  least  of  all  with  respect  to  the  Articulata,  because  their  number  and  importance  in 
relation  to  geology  is,  upon  the  whole,  comparatively  slight,  whilst  their  organization  also 
has  been  particularly  studied  only  by  a  few  Zoologists,  and  by  them  only  recently.  There  is 
no  family,  however,  among  the  Articulata  of  a  former  world  which  in  every  respect  deserves 
so  much  attention  as  the  family  of  the  Tnhhites ;  and  consequently  this  tiibe  has  been  the 
subject  of  much  research,  but  our  acquaintance  with  their  organization  is  still  very  defective, 
either  because  all  the  more  recent  observers,  from  a  consciousness  of  their  imperfect 
knowledge,  did  not  enter  into  the  study  of  them  in  a  zoological  point  of  view ;  or  because, 
from  the  deficiency  of  their  zoological  studies,  they  could  not,  on  attempting  to  do  so,  disguise 
their  ignorance  on  those  points.  And  yet  it  is  undeniable  that  wc  may  obtain  as  clear  and 
perfect  an  acquaintance  with  the  organization  of  these  creatures  as  of  the  Mammalia,  since 
the  organization  of  a  crustacean  being  evidently  less  complex  than  that  of  a  mammal, 
a  perfect  idea  may  be  developed  with  even  greater  completeness  from  the  existing  fragments 
of  the  Trilobites,  than  was  possible  in  Cuvier's  representation  of  the  Vertebrata. 


INTRODUCTION. 


SECTION  II. 


The  object  of  the  present  work  is  the  carrying  out  such  an  illustration  of  the  subject 
in  all  its  parts.  Having  almost  e.xclusively  occupied  myself  with  the  study  of  the  Articulata, 
especially  of  insects  and  crustaceous  animals,  I  have  collected  the  materials  upon  which  I 
based  my  undertaking  with  diligence  and  circumspection ;  I  have  most  carefully  tested  all 
analogies  as  well  as  more  remote  relations ;  I  have  frequently  consulted  with  my  friends ; 
and  I  have  thus  gradually  pi'ogressed  with  my  subject  until  the  present  moment,  when 
leisure  is  at  last  afforded  to  me  to  devote  myself  entirely  to  the  work,  and  to  present  it  to 
the  public  in  its  present  state. 

Previous,  however,  to  communicating  my  own  researches,  I  beg  to  lay  before  my 
readers  a  short  sketch  of  the  information  which  has  hitherto  been  known  respecting  the 
Trilobites. 

SECTION  III. 

The  first  author  who  wrote  on  these  remarkable  animals  was  Edward  Lhwyd,  Curator 
of  the  Ashmolean  Museum  at  Oxford.  He  discovered  two  fragments  and  one  entirely 
preserved  specimen  of  the  Ogyyia  Buclm,  near  Llandeilo,  in  Carmarthenshire,  of  which  he 
sent  drawings  to  the  well-known  zoologist  Martin  Lister,  also  a  superintendent  of  the 
Ashmolean  Museum.  The  latter  gave  them  to  the  public  in  the  twentieth  volume  of  the 
'  Philosophical  Transactions.'  Lhwyd  owns  in  his  letter  that  he  did  not  know  what  to  make 
of  tliese  fragments  ;  in  Fig.  8  of  the  accompanying  plate  we  recognize,  however,  with 
tolerable  certainty,  a  cephalic  shield  of  the  genus  Trinudeus  of  Murchison,  {CryjjtoHflnis, 
Green,)  and  the  Ofjijgia  (Fig.  15)  is  perfectly  evident ;  but  Lhwyd  explains  it  to  be  the  skeleton 
of  an  unknown  fish.  The  same  author  published  in  the  year  following  his  '  Ichnographia 
Lithophyl.  Britann.,'  and  therein  enumerates  thirty  specimens  already  observed  by  him ; 
but  those  before  alluded  to  are  again  mentioned,  the  first  under  the  name  of  Trinudeus  fimbriatus 
vuhjaris,  the  subsequent  Dudley  fossil  as  Bur/Iossa  curta  sirif/osa.  These  communications, 
the  earliest  we  possess  on  the  Trilobites,  were  soon  followed  by  others  in  all  parts  of 
Europe,  but  although  the  number  of  observations  was  thus  increased,  the  knowledge  of 
these  animals  made  no  progress,  principally  because  correct  comparisons  with  living  forms 
were  wanting.  They  therefore  appear  in  subsequent  authors  merely  under  newly-invented 
names,  which  partially  indicate  very  incorrect  comparisons,  the  inappropriateness  of  which  is, 
however,  excusable,  since  the  observers  of  the  Continent  were  only  acquainted  with  mutilated 
specimens,  or  with  mere  caudal  shields,  and  therefore  were  much  inclined  to  mistake  these 
remains  for  shells.  One  author  (Hermann)  calls  them  Fcctunculites  trilohis  imbricatus,  another 
(Scheuchzer)  compares  them  with  Patella,  a  third  (Bromell)  fancied  that  he  recognized  in 
them  the  remains  of  insects,  while  a  fourth  (Brückmann)  also  compares  them  with  shells,  call- 
ing them  Armata  veneris,  and  so  also  does  Waltersdorf,  who,  in  his  System  of  Minerals,  styles 
them  ConcJiitcs  irihlus,  connecting  together  the  different  designations  of  his  predecessors  in 
"  Käfermuscheln,"  and  "  Muschelsteine."  But  the  correct  view  of  the  natural  affinity  of 
the  Trilobites  was  announced  at  almost  the  same  period.     Their  anomalous  form  induced  a 


INTRODUCTIOX.  5 

number  of  collectors  to  search  for  them  in  England,  where  the  most  beautiful  and  perfect 
specimens  have  always  been  found,  and  their  admirable  condition  in  that  country  readily 
caused  the  impression  that  they  must  be  Articulata  to  gain  ground.  We  learn  from 
Dr.  Shaw,  Lister's  successor  in  O.xford,  that  he  took  them  for  a  caterpillar  (eruca),  and 
Ch.  Lyttleton,  who  laid  new  specimens  before  the  Royal  Society  of  London,  coincides  in  this 
view ;  Ch.  Mortimer,  on  the  other  hand,  on  an  occasion  of  some  new  specimens  of  the 
Dudley  fossil  (as  the  Trilobites  were  usually  called  in  England,  from  the  principal  locality 
where  they  were  found)  having  been  sent  by  Dr.  Pocock,  expressed  the  opinion  that  they 
appeared  to  correspond  most  with  the  Monoctdus  apus,  Linn.,  shortly  before  described  by 
J.  Th.  Klein,  in  the  '  Transactions  of  the  Royal  Society'  (vol.  xl,  p.  150).  As  Klein  had  given 
the  name  of  Scolopendra  aqualka  scutata  to  this  animal,  Mortimer  proposed  the  designation  of 
ScoJopendrm  aquaticcB  scutata  oßne  animal  petrifcatiat/,  which,  however,  even  on  account  of  its 
length,  could  not  meet  with  any  great  approbation.  The  next  English  author  on  the 
Trilobites,  Emanuel  Mendez  Da  Costa,  endeavoured  therefore  to  find  a  better  name,  and 
on  again  laying  a  beautifully  preserved  specimen  before  the  Royal  Society,  he  declared 
it  not  only  to  be  a  crustaceous  animal,  but  also  to  be  one  nearly  related  to  the  sea-louse,  and 
he  called  it  Pediculus  mariniis  major  trilobus.  This  name  of  sea-louse  was  then  employed  to 
designate  several  of  the  larger  Isojwdes,  which  live  on  fishes  as  parasites,  and  from  amongst 
which  Linnaeus  constituted  his  genus  Oniscus.  Linnaeus,  whose  system  and  reform  of  the 
science  just  then  began  to  be  appreciated,  had  consulted  with  Mendez  Da  Costa  respecting 
the  Trilobites  in  the  same  year,  and  designated  all  the  species  belonging  to  it  as  modifications 
of  his  Entoniolithm  paradoxus,  deciding  himself  in  favour  of  their  near  affinity  to  Monoculim 
npus.  This  view  of  the  great  naturalist,  which  is  expressed  in  all  the  editions  of  the 
'  Systema  Naturae,'  certainly  ought  to  have  led  those  who  knew  little  more  of  the  subject 
than  the  fragments  lying  before  them  to  a  correct  conception  of  the  afiinity ;  but  their 
very  ignorance  of  the  points  of  comparison  made  them  overlook  it.  Several  authorities  now 
again  declared  in  favour  of  the  afiinity  to  the  Mvllasca ;  but  the  French  observer  Guettard 
correctly  enumerated  the  Trilobites  of  Angers  among  the  Crustacea,  designating  them  as 
allied  to  the  genus  Oniscus  of  Linnaeus.  This  author  was,  however,  perfectly  unacquainted  with 
Linnaeus,  and  equally  so  with  the  German  writers,  who  also  have  never  taken  any  notice 
of  him.  The  next  writer  on  the  subject,  Father  Joseph  Torrnbia,  having  been  a  native  of 
Spain,  where  the  sciences  were  in  a  dormant  state,  I  shall  not  lay  any  great  stress  upon  his 
opinion,  but  he  at  first  correctly  described  the  Trilobites  as  crustaceous  animals,  although 
subsequently,  misled  by  the  inspection  of  Rumphius's  figure  of  the  Liiiice  marina  {Chiton 
aculcatus,  Linn.),  imagined  the  latter  to  be  a  mollusc.  The  treatises  of  the  Provost  Genzmer 
of  Stargard,  of  Professor  D.  J.  G.  Lehmann  of  Petersburg,  of  the  well-known  secretary 
of  the  town-council  of  Danzig,  J.  Th.  Klein,  and  of  Professor  Zeno  of  Prague,  I  may 
enumerate  as  proofs  that  such  an  erroneous  conception  of  the  nature  of  Trilobites  has 
prevailed.  The  first  termed  them  Conchitce  ruyosi  irilübi,  and  Lehmann,*  as  also  Klein, 
adopted  this  designation,  whilst  their  contemporaries  enumerate  them  by  the  names  of 
"  Kiifer-muschel,"'  and  "  Kakadumuschel."     This  determined  anotlier,  but  more  enlightened 

*  In  the  summary  of  this  volume,  p.  56,   the  author  ex])rcsses  the   same   opinion   as  Liunseus, 
without,  however,  guaranteeing  its  correctness. 


(5  INTRODUCTION. 

collector  to  endeavour  to  diffuse  Linnaeus's  views  respecting  the  true  affinity  of  the  Trilobites 
among  his  readers,  and  to  prove  "  that  the  Conchologists  have  no  longer  any  reason  to 
consider  the  fossil  which  had  hitherto  been  known  by  the  name  of  a  Coiichifce  triloU  rnyosi 
as  a  part  of  their  science."  The  author  of  the  treatise  referred  to,  Ch.  Fr.  Wilkens, 
announced  his  name  in  the  following  year,  and  published  his  opinions  under  the  title  of 
'  Information  respecting  Rare  Animal  Petrifactions.'  He  treats  of  the  numerous  Trilobites 
in  his  collection  with  much  cleverness,  although  with  an  unnecessary  prolixity,  and  arrives 
finally  at  the  well-founded  result,  that  the  name  of  EntomoUthus  branchiopodis  cancnformis 
marinus  ought  to  be  given  to  them.  But  the  appearance  of  this  treatise  in  an  unknown 
periodical,  was  not  calculated  to  attract  attention,  or  procure  credit  and  appreciation  for  it,  and 
it  is  questionable  whether  it  would  ever  have  come  to  the  knowledge  of  subsequent  authors, 
if  J.  Imm.  Walch  had  not  particularly  referred  to  it  in  his  '  Natural  History  of  Fossils.'  It 
decided  Walch's  opinion,  however,  and  as  this  diligent  writer  brought  togetlier  everything 
that  had  hitlierto  been  written  on  the  Trilobites,  his  elaborate  work  became  an  authority 
on  which  succeeding  authors  might  rely  with  certainty  in  the  labyrinth  of  conflicting 
opinions.  Being  convinced  of  the  unfitness  of  tlie  names  hitherto  used,  either  owing  to 
their  incorrectness  or  their  length,  he  proposed  a  new  designation  for  them,  and  was  the 
first  who  called  these  animals  Trilobites,  a  designation,  which,  with  the  exception  of  Dalman, 
has  been  retained  by  all  the  subsequent  authors,  and  therefore,  being  the  oldest  and  by 
no  means  an  unsuitable  name,  will  also  be  retained  by  us.  Walch,  however,  was  not 
sufficiently  a  practical  zoologist  to  be  able  to  support  Wilkens's  \icws  by  additional  reasons, 
and  indeed  he  generally  speaks  more  of  the  ideas  of  others  than  of  his  own  opinions  on  the 
subject,  and  seems  inclined  to  consider  the  0/iisci  as  the  animals  most  nearly  allied  to  the 
Trilobites.  Henceforth  the  opinion  of  the  affinity  of  the  Trilobites  with  the  Mollusca  was 
nearly  buried  in  oblivion,  and  would  probably  never  have  been  known,  if  its  memory  had 
not  been  revived  again  nearly  fifty  years  afterwards  by  a  zoologist,  from  whom,  possessing  as 
he  did  an  accurate  knowledge  of  the  Articulata,  one  could  least  of  all  have  expected  it, 
namely,  by  Latreille.  The  next  writer  after  Walch,  John  Beckmann,  calls  them  Onisci,  without 
any  circumlocution,  and  Count  v.  Kinsky,  in  a  letter  to  the  Baron  von  Born,  uses  the  name 
given  by  Linnaeus,  while  M.  Th.  Brunich,  on  the  other  hand,  uses  Trilobus,  Walch's  designation 
in  an  abbreviated  form,  and  J.  K.  Gehler  retains  it  in  its  original  form.  Finally,  the  opinion 
of  A.  Modeer,  who  thought  that  he  could  recognize  the  structure  of  a  tube  beetle,  (Coccinella) 
in  the  Trilobites,  at  least  in  the  heads  of  liattus  and  Olcmts,  which  he  described,  was  new 
but  erroneous. 

SECTION  IV. 

Such  was  the  state  of  our  knowledge  of  the  Trilobites,  when  the  great  political  events 
which  took  place  at  the  conclusion  of  the  last  and  the  commencement  of  the  present  century 
rendered  all  serious  efforts  for  the  advance  of  science  impossible.  During  the  period 
extending  from  1793  to  1820,  we  only  meet  with  three  short  observations  on  the  Trilobites, 
of  which  the  first  is  contained  in  Blumenbach's  'Illustrations  of  Natural  History;'  the 
second  in  Parkinson's  '  Organic  Remains  of  a  Former  World ; '  the  third  in  Leonhard's 
'  Taschen-buch  fur  Mineralogie  ;'  in  which  the  Baron  v.  Schlotheim  describes  a  new  series 


INTRODUCTION.  7 

of  Trilobites  as  T.  coniir/crun,  directing  attention,  according  to  Bcckmann's  and  Briinicli's 
example,  to  the  necessity  of  distinguishing  several  species  of  these  animals.  This  very  correct 
view  he  furtlier  carried  out  in  his  '  Pctrefaktenkunde'  of  1820,  in  which  he  speaks  of  five 
different  species,  two  of  which,  however,  belong  to  doubtful  forms.  All  the  three  authors 
are  of  opinion  that  the  Trilobites  are  Crustacea,  without,  however,  determining  their  more 
intimate  affinity  with  any  particular  group. 

SECTION  V. 

The  year  1821  is  a  crisis  in  the  literary  history  of  the  Trilobites,  for  a  new  epoch  then 
commences,  which  may  be  designated  as  the  period  of  the  more  accurate  study  of  them. 
Four  distinguished  observers,  Latreille,  Audouin,  Wahlenberg,  and  Brongniart,  published  the 
result  of  their  studies  in  or  immediately  after  this  period,  the  two  former  only  paying  regard 
to  the  organization  of  these  animals,  the  two  latter  describing  the  differences  of  the  species. 

P.  A.  Latreille,  the  best  authority  on  the  subject  of  the  Articulata,  both  with  respect  to 
the  general  subject  and  its  details,  might  certainly  claim  attention  to  his  opinion  on  the  affinity 
of  the  Trilobites  ;  but  he  performed  his  task  in  a  manner  which  could  by  no  means  satisfy  those 
acquainted  with  the  subject.  After  having  formerly  determined  in  favour  of  the  affinity  of 
the  Trilobites  to  the  Articulata  (Cuv.  Regne  Anim.,  prem.  ed.  torn,  iii),  he  here  contradicts 
this  opinion  altogether,  and  endeavours  to  prove,  by  the  absence  of  feet,  that  the  Trilobites 
must  be  most  nearly  related  to  Chiton.  He  not  only,  therefore,  overlooked  the  articulation  of 
the  body,  pervading  all  parts  of  it,  but  also  the  eyes ;  he  asserts  also,  that  if  feet  had  been 
existing  they  must  be  recognizable,  and  from  their  absence  draws  the  conclusion  that  the 
Trilobites  are  Mollusca. 

V.  Audouin,  who  probably  had  only  shortly  before  completed  his  work  on  the  skeleton 
of  the  Articulata  (Annal.  des  Scienc.  Natur.,  pr.  ed.  tom.  i,  1824),  had  also  been  led  by  these 
studies  to  the  subject  of  the  Trilobites,  and  soon  recognized  their  articulate  nature  from  the 
remains  of  the  crust.  But  he  evidently  went  too  far  in  transferring  the  results  he  had  so  readily 
arrived  at  with  regard  to  insects  to  the  other  groups  of  the  Articulata,  and  in  this  he  sought 
analogies  which  do  not  exist  in  reality.  Indeed,  even  his  own  investigations  with  regard  to 
the  abdomen  of  the  Macrura,  with  which,  as  with  the  thorax  of  the  IsopoJa,  he  very  justly 
compares  the  crust  of  the  Trilobites,  ought  to  have  convinced  him  that  the  cpisterna  and  ejjimera, 
two  portions  of  the  thorax  of  insects  which  are  separated  by  particular  sutures,  do  not  at 
all  exist  in  the  gi'oups  enumerated,  and  that  even  the  boundary  between  back  and  sternum  is 
an  artificial  one.  He  nevertheless  views  the  lateral  lobes  of  the  shell,  which  in  many  of  the 
Trilobites  are  separated  by  an  oblique  diagonal  furrow  into  an  anterior  and  posterior  half,  as 
analogues  of  those  parts,  terming  the  anterior  cpisternum,  the  posterior  epimerum,  and  the 
middle  part  of  each  tergum;  appellations  manifestly  unsuitable,  since  several  Trilobites 
(e.  g.  Illanus)  do  not  possess  this  separating  furrow  at  all,  and  in  no  single  species  of  them  do 
the  regions  distinguished  by  him  constitute  isolated  pieces  connected  by  sutures.  AVe  arrive, 
however,  in  spite  of  these  subtleties,  for  which  there  is  no  natural  foundation,  at  the  four 
following  facts,  namely, — 

1st.  That  Trilobites  differ  only  from  the  other  Articulata  in  points  of  secondary 
importance,  and  that,  beyond  a  doubt,  they  belong  to  this  group  of  the  animal  kingdom. 


8  INTRODUCTION. 

2clly.  Tliat  they  exhibit  the  greatest  analogies  with  the  Isopodes,  particularly  with 
Cj/mofJioa  and  Lit/ia. 

3dly.  That  the  want  of  feet  seems  to  be  a  necessary  characteristic  of  their  skeleton 
formation,  although  this  point  still  remains  problematical. 

4thly.  That  these  feet,  if  they  existed  at  all,  were  most  probably  connected  with  the 
branchial  apparatus. 

An  important  result  was  evidently  gained  by  the  enunciation  and  establishment  of  these 
four  principles,  and  the  consideration  of  the  last  assumption  especially  has  given  that 
direction  to  future  researches  which  is  the  proper  result  of  a  preliminary  investigation. 

George  Wahlenberg  followed  more  closely  the  footsteps  of  Linnaeus  than  any  of  his 
predecessors,  and  endeavoured  to  maintain  his  view  respecting  the  afBnity  of  the  Trilobites, 
merely  also  changing  Linnaeus's  name  of  EntomoIifJtns  into  Entüwodrcic'ües.  But  as  he  was 
no  special  zoologist,  and  as  the  groups  of  the  Crustacea  in  general  could  not  be  very  strictly 
defined  at  that  period,  or  their  essential  characters  be  readily  distinguished  from  others,  he 
did  not  succeed  in  establishing  such  evidence  as  should  be  incontrovertible.  He  believed  that 
the  Trilobites  were  most  nearly  allied  to  Limulus,  and  was  inclined  to  transfer  this  similarity 
also  to  the  structure  of  the  feet.  The  feet  of  the  Trilobites,  in  his  opinion,  however, 
were  smaller  than  those  of  Limulus,  and  for  this  reason  were  absent  in  the  fossils.  In  some 
shields  and  rings  he  believes  that  he  recognizes  mere  membranes  that  had  been  cast  oflF, 
there  being  no  doubt  that  these  animals  must  have  cast  their  membranes  in  the  manner  of 
the  Articulata.  In  other  respects  he  still  leaves  all  the  species  in  one  genus,  and  describes 
fourteen  of  them. 

The  most  perfect  work  of  all  is  Al.  Brongniart's  'Histoire  Naturelle  des  Crustaces 
Fossiles,'  which  appeared  about  a  year  after  the  publication  of  Wahlenberg's  p.aper.  It  was 
this  work  which  first  pointed  to  the  generic  differences  of  the  Trilobites,  exhibiting  five 
genera  mostly  well-distinguished ;  the  species  were  more  accurately  determined,  and  the 
number  then  known  was  stated  to  be  seventeen ;  finally,  there  were  here  explained  many 
facts  with  regard  to  the  geological  history  of  Trilobites  more  elaborately  than  had  been  done 
by  Wahlenberg. 

Brongniart  expresses  the  correct  view  with  reference  to  the  zoological  relations,  namely, 
that  the  Trilobites  are  most  nearly  related  to  the  Bmnchiopodes  among  the  Crustacea,  and  that 
the  want  of  visible  feet,  as  well  as  of  visible  antennae,  accords  very  well  with  this.  He 
does  not,  however,  dispute  the  analogy  with  the  Impodes  so  distinctly  as  the  subject  requires. 
The  importance  and  influence  of  this  excellent  work  on  our  knowledge  of  the  Trilobites  was 
exhibited  immediately  after  its  appearance,  since  M.  Schlotheim  felt  himself  obliged  to  publish 
an  addition  on  this  subject  as  a  supplement  to  the  former  scanty  results  of  his  'Treatise  on 
Fossils ;'  and  in  this  supplement,  in  which  he  gave  an  extract  from  Brongniart's  work, 
together  with  a  description  of  some  new  species,  the  number  of  all  the  known  species, 
including  three  which  are  unsatisfactorily  described,  amounts,  according  to  his  enumeration, 
to  twenty-nine,  from  which,  however,  we  must  omit  three,  as  decidedly  not  belonging 
to  the  family.    ' 


INTRODUCTION. 


SECTION  VI. 


Having  thus  traced  the  history  of  tlie  Trilobites  in  detail,  and  almost  completely,  I 
shall  now  terminate  this  part  of  my  work,  since,  after  the  publication  of  M.  Brongniart's 
work,  the  multitude  of  authors  increased  with  every  year,  insomuch  that  a  mere  enumera- 
tion of  them  would  be  not  only  wearisome  but  superfluous,  since  the  contribution  of  each 
individual  being  merged  in  the  general  progress  of  the  study,  the  latter  only  requires 
to  be  made  prominent.  We  find,  however,  that  the  exertions  of  naturalists  henceforward 
were  especially  directed  to  the  establishment  of  species,  and  to  the  publication  of  new 
forms,  and  that  a  variety  of  errors  have  been  committed  in  this  respect,  which  principally 
originated  in  the  defective  knowledge  of  the  structure  of  the  body  of  the  Trilobites,  and  in 
the  imperfect  fragments  upon  which  such  new  species  have  been  founded.  An  immense 
number  of  new  names  and  characters  has  therefore  certainly  accumulated,  but  by  no  means 
in  the  same  ratio  is  the  number  of  really  new  facts.  Even  monographists  of  some  districts 
in  which  remains  of  Trilobites  are  found,  have  not  been  able  to  guard  against  confound- 
ing species  already  known  with  supposed  new  ones.  If  I  were  now  to  enter  upon  the 
particular  proofs  of  such  errors,  it  would  lead  me  into  an  investigation  of  the  differences  of 
species,  and  thereby  cause  subsequent  repetitions  ;  I  limit  myself  therefore  to  a  short 
notice  of  those  works  which  have  excited  attention,  and  on  that  account  deserve  a  par- 
ticular notice. 

Dalman's  '  Treatise,'  published  in  I82G,  is,  next  to  Brongniart's  '  Monography,'  the  most 
important  work  on  Trilobites,  but  it  does  not  add  any  important  new  facts  in  a  general 
point  of  view,  and  by  no  means  determines  the  zoological  affinity  of  the  Trilobites  de- 
cisively. In  the  particular  point  of  the  establishment  of  species,  it  is  only  richer  and  more 
complete  than  Brongniart's  work  with  reference  to  Sweden.  The  author's  proposal  to  use 
the  appellation  of  Palaadcs,  instead  of  the  family  name  of  Trilobites,  has  met  with  no  appro- 
bation, nor  does  it  merit  such,  since  nothing  more  is  expressed  by  it  than  by  the  older  name, 
which  at  least  indicates  correctly  a  portion  of  the  family  characteristics. 

The  Trilobites,  however,  were  made  the  subject  of  researches  at  many  different  places, 
almost  simultaneously  with  Dalman,  and  many  new  forms  and  views  were  thereby  more 
intimately  explained.  Dekay  (1824)  was  the  first  who  described  the  North  American 
Trilobites  in  several  treatises,  but  his  results  were  not  appreciated  by  the  scientific  men  of 
Europe  till  afterwards.  Count  Sternberg  (in  1825)  described  the  Trilobites  of  Bohemia  with 
his  usual  accuracy,  and  had  in  Boeck  (1827)  a  successor  equally  careful  and  ingenious.  It 
is  to  the  latter  that  we  are  particularly  indebted  for  a  correct  view  of  the  facial  line  or  suture, 
which  extends  through  the  cephalic  shield.  Payton  wrote  on  the  Trilobites  at  about  the  same 
period  in  England,  but  I  am  not  able  to  say  with  what  success,  since  I  have  never  seen  his  work. 
Four  authors  were  within  a  short  time  successively  employed  on  this  subject  in  Russia,  who 
furnished  by  their  joint  efforts  many  valuable  contributions.  Eichwald,  the  earliest  of  them 
(1825),  gave  a  perfect  monography  of  the  Trilobites  of  Esthonia,  and  also  enlarged  on  their 
zoological  affinities.  His  endeavour,  however,  to  trace  the  analogy  of  the  Trilobites  with  the 
Isopodes  was  not  more  successful  than  his  establishment  of  thirteen  different  species  was  accu- 
rate.   After  carefully  analysing  them,  we  can  only  recognize  in  them  four  really  distinct  species. 


10  INTRODUCTION. 

Razoumowsky's  observations  (1826)  are  aphoristic,  and  are  limited  only  to  some  forms  from 
the  neighbourhood  of  the  Ladoga  Lake,  all  of  which  were  already  known.  StscheglofFs 
treatise  (1827),  on  the  Trilobites  of  Petersburg!!,  written  in  the  Russian  language,  I  only 
know  through  Pander's  work.  The  latter  careful  observer  treated  the  same  subject  (1830) 
with  great  minuteness,  but  without  important  results.  He  certainly  succeeded  in  partially 
reducing  Eichwald's  species,  but  he  himself  mistook  his  own  species,  and  considered  them 
as  new  ones,  which  is  not  the  case  with  any  one  of  them.  The  general  part  of  his 
work  exhibits  the  greatest  diligence  and  research,  but  it  also  shows  an  entire  want  of 
knowledge  of  living  Crustacea,  owing  to  which  it  was  impossible  for  the  author  to 
communicate  new  and  certain  information  on  tlie  structure  of  the  Trilobites.  Eich- 
wald,  Razoumowsk}',  and  Pander,  however,  also  recognized  the  peculiar  swelling  at  the 
lower  side  of  the  cephalic  shield,  which  lies  before  the  mouth,  first  observed  by  Stokes, 
and  which  corresponds  with  the  dypeiis  of  the  Crustacea  and  Insects.  Goldfuss  (1828)  en- 
deavoured to  give  information  on  the  feet  of  the  Trilobites,  which  had  hitherto  escaped  the 
attention  of  observers,  but  although  he  explained  their  structure  correctly  in  a  theoretical 
point  of  view,  his  illustrations  are  not  calculated  to  convey  the  idea  they  are  intended  to 
represent.  The  endeavours  to  trace  these  organs  in  our  fossil  remains  must  always  remain 
unsuccessful,  since  it  is  impossible  that  parts  of  such  a  tender  nature  as  we  must  suppose 
them  to  have  been,  judging  from  the  living  analogues  of  the  genus,  can  have  left  trace  of 
their  existence.  Tlieir  very  absence  in  fossils  most  distinctly  proves  their  former  real 
structure. 

Next  to  Pander's  work  there  was  published  (in  1832)  Green's  '  Monography  of  the 
American  Trilobites,'  a  work  abounding  in  names  and  words,  but  as  poor  in  really  available 
facts.  Indeed,  if  the  author  had  not  also  caused  plaster  casts  of  his  best  specimens  to  be 
manufactured,  it  would  liave  been  impossible  to  recognize  even  one  half  of  the  really  new  species 
from  his  descriptions  and  illustrations.  This  period,  indeed,  was  rich  in  a  number  of  publi- 
cations on  the  subject,  the  appearance  of  which  was  of  no  great  importance  to  the  furtherance 
of  our  knowledge,  and  the  value  of  which  was  very  correctly  estimated  by  L.  v.  Buch, 
when  he  considers  them  as  of  less  consequence  than  "  two  important  observations  of 
Quenstedt  in  Wiegmann's  Archives,"  on  which  I  shall  soon  more  particularly  enlarge.  Among 
these  writers  we  may  enumerate  Zenker,  the  more  recent  (1833)  observer  of  Bohemian 
Trilobites,  the  results  of  whose  labours  were  already  successfully  portrayed  in  the  same 
year  by  Count  Sternberg.  Kloden's  statements  also,  respecting  the  structure  and  mode  of 
living  of  the  Trilobites  on  those  remains  which  are  found  in  the  Mark  Brandenburg  (1834) 
only  contain  ill-founded  assertions.  This  certainly  cannot  be  asserted  of  Sai''s  communi- 
cations (Isis,  1835),  although  not  all  the  species  are  new  which  he  describes  as  such.  We 
regret  that  the  same  may  be  said  of  Murchison's  description  of  the  English  Trilobites, 
given  in  his  great  and  excellent  work  on  the  '  Silurian  System  of  the  British  Islands' 
(London,  1837).  The  author,  being  merely  a  geologist,  has  preferred  allowing  W.  S.  M'Leay 
to  speak  on  the  zoological  affinity  of  these  animals,  but  the  peculiar  ideas  of  the  latter  are 
not  calculated  to  afford  a  real  explanation  of  such  questions.  The  division  of  the  Crustacea, 
in  which  the  AnqjJiipocles  (together  with  the  Isopodes),  Trilobites,  and  Entomostraca  are  enume- 
rated as  three  subdivisions  of  equal  value  with  one  great  principal  group,  which  is  considered 
as  founded  in  nature,  is  not  calculated  to  create  any  great  confidence  in  the  systematic  talent 


INTRODUCTION.  1 1 

of  their  author.  M'Leay,  too,  on  this  occasion,  as  he  lias  often  clone  clscwhei'c,  confounds  the 
ideas  of  analogy  and  affinity,  the  first  distinction  of  which  in  England  is  justly  considered 
as  his  greatest  and  generally  acknowledged  merit.  Another  English  author,  however.  Dr. 
Buckland,  had  not  long  before  (183G)  already  explained  the  same  subject  with  much  genius 
and  vigour.  He  believes  that  Scrolls,  Limulus,  and  Bramkipus  are  the  three  genera  of  living 
Crustacea,  to  which  the  Trilobites  are  most  nearly  related,  and  he  founds  his  comparison 
on  the  resemblance  of  general  form  in  the  first,  the  structure  of  the  cephalic  shield  in  the 
second,  and  the  structure  of  the  feet  and  nature  in  the  eyes  in  the  third.  How  far  these 
assumptions  are  well  founded,  we  shall  subsequently  investigate. 

I  will  not  here  touch  at  greater  length  upon  the  several  observations  of  contemporary 
writers,  as  of  Hönighaus,  Bronn,  H.  v.  Meyer,  Hünefeldt,  J.  V.  Thompson,  Sowerby,  Jukes, 
Esmark,  Green,  and  Harlan,  but  will  proceed  to  some  more  recent,  more  elaborate,  and  more 
important  works,  which  form  the  conclusion  of  the  researclies  hitherto  made.  Hiesinger, 
in  his  General  View  of  the  Swedish  Trilobites  (1837),  the  first  of  these  publications, 
follows  Dalman's  example  exactly,  and  gives  but  few  new  facts.  Quenstedt's*  statement  in 
Wiegmann's '  Archiv'  (1837,  1),  deserves  greater  attention,  especially  on  account  of  the  import- 
ance which  was  here  first  attached  to  the  numerical  proportions  in  the  difi"erent  divisions 
of  the  body,  particularly  of  the  trunk.  I  must,  however,  dispute  the  correctness  of  the 
author's  representation  of  the  eyes,  of  which  he  assumes  two  types,  and  also  his  assertion 
that  a  division  of  the  group  into  genera  is  not  yet  necessary.  With  regard  to  the  latter 
point,  it  should  be  remembered  that  the  object  of  the  descriptive  natural  sciences  consists  by 
no  means  in  the  mere  registering  of  natural  bodies,  but  involves  the  unveiling  of  those 
differences,  subordinate  one  to  another,  by  which  nature  has  changed  the  original  simple 
type  into  so  many  various  forms.  Having  once  correctly  recognized  such  distinct  degrees 
of  modification,  and  having  made  out  the  characteristics  of  these  modifications,  we  then 
consider  them  as  genera,  or  speaking  generally,  as  groups  to  which  we  give  special  names, 
in  order  to  remind  us  of  the  peculiarity  in  the  modification  of  the  fundamental  type.  For 
this  and  for  no  other  reason  is  it  that  we  give  names  to  the  groups,  intending  simply 
to  facilitate  the  interchange  of  ideas  and  experiences,  just  as  the  use  of  coin  facilitates 
commercial  intercourse.  Quenstedt's  predecessors  knew  this  quite  as  w-ell  as  his  successors 
have  appreciated  it,  and  made  it  their  object  to  establish  well-founded  genera.  Boeck  onl)^ 
attempted  to  indicate  these  (in  Keilhaus  'Gaea  Norwegica,'  1838),  reserving  for  himself 
the  particular  description  in  a  '  Monography  of  the  Trilobites,'  which  has  long  been  an- 
nounced, but  which  has  not  yet  made  its  appearance.  Emmerich  in  this,  howevei",  has 
anticipated  him,  succeeding  Quenstedt  as  assistant  at  the  Mineralogical  Museum  at  Berlin, 
and  likewise  following  in  the  footsteps  of  the  latter  naturalist,  and  choosing  the  Trilobites  as 
the  particular  object  of  his  studies.  In  his  carefully  executed  work  (Diss.  Inaug.  Berol. 
1839)  the  general  part  is  certainly  not  much  enriched  by  new  facts  or  views,  but  the  special 
part  is  written  with  a  careful  investigation  of  the  manifold  synon)'ms,  and  built  on  the  gene- 

*  I  believe  that  I  was  the  occasion  of  this  statement.  During  a  visit  to  the  !Mineralogical 
Museum  at  Berlin,  at  which  ]M.  Quenstedt  ^^as  tlien  assistant,  I  explained  to  him  my  views  respecting 
the  Ti-ilobites,  their  structure  and  their  affinities,  and  laid  particular  stress  on  tlic  importance  of  the 
numerical  proportions.  The  statement  alluded  to  was  published  a  few  months  subsequent  to  that 
conversation. 


12  INTRODUCTION. 

rally  correct  basis  which  Quenstedt  exhibits  in  this  respect.  The  group  of  the  large-eyed 
species,  furnished  with  eleven  articulations,  which  was  first  recognized  by  the  latter,  was  named 
Vhacops  by  Emmerich,  and  appears  as  a  genus,  besides  eight  others,  of  which  the  second 
{Odontopleura)  is  also  new  and  well-founded,  but  cannot  be  satisfactorily  recognized  by  the  very 
defective  illustrative  figure.  Emmerich  has  also  followed  his  predecessor  in  this  respect,  that 
he  extends  the  identity  of  Ilomalonotus  and  Trimerm,  first  announced  by  Murchison  (and  to 
which  Brenn  subsequently — 1840 — also  added  Blpleuni),  to  Co/ywrae,  considering  the  group 
merely  as  a  subdivision  of  it.  He  unquestionably,  however,  goes  too  far  in  this  respect, 
especially  when  he  separates  from  it  Bipleum,  which  of  all  the  three  forms  is  most  nearly 
related  to  Cali/meue. 

Next  to  this  work  there  follows  a  brief  but  sound  and  valuable  account  of  the  Russian 
Trilobites  by  L.  v.  Buch  (1840),  containing  a  correct  view  of  all  essential  characters,  namely, 
a  comparative  study  of  the  relative  proportions  of  the  head,  trunk,  and  tail,  and  the  relation 
of  the  separate  parts  to  the  whole.  "  By  proceeding  in  this  manner  only  can  we  expect  real 
natural  historical  classifications,  such  as  rise  above  the  poor  purpose  of  serving  as  con- 
venient indices  to  collections  and  catalogues."  This  is  perfectly  true,  but  the  contemporary 
works  of  the  Count  v.  Münster  (1840  and  1842)  unfortunately  do  not  soar  beyond  that 
purpose,  for  they  scarcely  furnish  a  single  perfect  description  of  the  many  new  species 
exhibited,  and  only  indicate  obscurely  in  the  illustrative  plates  the  real  forms  to  which  they 
probably  belong. 

The  paradoxical  forms  which  Goldfuss  has  published  (1841)  offer,  both  in  perfection 
of  representation  and  description,  a  magnificent  contrast  to  the  last  work,  and  cannot  be  too 
strongly  recommended  as  a  pattern  to  those  who  henceforth  wish  to  describe  Trilobites  from 
fragmentary  specimens.  The  newest  work  on  this  subject,  one  recently  published  by 
Milne  Edwards,  in  the  third  volume  of  his  '  Histoire  Naturelle  des  Crustaces,'  tom  iii,  1841, 
embraces  indeed  everything  connected  with  the  subject,  but,  on  the  other  hand,  is  by  no 
means  worthy  of  the  name  which  this  distinguished  French  naturalist  has  procured  for 
himself  by  many  excellent  works.  The  arrangement  of  the  Trihhites  between  Isojmks  and 
Phyllopodes,  which  the  author  follows,  does  homage  to  all  the  different  views  hitherto  pro- 
posed on  the  subject,  and  therefore  does  not  bring  the  matter  to  a  decision  ;  but  in  this 
case  the  truth  lies  by  no  means,  as  it  often  does  in  other  cases,  in  the  middle.  Among  the 
assumed  twelve  genera,  several,  as  Pleuracanthus,  Peltura,  and  Otarion,  are  founded  on  mis- 
understood fragments,  and  the  same  may  be  said  of  many  species  which  the  author  copies 
from  his  predecessors  without  any  further  investigation.  It  is  to  be  regretted  that  so  pro- 
found a  zoologist,  who  may  justly  be  considered  by  the  many  as  a  distinguished  authority, 
has  paid  so  little  attention  to  this  part  of  his  otherwise  very  meritorious  volume,  and  has 
thus  furnished  a  work  which  can  only  be  considered  valuable  as  a  mere  compilation.  It 
certainly  has  not  advanced  us  one  step  in  our  knowledge  of  the  structure  of  these  animals. 


THE  ORGANIZATION  OF  TRILOBITES. 


CHAPTER  I. 

ON  THE  VISIBLE  STRUCTURE  OF  THE    BODY  OF  THE  TRILOBITES. 

SECTION  I. 

The  body  of  all  Trilobites  consists  of  three  distinct  divisions,  which  have  received  the 
denominations  of  cajmt,  thorax,  and  abdomen.  They  may  be  recognized  as  Articulata  by  this 
characteristic  alone.  The  first  two  divisions  include  many  associated  parts,  constituting 
the  cephalothorax ;  but  these  remain  separated  in  the  Trilobites,  and  this  circumstance  not 
only  greatly  facilitates  the  special  examination  of  their  body,  but  also  affords  convincing 
information  respecting  their  afiinity  to  existing  species.  Postponing  the  investigation  of 
their  affinity  to  the  next  chapter,  we  shall  now  consider  the  remains  of  the  Trilobites,  as 
they  are  presented  for  our  examination. 

SECTION  II. 

The  remains  of  the  Trilobites  are  limited  to  the  shell  and  its  impressions,  and  no  softer 
part  of  their  body  has,  or  indeed  could  be  preserved.  Hence  it  appears  to  me  certain  that 
all  those  parts  which  possess  the  hardness  of  the  shell,  or  at  least  were  clothed  by  any 
substance  as  hard,  must  exist  in  the  impressions  of  the  Trilobites ;  and  that,  on  the  other 
hand,  those  parts  which  probably  existed,  but  which  are  wanting  in  these  impressions,  did 
not  possess  the  firmness  of  the  shell,  and  are  absent  on  that  account.  If,  therefore,  as  is  the 
case,  we  no  longer  perceive  the  entire  abdominal  sui'face  of  the  Trilobite  body  with  all  its 
attached  organs,  we  must  infer  that  they  had  a  much  softer  membraneous  covering  and 
consistency,  but  we  can  by  no  means  infer  that  those  parts  did  not  exist.  This  view  of  the 
subject  is  rendered  more  probable,  when  we  observe  the  same  quality  of  the  abdominal 
surface  and  its  organs  in  still  existing  organic  bodies  which  are  similar  to  tlie  Trilobites ; 
indeed,  a  more  particular  comparison  of  the  existing  Trilobite  remains  with  the  shells  of 
such  living  animals  raises  our  assumption  to  a  positive  certainty,  since  we  also  recognize  the 
greatest  similarity  in  the  latter.  An  accurate  knowledge  of  the  shell  of  the  Trilobites  is, 
therefore,  the  first  and  most  important  requirement  for  the  observer. 


14  VISIBLE  STRUCTURE 


SECTION  III. 


My  observations  on  this  subject  must  be  preceded  by  the  explanation,  that  the  real 
shell  has  by  no  means  been  preserved  in  all  the  Trilobites,  but  that  a  great  part  of  their 
remains  consists  merely  of  impressions  from  the  shell.  This  is  the  case  in  all  the  Trilobites 
of  the  grauwacke  and  of  the  clayslate,  therefore  particularly  in  the  OJenida ;  undoubted 
remains  of  the  shell  itself  are  first  found  in  the  specimens  from  the  alum  slate,  and  the 
same  is  more  or  less  perfectly  preserved  in  most  of  the  individuals  inclosed  in  the  transition 
limestone.*  In  individuals  from  this  rock,  especially  in  such  as  are  found  as  loose 
stones  in  many  localities  of  Northern  Germany,  and  which  are  already  perfectly  freed 
from  the  limestone  that  formerly  surrounded  them,  we  see  most  distinctly  that  the  shell  con- 
sisted of  two  layers,  of  which  the  external  one  extended  itself  over  the  lower,  thicker,  darker 
layer  as  a  very  thin,  and  generally  clear  coloured,  coat.  This  fine  coat  is  closely  covered  with 
small  uneven  tubercles,  or  is  granulated  on  its  whole  external  surface,  and  has  therefore  quite 
the  appearance  of  the  horny  shell  of  our  river  crawfish,  especially  at  the  claws.  These  granu- 
lations were  so  slight  over  most  parts  of  the  body,  that  they  left  no  trace  at  all  in  the  second 
or  lower  layer  of  the  shell ;  but  their  presence  in  the  more  elevated  portions,  as,  for  instance,  in 
the  arched  anterior  portion  of  the  head,  and  on  the  rings  of  the  body,  betrays  itself,  even  when 
the  upper  membrane  is  wanting,  by  light  but  larger  tubercles,  which  cover  these  spots.  They 
attain  their  greatest  development  in  the  CaJijinene  variolaris,  which  derives  its  name  from 
them,  but  they  are  likewise  not  wanting  in  the  Dudley  Trilobites  {Calymene  Bhnnenbaclni).  It 
is  only  in  these,  and  in  the  smaller  specimens  (var.  jmJcheUa),  that  I  have  hitherto  been 
able  to  observe  the  external  layer  with  its  granulations  in  a  well-preserved  state  ;  the  upper 
layer  is  almost  always  wanting  in  the  granulated  species  of  Pliacops ;  the  general  granu- 
lation, therefore,  can  only  be  inferred  from  the  existence  of  those  larger  granulations  of 
the  lower  layer  of  the  shell.  The  granulated  surface,  however,  seems  to  have  been  a  general 
quality  of  the  group  in  the  two  genera  Cali/meiie  and  Pliacops,  and  seems  to  belong  to  all  their 
species.  Most  published  figures  of /"//«fo/)«  confirm  this  opinion;  the  granulation  in  the  genus 
Calymene  has  generally  been  overlooked,  because  it  is  here  much  finer  and  slighter,  and 
because  it  is  usually  only  recognized  on  the  upper  membrane  itself.  If,  however,  the 
second  layer  of  the  shell  has  likewise  been  cast  ofi',  and  if  the  impression  of  the  interior  of 
the  shell  of  the  Trilobite  only  is  existing,  those  indistinct  coarser  traces  of  granulation  are, 
as  a  matter  of  course,  also  wanting,  and  the  surface  appears  to  be  smooth.  This  is  not  only 
veryfrequently  the  case  with  regard  to  Calymene  Blnmenhackii ,  but  also  very  often  with 
Pliacops  latifrons,  and  with  regard  to  the  latter  has  given  rise  to  the  enumeration  of  several 
species  (C.  latifrons,  and  C.  Schlotheimii,  Bronn).  P.  iwofuherans,  and  all  the  species  of 
this  genus  which  are  described  as  smooth,  seem  to  originate  from  those  individuals  the 
membranes  of  which  have  been  cast  off. 

*  These  remarks  ^Tere  intended,  no  doubt,  bj^  the  author,  to  refer  chiefly  to  the  distribution  of 
Trilobites  in  the  rocks  in  his  own  neighbourhood.  The  actual  shell  of  these  animals  is  found  frequently 
in  the  Siliu'ian  limestones  in  England,  and  sometimes  in  the  Caradoc  sandstone,  the  oldest  rock  in 
^vhich  they  appear.      The  shell  is  found  also  in  the  Devonian  and  carboniferous  limestones. — Eng.  Ed. 


OP  THE  TRILOBITES.  15 


SECTION  IV. 

The  upper  membrane  just  described  seems  only  to  be  a  peculiarity  occurring  in  the  genera 
mentioned,  and  of  some  others  {Brontius,  Odontopleura,  Jloiiialoiiotus),  but  wanting  in  most  of 
the  Trilobites.  Not  even  the  slightest  trace  of  a  more  delicate  layer,  capable  of  being 
thrown  off,  can  ever  be  discovered  on  the  surface  of  the  shell  of  perfectly  well-preserved 
remains  of  the  genera  Asapliiis  and  Illanus,  indicating  a  different  quality  of  the  horny 
covering  of  these  genera.  In  individuals  whose  external  surface  is  in  some  places  not  at  all 
injured,  I  perceive,  on  the  other  hand,  fine  deeply  cut  lines,  which  run  pretty  much  in  the 
same  manner  as  the  furrows  in  the  palm  of  the  human  hand,  but  are  situated  more  remote 
from  one  another,  and  have  fine  punctured  dots  between  them.  I  observed  this  character  of 
the  surface-membrane  in  Calymene  and  Phacops,  but  most  distinctly  in  Asaphus  expanms,  var. 
cornigerus,  upon  the  arched  anterior  portion  of  the  head,  and  at  the  most  elevated  parts 
of  the  rings  of  the  body,  and  often  exactly  at  those  points  where  the  granulation  is 
most  perfect ;  on  the  other  hand,  I  noticed  those  fine  points  in  greater  number  and  in  a 
closer  position  on  the  lateral  portions  of  the  cephalic  shield,  on  the  lateral  lobes  of  the  rings 
of  the  body,  and  on  the  caudal  shield,  but  in  those  places  they  are  only  single,  coarse,  rather 
elevated  diagonal  lines,  which,  however,  are  distributed  in  a  tolerably  symmetrical  manner. 
This  formation  likewise  meets  with  its  analogue  in  living  Crustacea,  and  may  be  found  in  the 
thorax  of  the  lobster,  particularly  as  regards  the  punctures. 

These  granulations  and  punctures,  however,  only  exist  on  that  surface  of  the  shell 
which  is  at  the  superior  side  of  the  animal,  for  the  inferior  surface,  as  far  it  has  been 
preserved,  has  a  diS'erent  structure.  It  was  likewise  covered  by  a  peculiar,  but  always 
thinner,  horny  membrane,  which,  however,  gradually  became  more  delicate  the  nearer  it 
approached  the  middle,  being  everywhere  separated  from  the  upper  side  of  the  shield  by 
a  layer  of  muscle,  and  itself  consisting  of  a  softer  structure.  These  statements  may  be 
verified  by  observations  ;  and,  as  one  reason  in  support  of  them,  I  may  state  that  we  always  find 
in  the  remains  of  Trilobites,  in  which  both  layers  of  the  shell  are  existing,  that  there  is  a  layer 
of  rock  between  them,  which  indicates  their  distance  from  one  another.  As  another  reason, 
we  may  state  that  we  observe  at  once  the  thickness  of  the  petrified  shell  by  such  layer  of  stone, 
and  perceive  that  the  lower  layer  is  thinner  than  the  upper.  For  the  better  understanding  of 
these  proportions,  I  beg  to  refer  my  readers  to  the  illustration  of  the  large  Asapjhts  shield, 
which  I  have  given  in  Plate  V,  Fig.  4.  This  shield  is  still  covered  on  its  left  side  by  its  old 
petrified  shell,  furnished  with  its  natural  surface,  and  therefore  only  exhibits  a  tolerably 
well-defined  system  of  parallel  striae  at  that  part  of  the  anterior  margin  which  was  overlapped  by 
the  lateral  lobes  of  the  last  thoracic  ring.  A  sharp  broken  edge,  which  at  first  runs  along 
the  whole  length  of  the  middle  of  the  abdomen,  and  then  turns  towards  the  left,  indicates 
the  limit  of  the  broken  shell.  That  which  is  still  visible  towards  the  right  is  only  the 
impression  of  the  shell  on  that  part  of  tlie  stone  which  penetrated  into  the  shield  of  the 
abdomen.  From  this  part,  however,  a  considerable  piece  is  broken  off  at  the  posterior 
margin,  and  there  is  not  only  visible  a  part  of  the  lower  shell,  but  also  its  impres- 
sion into  the  stone  situate  beneath  it,  at  those  points  where  the  shell  itself  is  wanting. 
This    accidental  quality  of   the    shield    proves   distinctly  that    the    lower  surface    of   the 


16  VISIBLE  STRUCTURE 

shell  is  furnished  with  fine  parallel  lines,  as  in  the  covered  part  of  the  upper  surface  at  the 
anterior  margin ;  that  it  consists  of  a  horny  membrane,  thinner  than  the  latter ;  and  that 
the  distance  of  the  two  membranes  from  each  other  was  much  greater  in  an  angle  of  the 
lower  layer  than  at  the  other  parts  of  the  whole  shield,  greater  indeed  even  than  at  the  end 
of  the  real  abdomen,  the  lancet-formed  point  of  which — at  least  in  this  case — seems  to  have 
been  flat.  For  there  seems  to  me  no  reason  for  supposing  that  this  part  was  flattened  by 
external  force,  and  was  originally  aixhed  downwards,  since  the  parallel  angle  of  the  lower 
side  is  perfectly  preserved,  and  not  flattened,  which  certainly  would  have  been  the  case  if 
the  whole  shield  had  sufi^ercd  considerable  pressure. 

The  lateral  lobes  of  the  joints  of  the  body  and  the  whole  cephalic  shield  are  formed 
also  like  this  shield  of  the  abdomen.  Thus  we  may  most  distinctly  convince  ourselves,  from 
many  fragmentary  specimens,  that  the  entire  lower  surface  of  the  shell  of  the  head  was  covered 
in  the  neighbourhood  of  the  anterior  margin  with  such  deeply  cut  parallel  lines,  giving 
that  surface  the  appearance  of  a  regular  striation,  the  furrows  of  which  run  parallel 
with  the  circumference.  The  interior  as  well  as  the  exterior  surface  of  the  lateral 
lobes  is  formed  in  a  somewhat  similar  manner,  though  not  entirely  so,  as  far  as  the  latter  is 
covered  by  the  preceding  lobe.  On  this  lobe,  however,  the  lines  run  lengthwise,  are  not  so 
deep,  are  frequently  furcated,  and  are  in  general  not  so  regular  as  at  the  cephalic  and 
caudal  shield.  I  have  nowhere  been  able  to  perceive  the  dots  between  these  lines  of  the 
lower  surface,  which  are  situated  between  them  at  the  upper  surface,  and  which  even  occur 
at  many  places  by  themselves,  without  the  lines ;  they  are  here,  as  they  are  generally, 
wanting  as  the  granulations  at  the  lower  surface  of  the  species  of  Calymene  and  PJiacops,  in 
which,  however,  the  cross  striae  described  are  as  generally  found  as  they  are  in  Asaphus  and 
lllanus.  We  have  not,  however,  so  many  opportunities  of  observing  them,  since  most 
specimens  of  these  genera,  and  indeed  always  the  most  beautiful  ones,  are  rolled  up,  so  that 
we  are  unable  to  observe  any  of  the  parts  of  the  lower  surface. 

This  is  all  that  I  have  been  able  to  ascertain  with  certainty  as  to  the  nature  of  the  shell 
of  the  Trilobites.  I  suppose  the  same  structure  to  be  existing  in  the  Olenides  as  in  Asaphus, 
at  least  I  have  been  able  to  convince  myself  of  a  similar  striation  of  the  lower  surface.  Genker 
has  also  observed  the  same,  and  indicated  it  in  his  figures,  for  instance,  in  Table  V,  Fig.  c  d. 


SECTION  V. 

Proceeding  to  the  subject  of  the  divisions  of  the  body,  and  commencing  with  the 
consideration  of  the  head  as  the  first,  we  shall  soon  observe  that  this  part  is  encased 
in  a  great  parabolical  semicircular  lunate  shield  {scidiim  capitis,  cephalic  shield),  in  which 
the  head  itself  only  occupies  the  central,  and,  therefore,  the  more  highly  arched  part. 
This  central  part,  the  head  itself,  which  1  shall  henceforth  call  head-tubercle  {Kopfbxckel — 
glabella,  according  to  Dalraan),  is  very  distinctly  characterized  by  a  furrow  round  it  of 
greater  or  lesser  depth,  is  always  rather  longer  than  broad,  generally  broader  and  thicker 
at  the  anterior  part,  and  is  there  also  more  highly  arched  and  more  strongly  projecting.  In 
many  instances  impressions  exhibit  themselves  on  the  whole  elevation,  which  proceed  from 
the  furrow  surrounding  it,   and  which,  more  or  less,  penetrate  into  the  head-tubercle,  some- 


OF  THE  TRILOBITES.  17 

times  even  (as  in  Pamdod'iilcs  and  Ohnm)  becoming  complete  cross  furrows.*  There  are 
at  tlie  utmost  tliree  such  furrows  at  eacli  side,  separating  lobes  from  the  lateral  margin 
of  the  head,  which  are  partly  even,  partly  uneven,  and  in  the  latter  case  form  the  broader 
lobes  either  on  the  posterior  part  [Cali/mene),  or  on  the  anterior  part  [PJiacops).  In  other 
cases  they  are  entirely  wanting  {Illa-nus),  or  are  only  indicated  as  slight  depressions  of  the 
margin  of  the  head  {AsojjJims).  Next  to  the  central  head-tubercle  is  seen  the  cephalic  shield, 
which,  however,  generally  is  not  quite  flat,  but  likewise  slightly  arched,  so  that  it  declines 
more  or  less  towards  the  circumference,  thereby  forming  a  cavity  beneath  it.  Of  its  two 
margins  the  anterior  is  always  more  strongly  curved  than  the  posterior,  the  former  frequently 
representing  a  very  pointed  parabola  or  hyperbola  [Isotclrs),  whilst  the  latter  only  exhibits  a 
circular  arch.  The  latter  becomes  deeper  in  proportion  to  the  greater  or  lesser  projection  of 
the  frequently  long  pointed  lateral  angles.  The  margin  of  this  cephalic  shield  is  either 
extended  flatly  {Amplius,  Isoicles),  or  has  a  distinctly  protuberant  margin ;  in  the  latter  case 
either  having  an  acute  angle  [Calijmene)  or  being  rounded  off  [Phacops).  The  central  portion 
of  the  posterior  margin,  at  the  part  where  it  covers  the  first  ring  of  the  body,  usually 
projects  in  a  thickened,  swollen,  and  even  ring-like  form  {Jscqj/iuis) ;  the  furrow-deposit, 
however,  which  I  shall  call  neck-collar  {Gelenkwulsf,  sulcus  verticalis  of  Dalman),  also  usually 
disappears  towards  both  sides  so  rapidly,  that  it  scarcely  extends  bc3'ond  the  middle  of  the 
lateral  lobes.  In  other  numerous  cases  the  collar  extends  quite  as  prominently  in  the 
middle  of  the  posterior  margin,  but  is  distinctly  separated  from  the  central  part,  as  far  as  the 
lateral  angles,  then  passes  round,  surrounding  the  latter,  and  is  continued  along  the  entire 
anterior  margin,  frequently  appearing  there  still  higher,  stronger,  and  more  distinct  than  at 
the  posterior  margin  {Calymene,  Phacops).  All  these  differences  are  pretty  constant  charac- 
teristics of  genera  or  groups,  and  therefore  demand  an  attentive  observation  ;  this  particularly 
has  reference  to  the  lateral  impressions  of  the  head- tubercles,  since  these  are  probably 
not  mere  ornaments,  but  may  perhaps  have  reference  to  the  organization  of  the  mouth. 
We  usually,  indeed,  find  swellings  and  protuberances  on  those  localities  of  the  shell  of 
the  Articulata  where  strong  muscles  are  attached  internally,  and  the  elevations  situated 
between  the  transverse  impressions  may,  therefore,  probably  originate  from  such  attachments 
of  the  tracheal  muscles ;  so  that  from  their  number  we  might  infer  the  number  of  gills. 
It  certainly  seems  opposed  to  this  conjecture  that  the  organization  of  the  internal  part  of  the 
mouth  in  the  case  of  other  natural  groups  of  Articulata  is  generally  uniform,  while  in  the 
Trilobites  the  impressions  on  the  head  are  generally  very  different.  The  force  of  this 
objection,  however,  may  be  diminished  by  assuming  that  the  forms  in  which  we  find  defective 
impressions  were  characterised  either  by  a  greater  thickness  of  the  shell,  or  by  a  slighter 
development  of  the  muscles,  so  that  the  traces  of  the  impressions  of  the  muscles  were 
rendered  less  distinct,  or  were  entirely  effaced.  And,  in  fact,  the  genera  in  which  such 
impressions  are  wanting  {Illanus,  Asajjhus,  and  some  species  of  Phacops)  seem  to  possess  a 

*  If  we  place  confidence  in  this  characteristic  of  many  perfectly  preserved  Olenvulcs,  namely,  that 
the  cross  furrows  of  tlie  head-tubercle  are  complete,  and  if  we  may  consider  it  as  a  general  family 
characteristic,  several  forms  would  belong  to  th;m  which  have  hitherto  only  been  observed  in  imperfect 
specimens.  According  to  this,  we  should  particularly  have  to  enumerate  Trilobites  Sternbergii  (Table  III, 
Fig.  7),  which,  in  point  of  the  cephalic  stnictiire,  is  most  nearly  related  to  Olenus  scaraboeoides,  and 
Triarf/i/us  Breki  as  both  belonging  to  the  Oleneides. 

3 


18  VISIBLE  STRUCTURE 

very  powerful  and  thick  shell,  whilst  in  the  Oleneides,  which  always  present  impressions,  the 
shell  was  decidedly  thinner,  and  consequently  became  entirely  lost.  The  few  existing 
positive  facts,  however,  do  not  permit  us  to  determine  this  point  with  certainty,  and  we  must, 
therefore,  content  ourselves  with  having  pointed  out  the  possibility  of  one  or  the  other  mode 
of  organization. 

SECTION  VI. 

The  number,  position,  and  structure  of  the  eyes  can  be  ascertained  with  much  more 
certainty,  and  are  therefore  comparatively  well  known.  There  are,  however,  still  many 
deficiencies  in  the  knowledge  existing  on  these  points,  which  is  the  more  surprising  since 
we  are  enabled  to  make  a  perfect  representation  of  them  from  actual  observation. 

In  all  those  Trilobites  the  eyes  of  which  can  be  distinctly  recognized,  we  see  them  in  the 
shape  of  more  or  less  considerable  prominences  at  the  sides  of  the  head,  nearly  on  the  centre 
of  the  lateral  portion  of  the  shield,  projecting  from  the  latter.  They  are  here  seen  as  portions 
of  a  spherical  or  parabolic  surface,  under  a  semicircular  projection  (the  cover  of  the 
eye,  or  of  the  horny  covering  of  the  head),  which  projection  is  formed  by  the  sutura  tempo- 
ralis, (of  which  a  description  will  be  found  subsequently,)  and  in  reality  they  fill  out  a  chasm 
that  is  situated  at  this  locality  between  the  two  opposite  margins  of  the  suture.  The 
eyes  project  in  the  shape  of  a  half-cone,  flattened  on  the  upper  part,  if  this  vacuity  is  large ; 
if  small,  it  forms  a  lunate  protuberance,  which  is  so  slight  in  some  species  that  it  scarcely  rises 
above  the  contiguous  surface  of  the  head.  Such  Trilobites  have  been  considered  as  blind ; 
and  with  regard  to  Oleums,  which  genus  possesses  the  structure  described,  it  is  given  as  a 
generic  character.  The  eyes  of  the  lUamiis  are  in  the  shape  of  a  moderately  arched,  lunate 
swelling ;  in  Ascqjhus,  CaJijmene,  and  Phacops,  they  appear  as  more  highly  elevated  tubercles 
or  hemispheres.  Whilst  the  external  surface  of  the  eyes  in  the  other  genera  is  per- 
fectly smooth,  and  even  more  so  than  the  neighbouring  horny  covering,  there  appear  in 
PJiacops,  instead  of  these,  small  hemispherical  elevations  distributed  over  the  entire  surface 
in  regular  order,  the  small  interstices  shaping  themselves  into  protuberantly  swollen  in- 
cisures of  the  hemispheres.  Owing  to  this,  the  eyes  of  the  Trilobites  ai'e  usually  represented 
as  being  formed  on  two  different  types,  assigning  to  the  former  a  smooth,  to  the  latter 
a  facetted  cornea.  This  view,  which  is  entertained  by  all  fomner  observers,  I  must  consider 
as  decidedly  incorrect :  first,  because  there  is  not  a  single  existing  family  of  Articulata 
in  which  the  eyes  are  formed  according  to  two  different  types;  and,  secondly,  because 
the  character  of  the  facettes  in  Plutcops  is  quite  different  from  the  mode  of  formation  pre- 
dominating among  the  Articulata  with  a  facetted  cornea.  I  am  rather  of  opinion  that  all 
Trilobites  possessed  compound  eyes  with  a  smooth  cornea,  and  that  the  latter  has  merely 
been  lost  in  those  genera  in  which  facettes  are  perceived.  In  addition  to  the  two  reasons 
mentioned,  I  am  further  justified  in  this  assumption  by  the  fact  that  the  cornea  of  most 
of  the  Trilobites  is  really  smooth,  and  that  the  structure  of  the  eyes  of  those  species, 
to  which  a  facetted  cornea  is  attributed,  is  in  every  respect  such  as  it  would  be  if  their 
eyes  possessed  a  simple,  smooth  cornea,  which  was  subsequently  lost.  This,  therefore, 
seems  to  be  the  proper  place  to  explain  more  particularly  the  structure  of  the  compound 
eyes  with  a  simple,  smooth  cornea. 


OF  THE  TRILOBITES.  19 


SECTION  VII. 


Eight  years  have  ah'cady  elapsed  since  I  particularly  described  the  type  of  this  form  of 
the  eye  (to  which  Midler*  first  directed  attention),  in  its  most  important  living  representative, 
the  Branchipus  sta(jiiaUs,  and  I  then  showed  that  the  eye  of  this  animal  consists  of  four  suc- 
cessive layers  of  different  kinds.  The  external  layer  is  a  smooth,  homogeneous,  transparent 
cornea.  Beneath  it  lies  a  facetted  membrane,  which,  seated  in  a  clear  substance,  contains 
rather  darker,  firmer,  circular,  apertures,  of  equal  size,  and  regularly  distributed  in  such  a 
manner  that  every  ring  is  surrounded  by  six  others,  at  equal  distances  from  each  other. 
The  third  layer  of  the  eye  consists  of  egg-shaped,  transparent,  very  hard  lenses,  each  of 
which  is  situated  behind  one  of  the  little  window-like  apertures  described,  resting  upon  the 
surface  of  the  latter  with  its  flatter  extremity,  and  raising  this  a  little  with  that  convex 
surface.  The  fourth  layer  consists  of  an  oblong,  club-shaped,  crystalline  body,  which 
encircles  with  its  upper  thicker  end  the  more  pointed  end  of  the  egg-shaped  lens,  and  is 
surrounded  by  a  delicate  membrane.  A  continuation  of  this  membrane  also  overspreads 
the  lens,  and  attaches  itself  to  the  thickened  margin  of  the  little  aperture  before  each 
lens.  Behind  the  crystalline  body  there  then  follows  the  dark  pigment  as  the  principal 
mass  of  the  whole  eye,  through  which  the  fibres  of  the  optic  nerves  extend  themselves  to 
the  respective  ocelli,  resting  on  the  basis  of  the  crystalline  bodies,  as  their  sheaths  pass  into 
the  sheaths  of  the  crystalline  body,  and  the  lenses,  and  through  those  sheaths  likewise 
attach  themselves  to  the  facetted  second  membrane,  f  This  representation  of  the  eye,;}: 
which  is  perfectly  applicable  to.  the  Trilobites  with  a  smooth  cornea,  shows  us  that  the 
loss  of  the  external  smooth  cornea  immediately  occasions  the  projection  of  a  facetted 
cornea, §  and  we  therefore  only  need  assume  with  respect  to  Phacops  that  their  cornea  must 
have  been  more  destructible  than  that  of  the  other  Trilobites,  in  order  to  explain  their 
facetted  character.  Sufficient  reasons  are  also  in  this  respect  furnished  to  us  by  the  propor- 
tions of  organization  in  existing  genera.  The  study  of  all  those  Crustacea,  for  instance, 
that  are  furnished  with  a  smooth  cornea,  and  they  are  only  found  in  Articulata  of  that 
description,  proves  to  us  the  important  fact,  that  the  number  of  the  separate  ocelh  does  not 
at  all  depend  on  the  size  of  the  whole  eye,  since  they  merely  become  more  minute  as  the 
eye  diminishes,  their  absolute  number  in  that  case  sometimes  actually  becoming  greatei'. 
The  cornea  becomes  thinner  in  proportion  to  the  increased  size  of  the  eye,  and  thicker 
as  the  eye  is  smaller;  so  that  very  large  eyes  with  a  smooth  cornea  possess  a  thin  cornca,|| 
very  small  ones,  on  the  other  hand,  a  thicker  and  more  compact  cornea.      Now  Phacop.'s 

*  MüUer's  Archiv  for  18.35,  pp.  529,  613. 

t    Vide  Table  YI,  Fig.  4,  and  its  explauatiou. 

X  Vide  Quenstcdt  in  AViegmaun's  Aj-cliiv  für  Nat.  Gesch.,  series  1837,  i,  340 ;  where  the  structure 
of  the  eye  of  the  Trilobites  with  a  smooth  horny  membrane  is  correctly  recognized  and  described. 

§  In  .Toll.  ]Müller's  description,  which  we  ha\e  before  alluded  to,  the  facetted  membrane  and 
glassy  substance  is  not  mentioned.  AVe  need  not,  however,  infer  from  this  that  they  ai-e  wanting  in 
some  eyes ;  they  have  only  escaped  the  attention  of  the  observer  at  this  first  investigation,  and  are  cer- 
tainly met  with  in  all  the  Articulata  Avitli  the  described  form  of  eyes. 

II  Compare  in  these  respects,  for  instance,  the  genera  Branchipus  and  Apus,  or  Polyphemus  and 
Daphnia. 


20  VISIBLE  STRUCTURE 

has,  relatively  speaking,  the  largest  e)'es  among  the  Triloliites,  consequently  also  the  largest 
lenses  and  the  thinnest  cornea  :  a  fact  which  is  decidedly  cstalilishcd,  and  suSiciently  explains 
the  absence  of  a  smooth  appearance  in  the  eyes  of  this  genus.*  The  truth  of  this  view  is, 
however,  still  further  supported  by  the  circumstance  that  the  facettes  in  all  the  Crustacea,  and 
in  most  of  the  Articulata  with  a  facetted  cornea,  are  perfectly  contiguous,  leave  no  open  in- 
terstices, and  individually  are  much  less  convex  than  in  Phacops.  The  eye  of  the  latter  genus, 
if  it  possessed  a  facetted  cornea,  could  only  be  compared  with  the  eyes  of  some  nocturnal 
insects,  for  instance,  of  the  Redavies,  or  of  some  of  the  parasites,  such  as  the  RMpUdoptera, 
in  which  the  facettes  are  larger,  more  strongly  arched,  and  situated  more  remotely  from  each 
other,  or  it  might  be  explained  as  an  aggregate  of  simple  eyes ;  against  which  conjecture, 
however,  there  would  always  be  the  fact  of  their  peculiar  circumscribed  form.  Aggregates 
of  simple  eyes,  as  they  occur  in  Mjnopock,  and  in  some  of  the  hopods,  consist  however 
always  of  a  smaller  number  of  ocelli,  whilst  the  number  found  in  Phacojjs  is  very  considerable.f 
Thus  I  beheve  I  have  proved  the  correctness  of  my  assertion,  that  this  genus,  in  common  with 
all  other  Trilobites,  possessed  a  smooth  cornea.  Before  concluding  this  part  of  the  subject 
I  might,  however,  refer  to  the  frequent  actual  deficiency  of  the  cornea  and  lenses  in  Cahjmene 
BlumenhacJiii,  and  quote  the  absence  of  the  latter,  which  naturally  arose  from  the  small  size, 
as  an  additional  argument  in  favour  of  my  view.  These  parts  of  the  eye  were,  indeed,  so 
small  in  this  instance,  and  their  coats  so  tender,  that  they  could  not  have  been  petrified 
after  the  loss  of  the  protective  horny  cornea  membrane. 


SECTION  VIII. 

We  shall  now  return  to  the  already  mQwiwweA  liiiea  facinlis,  or  sidiira  temporalis,  and  trace 
the  principal  variations  of  these  lines.  There  can  certainly  be  no  doubt  that  the  possession  of 
a  temporal  suture  is  a  common  character  of  all  Trilobites  ;  it  exists  equally  in  Paradoxides  and 
Olenus.  It  is  generally  first  recognized  at  the  anterior  margin  of  the  common  cephalic  shield, 
at  a  moderate  distance  from  its  centre,  so  that  both  lines  remain  at  a  rather  greater  distance 
from  each  other  than  the  transverse  diameter  of  the  cephalic  protuberance  at  its  broadest  part. 
But  in  Ogijqia,  Phacops,  Homalonoins,  and  AsapJuis,  the  temporal  sutures  extend  themselves  at 
the  anterior  margin  to  the  extreme  point  of  the  cephalic  shield,  and  here  unite,  forming  an 
arch  or  angle.  In  the  other  genera  they  are  curved  on  the  lower  side,  round  the  anterior 
margin  of  the  head,  and  terminate  in  the  margin  which  separates  the  cephalic  shield  from  the 
mouth.  Converging  a  little  towards  the  posterior  part,  they  now  approach  from  the  margin  to 
the  protuberance,  as  far  as  the  region  where  the  eyes  are  situate,  here  they  describe  the  outward 
curved  lobe  over  the  eye  (operculum  oculi)  already  alluded  to,  and  again  extend  behind  it 
rather  more  towards  the  outer  part  to  reach  the  margin  of  the  cephalic  shield  at  a  second  point. 

*  Since  the  publication  of  tlie  German  edition,  I  have  observed  in  the  eyes  of  Phacops  mucronatus, 
from  Bohemia,  the  globular  spots  hollowed  out  like  a  funnel,  all  regularly  in  the  same  manner ;  a  form 
impossible,  I  think,  if  the  spots  were  coruese. 

t  I  counted  163  hemispheres  of  leuses  in  each  C3'e  of  the  Phacops  arachnoides ;  of  Phacops 
mucronatus,  on  the  other  hand,  209;  of  Phacops  lat'ijrons,  only  90- 100. 


OF  THE  TRILOBITES.  21 

Tlie  part  where  this  takes  ph^ce  is  very  differently  situated,  and  is,  in  some  cases,  at  the  posterior 
part  of  the  margin  of  the  liead,  but  in  otiiers,  at  the  exterior  part.  Each  g-enus  has  a  certain 
point  at  which  this  takes  place,  and  it  is  different  in  each.  Paraclondex  stands  in  this  respect 
at  one  end  of  the  series  and  Phacops  at  the  other.  The  point  of  termination  in  Paradoxidcs 
is,  for  instance,  situated  much  nearer  to  the  raised  margin  of  articulation  or  collar  of  the 
cephalic  shield  than  to  the  lateral  margin,  and  both  extremities  of  the  suture  are  only 
just  as  far  removed  from  each  other  as  the  eyes  are.  The  latter  proportion  exists  also 
in  Ulcenus,  but  owing  to  the  great  distances  of  the  eyes  from  each  other,  the  distance  of  the 
ends  of  the  sutures  from  the  central  line  is  much  greater  than  their  distance  from 
the  lateral  margin.  In  both  these  genera,  however,  the  sutures  posteriorly  run  parallel 
in  the  principal  direction ;  but  they  diverge  in  all  others.  This  divergency  is  slightest  in 
the  species  of  Ogyyia  and  Ascqjhus  and  in  Parado.vides  gihboms,  and  Calymcne  conciiina,  which 
do  not  however  belong  to  the  genera  the  names  of  which  they  bear,  and  it  is  so  great, 
that  it  extends  beyond  the  centre  of  each  lateral  lobe  of  the  posterior  margin  of  the  head  ;  in 
Calymene  Blumenhachii,  and  in  the  other  real  species  of  the  same  genus,  it  increases  to  an  im- 
mediate termination  into  the  angle  of  the  cephalic  shield  itself,*  and  in  Phacops  even  passes 
over  to  the  external  margin  of  the  cephalic  shield,  as  Dalman  has  already  illustrated  this  in 
Ph.  sderops,  his  Cahpiiene  sderojjs  (Tab.  Ill,  Fig.  1,  d).  The  two  ends  of  the  sutures  in  this 
case  nearly  describe  single  straight  lines  along  their  principal  direction,  and  these  lines  are 
at  right  angles  with  the  longitudinal  dimension  of  the  body,  so  that  they  are  therefore 
removed  by  about  90°  from  the  dii'ection  observed  in  Paradoxides  and  Illanus,  as  well  as  from 
the  other  extreme.  It  is  evident  that  so  constant  and  regular  a  course  must  be  particularly 
calculated  to  afford  safe  characteristics  of  genera.  Besides  this  temporal  suture,  which  is  com- 
mon to  all  Trilobites,  I  have  further  observed  a  second  real  suture  in  the  crust  of  the  head,  which 
has  been  overlooked  by  most  authors.f  It  is  only  found  in  the  genera  Calymcne  and  IUcbiihs, 
immediately  beneath  the  upper  angle  of  the  anterior  rim,  on  that  side  of  the  latter  which  is 
turned  downwards,  and  connects  the  two  parts  of  the  temporal  Suture,  which  in  their  termi- 
nation incline  somewhat  inwards.  It  is,  however,  only  to  be  detected  in  very  well  preserved 
specimens,  but  in  such  it  can  be  seen  quite  distinctly,  and  in  CaJymeiie  it  not  only  occurs  in 
the  granulated  upper  membrane  already  described,  but  it  also  exists  in  the  second  layer  of  the 
crust  lying  beneath  the  former.  In  all  other  genera,  I  could  not  discover  any  trace  of  this 
second  suture,  or  sntnrn  marginal  is,  and  must  therefore  assume  that  it  does  not  exist  in  these 
genera.;}:  Indeed  I  find  that  we  meet  with  three  quite  different  types  in  the  composition  of  the 
cephalic  crust  among  the  Trilobites,  the  principal  differences  of  which  consist  in  the  circum- 
stance that  this  entire  shell,  as  far  as  we  know  it,  may  consist  of  two,  three,  or  four  pieces. 

*  The  edges  of  the  liearl  are  always  short  if  the  suture  divides  them,  but  (jften  elongated  into 
angular  processes  if  the  suture  goes  to  the  basal  or  external  margin.  These  processes  are  only  pro- 
ductious  of  the  crust,  and  are  soUd,  without  any  hollow,  so  that  they  could  not  exist  if  the  fossil  were  a 
crust,  but  only  if  the  crust  itself  of  the  animal  be  petiified.  Hence  it  is  that  individuals  of  the  same 
species,  as  Phacops  sclerops,  occur  some  with  long  horny  head-processes,  and  others  without  any. 

t   It  has  been  pointed  out  in  Buckland's  Fig.  3,  Table  XL VI,  and  INInrchison's  Fig.  7,  Table  VII. 

X  M.  Emmerich,  in  his  '  Dissertatio  de  Trilobitis,'  p.  8,  (Berolis,  1839,  8vo,)  also  speaks  of  two 
sutures  at  the  cephalic  shield,  hut  describes  the  temporal  suture  only  more  accurately;  the  second 
(quae  partem  inferiorem  a  superiore  separat)  he  merely  refers  to  in  these  words.  I  have  nowhere  seen 
it  at  the  whole  circumference  of  the  cephalic  shield. 


22  VISIBLE  STRUCTURE 

The  temporal  sutures  in  the  first  case,  by  no  means  pass  over  to  the  lower  side  of  the 
cephalic  shield,  but  continue  at  the  anterior  margin  of  it,  and  there  meet  together,  so  that 
both  are  only  the  different  directions  of  one  suture  going  towards  the  left  and  the  right. 
This  formation  I  observed  in  Oqi/f/ia,  Pliacopfs,  Amphits  expanms,  Wahl.,  and  in  all  flat-headed 
species  of  this  genus,  as  far  as  I  have  been  able  to  investigate  them.  This  transition  takes 
place  in  the  shape  of  an  arch  terminating  near  to  the  anterior  margin  in  Amphus  cxpaiisus, 
A.  laviceps,  and  A.  {Nilens)  armadillo,  as  also  in  Oyyyla  and  Phacops;  it  takes  place,  however,  in 
A.  ramiceps,  A.  anpistifrons,  and  A.  extemiatus,  in  a  sharp,  more  or  less  pointed,  angle.  I  could 
never  recognize  a  suture  proceeding  from  this  point,  which  had  divided  the  lower  surface  of 
the  shell,  v*^ith  any  degree  of  certainty  ;  Pander,  however,  has  found  such,  and  considered  it 
as  the  line  of  separation  of  his  side  branchiae  {vide  Table  IV,  B,  of  his  work).  The  entire 
cephalic  shield  of  this  pointed  headed  Ampjlnis  likewise  therefore  only  consists  of  three  pieces, 
an  upper  internal  one,  which  covers  the  cephalic  pi'otuberance,  and  which  I  term  central 
shield  {scutum  centrale),  and  two  upper  external  ones,  which  at  the  same  time  pass  over  to  and 
form  the  lower  side,  as  far  as  we  are  acquainted  with  it.  I  call  them  margin  shield  {scuta 
marginalid),  or  temporal  shields  {scuta  temporalin).  In  the  second  case  the  two  temporal  sutures 
extend  themselves  over  the  anterior  margin  of  the  head,  and  reach,  separately,  that  lower 
margin  of  the  cephalic  shield  which  incloses  the  region  of  the  mouth,  and  which  I  shall 
subsequently  describe,  separating  it  from  the  cephalic  shield.  The  anterior  end  of  the  central 
shield  in  this  case,  therefore,  also  passes  over  to  the  lower  side,  and  thus  we  have  three 
shields  of  the  head-crust,  a  simple  central  shield,  and  two  margin  shields.  The  Oleneides 
belong  to  this  group.  The  central  shield  in  these  only  occupies  the  central  part  of  both 
margins,  and  the  entire  lateral  portions  complete  tlie  marginal  shields.  The  two  temporal 
sutures,  in  the  third  case,  also  terminate  quite  separately,  reach  exactly  the  angle  of  the 
head-crust  at  the  posterior  part,  but  are  connected  anteriorly  beneath  the  protuberant 
margin  of  this  crust  by  a  transverse  suture,  which  here  separates  a  piece  of  the  lower 
surface  of  the  shell  placed  anteriorly  to  the  region  of  the  mouth,  so  that  four  pieces  are  thus 
formed,  viz.  a  central  shield,  two  marginal  shields,  and  a  shield  situated  in  front  of  the  mouth, 
which  I  term  scutum  rostrale,  and  the  suture  which  separates  it  I  also  term  sutura  rostrcilis 
Such  a  structure  may  be  met  with  in  Cahjmene  and  IllcEnus* 

Such  is  the  account  I  have  to  offer  concerning  these  sutures  of  the  head-crust ;  I  have 
only  further  to  observe,  that  similar  unions  of  the  pieces  of  the  crust,  by  means  of  sutures,  can- 
not be  traced  in  any  of  the  existing  Crustacea,  but  are  only  found  in  true  insects  of  the  present 
W'Orld  ;  they  constitute,  therefore,  a  most  remarkable  and  important  peculiarity  of  the  Trilobitcs. 
We  shall  see  subsequently  that  they  do  not  occur  again  at  any  of  the  other  segments  or  shields 
of  the  shell  of  the  Trilobites.  No  satisfactory  conjecture  as  to  their  purpose  can  indeed  be 
hazarded  without  an  accurate  observation  of  living  animals.  Pander's  opinion  (p.  117), 
"  that  the  connexion  of  the  parts  is  perfectly  dissolved  by  this  suture,"  and  that  in  the  living 
state  of  the  animal  it  had  served  for  the  purpose  of  removing  the  lateral  shields  from  the 
central,  and  thus  permitting  a  changeable  distance  of  both  from  one  another,  at  the  option 
of  the  animal,  can  scarcely  be  founded  on  fact,  for  at  the  present  day  we  by  no  means  find 

*  Professor  Löven  observed  in  the  genus  Trinucleus  or  Cryptolitlius  a  new  and  very  different  type 
marked  by  the  course  of  the  sutures,  which  I  shall  describe  in  giving  the  character  of  the  genus. 


OF  THE  TRILOBITES,  23 

so  great  a  mobility  in  those  Articulata,  whose  shell  pieces  are  connected  by  sutures ;  on  the 
contrary,  the  mobility  of  the  plates  upon  one  another  is  always  very  slight,  and  a  considerable 
distance  of  the  margins  of  the  suture  from  one  another  is  impossible,  if  it  were  only  because 
a  soft  membrane  arises  from  the  internal  margin  of  the  sutures,  connecting  intimately  both 
tlie  suture  margins.  Owing  to  this,  the  elements  of  the  skeleton  of  the  liighest  Articulata 
can  at  the  utmost  be  only  bent  towards  each  other,  never  being  separated  from  one  another 
to  any  considerable  extent.  The  facial  suture  of  the  Trilobitcs  probably  likewise  admitted  of 
such  an  easy  bending  of  the  lateral  shields  towards  the  central  shield,  and  might  be  intended 
for  the  purpose  of  arching  the  space  beneath  the  cephalic  shield  somewhat  more  during  the 
contraction,  so  that  the  requisite  height  might  be  gained  for  the  feet,  which  were  then  hidden 
beneath  the  cephalic  and  caudal  shields.  Indeed  the  intimate  union  of  the  lateral  lobes  of  the 
segment  of  the  trunk  in  one  section  at  the  posterior  angle  of  the  scuta  temporalia  testifies  that 
the  object  was  to  conceal  all  the  lower  parts  as  much  as  possible  beneath  the  head-crust 
during  the  rolling  up  of  the  Trilobitcs.*  Such  a  section  is  found  at  the  lower  side  of  the  angle 
alluded  to,  immediately  behind  the  external  margin ;  it  is  particularly  distinct  in  the  genera 
Asapltus  and  lUcemm,  visibly  sharpens  the  margin,  which  before  that  point  is  thick,  broad, 
and  rounded  off,  and  thereby  causes  a  cavity  in  the  margin  itself,  running  parallel  with  the 
acute  angle,  the  cavity  being  intended  for  the  reception  of  the  lower  end  of  the  last  lateral 
lobe,  situated  before  the  caudal  shield,  when  the  Trilobite  was  rolled  up.  The  axis, 
around  which  the  animal  doubles  itself,  is  situated  very  near  to  the  locality  where 
the  two  furrows,  which  run  parallel  with  the  lateral  and  posterior  margin  of  the  scuta 
temporalia,  meet  together  before  the  posterior  angle,  and  the  lowest  ends  of  the  lateral  lobes 
of  the  joints  of  the  trunk  also  usually  conceal  themselves  to  that  extent  beneath  the 
cephalic  shield.  The  excavation  behind  the  margin  before  described  serves,  therefore,  for 
their  reception,  and  indicates  that  a  Trilobite  possessing  it  had  the  power  of  doubling 
itself  together.  On  the  other  hand,  however,  it  will  not  do  very  well  to  infer  from  the 
absence  of  the  section,  that  such  a  Trilobite  could  not  have  rolled  itself  up.  I  certainly  have 
always  looked  in  vain  for  it  in  all  the  Oleneides,  nor  have  I  ever  perceived  any  traces 
of  the  capability  of  doubling  themselves  in  these  Trilobitcs ;  but  I  could  quite  as  little 
discover  that  section  in  Phacops  and  Calijmeno. 


SECTION  IX. 

We  have  now  still  to  investigate  those  remains  of  the  existing  parts  of  the  cephalic 
crust,  which  have  been  observed  on  its  lower  surface  behind  the  margin,  and  evidently  in 
front  of  the  mouth.  The  first  who  observed  this  region  of  the  head  in  Olenus  Tessini,  Dalm., 
was  Wahlenberg ;  he  took  it,  however,  for  the  impression  of  the  upper  side  of  another 
species,  and  described  it  as  Entomostracites  buccphalus  (p.  37,  10,  Table  I,  Fig.  6,  of  his  work). 
Subsequent  to  him,  the  same  region  was  observed  and  represented  by  Stokes  in  Isoteles  gigas 
(his  AsupJi.  plufi/ccj)Jialus),  and  by  Eichwaldt  in  Asaph  us  eapansus,  Wahl,  (his  CryjAonymus 
Panderi),  but  they  were  not  correctly  observed  by  them.     The  same  may  be  said  of  Pander, 

>  Tabic  ^'I,  Fig.  8,  // 


24  VISIBLE  STRUCTURE 

whose  representation  is  certainly  more  particular,  but  without  any  correct  interpretation  of 
what  these  parts  really  are.*  Sars  was  the  first  who  recognized  them  for  what  they  are, 
namely,  for  the  lower  protuberance  of  the  head  before  the  mouth,  and  described  them  as 
such  in  the  genera  Illa'uun  and  xhaphis  ('Isis,'  1835,  p.  340,  Table  IX).  I  myself  have  only 
hitherto  observed  this  region  pei'fectly  in  Phacnps  and  Parado^rides ;  in  Amphus  and  Illanxs, 
however,  I  have  discovered  them  so  distinctly,  that  I  cannot  doubt  their  existence,  and  the 
correctness  of  those  former  representations.  The  great  similarity  in  the  figures  of  the  four 
authors,  who,  however,  were  not  acquainted  with  the  works  of  their  predecessors,  also  speaks 
in  favour  of  this  opinion.     The  following  is  the  structure  observed. 

A  moderately  arched  protuberance,  which  in  size  and  circumference  corresponds  pretty 
nearly  with  the  most  anterior  portion  of  the  head  on  the  ujjper  side,  exhibits  itself  immediately 
behind  the  thickened  anterior  margin  of  the  cephalic  shield,  that  part  which  Pander  terms 
lateral  gill.  It  was  intimately  connected  with  the  anterior  margin  of  the  head,  and  has 
certainly  not  been  moveable  at  pleasure,  as  Pander  supposes,  in  consequence  of  its  isolated 
position  in  some  individuals.  {Vide  Table  IV,  B,  Figs.  3,  4,  of  his  w^ork.)  From  the 
anterior  part  it  extends  itself  with  a  pair  of  lateral  lobes,  which  are  more  or  less  distinctly 
separated  from  the  central  lobe,  along  the  margin  indicated,  towards  the  external  part,  and 
there  terminates  in  a  long,  more  pointed,  less  arched  projection.  Towards  the  posterior 
part  in  Puradoxides  there  is  a  rather  protuberant  margin,  curved  outwards,  and  before  it  a 
considerable  oblique  excavation.  This  margin  in  Asaplms  and  Illceiuis,  on  the  other  hand,  is 
deeply  notched  and  strongly  double  lobed.  In  all  three  are  exhibited  on  the  whole  surface 
the  same  indented  concentric  lines,  which  cover  the  lower  surface  of  all  parts  of  the  shell. 
Sars  certainly  represented  such  lines  only  on  the  lateral  lobes,  but  I  have  found  them 
everywhere  on  the  whole  surface  in  P.  bohemiciis  {Enf.  hiicrpJialiis,  Wahl.),  but  certainly 
slighter  in  the  centre,  and  therefore  I  suppose  that  Sars  must  have  overlooked  them.  I 
have  represented  this  region  of  P.  boliemiciis  on  Table  I,  Fig.  7,  and  have  availed  myself  of 
■Sars'  figures  of  Asaplms  in  my  drawing,  Table  VI,  Fig.  8. 

There  can  now  scarcely  be  a  doubt  that  this  region  is  the  ordinary  enlargement  before 
the  mouth,  which  we  perceive  in  the  Plii/llojiodes,  and  which  is  usually  called  hyposioma. 
This  certainly  testifies  as  decidedly  in  favour  of  the  affinity  of  the  two  groups,  as  it  negatives 
the  affinity  with  the  Isopudes.     But  of  this  hereafter. 


SECTION  X. 

The  tliornx  or  bodu  of  the  Trilobites,  to  the  description  of  which  we  now  proceed, 
consists  of  a  number  of  homogeneous  rings,  of  which  every  one  likewise  possesses  a  horny 
crust.  The  latter  has,  as  on  the  cephalic  and  caudal  shield,  lateral  freely  projecting 
lobes  {pleurcB)  at  each  ring,  which  are  readily  distinguished  by  their  flattened  and  ge- 
nerally incurved  form,   from   the  uniformly  arched  semi-cylindrical  body.      These  lateral 

*  Pander  supposed  that  these,  as  ^ell  as  the  lateral  margins  of  the  head  that  are  turned  over,  were 
gills ;  and  terms  the  hitter  lateral  gills,  the  central  swelling  bcliind  the  anterior  margin  central  or  lower 
gill,  and  even  believes  that  there  were  respiratory  organs  iu  the  swelling  before  the  mouth.  [Vide  pp. 
134  and  128  of  his  work.) 


OF  THE  TRILOBITES.  25 

lobes  consisted  (exactly  as  in  the  already  described  flattened  extensions  of  the  cephalic  and 
caudal  shield)  of  two  layers,  between  which  there  was  a  thin  layer  of  the  substance  of  the 
body,  and  these  were,  on  the  external,  open,  upper  surface,  partly  smooth,  partly  granulated  ; 
but  on  the  lower  hidden  surface  furnished  with  parallel  striee.  This  is  distinctly  seen  in  the 
fragments  of  Amplius  and  IUwiiks,  in  which  both  coverings  of  the  lateral  lobes  arc  generally 
preserved,  showing  that  the  intermediate  layer  at  the  upper  and  internal  parts  of  the  lateral 
lobes  was  thicker  than  at  the  lower  part,  (which  is  curved  forwards,)  where  each  lobe 
terminated  in  an  acute  angle  towards  the  external  and  upper  part.  On  the  other  hand,  it 
formed  a  broader  rounded  facing.  If  I  appreciate  these  impressions  correctly,  I  should 
say  that  the  internal  horizontal  part  of  each  lateral  lobe  must  have  been  in  immediate 
connexion  with  its  neighbour,  and  that  this  whole  region  of  the  body  has  participated 
in  the  protection  of  the  fleshy  muscular  layer,  situated  beneath  the  arched  central  part, 
or  may  even  have  been  partly  the  support  of  this  muscular  portion.  This  is  probable, 
since  in  all  the  specimens,  even  those  that  are  rolled  up,  these  regions  of  the  lateral  lobes 
are  not  projected  one  al)ove  another,  but  are  at  the  usual  distance  from  each  other ;  and 
I  think  I  can  perceive  a  kind  of  articulation  in  the  anterior  angle  of  each  posterior  ring, 
■where  the  external  part  of  the  lateral  lobes  bends  downwards.  Such  an  articulation 
certainly  exists  at  the  place  where  the  central  arched  part  of  each  ring  meets  the 
lateral  lobes,  not,  however,  between  this  part  and  its  lateral  lobe,  but  between  the  central 
arched  body  rings  themselves.  At  this  spot,  indeed,  may  be  observed  a  strong  hemispherical 
articulated  head,  immediately  before  the  open  posterior  margin  of  the  ring  at  its  lower 
surface ;  and  this  head  fits  into  an  articular  cavity,  formed  to  fit  it  in  the  succeeding  ring. 
The  latter  exists  at  the  anterior  margin  of  the  caudal  shield,  and  is  distinctly  represented 
in  Table  V,  Fig.  4.  The  first  pair  of  articular  processes  occurs,  however,  at  the  posterior 
margin  of  the  cephalic  shield,  and  thus  each  segment  has  a  pair  of  articular  cavities  on 
its  upper  side  anteriorly,  at  the  junction  of  all  the  rings  with  the  preceding  covered 
margin  ;  and  on  the  other  hand,  at  its  lower  free  side,  which  partially  projects  over  the 
succeeding  ring,  it  has  a  pair  of  hemispherical  articular  processes.  These  and  the  cavities 
may  be  very  distinctly  recognized  in  the  larger  specimens  of  the  species  of  Phacops,  whose 
horny  coat  has  been  lost ;  the  fractured  «irticular  prominences  being  usually  still  found  in 
the  articular  cavities  beneath  them.  There  can  also  be  no  doubt,  from  the  analogy  of  living 
Articulata,  that  besides  this  a  soft  articular  membrane  connected  the  margins  of  the  rings, 
situated  opposite  to  each  other ;  but  in  all  other  respects,  each  separate  ring  was  complete 
in  itself,  its  lateral  lobes  being  immediate  continuations  of  the  central  arched  principal 
portion,  and  nowhere  connected  with  the  latter  by  means  of  sutures.  It  is  true  indeed 
that  deep  impressions  are  found  at  the  sides  of  the  thorax  in  well-preserved  specimens 
of  Ogyyia  Buchn  and  Conocev/iahts  Sitheri,  separating  the  latei'al  lobes  of  each  individual 
ring  from  its  axis ;  but  I  should  not  be  inclined  to  look  upon  these  as  sutures,  which 
Emmerich  declares  them  to  be,  because  nothing  of  the  kind  is  found  in  the  other  Trilobites ; 
and  there  are  no  apparent  means  b)'  which  these  lobes  could  have  been  moved  (as  their 
mode  of  insertion  indicates  that  they  might  have  been),  since  they  could  only  have  had 
a  very  slight  muscular  layer  on  account  of  the  thinness  of  the  lateral  lobes.  I  believe, 
therefore,  that  the  suture-like  furrow  alluded  to  does  not  indicate  a  suture,  but  originates 
from  an  acute  angle,  which  projected  here  at  the  internal  surface  of  the  crust,  between  the 

4 


26  VISIBLE  STRUCTURE 

axis  and  lateral  lobes  ;  for,  considering  the  entire  absence  of  remains  of  the  crust  itself, 
there  can  be  no  question  that  in  the  impressions  of  both  species  we  see  the  impression 
of  the  internal  surface  of  the  shell. 

As  little  can  I  agree  with  Emmerich,  who  adopts  the  views  of  Audouin,  that  the 
lateral  lobes  consisted  of  two  pieces,  which  correspond  with  the  episternon  and  epimeron  in 
the  thorax  of  insects.  There  is  not  only  no  reason  whatever  for  such  a  conjecture,  but  a 
decisive  argument  can  be  brought  against  it  by  referring  to  the  fact,  that  the  plates  alluded 
to  in  insects  are  always  portions  of  the  crust,  which  encases  the  axis  itself;  while  here 
they  would  appear  as  lateral  projections,  without  forming  part  of  the  covering  of  the  axis. 
Where  there  are  no  especial  parts  of  the  skeleton  at  each  separate  ring,  as  is  the  case 
with  respect  to  the  Trilobites,  those  names  should  not  be  applied  which  refer  exclusively 
to  such  particular  parts  of  the  skeleton ;  nor  should  they  even  be  made  use  of  in  the  way 
of  analogy  if  they  were  introduced  to  describe  parts  differently  situated,  for  such  a  mode 
of  proceeding  will  cause  the  utmost  confusion.*  In  fact,  I  must  repeat  that  the  lateral 
lobes  are  nothing  more  than  lateral  continuations  of  the  crust  covering  the  rings  of  the 
body,  that  they  are  incapable  of  independent  motion,  and  that  they  serve  no  other  purpose 
than  that  of  protecting  the  delicately  constructed  feet  situated  beneath  them.  On  this 
subject  I  shall  proceed  to  enlarge  in  the  following  chapter,  and  then  endeavour  to  reproduce 
the  absent  organs  of  the  Trilobites  from  the  analogy  of  living  forms  of  Crustacea ;  but 
it  still  remains  to  be  mentioned  witli  regard  to  the  central  parts  of  the  body,  (tlie  real 
body  rings,)  that  each  generally  consists  of  two  semicircular  protuberances,  situated  one 
behind  another,  of  which  the  anterior  and  smaller  one  is  hidden  beneath  the  projecting 
margin  of  the  preceding  ring  when  the  body  is  in  a  stretched  position,  but  which  can 
be  very  distinctly  seen  when  the  body  is  curved  or  doubled  together.  At  the  end  of  the 
furrow,  which  separates  the  two  protuberances,  there  is  seen  at  each  side  the  articular 
cavity,  which  is  nearly  circular  in  the  species  of  Fhacops  and  Cali/me»e,  and  rather  transverse 
in  Asaphtis  and  Illcenus ;  concerning  the  use  of  this  I  have  already  given  the  necessary 
information.  We  miss  it  entirely  in  all  species  and  fragments  deficient  in  the  horny  shell, 
since  both  parts,  that  is,  the  articulating  process  and  the  corresponding  articular  cavity, 
merely  belong  to  the  horny  coverings.  The  transverse  furrow  of  the  central  body,  by  which 
the  anterior  protuberance  of  each  ring  is  separated  from  the  posterior  one,  in  most  cases 
partially  extends  itself  to  the  lateral  lobes,  and  only  disappears  at  the  place  where  the 
latter  bend  themselves  downwards  by  approaching  to  the  posterior  margin  of  the  lobe,  and 

*  Audouin,  in  his  well-known  work  on  the  skeleton  of  insects,  (Annal.  des  Scienc.  Natur.,  Prem. 
Ser.,  torn,  i,  1824,)  calls  that  part  of  the  skeleton  epimeron,  which  is  situated  between  the  freely  move- 
able paunch  (?)  and  the  back  plate ;  episternon,  on  the  other  hand,  he  terms  that  part  of  the  skeleton 
situated  between  the  sternum  itself  and  the  back  plate.  Among  the  Trilobites,  we  find  the  only 
instance  of  these  divisions  of  the  external  skeleton  into  separate  pieces,  in  the  head ;  in  all  the  other 
parts  of  the  body  there  is  nothing  of  the  kind.  This  circumstance  is  a  most  remarkable  one ;  and  it 
is  without  any  an.alogy  in  living  Crustacea,  the  shell  of  which  always  forms  a  continuation  at  the  iu- 
di\idual  rings,  and  never  consists  of  separated  pieces,  connected  by  sutures,  not  even  when  it  distinctly 
covers  several  rings.  Dalman  has  already  recognized  and  publislicd  (Palaead.  p.  13)  an  account  of  this 
exception  from  the  general  rule,  that  the  skeleton  parts  of  living  Crustacea  never  have  sutures  ;  and  I 
must  once  more  particularly  enumerate  it  as  a  most  singular  character  of  the  Trilobites,  although  at 
the  same  time  it  is  necessary  to  observe  that  the  peculiarity  which  distinguishes  the  head-crust  of  these 
animals  does  not  appear  in  the  other  rings  of  the  crust. 


OF  TIIH  TRILOBITES.  27 

passing  over  into  the  anterior  angle  of  the  arched  margin  of  the  h)he.  I  doubt  very  much 
whether  the  presence  of  this  furrow  on  the  lateral  lobes  is  of  any  material  importance  in  the 
organization  of  the  Triiobites  in  ^Yhieh  it  occurs,  for  if  this  were  the  case,  it  could  not  be 
entirely  wanting  in  some  genera,  for  instance,  in  Ilhcnm ;  and  I  rather  consider  it  as  a 
secondary  matter,  caused  by  the  presence  of  the  transverse  furrow  on  the  central  rings 
themselves,  and  thus  continued  to  the  lateral  lobes.  This  view  can  be  supported  by  the 
structure  of  Illaiius,  in  which  the  transverse  furrow  is  as  much  wanting  on  the  central 
principal  ring  as  on  the  lateral  lobes,  and  which  therefore  have  a  much  flatter,  and  more 
uniformly  arched  back  than  the  other  species,  the  back  rings  being  always  individually 
very  strongly  arched.  The  organization  of  the  abdomen  of  the  Macmra  furnishes  among 
the  living  Crustacea  an  exact  counterpart  to  the  usual  Trilobitc  structure  with  furrowed 
rings ;  while  the  organization  of  the  thorax  of  the  Amph'qwdcs  and  Iwpode-s,  on  the  other 
hand,  represents  the  form  existing  in  lUcenus.  Both  modes  of  formation,  however,  admit 
the  power  of  rolling  up,  both  by  the  Triiobites  and  by  their  living  analogues  referred  to. 


SECTION  XI. 

The  number  of  rings,  of  which  the  thorax  consists,  is  a  circumstance  of  great  import- 
ance. The  number  may  be  readily  ascertained  in  those  genera  which  have  a  large  caudal 
shield,  but  with  greater  difficulty  in  those  where  the  body  terminates  in  a  very  small  shield, 
in  which  only  four  rings  are  contained.  The  question  arises  here,  whether  the  thorax 
can  really  be  assumed  as  extending  to  this  shield,  or  whether,  judging  from  the  analogy 
of  living  forms,  a  portion  of  the  rings  before  the  terminating  shield  does  not  belong  to  the 
abdomen,  the  real  boundary  of  the  latter  being  determined  by  the  position  of  the  sexual 
opening,  as  in  Apis.  Nothing  of  course  can  be  decided  in  this  respect,  owing  to  the  absence 
of  all  soft  parts ;  and  we  have  therefore  no  alternative  but  to  consider  the  thorax  in  the 
Triiobites  as  extending  to  the  simple  caudal  shield,  and  the  rings  contained  in  the  latter 
as  the  abdomen. 

Assuming  then  this  to  be  the  case,  we  find  a  very  great  difference  in  the  number  of  the 
thoracic  rings.  The  smallest  number  appears  to  be  five  ;*  Sarsf  at  least  asserts  that  he  saw 
no  more  in  Ampyx  ro.strafi/s ;  whilst,  according  to  Dalman,  Ampi/x  nasufii«  possesses  six  rings ; 
and  since  I  am  not  aware  of  any  authenticated  case  in  which  different  numerical  proportions 
of  the  rings  occur  in  the  same  genus,  I  must  assume  that  the  first  number  is  incorrect.  The 
latter  number  is  also  found  in  Crijptoliihts,  Green ;  and  Trinucleus,  Murch.  I  have  hitherto 
nowhere  been  able  to  perceive  seven  distinct  rings ;  and  although  this  number  is  stated  by 
some  authors  as  existing  in  Of/i/yin,  the  number  of  eight  stated  by  others  seems  to  con- 
tradict the  correctness  of  this  calculation.     Eight  articulations  are  possessed  by  all  species 

*  Dr.  Beyrich,  in  his  'Treatise  on  some  Bohemian  Triiobites'  (Berlin,  1815,  4to),  describes  a 
perfectly  preserved  specimen  of  Battus  integer  with  two  body  rings.  This  number  therefore  was  the 
smallest. 

t   '  Isis,'  1835,  p.  335. 


28  VISIBLE   STRUCTURE 

of  the  genus  Amplim  in  their  entire  extent,  also  by  Arr/es  and  Odontophura.  Dalman  enu- 
merates nine  rings  in  lUcenm  cettlrofiis,  but  one  ring  might  perhaps  have  escaped  the  attention 
of  the  observer,  since  they  are  so  remarkably  small  in  this  species.  With  perfect  certainty, 
I  only  find  this  number  in  Archcgonm  (De  Koninck's  PhiUipsia).  The  true  Illani  have  ten 
rino-s.  Dalman's  Cahjmene  concinna  possess  the  same  number,  and  if  on  that  account  only 
cannot  belong  to  Cahjmene,  nor  can  it  indeed  be  referred  to  Amplim,  among  which  Emmerich 
places  it.  The  species  of  Phacops  have  eleven  rings,  EUipsocephalus  twelve,  Cali/mene  thirteen, 
Oleims  gibbosus  and  Conocephalus  fourteen,  Olenus  spinulosus  sixteen,  and  Parado.cides  bohemiciis 
has  twenty  rings.     This  seems  to  be  the  highest  number  of  rings  existing. 


SECTION  XII. 

The  abdominal  or  caudal  shield  {scutum  canda;  ^.pggidlim),  which  we  have  next  to  describe, 

has  already  been  mentioned  as  an  extension  of  the  coverings  of  the  real  abdomen,  analogous 

to  the  cephalic  shield,  and  has  been  exhibited  as  consisting  of  two  layers,  of  which  the  upper 

possesses  the  same  quality  as  the  rest  of  the  upper  surface  of  the  shell,  while  the  latter  more 

tender  layer  is  marked  with  lines  on  its  open  surface  in  a  similar  manner.     Between  both  of 

these,  however,  a  thicker  layer  of  the  substance  of  the  body  must  have  existed.     There 

remains  therefore  now  only  to  treat  of  the  axis  of  the  shield,  the  true  abdomen,  in  which  we 

may  also  usually  observe  an  articulation,  although   the  rings  are  never  so  distinctly  and 

regularly  disposed  as  in  the  thorax.     With  respect  to  their  distinctness,  three  stages  may 

be  enumerated,  which  may  be  termed  the  stage  of  perfect  distinctness,  of  the  indication,  and 

of  the  deficiency  of  rings.     The  genera  Tmiudeus,  Ogygia,  Calymene,  Phacops,  JEonia,  exhibit 

perfectly  distinct  rings.     Very  distinct  rings  are  also  to  be  observed  in  Olenus  gibbosus.     The 

arch  of  the  ring  itself  in  this  case  is  continued  to  the  lateral  portions  of  the  caudal  shield, 

but  the  number  of  ribs  is  usually  less  by  one  or  two  than  the  number  of  rings  in  the"  axis  ; 

at  least,  I  have  counted  only  seven  ribs  in  Phacops  latifrons,  while  there  are  eight,  or  even 

nine  rings  in  the  tail,  of  which  the  last  two  are  certainly  very  small,  and  merge  into  each 

other.     Calgmene  Blumenbackii  has  always  five  ribs  at  the  caudal  shield,  but  seven  distinct 

articulations  in  the  tail  itself.    In  Ogggia  Bitcliii  I  have  counted  eleven  ribs  at  each  side  of 

the  caudal  shield,  but  twelve  rings  at  the  tail  itself,  of  which  the  last  has  a  long  oval  shape, 

and  in  all  probability  consists  of  several  articulations.     Phacops  caudatus  has  at  each  side 

seven  I'ibs  divided  by  a  groove,  and  thirteen  distinct  articulations,  besides  an  oval  terminal 

articulation,  which  may  be  considered  as  a  union  of  several  articulations  ;  Phacops  Hausmanni, 

finally,  has  most  of  all,  namely,  nineteen  to  twenty-one  in  the  axis,  and  thirteen  to  fifteen 

grooved  ribs  at  each  side.     The  terminal  articulation  of  all  the  Trilobites  is  of  a  similar 

nature  as  described,  and  therefore  probably  only  not  articulated  at  the  upper  part,  because 

the  thick  crust  prevents  the  ring  from  becoming  distinctly  visible.    In  Moni  a  {Gerastos  Goldf.) 

I  have  counted  seven  very  distinct  articulations  in  the  axis,  but  I  have  not  perceived  any 

ribs  at  the  side  of  the  caudal  shield ;  in  Olenus  gibbosus,  on  the  other  hand,  six  rings  in 

the  axis,  and  five  on  the  shield,  may  with  certainty  be  recognized. 


OF  TUb;  TRlLOlUTliS.  29 

Asaphiis  c.vpa/isia  s.  conii/jeruii  belongs  to  the  form  with  iiulistiuct  rings  in  the  axis  of  the 
caudal  shield ;  I  have  counted  in  it  six  siiort  articulations,  and  a  long,  oval,  terminal  articula- 
tion. In  another  imperfect  one,  I  believe  I  recognize  nine  rings,  and  a  shorter,  almost 
circular,  terminal  ax'ticulation.  In  .-Isap/ius  ti/ra/iiiiis,  of  which  I  know  only  the  caudal  shield, 
represented  in  Table  V,  Fig.  4,  there  are  nine  articulations,  together  with  a  long  oval  arti- 
culation. Indeed  there  seems  to  be  an  articulated  axis,  without  elevated  lateral  ribs  of  the 
shield  in  most  species  of  Asapkm,  while  the  species  referred  to  the  group  Isoteles  might  also 
belong  to  this,  their  ai'ticulation  being  merely  very  slight.  I  have  seen  no  species  of  Amplw:^ 
without  articulation  at  the  axis. 

On  the  other  hand,  we  miss  the  articulation  entirely  in  Hheni/.s  and  Broutcs,  so  that  both 
these  genera  are  representatives  of  the  third  form  of  the  caudal  shield. 

The  caudal  shield  corresponds  almost  completely  in  point  of  size  and  form  with  the 
cephalic  shield  in  the  genera  AsapJms,  Illanus,  Ampi/x,  and  Trinudeus  or  CryptolUlms  -,  it  is 
smaller  in  all  other  genera,  because  some  of  the  body  rings  belonging  to  it  in  those  genera 
have  become  isolated  independent  rings.  Its  size  therefore  decreases  with  the  number  of 
rings,  and  becomes  smaller  in  the  species  of  Phacops,  Cal^mene,  Paradoxides,  Conocephalm, 
Ellipsocophnhm,  and  0/eji//s,  in  the  latter  consisting  only  of  one  or  two  rings,  ^onia  or 
Gerastos,  a  genus  which  we  have  already  mentioned  as  the  t3'pe  of  a  peculiar  structure, 
is  at  the  head  of  this  series.  A  certain  limit  therefore  seems  to  have  been  placed  to  the 
number  of  the  body  rings,  and  those  of  the  abdomen  seem  to  increase  when  those  of  the 
thorax  decrease.  Emmerich,  indeed,  has  already  considered  this  as  the  correct  relation, 
but  a  more  particular  investigation  does  not  confirm  this  view ;  and,  indeed,  the  fallacy 
of  such  a  conjecture  may  be  proved  by  the  mere  comparison  of  the  species  of  Phacops 
among  one  anothei',  inasmuch  as  they  never  possess  more  than  eleven  thoracic  rings,  and 
yet  fluctuate  between  nine  and  twenty-one  in  the  number  of  their  al)dominal  rings.  The 
same  thing  is  also  seen  in  Calymene,  but  the  limits  of  the  series  are  not  there  so  very  dif- 
ferent from  one  another,  but  merely  fluctuate  between  seven  and  eleven.  {Cal.  polyioma, 
according  to  Dalman.)  It  appears,  however,  that  the  rings  of  the  thorax  and  abdomen 
together  do  not  generally  exceed  the  number  of  thirty,  and  that  in  many  Trilobites  the 
number  in  both  divisions  of  the  body  does  not  amount  to  so  man)%  while  the  total  number 
of  rings  is  quite  uncertain  where  the  articulation  at  the  abdomen  cannot  be  recognized.  For 
the  rest,  I  have  only  to  observe  that  the  divisions  at  the  axis  of  the  head  of  Trilobites 
are  likewise  nothing  more  than  indications  of  rings,  but  this  can  be  easily  reconciled  with  the 
view  I  have  before  expressed,  namely,  that  they  may  be  looked  on  as  protuberances  of  the 
gill  muscles  situated  beneath  them,  since  as  many  body  rings  are  always  missed  in  all 
Crustacea  as  there  are  accessory  pairs  of  gills  at  the  head ;  from  which  it  is  evident  that 
every  pair  of  gills  is  aflixed  to  a  particular  ring,  the  latter,  however,  losing  its  independency 
by  its  intimate  junction  with  the  head.  Since  also  the  number  of  lateral  furrows  of  the  head 
is  never  more  than  three,  by  which,  however,  there  are  never  formed  more  than  four  pro- 
tuberances, we  might  assume  as  many  gills  in  the  Trilobites,  and  suppose  that  in  all  cases 
where  these  protuberances  are  wanting,  and  where  the  anterior  lobe  contains  all  the  others 
within  itself,  one  pair  of  the  gills  must  have  grown  very  large  (this  would  be  the  first  pair 
according  to  analogy),  whilst  the  others  have  disappeared,  although  they  have  not  perhaps 


30  VISIBLE  STRUCTURE  OF  THE  TRILOBITES. 

been  absolutely  lost.  But  considerations  of  this  kind  belong  to  the  following  chapter,  since 
I  merely  intended  to  describe  the  immediately  recognizable  structure  in  the  present  chapter, 
and  this  I  believe  I  have  now  accomplished  as  completel}'  and  generally  as  possible.* 

*  The  lobes  of  the  cephalic  protuberance,  even  if  the}-  are  not  complete  divisions,  might  at  once 
be  termed  rings  ;  the  anterior  being  denominated  frontal  or  antennary  ring ;  the  second,  the  ophthal- 
mic ring ;  the  third,  the  gill  ring ;  and  the  fourth,  the  labial  ring ;  to  which  latter  the  accessory  parts 
of  the  mouth  were  affixed.  The  transverse  protuberance  at  the  posterior  margin,  which  is  constant!}' 
present,  and  has  aheady  been  mentioned  as  the  articular  border,  might  also  be  termed  the  arti- 
cular ring. 


CHAPTER  II. 

AFFINITY  OF  THE  TRILOBITES  TO  THE  EXISTING  ARTICULATA. 

SECTION  XIII. 

The  fact  that  Trilobites  are  now  generally  recognized  as  Articulata,  saves  nie  the 
necessity  of  speaking  at  greater  length  with  regard  to  their  affinity  with  the  3foIliisca ;  such 
an  investigation  here  being  the  more  superfluous,  since  I  have  already  sufficiently  shown 
that  the  view  is  opposed  by  the  general  structure  of  Trilobites.  For  animals  with  eyes 
cannot  be  conchiferous  molluscs,*  certainly  not,  at  least  when  they  are  furnished  with  two 
symmetrical  compound  eyes ;  and  this  is  a  characteristic  which  also  removes  them  from  the 
other  orders  of  the  Mollusca,  and  associates  them  beyond  a  doubt  with  the  Articulata. 
Among  the  four  subdivisions  of  the  Articulata,  the  Insects  and  Arachnoids  (the  heteronomous 
or  ArachnidcB,  as  well  as  the  homonomous  or  Mi/riojjoda)  possess,  however,  so  constant  a 
type  that  it  is  impossible  to  associate  the  Trilobites  with  them  ;  since  even  the  apparently 
similar  Glomerides  ai'c  immediately  to  be  distinguished  from  the  Trilobites  by  the  constant 
proportion  of  the  numbers  of  their  body  rings,  by  the  head  not  being  shield-formed,  by  the 
absence  of  an  abdomen  or  tail,  by  the  aggregate  of  simple  eyes,  by  the  horny,  articulated, 
numerous  feet,  and  by  many  other  cliaractcrs.  The  Trilobites,  likewise,  cannot  be  worms 
{Vermes),  the  horny  covering  of  their  body,  their  compound  eyes,  and  their  heteronomous 
type  being  opposed  to  such  a  conjecture.  They  are  therefore  Crustacea,  and  that  not 
only  on  account  of  those  negative  characters  hitherto  enumerated,  but  also  on  account 
of  their  positive  and  perfectly  crustacean  characters.  To  enable  the  reader  to  understand 
and  to  appreciate  the  latter,  I  shall  preface  this  chapter  by  some  introductory  remarks  on 
the  systematic  arrangement  of  the  Articulata,  and  particularly  on  the  characters  of  the 
Crustacea. 

SECTION  XIV. 

Our  present  system  of  the  animal  kingdom  is  still  tinged  with  one  fundamental  error, 
which  consists  in  the  circumstance  that  we  exhibit  individual  characters  as  characters  of 
groups,  instead  of  determining  the  type,  which  is  always  imaginary,  with  scientific  precision. 

*  When  saying  this,  I  would  guard  against  being  supposed  ignorant  of  tlie  fact,  that  numerous 
eyes  have  recently  been  observed  in  the  species  of  Pecten.  Previously  to  Krohu's  interesting  com- 
munication, I  had  read  of  this  structure  as  probably  belonging  to  these  annuals,  in  the  '  Diet,  des  Scienc. 
Natur.'  torn,  xxxviii,  p.  236. 


32  AFFINITY  OF  THE  TIIILOBITES  , 

I  have  endeavoured  in  various  ways  to  meet  this  obstaele,  and  liave  ah'eady  laid  down  the 
fundamental  features  of  my  system,  which  I  have  rendered  as  much  as  possible  independent 
of  every  subjective  mode  of  consideration,  in  my  '  Hand-book  of  Natural  History,'  (Berlin, 
1837-8,  2d  division.)  It  would  lead  me  too  far  here  if  I  were  now  to  communicate  similar 
results,  and  it  would  also  be  unnecessary,  since  I  have  already  published  the  principal 
facts  in  the  work  alluded  to,  and  am  even  now  engaged  in  carrying  out  the  subject  more 
in  detail.*  I  will  therefore  merely  state  that  the  conceptions  of  the  homonomous,  and 
hc.teronomom  systems  of  the  articulated  fundamental  type  are  the  characteristics  which, 
according  to  my  view,  principally  determine  that  type :  the  former  notion  intimating  an 
always  fluctuating,  indefinite  numerical  proportion,  the  latter  an  immutable,  constant  nume- 
rical proportion  either  in  all,  or  in  some  of  the  heteronomous  divisions  of  the  body.  This 
numerical  proportion  in  the  latter  case  generally  exhibits  itself  in  the  multiple  of  a  simple 
combination,  consisting  either  of  the  number  three  or  five,  the  former  being  generally 
applicable  to  the  lower  heteronomous  Articulata;  the  latter,  on  the  other  hand,  to  the 
higher.  The  class  of  Crustacea  certainly  exhibits  an  heteronomous  type  throughout,  having 
no  generally  equal  number  of  body  rings,  but  a  varying  one  corresponding,  to  its  character 
as  a  transition  group  of  the  Arlleulaia.  The  separation  of  the  body  into  caput,  thorax, 
and  abdomen,  of  which  each  ought  to  be  treated  as  an  independent  whole,  according  to 
peculiar  laws,  justifies  the  assumption  of  their  heieronomity,  which  I  consider  as  the  most 
essential  class-characteristic  of  the  Crustacea.  The  two  typical  numbers,  and  as  it  appears 
generally,  always  the  maximum  number,  predominate  among  the  Crustacea  in  the  thorax, 
which  here,  as  among  all  other  Articulata,  presents  the  best  systematic  characters  for  the 
determination  of  the  class.  But  the  presence  of  these  typical  numbers,  owing  to  the 
frequent  absence  of  so  many  thoracic  rings  in  the  shape  of  isolated  divisions,  and  also 
by  the  conversion  of  the  organs  of  motion  into  accessory  parts  of  the  mouth,  for  the  service 
of  the  head  and  of  its  organs,  is  frequently  obscure  on  the  first  superficial  observation. 
We  must  therefore,  if  we  wish  correctly  to  recognize  the  typical  number  of  the  thorax, 
always  consider  the  accessory  parts  of  the  mouth  as  organs  of  motion,  and  these  must 
add  to  the  true  organs  of  motion  of  the  thorax,  and  then  divide  the  total  by  3  or  5,  in 
order  to  arrive  at  the  fundamental  number  and  its  multiple.  This  mode  of  proceeding 
soon  leads  us  to  the  interesting  result  that  all  the  higher  Crustacea  together  with  a  constant 
type  of  antennae,  eyes,  mouth,  and  organs  of  motion,  also  possess  an  equally  unchangeable 
numerical  proportion  with  regard  to  the  rings  of  the  thorax,  which  is  always  2  x  5  or  10, 
and  is  therefore  the  simple  multiplication  of  the  second  higher  typical  number ;  while,  on 
the  other  hand,  all  the  other  Crustacea  with  fluctuating  typical  character  of  antennre,  eyes, 
parts  of  the  mouth,  and  organs  of  motion,  never  exhibit  the  fundamental  number  of  5, 
but  either  possess  no  fundamental  number  which  can  be  considered  as  generally  peculiar 
to  them,  or  at  least  as  far  as  I  have  been  able  to  convince  myself  by  exact  personal 
investigation,  and  in  the  majority  of  cases  possess  the  number  3  in  a  formula  of  multiplication 
which  fluctuates  from  1  to  4. 

Tiie  typical  coincidence  of  both  groups,  already  suggested  in  point  of  several  charac- 
teristics, renders  it  possible  to  define  them  with  still  greater  certainty  than  this  can  be  done 

*  I  intend  to  puljllsli  tliis  ^vork  sLortly,  under  tLe  title  of  'An  Attemiit  at  a  Rational  Zoology.' 


TO  THE  EXISTING  ARTICULATA.  33 

from  the  mere  numerical  proportion,  and  to  establish  the  followin«)-  g'cneral  characters  of 
them :  namely,  the  Crustacea  with  the  numerical  proportion  2x5,  have  always  two  pair  of 
antennae,  compound  eyes  with  facetted  cornea,  no  simple  eyes  (with  a  few  exceptions, 
however,  as  in  J/ysv'y),  articulated  walking  feet  at  the  thorax,  and  always  fin  feet  at  the 
abdomen  when  this  part  of  the  body  is  present ;  the  number  of  articulations  never  less 
than  three,  or  exceeding  seven.  They  form  the  group  of  the  Malacostraca  of  former  modes 
of  division. 

The  Crustacea  with  the  fundamental  number  of  three,  have  fewer  general  charac- 
teristics, owing  to  the  very  circumstance  that  they  represent  a  lower  division,  but  I  have 
always  found  in  them  compound  eyes,  with  a  simple,  smooth  cornea  ;*  sometimes  also  simple 
eyes,  or  (occasionally)  only  the  latter,  and  then  in  a  simple  number,  especially  when  young ; 
they  generally  have  fin  feet,  and  usually  in  that  case  no  feet  at  the  abdomen,  which  is  fre- 
quently very  short,  but  in  some  cases  very  large ;  there  is  further  a  remarkable  uncertainty 
in  the  formation  of  the  antennae  and  organs  of  the  mouth,  the  type  of  which,  therefore,  is 
fluctuating.  All  run  through  different  stages  of  metamorphosis,  and  exhibit  much  greater 
differences  in  the  respective  periods  than  the  members  of  any  other  division.  I  call  them 
Ostracodennata. 

The  metamorphosis  with  its  various  differences  seems  to  be  the  circumstance  which 
deserves  particular  attention  in  the  subdivisions,  inasmuch  as  it  exhibits  itself  partially  as 
retrogressive.t  partially  as  progressive.  The  retrogressive  metamorphosis  is  not  peculiar  in 
an  equal  degree  to  all  members,  since  it  is  occasioned  by  external  circumstances ;  and  with 
regard  to  retrogression,  as  there  is  in  reality  no  such  process  in  nature  in  a  strict  sense,  it 
cannot  be  a  general  character  of  the  whole  group,  but  only  an  indication  of  some  members 
of  certain  sub-groups.  If  therefore  I  avail  myself  of  it  as  a  mode  of  division,  I  do  it  only  in 
the  same  manner  as  oviparous  propagation  is  mentioned,  as  a  partial  characteristic  of  some 
of  the  cold-blooded  vertebrate  animals,  although  it  does  not  exhibit  itself  in  all  in  the  same 
wav.  The  Ostracodermata,  then,  are  divided  into  two  groups,  and  each  group  in  three  tribes. 
The  absence  of  a  distinct  head  with  true  antennae  and  eyes  is  as  characteristic  for  the  first 
group,  among  the  members  of  which  a  retrogressive  metamorphosis  is  peculiar,  just  as 
the  presence  of  very  large,  frequently  monstrously  developed  eyes  is  exhibited  with  a 
progressive  metamorphosis ;  and  in  the  same  way  also  very  powerfully  developed  antennae, 
especially  if  the  eyes  become  smaller,  is  characteristic  of  the  second  group.  The  further 
differences  consist  in  various  peculiarities,  the  explanation  of  which  in  detail  would  occupy 
too  much  time ;  but  I  have  put  them  together  in  a  tabular  sketch,  and  by  indicating  all 
the  higher  groups  of  Crustacea  in  this  table,  according  to  their  most  important  typical 
characteristics,  I  have  enabled  my  readers  to  determine  by  their  own  observation  how  far 
the  Trilobites  are  related  to  each,  and  with  which  group  most  intimately.  (See  the  Table, 
p.  34.) 

*  In  several  species,  for  instance,  in  Limulus,  it  appears  facetted  «lien  in  a  dried  state,  but  again 
becomes  smooth  by  being  softened  with  water. 

t  The  phenomenon  of  the  retrogressive  metamorphosis,  on  \\\\\ch  Rathkc  has  recently  written 
more  specially,  I  Lad  availed  myself  of  as  a  mode  of  division  when  giving  lectures  at  Berlin,  and  have 
published  this  view  two  yeai-s  ago,  in  Ersch  and  Gruber's  Encyclop.,  vol.  xxv,  section  i,  p.  119. 


34 


AFFINITY  OF  THE  TRILOBITES 


2  *- 


«  3 


be  S 


.H   o 
"5  -2 


^     a  *j 

~   o 

bcS 

-2 'S 
CZ3    'II 

o  „  a 

o  4"|  i 


■5    S    Oi 


V 

CS 

-le 

;^ 

S 

o 

o 

^ 

^ 

H 

o 

r^ 

^ 

^ 

r, 

^ 

o 

!U 

o 

a 

ID 

z 

.2 

o 
o 

1. 

The  fundamental  number  of  rings  of  the  thorax  is  ßve,  and  its  multiple  is  always  the  simple 
duplication  (2  x  5).    The  compound  eyes  have  a  facetted  cornea,  and  there  are  no  simple  eyes. 
The  young  ones  resemble  the  old,  entirely  or  partially,  and  the  metamorphosis  is  progressive. 
Organs  of  motion  always  double,  and  the  abdomen  always  furnished  with  fins. 

1 
1 

J. 

1 

a 

PS 
O 

Head  moveable,  but  the  eyes  immoveable ; 
no  common  shell  of  the  thorax.    Of  the  10 
rings  of  the  thorax  3   always  bear  accessory 
parts  of  the  mouth ;  likewise  7  walking  feet. 
Formula,  3x7. 

P. 

m 
S 

H 

Body    flatly 
pressed ;      al- 
ways seven  free 
rings,  withrow- 
ing  or  walking 
feet.  Abdomen 
small,   consist- 
ing of  from  one 
to  seven  joints, 
with  fbis  bear- 
ing gills.  Many 
of  them  are  pa- 
rasites, and  in 
that  case  have 
rudimentary 
eyes  and  organs 
of  motion.  The 

young        ones 
only  possess  six 
walking     feet, 
and    the     last 
pair  follows  af- 
terwards  with 
the  ring  of  the 
body. 

REMARK. 

The  Isopoda 
that  live  on  the 
land  have  ag- 
gregates of  sim- 
ple eyes. 

3 

•1 

1 
1 

Body  round 
or    flat  ;     the 
fourth        rinij 
closely  jointed 
to    the    head ; 
therefore   only 
six   free   ring's 
remain.  Abdo- 
men   wanting, 
or      furnished 
with  one  joint, 
and  very  much 
shortened. 

« 

EJ 
1 

1 

Body     com- 
pressed at  the 
sides,  with  va- 
riously fonned 
feet.  Abdomen 
always  furnish- 
ed  with   seven 
joints,  with  end 
fins,   but  with- 
out gills,  which 
are  only  seated 
at  the  thorax. 
The  youngones 
perfectly      re- 
semble the  old, 
excepting  only 
in  size. 

1 

g 
Pa 

o 

Head  immoveable,  with  pedunculated  move- 
able eyes;  thorax  entirely,  or  for  the  greater  part, 
covered  by  a  simple  shell.     Abdomen  always 
having  seven  joints. 

Of    the    10 
rings    of    the 
thorax  only  2 
bear  accessory 
parts    of    the 
mouth,    there- 
fore 8  feet,  of 

wluch  the  most 
posterior  ones, 
or  all  of  them, 
resemble    fins. 
Form   2x8. 
GiUs    variable, 
but     generally 
on    the    abdo- 
men.   The  lat- 
ter    furnished 
with    a    large 
caudal  fin. 

3      1 
^      S5 

Of  the  10  rings  of  the  thorax 
5  bear  accessory  parts  of  the 
month,  therefore  only  5  walking 
feet,  the  number  of  which  on 
that  account  is  10.  Fonn,  5x5. 

s 

1 

The  fin  feet 
of  the  last  ring 
but  one  of  the 
abdomen      are 
stretched     to- 
wards the  pos- 
terior part,  and 
form    a    large 
end  fin.  Abdo- 
men     usually 
not  closed,  but 
extended. 

-     1 

pi 

i 

The  fin  feet 
of  the  last  ring 
but  one  of  the 
abdomen     are 
never  nsed  for 
the    formation 
of  the  terminal 
fin,  but  are  en- 
tirely wanting. 
The    abdomen 
is     closed     a- 
gainst  the  tho- 
rax. 

s 

The  fundamental  number  of  rings  of  the  thorax  is  t/iree  (query  always  ?),  and  the  multiples  of 
it  vary  from  1  to  4.     The  compound  eyes  have  a  simple,  smooth  cornea.     The  young  of  iJl  the 
species  are  monoculous,  and  generally  have  only  antennae  and  palpi  as  organs  of  motion.     They 
undergo  a  metamorphosis,  and  are  essentially  iiihabitants  of  the  water. 

g 

1 

f 

Ö 

o 

o 

They  always  have  eyes,  and  generally  anten- 
niB.    The  number  of  thoracic  rings  varies  from 
1  to  4  X  2.   Tlie  sexes  are  separate ;  the  meta- 
morphosis  is   progressive.      They   never    affix 
themselves,  and  are  never  parasites. 

B.   Ambula- 
tory feet  at  the 
thorax,  giU  feet 
at    the    abdo- 
men; the  latter 

3    § 

gilfs.    N  umcri- 
eal   proportion 
in     both    divi- 
sions    of    the 
body   2x3. 
Compound  and 
simple       eyes. 
Articulate  tho- 
rax and  abdo- 
men,  each  co- 
vered by  a  larn;e 
shield-formed 
sheU. 

>      1 
^     1 

A.  Notliin^  but  homonomous 
organs  of  motion,  onlycalculated 
for  rowing ;  true  gills,  aud  from 
1  to  3  pairs  of  accessory  parts  of 
the  mouth. 

1 
gi 

Feet  consist- 
ing of  unarti- 
culated,   cleft, 
fringed,    mem- 
branous lobes. 
Compound  and 
simple  eyes;  ar- 
ticulated   tho- 
rax and  abdo- 
men.   Number 
of  rings  in  tlie 
thorax  4x3; 
in  the  abdomen 
2  to  6  X  3. 

».WithasheL 
a.  Shell  double 

lobed. 

Limniadiidts. 
ß.  Shell  shield- 
formed. 

Apodidre. 
b.  Without    a 
sheU. 

Brunchipidce. 

> 

1 

Feet  articu- 
lated, simple  or 
cleft    in    two, 
with  long  bris- 
tles.   Number 
of  rings   1   to 
3X3. 

a.  Gymnota  s. 

Copepoda. 

Without  any 
material  shell, 
•ivith  articulat- 
ed thorax,  and 
articulated  ab- 
domen. Long 
feelers. 

b.  Ostracoda. 
With  a  large 
bivalvcd  shell, 
simple  eye,  and 
unarticulated 
abdomen;  short 
antennte. 

1 

1 

1-, 

'1 

1 

i 

Q 
bS 
O 

At  a  mature  age  they  generally  have  no  eyes. 
The  number  of  thoraeie  rings,  wiien  they  can  be 
distinctly  traced,  are  2x3.      The  abdomen  is 
wanting,  or  there  are  no  organs  of  motion.   The 
metamorphosis  is  retrogressive. 

""I 

i 

P5 

1 
I 

The  mouth  is 
formed,     more 
or  less,  in  the 
shape  of  abeak; 
two  pairs  of  an- 
tenna    before 
the  mouth,  and 
six  pairs  of  or- 
gans of  motion 
behind    it,     il' 
theyare  all  per- 
fect. Affixed  or 
moveable  para- 
sites, with  me- 
tamorphosis — 
most  of  them 
with  an  abdo- 

o    . 

1:1 

II 

It 

1 

t 

Six  pairs  of 
articulated  eir- 
riformorgansof 
motion.   Open- 
ings of  rectum 
and  genitals  se- 
parate.  No  ab- 
domen, no  an- 
tenuie,  or  eyes. 
Metamorpliosis 
complete.     Al- 
ways        fLxed 
when  aged,  and 
encased    by   a 
thick   shell   or 
membrane. 

3* 

1 

Unartieulat- 
ed,wart-formed 
organs  of  mo- 
tion, with  cuia 
or  bristles.  Rec- 
tum and  geni- 
tals opening  in 
one  cloaca ;  ab- 
domen    rarely 
wanting;  form- 
ed   of    several 
jomts,  and  not 
pierced  by  the 
Ultestme;  eyes 
simple  or  none; 
metamorphosis 
none  or  miper- 

« 

TO  THE  EXISTING  ARTICULATA.  35 


SECTION  XV. 


A  correct  estimation  of  the  characters  exhibited  by  the  Malacostraca  will  prove  to  us 
at  once  that  the  Trilobites  cannot,  at  all  events,  belong  to  this  second  principal  division  of 
the  Crustacea,  for  they  have  neither  facetted  eyes  (see  Sect.  V),  nor  a  common  thoracic  shell, 
nor  a  constant  number  of  (from  five  to  seven)  thoracic  rings,  which  would  necessarily  belong 
to  them  if  the  thoracic  shell  were  wanting ;  at  least,  the  number  could  not  be  exceeded.* 
This  view,  however,  is  likewise  further  confirmed  by  the  absence  of  feelers  with  a  horny 
shell,  by  the  enlarged,  shield-formed  head,  by  the  absence  of  visible  articulated  equal  feet, 
and  by  the  unequal  numerical  proportion  of  the  abdomen,  which  is  covered  by  one  common 
shield.  Thus  we  disprove  the  aifinity  of  the  Trilobites  with  the  Impoda,  and  especially  with 
the  genus  Serolis,  which  was  insisted  upon  by  so  man}'  of  my  predecessors.  In  order  to 
manifest  the  incorrectness  of  such  afiinity  to  every  one,  I  have  represented  Serolis  paradoxa 
(Onisc.  paradoxus,  Fabr.)  side  by  side  with  species  of  the  Phyllopoda  (Table  II,  Fig.  2),  and 
I  think  that  the  mere  inspection  of  these  different  forms  must  convince  every  unprejudiced 
person  that  the  opinion  of  the  aflänity  of  the  Trilobites  with  Serolis  cannot  for  a  moment 
be  entertained.  No  single  genus  of  the  Trilobites  has  exactly  the  same  numerical  pro- 
portion, nor,  indeed,  is  there  any  other  similarity  with  Serolis,  excepting  that  which  is 
founded  in  the  general  class  characteristics,  and  I  must  therefore,  most  decidedly,  declare 
myself  against  the  arrangement  of  the  Trilobites  among  the  Malacostraca,  being  unable  to 
perceive  a  single  reason  in  favour  of  such  view.  Indeed,  even  the  moveable  lateral  lobes 
at  the  thorax  rings  of  many  of  the  Isopoda  cannot  be  compared  with  the  lateral  lobes  of  the 
Trilobites  :  first,  because  they  are  moveable  ;  and  secondly,  because  they  belong  to  the  leg, 
properly  speaking,  and  represent  the  modified  hip  of  the  latter,  as  I  shall  subsequently 
prove ;  I  will  here  only  remark  that  all  the  Isopoda,  in  which  the  moveable  lateral  lobes 
are  wanting,  possess  in  lieu  of  them  a  fundamental  joint  on  each  leg  above  the  hip,  which 
represents  the  rudiment  of  a  lateral  lobe. 

It  can  also  be  shown  with  as  little  difiiculty  that  the  Trilobites  have  nothing  in 
common  with  Liniulus,  excepting  a  very  superficial  resemblance.  The  absence  even  of  a 
separated  head  and  thorax  in  this  genus  would  render  the  afiinity  impossible ;  the  hard, 
powerful,  horny  feet,  however,  which  have  been  so  well  preserved  among  the  petrified  Limidi 
of  the  Jura  formation,  and  which,  therefore,  we  cannot  doubt  would  be  seen  also  in  their 
analogues  of  a  more  ancient  period,  are  a  still  greater  reason  against  it.  The  well-known 
power  in  the  Trilobites  of  doubling  themselves  up  would  have  been  a  very  unnecessary 
gift,  if  they  had  had  legs  like  those  of  the  Limuli,  since  the  latter  are  much  too  large  to 
admit  of  their  being  concealed  when  folded,  and  the  animal  is  much  too  powerful  to  require 
the  protection  afl'orded  by  that  process.  Nevertheless  we  must  admit  that  the  general  form 
of  the  cephalic  shield,  the  absence  of  antennae,  the  position  of  the  eyes,  and  the  existence 

*  Some  Arthrosiaca,  as  also  the  Lamodlpoda,  have  only  six  thorax  rings ;  some  Isopoda  (Praniza) 
only  five,  but  no  member  of  this  group  exhibits  more  than  seven.      Those  exceptions,  however,  can 

rcachly  be  explained,  and  their  origin  traced. 


36  AFFINITY  OF  THE  TRILOBITES 

of  a  simple  shell  of  the  abdomen,  present  facts  in  favour  of  an  analogy  existing  between  the 
two  groups,  which  ought  not  to  be  overlooked,  and  which  place  the  Trilobites  much  nearer 
to  this  genus,  than  among  the  Maloscostraca  near  the  Isopoda. 


SECTION  XYI. 

I  think  I  have  now  shown  that  the  Trilobites  can  only  belong  to  the  first  principal 
group  of  the  Crustacea,  or  to  the  Ostracodennata ;  the  only  question  being  with  which  of 
the  two  orders  assumed  in  this  group,  it  stands  in  the  nearest  relation.  The  reply  to 
this  question  will  follow  of  itself,  when  we  observe  that  the  Trilobites  in  an  advanced 
stage  of  life  possessed  large  eyes,  and  on  that  account  must  have  had  considerable  loco- 
motive powers,  so  that  beyond  all  question  they  must  be  Aspidostraca  or  Eittomostraca.  This 
result  can  be  distinctly  proved  by  the  following  reasons  : 

1.  All  Aspidostraca  have  compound  eyes  with  a  smooth  cornea,  the  Trilobites  likewise. 

2.  They  are  frequently  covered  by  large  shells,  which  widely  project  over  the  axis  of 
the  body ;   the  Trilobites  possess  quite  an  analogous  formation  of  the  shell. 

3.  These  shells  consist  of  two  membranous  layers,  with  a  thin  stratum  of  the  substance 
situated  between  them.  The  lower  layer  is  much  more  tender  than  the  upper,  quite  in  the 
same  manner  as  we  have  found  it  among  the  Trilobites. 

4.  The  Aspidostraca  possess  tender,  soft  feet,  very  easily  injured,  and  such  must  have 
been  possessed  by  the  Trilobites,  to  account  for  their  absence  in  all  the  fossil  remains  of  the 
latter. 

5.  They  are  exclusively  inhabitants  of  the  water,  and  only  move  by  swimming ;  the 
habits  of  the  Trilobites  must  have  been  similar,  because  they  have  no  hard  organs  of  motion 
suitable  for  crawling. 

6.  The  Aspidostraca,  at  least  those  covered  by  shells,  have  usually  very  small  antennae, 
or  none  at  all,  while  among  the  Malacostraca  they  are  very  large,  and  covered  by  a  hard 
upper  membrane.     This  explains  immediately  why  we  miss  these  organs  in  the  Trilobites. 

7.  The  different  subdivisions  of  the  Aspidostraca  exhibit  different  numbers  of  body  and 
caudal  rings,  and  correspond  partially  in  this  respect  with  the  numerical  proportions  of  the 
Trilobites.  The  fundamental  number  of  the  thorax  divisions  is  exactly  the  same  among 
all  PsendocephaJa  and  Malacostraca,  and  differs  only  relatively,  according  to  the  greater  or 
lesser  number  of  rings  which  have  become  combined  in  the  head. 

It  appears  unnecessary  to  seek  for  any  further  reasons  in  proof  of  the  affinity  of  the 
Trilobites  and  Aspidostraca,  after  having  exhibited  so  many  important  points  of  similarity 
between  them  ;  I  therefore  now  conclude  this  investigation  with  a  short  consideration  on  the 
true  relations  of  affinity  which  probably  obtain  between  the  two  groups  alluded  to. 


TO  THE  EXISTING  ARTICULATA.  37 


SECTION  XVII. 

At  tlic  commencement  of  this  discussion,  and  as  expressing  the  view  whicli  I  shall 
endeavour  to  prove,  I  make  the  following  statement : 

That  the  Trilobites  do  not  belong  to  any  of  the  still  living  families  of  Crustacea,  but 
represent  a  distinct  group  most  nearly  related  to  the  Aqndosiraca ;  that  their  organization, 
however,  exhibits  peculiarities,  which  at  the  present  day  do  not  occur  together  in  one 
family,  but  are  dispersed  in  several  heterogeneous  groups ;  thus,  although  we  have  proved 
in  the  preceding  paragraph  that  the  Trilobites  correspond  in  many  essential  points  of 
organization  with  the  Aspidostraca,  and  are  not  related  to  any  of  the  still  living  groups  of 
Crustacea,  yet  we  must  not  neglect  to  observe  that  various  important  and  even  typical 
differences  take  place  between  Aspidostraca  and  Trilohites.  These  differences  consist  prin- 
cipally in  the  numerical  proportions  of  the  thoracic  rings,  since  although  the  latter  certainly 
vary  among  the  Asjndostraca,  they  may  yet  be  reduced  to  several  constant  fundamental 
numbers  (6,  9,  and  1 2) ;  wliilst  the  Trilobites  only  exhibit  a  constant  number  of  rings 
for  each  separate  genus,  and  the  total  number  cannot  be  reduced  to  certain,  unchange- 
able, fundamental  numbers  or  numerical  types.  In  attempting  to  ascertain  with  certainty 
the  number  of  thoracic  rings,  we  certainly  meet  with  the  obstacle  that  we  do  not  know, 
nor  ever  can  know,  the  position  of  the  sexual  openings  among  the  Trilobites,  which  position 
alone  indicates  with  certainty  the  boundary  of  the  thorax.  But  even  if  we  exclude  for  the 
present  the  Oleneides  with  their  many- articulated  body,  and  in  which  the  capacity  of 
doubling  themselves  up  is  wanting,  (since  there  is  the  greatest  probability  that  in  them  the 
sexual  opening  was  not  situated  at  the  last  ring  before  the  caudal  shield,  but  on  a  pre- 
ceding ring,)  yet  in  the  other  genera  we  have  the  constant  numbers  6,  8,  9,  10,  11,  and  13, 
which  cannot  be  reduced  to  a  common  fundamental  formula.  If,  therefore,  we  do  not  assume 
that  the  sexual  opening  in  these  genera  was  also  situated  at  a  certain  ring  of  the  body 
before  the  caudal  shield, — say  for  example's  sake  at  the  sixth  (2  x  3),  or  ninth  (3  x  3), — 
we  find  ourselves  obliged  to  adopt  the  view  that  the  Trilobites,  in  point  of  the  fundamental 
numbers  of  their  thoracic  rings,  are  not  constructed  according  to  the  law  which  we  have 
discovered  to  obtain  amongst  all  Crustacea  of  the  present  world. 

This  is  a  most  important  result,  and  it  perfectly  confirms  the  opinion  which  I  have 
already  pronounced  several  times,  that  the  ancient  types  of  organization  do  not  correspond 
with  the  existing  ones,  but  that  they  more  or  less  deviate  from  the  plan  of  the  present 
creation. 

Cuvier,  indeed,  has  acknowledged  the  truth  of  this  principle,  but  he  did  not  carry  it 
out ;  it  has  subsequently  been  often  touched  upon,  especially  when  speaking  of  extinct 
amphibious  animals,  but,  so  far  as  I  am  aware,  it  has  not  even  yet  been  fully  recognized  by 
any  naturalist.  The  consideration  of  this  subject  is,  notwithstanding,  the  means  by  which  we 
should  be  able  to  show  most  distinctly  that  the  organized  beings  of  our  earth  were  originally 
created  according  to  one  uniform  plan,  but  that  the  nature  of  this  plan  with  regard  to  the 
different  types,  was  at  first  by  no  means  so  clearly  and  distinctly  established  as  it  appears  to 
us  now  in  the  present  representative  species.  The  earlier  types,  in  fact,  seem  to  present 
the   various   peculiarities  of   several    gi'oups  passing  into  one  another,  resulting  in  forms 


38  AFFINITY  OF  THE  TRILOBITES 

which  exhibit  in  association,  although  incompletely,  the  peculiarities  now  found  detached 
and  characteristic  of  very  distinct  groups.  Minute  and  careful  observation  has  seemed  to 
confirm  this  view,  and  exhibits  also  another  important  fact,  namely,  that  in  proportion  to  the 
geological  age  of  the  extinct  species,  the  rvmning  of  the  various  typical  forms  into  one 
structure  is  more  marked,  and  therefore  the  peculiar  and  organic  individuality  and  dis- 
tinctiveness less  obvious. 

Such  being  the  case,  it  will  no  longer  appear  strange  that  the  Trilobites,  the  oldest 
Articulata  that  we  are  acquainted  ^^ith,  should  not  exactly  correspond  with  any  one  group 
of  living  Articulata ;  and,  on  the  contrary,  it  would  rather  be  a  matter  of  surprise  if  such 
were  the  case,  for  their  identity  with  any  recent  family  would  overturn  those  laws  which 
have  been  developed  with  so  much  labour  and  care  in  the  course  of  various  researches  on 
the  organic  beings  of  a  previous  creation.  If  therefore  any  one  should  assert  that  the 
identical  representative  had  been  discovered  of  an  animal  whose  period  of  existence  in  a 
living  state  was  unquestionably  very  remote,  and  long  antecedent  to  the  commencement  of 
the  present  era,  we  might  safely  assert,  wherever  the  discovery  was  said  to  have  taken  place 
and  even  without  seeing  the  supposed  representative,  that  it  is  not  what  is  thus  assumed. 
No  doubt  the  assertion  might  be  credited  by  many  imperfectly  informed  persons  without  due 
investigation,  but  the  naturalist  acquainted  with  the  unity  and  uniformity  of  the  great  plan 
of  Nature,  and  her  method  of  producing  results  by  laws  which  are  invariable,  will  not  for  a 
moment  entertain  a  belief  of  the  present  existence  of  any  species  of  Trilobites,  however 
comparatively  insignificant  the  creature  may  be. 

I  would  by  no  means  assert,  however,  tliat  Trilobites  wholl}'  deviate  from  the  tvpes  of 
all  existing  Crustacea,  for,  on  the  contrary,  many  important  resemblances  are  found,  which  I 
have  already  indicated  and  partially  explained.  We  are  even  able,  by  a  careful  and  accurate 
estimate  of  these  resemblances,  and  by  comparing  the  details  of  structure  exhibited  in  the 
remains  handed  down  to  us,  to  restore  those  points  in  the  organization  that  are  wanting 
by  considering  the  affinities  with  recent  forms.  It  is  this  task  which  I  now  proceed  to 
perform. 


SECTION  XVIII. 

In  order  to  proceed  with  due  caution  it  will  be  proper,  however,  first  to  explain  more 
particularly  the  peculiarities  of  that  group  of  Crustacea  with  which  the  Trilobites  are  most 
nearl}'  related,  for  the  purpose  of  being  able  to  infer  thence  whether  they  may  possibly 
stand  in  a  more  intimate  relation  of  affinity  to  an)'  one  subdivision  of  the  group,  or  whether 
they  exhibit  a  similar  relation  to  all.  According  to  the  tabular  sketch  already  given,  the 
group  of  Aspidostraca  is  divided  into  three  tribes,  bearing  the  names  of  LojjJiyropoda, 
PhllUopoda,  and  Pcccilopoda.  These  denominations  indicate  important  diiferences  with  regard 
to  the  feet ;  for  the  first  two  divisions  possess  soft,  membranous  organs  of  locomotion, 
solely  calculated  for  swimming ;  while  the  Fcecilopoda  possess  hard,  articulated,  walking 
feet,  and  in  this  group  serve  also  as  gills,  and  aerate  the  blood.  This  circumstance  has 
already  been  taken  into  consideration,  and  an  important  difference  between  the  animals  of 
this  group  and  the  Trilobites  has  been  thence  inferred.     The  genus  Limidtits,  which  con- 


TO  THE  EXISTING  ARTICULATA.  39 

stitutes  this  group,  corresponds  only  in  some  peculiarities  of  the  cephalic  shield  or  of  the 
cephalothorax  with  the  Trilobites,  and  for  this  reason,  and  since  it  is  only  a  partially  analogous 
form,  I  shall  not  say  more  concerning  the  group. 

Of  the  two  other  groups,  the  Lopltyropoda  generally  exhibit  a  slighter  or  less  compact 
form  of  the  body,  and  rather  large  antenme  ;  they  also  have  cither  a  single  eye,  (which  in 
some  species  is  large,  in  others  small),  or  two  very  small  eyes,  and  therefore  exhibit 
characters  which  correspond  less  completely  with  the  type  of  the  Trilobites  than  the  more 
considerable  size  of  body,  larger  eyes,  and  undeveloped  antennae  of  the  PhyUopoda;  I 
therefore  do  not  hesitate  to  recognize  in  the  latter  the  nearest  affinities  of  the  Trilobites,  for 
which  reason  I  shall  now  describe  their  organization  more  particularly. 


SECTION  XIX. 

The  Phi/Uopoda  have  a  soft,  fleshy  body,  the  thorax  generally  consisting  of  eleven 
members,  bearing  the  same  number  of  fin-shaped  organs  of  motion.  The  head  is  an 
independent  division,  to  which,  besides  the  antennae  and  organs  of  mastication,  a  rudi- 
mentary pair  of  feet  is  attached,  by  which  the  number  of  feet  of  the  tliorax  is  increased  to 
twelve  (4  x  3).  The  other  organs  vary ;  there  are  generally  two  pair  of  antennae  before 
the  mouth,  but  these  are  either  remarkably  small,  as  in  Ajms  ;*  or  only  one  pair  consists  of 
distinct  antennae,  whilst  the  other  is  prehensile,  and  assists  in  the  act  of  copulation,  as  in 
BrancMpm ;  or  else,  lastly,  the  former  pair  of  antennae  assists  in  locomotion  as  a  fin-foot, 
while  the  latter  is  a  short,  almost  jointless,  lobe  of  flesh,  as  in  Limnadia.  The  eyes  present 
similar  differences.  There  are  two  large  compound  eyes,  and  one  simple  eye,  in  all  Phyllo- 
poda,  but  the  former  are  either  planted  on  a  long  peduncle,  and  are  moveable,  as  in 
Brancliipus,  or  are  immoveable,  and  in  that  case  partly  united  in  a  circular  form,  as  in 
Limnadia,  and  partly  arranged  in  two  distinct  semicircles,  as  in  Apms.  The  simple  eye 
stands  between  them  at  the  extremity  of  the  forehead,  or  if  they  are  close  to  each  other  is 
behind  them.  It  is  remarkable,  however,  that  BrancMpm,  the  genus  having  laro-e,  greatly 
projecting,  moveable  eyes,  does  not  possess  any  protecting  covering,  whilst  Ajom  and 
Limnadia  are  so  provided,  the  protecting  envelope  in  the  former  of  these  genera  {Apus) 
consisting  of  a  head  plate  enlarged  into  a  shield,  which  only,  indeed,  covers  the  head,  but  is 
intimately  connected  with  the  body  of  the  animal ;  while  in  the  latter,  on  the  other  hand, 
{Limnadia),  it  consists  of  a  shell  formed  as  in  shells  with  double  flaps,  and  this  shell  is  placed 
at  the  junction  of  the  head  and  body,  (and  therefore,  properly  speaking,  also  at  the  head,) 
and  can  be  opened  and  shut  below  at  the  will  of  the  animal.  Another  important  relation 
harmonizes  with  the  presence  of  this  shell,  namely,  the  structure  of  the  abdomen,  which 
in  the  genera  covered  by  shells,  exhibits  no  marked  distinction  from  the  thorax  ;  and  even 
(which  is  the  only  case  in  the  whole  class  of  Crustacea)  bears  feet  constructed  in  exactly  the 
same  manner,  only  successively  smaller,  and  not  merely  is  there  a  single  pair  at  each  ring,  but 
at  first  two  at  each,  and  afterwards  even  three  or  four.     The  number  of  organs  of  motion  is 

*  Apus,  Branchipus,  and  Limnadia,  are  represented  in  Table  VI,  Figs.  1,  3,  and  15. 


40  AFFINITY  OF  THE  TRILOBITES 

thus  increased  in  an  extraordinary  degree,  and  the  difference  between  thorax  and  abdomen 
disappears  entirely  on  a  superficial  observation.  It  is  only  the  internal  anatomical  examina- 
tion which  determines  the  boundary  of  the  two  divisions,  and  exhibits  the  sexual  opening 
behind  the  eleventh  ring,  but  this  is  seen  even  in  Apns,  exactly  at  the  same  spot  at  which 
it  is  situated  in  Branclilpus.  The  two  last  rings  are,  however,  excepted  from  this  remark- 
able and  unique  instance  of  the  approximation  of  the  abdomen  to  the  type  of  the  thorax, 
these  rings  retaining  the  shape  of  the  abdomen,  but  bearing  no  further  organs  of  motion, 
and  terminating  with  simple  horny  appendages,  as  in  Limnadia,  or  with  articulated  ones 
as  in  Apus,  and  these  are  attached  to  the  remarkably  developed  last  joint  of  the  body. 
Between  them  is  the  anus.  Brancldpus  shows  no  trace  of  any  of  these  characters,  its 
abdomen,  consisting  of  nine  joints,  has  no  feet;  and  instead  of  the  horny  appendages,  we  find 
in  them  either  two  large  soft  caudal  fins,  or,  as  in  Artcmia,  nothing  whatever  to  represent 
them  ;  but  the  females  here  also  possess  distinct  egg-capsules  at  the  commencement  of  the 
abdomen,  and  the  males  smaller  seminiferous  sacs.  Nothing  of  this  kind,  however,  is  found 
either  in  Apii>i  or  in  LiuiuacUa ;  the  males  in  the  former  bearing  such  a  resemblance  to 
the  females,  that  the  former  a  few  years  ago  were  not  known  at  all,*  and  Mr.  Kollar,  of 
Vienna,  was  the  first  who  discovered  them  ;  f  while  in  the  latter  the  males  possess  organs 
of  copulation  in  the  first  modified  part  of  the  thorax,  (or  at  least  this  is  the  case  in  a  species 
which  has  in  consequence  been  detached  to  form  the  new  genus  Estheria).  The  females  of 
Apns,  however,  can  easily  be  recognized  by  the  sacs,  which  are  situated  at  the  eleventh 
pair  of  feet,  and  which  serve  as  the  repository  of  the  eggs,  but  are  placed  towards  the  back, 
beneath  the  shield. 

The  feet  of  these  animals  exhibit  also  a  difference  corresponding  with  that  presented 
by  the  structure  of  the  body,  both  in  the  case  of  those  which  have  shells  and  which  are 
without  such  defence.  Tliey  consist  in  all  cases  of  soft,  membranous  lobes,  which  are 
mei'ely  supported  by  muscular  bundles,  the  circumference  of  which  is  intersected  at  intervals 
irregularly,  and  at  the  margin  they  are  covered  with  long,  fine,  hairy  fin-bristles.  At  the 
inner  side  six  principal  lobes  are  seen,  of  which  the  first  four  are  of  nearly  equal  size  in 
Limnadia  (Fig.  15,  B) ;  but  in  Ajms  (Figs.  9,  10,  11)  the  first  (B)  differs  very  much,  and  the 
succeeding  ones  resemble  one  another,  only  they  become  larger  from  the  basis  to  the  point. 
In  Branchipus,  however  (Fig.  12),  they  become  smaller  in  the  other  direction  ;  and  the  fifth 
lobe,  the  last  but  one,  which  is  very  long  and  small  in  Limnadia,  is  very  broad  and  rounded 
in  BraticJripiis,  and  in  Ajms  is  similar  to  the  preceding  lobes.  The  last,  the  sixth,  lobe  is 
connected  by  a  special  joint  with  the  rest  of  the  foot,  and  is  therefore  more  freely  moveable  ; 
it  has  a  long  stretched,  rudder-like  form,  and  seems  to  be  the  most  important  of  all  the 
divisions  of  the  foot.  Every  foot,  at  the  opposite  outer  side,  bears  a  bladder-formed  gill 
(K,  in  the  plate),  and  is  also  provided  with  broad  lobes  of  membranes.  Of  these  we  only 
find  one  very  large  lobe  beneath  the  gill  in  Apus  and  Limnadia  (L) ;  but  in  BramUjms  there 
are  two  lobes  (which,  however,  are  both  situated  at  the  gill),  one  of  them  a  large  one, 

*  In  a  work,  otherwise  very  excellent,  h\  E.  G.  Zaddack,  (de  Apod,  cancriformis  anatome  et 
evolutione,  Bonn,  1841,  4to),  these  animals  are  described  as  hermaphrodites,  which  probably  is  only  to 
be  attributed  to  a  defective  microscopical  aualj-sis  of  the  organs  of  generation. 

t  'Isis,'  1831,  p.  G80;  Froriep's  'Notizen,'  1833,  vol.  xxxviii,  p.  148,  etc.  Mr.  Kollar  had  tlie 
kindness  to  present  me  with  a  male  specimen. 


TO  THE  EXISTING  ARTICULATA.  41 

similar  in  circumference  to  the  latter,  and  placed  next  to  it  (Fig.  12,  L) ;  and  the  other 
smaller,  and  situated  rather  higher  upwards  (I).  The  gill  is  easily  known  by  its  bladder-like 
form,  by  the  want  of  muscles  extending  towards  or  penetrating  into  it,  and  by  the  absence 
of  fin-bristles  at  its  margin ;  while  all  the  other  lobes  are  surrounded  both  by  fin-bristles  and 
are  also  supported  by  muscles,  which  latter  extend  towards  them,  and  serve  to  assist  in 
locomotion.  The  lobes  of  the  outer  side,  although  the  largest,  are  yet  the  most  delicate 
and  the  least  protected ;  they  are,  however,  furnished  with  muscles,  and  they  therefore 
appear  to  be  more  intended  for  the  protection  of  the  gill,  than  for  locomotion.  This  is 
further  confirmed  by  their  inverted  position  in  relation  to  the  gill  in  the  case  of  those  genera 
covered  with  shells,  as  well  as  in  the  naked  genera.  I  would  therefore  call  them  "protecting 
lobes." 

There  is  no  doubt  that  the  absence  or  presence  of  a  shell  is  the  main  distinctive 
character  of  the  group ;  and  since  a  classification  in  which  the  natural  characters  are  placed 
in  opposition  becomes  necessary,  I  have  planned  the  following  formula  : 

First  Group. 

Genera  with  SJicUs. 
Cliaracfers. — Eyes  immoveable,  placed  closed  to  one  another.      The  rings  of  the  body 
partialhr  spinous ;    those  of  the  abdomen  likewise  bear  feet ;   the  last  is  a  horny  capsule, 
furnished  with  various  appendages.     Gill  of  the  feet  attached  above  the  protecting  lobe. 

Division  A. — Shell  with  two  Flaps. 

Eyes  united  into  a  circular  group  ;  anterior  antennae  having  two  rows  of  filaments, 
posterior  simple  ; — all  the  antennae  at  least  as  long  as  the  head.  No  accessory  parts  of  the 
mouth,  fifteen  abdominal  rings,  the  moveable  terminal  spines  unarticulated. 

Genera. — Limnadia,  Estheria. 

Division  B. — Shell,  Shield-like. 

Eyes  crescent-shaped,  more  distinctly  separated ;  the  antennae  scarcely  recognizable ; 
two  pair  of  accessory  parts  of  the  mouth  behind  the  jaws  ;  first  pair  of  feet  (not  including 
the  real  first,  but  rudimentary  pair)  furnished  with  four  long,  many-jointed  fibres,  instead 
of  the  fin-lobes ;  abdomen  formed  of  more  than  fifteen  rings,  the  terminal  spine  of  the 
last  ring  long,  moveable,  and  articulated. 

Genera. — Lepidurus  (with  a  flap  between  the  end  bristles),  Apus  (without  this  flap). 

Second  Group. 

Genera  without  Shells. 
Character. —  Eyes  pedunculated,  moveable.      Antennae  unequal ;  the  anterior  consisting 
of  simple  fibres ;    the  posterior  tongue-shaped,  and  serving  as  organs  of  copulation.      No 
accessory  parts  of  the    mouth  behind  the  jaws ;  the  gills  of  the  feet  beneath  the  protecting 
lobes ;  abdomen  without  feet  and  smooth  ;  ovarian  and  seminiferous  sacs,  external. 

Genera. — Branchipus  (abdomen  furnished  with  nine  joints,  with  two  caudal  fins), 
Artemia  (abdomen  furnished  with  six  joints,  with  two  terminal  lobes). 

6 


42  AFFINITY  OF  THE  TRILOBITES 


SECTION  XX. 

The  near  analogy  of  the  Trilohites  to  the  PhyUopoda  appears  to  me  to  be  especially 
illustrated  by  the  points  of  resemblance  already  alluded  to ;  viz.  the  double  large  eyes,  the 
undeveloped  antennse,  and  the  very  soft  membranous  feet.  But  Bratwhipus  seems  to  be  that 
form  among  them,  with  which  the  organization  of  the  Trilohites  has  the  nearest  affinity.  In 
order,  however,  to  render  this  quite  manifest,  I  have  drawn  the  shell  of  a  Trilobite  round 
the  body  of  a  Branchipm,  and  thus  obtained  an  imaginary  form  (Fig.  16,  Table  VI) ;  which, 
I  think,  will  scarcely  leave  a  doubt  respecting  the  near  analogy  of  the  two  forms.  Referring 
to  this  figure,  the  real  head  will  be  seen  projecting  from  the  cephalic  shield,  but  with  this 
difference  in  Branchipus  that  in  it  the  projecting  boss  forming  the  head  consists  of  only  two 
divisions,  the  anterior  of  which,  bearing  the  antennae  and  eyes,  is  smaller  than  the  posterior, 
to  which  the  branchial  apparatus  and  accessory  parts  of  the  mouth  are  affixed.  In  Trilo- 
hites, on  the  other  hand,  the  projection  of  the  head  is  either  simple  or  divided  into  four 
parts,  and  in  the  latter  case  the  first  is  either  the  smallest,  as  in  Oleiius,  Triartlini-s,  Trilobites 
Sternher(/n,  and  other  allied  forms  ;  or,  as  is  sometimes  seen,  the  first  is  the  largest,  the  others 
being  all  smaller.  This  proportion  indicates  very  large  eyes  and  antennae,  a  view  which  seems 
verified  in  the  case  of  the  genera  enumerated,  since  even  the  so-called  species  of  Olenus  have 
small  eyes,  while  Asaphus,  lUanus,  species  of  Pliacops,  and  Oyygia,  have  very  large  ones.  For 
the  same  reason  we  might  also  draw  an  inference  from  the  development  of  the  antennae, 
and  assume  that  one  pair  of  them  perhaps,  as  in  Branchipns,  were  organs  of  copulation. 
I  consider  myself  further  justified  in  this  assumption  by  the  structure  of  the  lower  side 
of  the  head  ;  for  a  very  large,  broad,  cephalic  shield,  such  as  that  seen  in  Asaphus  (Table  VI, 
Fig.  8,  a),  and  Paradoxides  (Table  I,  Fig.  7,)  indicates  developed  organs  towards  its  side. 
The  anterior  enlargement  beside  it  (Table  VI,  Fig.  8,  b,  h)  may  perhaps  have  been  the 
peduncles  of  linguiforni  antennae,  or  the  latter  may  have  been  attached  to  the  lateral  enlarge- 
ment beside  the  cephalic  shield  (Table  VI,  Fig.  8,  c,  c),  while  the  anterior  enlargement 
bore  small,  short,  true  antennae,  as  in  Bra/ic/tipi/s.  If  this  conjecture  is  well  founded,  we 
may  also  easily  understand  why  the  anterior  division  of  the  head  of  the  Trilobites  is  so 
large,  sometimes  even  (as,  for  instance,  in  PZ/acops — Division  A, — and  Asaphus)  obliterating 
the  succeeding  divisions,  and  thereby  causing  an  undivided  projection  of  the  head.  The 
wide-arched  space  of  the  shield  beside  the  projection  of  the  head  beneath  the  eyes,  would 
also  be  very  well  calculated  for  the  reception  of  such  linguiforni  antennae.  The  moveable 
upper  lip  was  unquestional)Iy  affixed  to  the  posterior  margin  of  this  lower  pi'ojection  of  the 
head  (the  real  Ch/peiis,  Table  VI,  Fig.  8,  d),  and  the  size  of  the  lip  depended  on  the  width 
of  this  margin,  and  on  the  magnitude  of  the  incision.  As  in  Apiis  and  Branchipus,  this  lip 
covered  the  upper  jaw,  the  form  of  which  perhaps  rather  resembled  the  upper  jaw  of  Apus 
than  that  of  Branchipus,  since  the  hard  horny  shell  also  indicates  more  solid  organs  of 
mastication.  The  third  division  of  the  projection  of  the  head,  which  is  generally  the  largest 
after  the  first,  probably  corresponds  with  the  position  of  the  jaws,  and  formed  the  basis  of 
attachment  for  the  muscles.  It  represents  that  ring  of  the  body  which,  in  the  typical  form, 
is  independent,  and  has  the   organs  of  locomotion  changed  into  gills ;   and  since   only  a 


TO  THE  EXISTING  AIITICULATA.  43 

smaller  division  exhibits  itself  behind  this  one,  and  anterior  to  the  articulation  of  tlie 
succeeding  one,  we  might  thence  infer  that  there  were  accessory  parts  of  the  mouth,  an 
inference  which  is  highly  probable,  since  in  /Ipus  there  are  also  two  pair  of  accessory  parts 
of  the  mouth  at  that  spot.  The  structure  of  Limnadia  and  Branchipus,  neither  of  which 
possesses  any  true  accessory  parts  of  this  kind,  exhibits,  however,  an  indication  that  these 
may  likewise  have  been  wanting  in  those  Trilobites  characterized  by  a  simple  projecting 
head.  Such  genera  are  Asaphis,  Nileiis,  Illanus,  Trinudeus,  0(/i/(/ia,  and  Phacops  (Division  A), 
all  of  which  are  Trilobites  in  which  a  pair  of  small  bosses  are  always  exhibited  more  or  less 
distinctly  behind  the  large,  simple  projection  of  the  head.  These  little  bosses  seem  to 
indicate  the  traces  of  the  rings  to  which  the  jaws  were  attached,  but  I  should  be  inclined  to 
question  the  existence  of  accessory  parts  of  the  mouth  in  all  S'uch  Trilobites  ;  and  this 
affords  a  decided  reason  for  separating  the  species  of  Phacojjs  referred  to  Division  A,  even 
generically,  a  view  which  is  also  favoured  by  the  whole  structure  of  the  body. 

It  will  now  probably  be  admitted  that  in  the  structure  of  the  PhyUopoda  may  be 
recognized  the  typical  characters  exhibited  in  the  general  configuration  and  proportions  of 
the  head  in  Trilobites,  and  that  those  writers  have  been  fully  justified  who  have  considered 
the  two  groups  as  related  and  nearly  analogous.  It  will  be  seen  as  we  advance,  that 
there  are  still  additional  reasons  in  support  of  the  view  I  have  taken,  especially  when  we 
come,  in  the  next  place,  to  consider  the  structure  of  the  feet,  since  the  varying  numerical 
proportion  of  the  rings  which  compose  the  body  of  Trilobites  separates  the  group  from 
PhyUopoda,  where  this  number  is  constant  (4  x  3 — 1). 


SECTION  XXI. 

There  is  good  proof  that  the  feet  of  the  Trilobites  must  have  been  soft  membranous 
organs,  for  the  absence  of  the  slightest  remains  of  these  organs  in  the  numerous  specimens 
observed  is  of  itself  sufiicient  evidence  of  the  fact,*  and  it  can  indeed  scarcely  be  supposed 
that  hard  horny  extremities  should  be  affixed  to  a  soft  membranous  abdominal  surface  ; 
since  they  would  not  have  then  possessed  that  firm  basis,  which  all  solid  organs  of  locomo- 
tion require,  in  order  that  they  may  be  properly  available.  That  this  abdominal  surface  also 
must  have  been  of  a  membranous  nature  seems  quite  clear,  since  it  has  in  no  instance  been 
preserved  in  a  fossil  state,  whilst  the  hard,  horny,  perhaps  calcareous,  dorsal  surface  is 
invariably  retained,  and  there  can  be  no  reason  why  the  latter  only  .should  have  been 
handed  down,  if  the  former  was  also  hard.  We  may  then  safely  conclude  that  it  was  soft 
and  easily  destroyed,  and  I  would  only  have  the  reader  refer  to  the  rings  in  the  tail  of  the 
Crustacea,  formed  in  a  manner  very  similar  to  that  observed  in  the  case  of  the  Trilobites, 
in  order  that  he  may  be  convinced  that  if  there  had  been  hard  and  solid  coverings  of  the 

*  Eichwald  (1.  c.  39),  Goklfuss,  and  Coimt  Sternberg,  as  is  well  known,  fancied  they  recognized 
feet  in  the  remains  of  some  Trilobites ;  but  the  representations  and  descriptions  they  have  given  are 
too  indefinite  to  enable  us  to  draw  any  certain  conclusion.  Eichwald's  description  certainly  mentions 
the  number  of  joints  (five)  and  the  size  of  the  foot  (foui-  lines)  with  greater  exactitude ;  but  even  then 
it  is  very  unsatisfactory  and  obscure. 


44  AFFINITY  OF  THE  TRILOBITES 

abdomen,  they  must  have  been,  as  in  the  other  Crustacea,  directly  attached  to  the  hard 
upper  shell,  in  order  that  there  should  be  a  sufficiently  solid  basis  for  the  organs  of  locomo- 
tion. But  we  may  well  inquire  how  all  such  solid  girdles  inclosing  the  abdomen  could,  if 
they  ever  existed,  have  been  broken  off  with  such  perfect  regularity  that  they  have  not  even 
left  a  single  vestige.  Such  an  assumption  is  beyond  the  bounds  of  probability,  and  yet  we 
must  suppose  this  to  have  been  the  case,  if  we  suppose  that  the  abdominal  surface  of  Trilobites 
was  provided  with  a  solid  covering  like  that  of  the  back,  and  the  assumption  is  equall}' 
necessary  if  we  believe  these  animals  to  have  had  hard  horny  extremities,  since  such 
extremities  are  never  found  in  the  Articulata  unless  accompanied  by  a  solid  thorax. 

Considering  then  that  all  traces  of  the  extremities  are  absent,  we  may  be  permitted  to 
assume  that  the  feet  of  Trilobites  were  too  soft  and  delicate  to  have  left  even  their 
impressions,  and  this  is  precisely  what  might  have  been  expected,  if  my  view  of  the  affinity 
of  these  animals  to  the  Phyllopoda  is  correct ;  but  although  this,  and  other  reasons  already 
given,  might  of  themselves  be  considered  sufficient  to  establish  the  fact,  it  may  be  proved  yet 
more  distinctly  by  referring  to  the  power  possessed  by  most  species  of  the  extinct  family  to 
double  themselves  up,  a  faculty  often  exhibited  in  the  specimens  found  fossil  which  have 
been  preserved  in  this  form.  In  performing  this  evolution  the  animals  in  question  arched 
the  back,  and  bringing  the  caudal  shield  in  contact  with  the  under  part  of  the  head, 
concealed  all  the  abdominal  surface  beneath  the  hard  horny  coating  of  the  upper  side. 
Now  there  is  no  imaginable  reason  why  the  animal  should  have  been  endowed  with  a  power 
of  thus  rolling  itself  into  a  ball,  if  the  under  side  of  the  body  were  defended  with  a  horny 
or  solid  shield ;  but  we  can  well  understand  the  importance  and  meaning  of  it,  if  the  under 
side  Were,  as  we  suppose,  undefended,  for  it  is  then  a  simple  effort  of  nature  to  protect 
these  soft  and  vulnerable  parts  against  external  violence.  It  may,  indeed,  be  said  that 
some  genera,  such  as  Odontuphura,  Oc/ijc/ia,  Olenus,  &c.,  were  not  endowed  with  this  faculty, 
and  that  therefore  no  general  inference  can  be  drawn,  but  this,  in  point  of  fact,  is  not  a  valid 
objection,  since  it  appears,  from  the  frequent  absence  of  all  remains  of  the  hard  covering  in 
the  case  of  these  genera,  that  their  shells  must  have  been  softer  and  more  tender  than  the 
shells  of  other  Trilobites,  and  I  think  there  is  reason  for  concluding  that  this  was  the  case, 
from  certain  specimens  which  I  have  obsei'ved  and  examined  of  Olcnus  gibhosus  from  the 
alum  slate  of  Andrarum.  In  this  case,  if  the  shell  were  thus  thin  and  tender,  as  in  Apm,  the 
power  of  doubling  the  body  together  into  a  ball  would  have  been  useless,  as  it  would  offer 
no  protection.  Indeed,  in  these  cases,  the  lateral  lobes  are  so  constructed  that  undefended 
spaces  would  have  been  left  if  the  body  had  been  doubled,  so  that  no  advantage  would 
have  been  gained.  We  may  therefore  conclude  that  even  in  those  cases  where  the  body 
does  not  appear  to  have  been  capable  of  being  doubled  up,  the  feet  were  still  soft^  and  we 
may  venture  to  assert  that  in  the  OlenidcB  the  impressions  of  the  feet  themselves  would 
have  been  found,  if  they  had  been  as  hard  as  or  harder  than  the  soft  covering  of  the  body 
of  these  animals. 

Proceeding,  however,  with  the  comparison,  let  us  now  consider  the  structure  of  the 
extremities  of  the  living  PhyllojMda.  They  exhibit,  as  we  have  already  seen,  only  one 
principal  type,  modified  with  regard  to  the  arrangement  of  the  gills,  and  this  modification 
depends  on  the  presence  or  absence  of  a  horny  or  calcareous  covering  of  the  body.  Among 
the  Trilobites  whose  body  was  provided  with  a  shell  on  the  upper  surface,  and  which  were 


TO  THE  EXISTING  ARTICl  LATA.  45 

even  protected  by  lateral  lobes,  we  should  certainly  expect  to  find  that  modification  which  is 
characteristic  of  the  shell-bearing  Phyllopods,  but  we  are  not  at  lil)erty  to  assume  any  close 
analogy,  since  different  families  of  animals,  however  nearly  allied,  do  not  exhibit  the  same 
arrangements  in  detail,  each  particular  organ  not  being  similar  in  allied  groups,  but  such 
groups  rather  exhibiting  general  relations,  and  often  showing  marked  differences  in  particular 
points  of  structure.  This  law  is  illustrated  in  other  ways  in  the  case  of  the  Trilobites,  and 
we  cannot  doubt  its  universality ;  so  that  in  giving  a  certain  form  to  the  feet  in  the  restored 
figure  (See  Plate  VI,  Figs  7,  8),  I  have  done  so  rather  intending  to  indicate  what  they  may 
have  resembled,  than  with  any  idea  of  assuming  their  actual  form.  I  merely  assert  that  these 
organs  were  soft,  membranous,  and  fringed,  adapted  for  locomotion  in  water,  placed  on  the 
abdominal  portion  of  the  body,  and  extending  sidewise  beneath  the  lateral  lobes  of  the  rings, 
as  shown  in  the  ideal  transverse  section.  (Fig.  7.)  These  feet  were  also  indented,  and  thus 
divided  into  several  lobes  at  the  open  lower  side,  and  each  separate  lobe  was  furnished  at 
the  margin  with  small  bristles  serving  as  fins.  The  last  and  external  lobe  (c)  was  probably 
longer,  smaller,  and  more  moveable,  and  reached  to  the  termination  of  the  protecting  shell- 
lobe  (a),  bearing  a  bladder-shaped  gill  {I/)  on  the  inner  side.  The  protecting  lobes  of  the 
feet  of  the  P//////oj)oda  were  probably  entirely  absent  in  the  case  of  the  Trilobites,  the  hard 
shell  aff'ording  sufficient  protection,  and  the  space  beneath  its  lateral  lobes  not  being  large. 
How  far  along  the  body  the  feet  extended  is  a  matter  that  1  must  leave  undetermined,  but  I 
am  inclined  to  suppose  that  they  may  have  reached  the  abdomen,  as  in  Jpus,  since  the 
caudal  shield  frequently  exhibits  the  same  impressions  as  the  lateral  lobes  of  the  thorax, 
and  these  impressions  were  no  doubt  connected  with  the  existence  of  feet.  The  oblique 
transverse  furrow  at  each  of  the  lateral  lobes  indicates  perhaps  that  the  foot  was  situated, 
or  perhaps  partly  attached  behind  it,  at  the  broader  part,  which  issues  from  the  ring  of  the 
axis,  whilst  the  smaller  anterior  part  of  each  lobe  was  adapted  for  articulation  with  the 
preceding  one,  at  least  in  those  genera  possessing  the  capacity  of  doubling  themselves 
into  a  ball,  where  there  seems  to  be  a  deeper  insertion  at  the  spot  where  the  lateral  lobe 
turns  itself  downwards,  in  proportion  as  the  facility  the  animal  had  of  doubling  itself  up  is 
greater.  Since  also  the  anterior  oblique  surface  of  the  lateral  lobes,  which  was  pushed 
beneath  during  the  operation  of  doubling  up,  never  reaches  further  than  to  this  apparent 
point  of  articulation,  this  circumstance  renders  still  more  probable  the  supposition  of  a 
more  intimate  connexion  of  the  lateral  lobes  with  one  another,  from  the  axis  up  to  this 
very  spot. 

It  may  also  perhaps  be  a  subject  of  investigation,  whether  the  feet  of  Trilobites 
resembled  each  other  in  shape  and  size,  as  in  Branchipm,  or  whether  the  anterior  were 
different  from  the  rest,  and  the  posterior  ones  became  gradually  smaller,  as  in  Jpm.  Such 
questions  are  no  doubt  difficult  to  answer,  but  still  there  are  certain  circumstances  which 
may  help  us  in  coming  to  a  probable  conclusion  on  the  subject. 

And  first  of  all  I  do  not  iinagine  that  any  of  those  Trilobites  capable  of  rolling  them- 
selves into  a  ball  possessed  the  peculiar  swimming  apparatus  observable  in  the  first  pair 
of  feet  in  Ajnis ;  since  this  apparatus,  consisting  of  long  appendages  projecting  far  beyond 
the  margin  of  the  integuments,  would  seem  to  require  special  organs  of  retraction  to 
admit  of  being  folded  and  concealed  quickly  and  safely  while  the  animal  was  rolling 
itself  up  at  tlie  moment  of  danger,  and  this  difficulty  would  exist  even  if  they  were  not  so 


46  AFFINITY  OF  THE  TRILOBITES 

long  as  in  Apus.  I  presume,  therefore,  that  in  this  respect  the  Trilohites  resembled 
Branchipus  rather  than  Apus ;  or  that  those  at  least  which  possessed  the  power  of  doubling 
themselves  up  had  the  anterior  pair  of  extremities  perfectly  similar  to  the  rest.  And  this, 
indeed,  appears  also  to  have  been  the  case,  from  the  equality  of  the  thoracic  rings  observable 
in  Branch'qms  and  in  many  Trilobites  capable  of  doubling  themselves  up,  this  equality 
appearing  to  correspond  with  a  similar  equality  in  the  dimensions  of  the  extremities  attached 
to  them.  Since  also  in  Branchiptus  there  are  no  feet  attached  to  the  abdominal  rings, 
in  this  respect  also  we  might  expect  a  correspondence  with  the  group  of  Trilobites  now 
under  consideration,  and  this  seems  the  more  probable  in  the  case  of  those  genera  amongst 
them  which  have  a  short  axis,  and  no  lateral  ribs  on  the  caudal  shield  {Asaphm,  Illamtn, 
NiJeus,  Aiiqyyx).  For  similar  reasons,  however,  I  assume  that  this  structure  obtained  also  in 
the  other  genera  {Calymene,  Homahnotus,  Phacops)  capable  of  doubling  themselves  up,  and 
also  in  others  {Oc/ngidce,  Odonfoplcuruhe)  not  having  this  power,  but  characterized  by  equal 
thoracic  rings.  In  these,  however,  the  existence  of  abdominal  feet  may  perhaps  be  inferred 
from  the  lateral  furrows  of  the  caudal  shield. 

On  the  other  hand,  it  appears  pi-obable,  from  the  decrease  of  size  observable  in  com- 
paring the  anterior  with  the  posterior  portion  of  the  body,  that  in  the  other  groups  (the 
OlenidcB  and  Campylopleiira),  in  which  the  animal  was  not  able  to  roll  itself  into  a  ball,  the  extre- 
mities were  not  all  of  equal  size,  but  diminished  towards  the  posterior  part  of  the  body,  with  the 
diminution  in  the  size  of  the  rings ;  while  the  thoracic  rings  passed  gradually  into  abdominal 
rings.  This  is  the  case  in  Apus  and  Limuadia,  where  the  rings  increase  a  little  at  first,  but 
then  diminish  in  size  from  the  centre  of  the  thorax,  and,  becoming  progressively  smaller, 
pass  into  the  rings  of  the  abdomen.  From  the  analogy  here  presented,  we  might  also  expect 
that  the  first  pair  of  feet  from  the  thoracic  feet  of  the  Oleuidce  and  Campylopleura  were  pro- 
vided with  filaments  instead  of  fins,  or  that  at  least  the  antennse  of  the  head  were  larger  and 
more  like  those  of  Limnadia,  while  in  other  Trilobites  they  must  certainl}^  have  been  short 
and  small ;  and  they  could  not  have  projected  beyond  the  margin  of  the  cephalic  shield,  for 
the  same  reason  which  prevented  the  development  of  the  lobes  of  the  first  pair  of  feet  into 
filaments. 


SECTION  XXII. 

Convinced  that  the  reasons  already  offered  will  be  deemed  sufhciently  conclusive  to 
satisfy  the  unprejudiced  reader,  I  venture  now  to  offer  the  following  deductions  and  general 
conclusions  : 

The  Trilobites  zoere  a  pecidiar  fcunili/  of  Crustacea,  nearly  allied  to  the  existing 
Phyllopoda,  approaching  this  latter  family  most  nearly  in  its  genus  Branchipus,  and 
forming  a  link  connecting  the  Phyllopoda  with  the  P^ecilopoda. 

In  order,  however,  to  estimate  fairly  the  affinity  of  the  Trilobites  with  the  Phyllopoda, 
we  must  not  lose  sight  of  the  important  fact,  that  the  Trilobites  differ  not  only  from  the 
Phyllojjoda,  but  from  all  other  existing  families  of  Crustacea  in  the  varying  numerical  pro- 
portion of  their  thoracic  rings ;  a  peculiarity  neither  exhibited  at  present  as  a  characteristic 
of  any  natural  family  among  the  Crustacea,  nor  in  any  of  the  heterogeneous  Articulata. 


TO  THE  EXISTING  ARTICULATA.  47 

This  peculiarity  occurs,  it  is  true,  among  the  Aspidosfracn  (a  group  of  the  second  great 
division  of  the  Crustaceans),  but  only  in  a  modified  form,  the  difference  in  the  numerical 
proportion  being  always  reducible  to  one  fundamental  number.  This  law  is  apparently  not 
observed  in  the  case  of  the  Trilobites. 

It  would  seem  then  that  the  relation  existing  between  the  Trilobites  and  the  existing 
Crustacea  is  one  rather  of  analogy  than  affinity,  so  that  the  whole  group  may  be  considered 
as  a  separate  division,  corresponding  with  the  Jspidosfraca  in  the  formal  variation  presented 
from  the  typical  character,  but  not  to  be  looked  on  as  a  nearly  allied  or  similar  group  to 
this  or  to  other  tribes. 

Putting  out  of  the  question  the  important  difference  exhibited  in  the  numerical  pro- 
portion of  the  thoracic  rings  just  alluded  to,  this  analogy  to  the  Aspidostraca  might  certainly 
have  been  considered  as  very  close — all  the  other  relations  of  organization,  so  far  as  they 
can  be  traced,  corresponding  very  accurately — if  it  were  not  for  the  structure  of  the 
extremities.  These,  indeed,  which  are  hard,  horny,  and  articulated  in  a  subdivision  of  the 
present  Aspidostraca,  were  probably  entirely  absent  in  this  form  in  Trilobites ;  but  in  other 
respects  all  the  typical  characters  of  the  two  groups  will  be  found  to  correspond. 

The  present,  however,  appears  to  be  the  proper  place  to  institute  a  still  further  investi- 
gation into  this  subject,  which  may  serve  as  an  additional  illustration. 


SECTION  XXIII. 

It  follows  as  a  matter  of  necessity  that  the  Trilobites,  belonging  as  they  did  to  the 
great  natural  division  of  articulated  animals,  must  have  been  subjected  to  a  periodical 
growth,  during  which  their  horny  or  stony  cases  were  thrown  off  and  exchanged  for  new 
ones.  This  has  been  already  alluded  to  by  Wahlenberg,  who  has  also  suggested  that  some 
supposed  new  species  may  have  been  founded  upon  these  cast  shells.  I  am  not,  indeed, 
inclined  to  agree  to  the  probability  of  this  assumption ;  but  in  order  to  illustrate  my  own  views 
on  the  subject,  it  will  be  necessary  first  to  describe  the  process  of  exuviation  and  develop- 
ment of  the  recent  Pliyllojmdn. 


SECTION  XXIV. 

All  Pliyllopoda  are  subjected  to  a  true  metamorphosis,  and  that  a  progressive  one. 
They  leave  the  egg  as  unarticulated  pyriform  animals,  and  at  the  anterior  thicker  extremity 
of  this  pyriform  body  we  perceive  one  simple  eye,  two  pairs  of  unequal  oar-shaped  feet, 
rudimentary  antennae,  and  an  organ  of  locomotion,  in  addition  to  the  two  pairs  of  feet  which 
subsequently  converted  itself  into  the  real  branchial  apparatus.*  The  young  animals  are 
always  quite  naked  and  destitute  of  shells,  whether  the  parents  possess  shells  or  not.     If  the 

*  Fig.  14,  in  Table  VI,  represents  the  young  of  a  Branchipus  immediately  after  its  emergence 
from  the  egg;  Fig.  13,  the  young  of  Apus  after  the  first  moult — a  indicates  the  small  antenna;,  b  the 
large  ones,  c  the  foot  of  the  branchial  apparatus,  d  the  rudiments  of  the  subsequent  feet. 


48  AFFINITY  OF  THE  TRILOBITES 

latter  be  the  case,  the  young  never  receive  a  protecting  covering ;  if,  however,  the  parents 
have  shells,  then  the  first  traces  of  it  are  seen  immediately  after  the  first  moult,  in  the  form 
of  a  membranous  fold,  which  issues  from  the  neck,  and  which  at  once  covers  one  half  of  the 
body.  The  young  animal,  after  this  period,  has  become  considerably  larger,  and  its  body  has 
become  thicker  and  exhibits  lateral  notches  behind  the  third  organ  of  locomotion,  from  wliich 
the  feet  gradually  develop  themselves.  The  little  animal  still  retains  its  first  three  organs 
of  locomotion  in  an  unchanged  form  as  long  as  the  feet  remain  imperfect ;  as  soon,  however, 
as  the  feet  (which  grow  laterally  from  the  body)  have  attained  their  relative  development, 
in  proportion  to  the  dimensions  of  the  animal,  the  former  organs  of  locomotion  begin  to 
diminish,  and  are  gradually  metamorphosed  into  the  form  exhibited  in  the  full  grown 
animal,  which  is  frequently  very  rudimentary.  It  can  then  be  distinctly  seen  that  they  are 
the  true  tentacula  of  the  developed  animal,  and  that  according  to  their  size  in  the  subsequent 
stages  of  existence  .they  are  more  or  less  diminished  or  modified.  The  formation  of  the  eye 
progresses  equally  with  this  metamorphosis.  At  first  it  is  a  simple  small  point  or  dot,  and 
first  appears  about  the  time  when  the  anterior  half  of  the  thoracic  feet  have  formed  them- 
selves into  isolated  organs ;  but,  besides  this  little  dot,  there  are  a  couple  of  other  dark  spots 
in  the  head,  which  simultaneously  and  gradually  with  the  other  organs  form  themselves  into 
compound  eyes.  A  very  short  period  of  time  is  required  for  the  formal  development  of  the 
rest  of  the  animal,  for  the  subsequent  structures  are  already  conveniently  isolated  and  per- 
fectly formed  when  the  young  animal  has  scarcely  reached  the  hundredth  part  of  the 
dimensions  it  is  afterwards  to  attain.  From  this  time  forward,  therefore,  it  advances  regularly 
in  its  growth,  and  casts  its  membranes  from  time  to  time,  at  longer  or  shorter  intervals,  as 
the  rapidity  of  its  growth  may  demand.  The  cast-off  membranes  are  split  along  the  whole 
length  of  the  back,  and  the  animal  draws  forth  all  parts  from  this  opening  gradually  in 
such  a  manner  that  even  the  smallest  hair  remains  affixed  to  the  old  membrane  and  forms 
itself  anew  on  the  new  membrane.  The  cast-off  membrane,  however,  consists  only  of  the 
epithelium,  never  of  the  real  cutis,  and  it  is  therefore  ver}^  thin  and  delicate.  The  Trilobite 
remains  which  are  said  to  have  been  produced  from  such  exuviae  are  thus  probably  mere 
impressions,  and  do  not  exhibit  remains  of  the  shell  itself,  since  distinct  evidence  of  its 
having  been  cast  off  would  have  been  preserved  in  a  longitudinal  section  along  the  centre 
of  the  back,  and  such  a  section  not  having  been  yet  observed  in  any  Trilobite,  I  consider  the 
opinion  expressed  by  Wahlenberg,  that  in  many  supposed  Trilobite  shells  we  have  only  the 
cast-off  membranes  before  us,  to  be  incorrect. 

It  may  still  be  thought  probable,  however,  from  the  nature  of  the  metamorphosis  of  the 
Phyllojmda,  that  Trilobites  experienced  a  similar  change,  nor  do  I  at  all  question  the 
possibility  of  such  a  view  being  correct.  On  the  contrary,  I  am  inclined  to  recognize  the 
vestiges  of  such  early  stages  of  the  animal's  growth  in  the  obscure  shields  which  have  been 
supposed  the  types  of  new  genera,  under  the  names  Agnodus  and  Batfus ;  for,  on  carefully 
examining  specimens  of  the  former,  we  find  not  only  a  singular  variation  in  size,  occurring 
as  they  do  from  the  dimensions  of  a  mustard  seed  to  that  of  a  pea,  but  also  a  perceptible 
difference  in  the  form  of  their  constituent  parts,  and  I  think  I  can  distinguish  four  different 
forms,  which  may  be  brought  under  two  groups.  Before,  however,  explaining  these,  I  shall 
describe  the  Ai/nostus  shield  in  general,  referring  for  illustration  to  the  representations. 


TO  THE  EXISTING  ARTICULATA.  49 


SECTION  XXV. 

On  the  othei-  liand,  however,  there  arises  a  very  natural  suggestion,  that  the  Trilobites 
may  have  undergone  a  metamorphosis  similar  to  that  described  as  characterizing  the 
Phi/Uopoda.  I  by  no  means  question  the  great  probability  of  such  a  modification,  but  there 
is  as  yet  no  distinct  evidence  in  support  of  it,  for  up  to  the  present  time  no  one  has  been 
fortunate  enough  to  discover  a  specimen  in  the  young  state,  offering  any  distinct  indication 
of  gradual  development  or  metamorphosis.  My  original  notion,  that  the  so  called  genus, 
Battiis,  was  founded  on  the  shields  of  the  heads  of  young  Trilobites,  has  since  been  dis- 
proved by  Dr.  Beyrich,  who  has  shown,  on  the  other  hand,  the  probability  that  these  shields 
belong  to  a  particular  genus  of  Trilobites,  the  one  form  of  them  covering  the  head,  and  the 
other  the  tail,  while  the  two  were  connected  by  an  articulated  body  formed  of  two  rings. 
This  genus  we  shall  afterwards  describe  more  in  detail  in  its  proper  place. 


SECTION  XXYI. 

Although,  according  to  these  observations,  the  develojiment  of  the  Trilobites  has  not  yet 
been  proved  identical  with  that  of  the  P/i^Ilojjodu,  there  can  still  be  hardly  a  doubt  that 
there  exists  a  completely  analogous  organization  in  the  two  groups,  and  a  circumstance 
which  has  hitherto  been  overlooked  seems  to  render  this  analogy  still  more  probable. 
The  three  principal  stages  of  modification  of  the  fundamental  type,  which  at  present  exist 
in  the  three  families  of  the  Plii/Uopoda  above  described,  likewise  seem  to  be  presented  in  the 
case  of  the  Trilobites.  In  the  former  group  we  observed  that  there  are — (1)  Naked 
Phyllopoda  {Bra/ichijjus) ;  (2)  Plii/Ilojjoda  with  a  simple  horizontal  shield  {Apus)  -,  and  (3) 
PhyUopjodu  with  a  bivalve,  perpendicular  shield  {Limuadia).  Precisely  the  same  differences 
of  structure  are  also  found  among  the  Crustacea  that  lived  at  the  period  of  the  Trilobites, 
and  thus  the  analogy  of  those  early  types  with  their  present  representatives,  the  Phyllopoda, 
is  confirmed  in  a  very  singular  manner. 

Besides  the  true  Trilobites,  of  which  the  broad,  flat,  perpendicular  shield  leaves  no 
doubt  that  we  must  recognize  it  the  analogue  of  the  simple  perpendicular  shelled  Apu>i,  we 
find  also  in  the  Palaeozoic  strata  the  remains  of  two  other  crustaceous  animals,  one  of  which 
{Cytheruut)  was  covered  with  a  bivalve  shell,  offering  a  perfect  resemblance  to  that  of 
Estheria,  while  the  other  {Eurypterun)  was  entirely  without  any  shelly  covering,  and  seems  to 
have  been  analogous  to  Branchipus.  Of  Cytherina  nothing  has  been  preserved  but  the  shell, 
and,  according  to  Hisinger's  figure,*  it  so  perfectly  corresponds  in  structure  with  Estheria,^ 
that  it  is  scarcely  necessary  to  say  another  word  respecting  the  relations  of  afiinity  of  the 

*  Lethsea  Suecica. 

t  See  Strauss,  in  'Museum  Senkeubergianum,'  torn,  ii,  p.  110,  Table  ^  II,  aud  the  still  better 
figure  given  by  Joly,  in  the  '  Aunales  des  Sciences  Natur.'  Nouv.  Sor.  torn,  xvii,  p.  äü3,  PI.  7-9. 
1842. 

7 


50  AFFINITY  OF  THE  TRILOBITES 

two  forms.  It  must  l)e  evident  to  every  naturalist,  that  to  recognize  the  analogues  of  the 
genera  Ci/pris  or  Ci/lhere  in  these  shells,  is  far  less  probable  than  the  affinity  now  suggested. 
The  more  recent  forms  obtained  from  the  fresh-water  limestones  of  the  Weald,  and  described 
as  Cyprisfnha,  may,  however,  have  really  belonged  to  this  genus. 

To  prove  by  a  priori  reasoning  that  Euri/pterus  was  a  shell-less  Trilobite,  just  as 
IhancUpus  is  a  shell-less  Phyllopod,  may  appear  difficult ;  yet  even  in  this  view  I  think  I  am 
fully  justified.  The  figures  which  Harlan  has  recently  given  us  in  his  '  Medical  and  Physical 
Researches,'  p.  298,  leave  no  doubt  in  my  mind  on  the  subject ;  and  it  is  from  the  study 
of  these  figures,  and  from  the  similar  one  given  by  G.  Fischer  (Notice  sur  I'Eurypterus  de 
Podolie,  Moscow,  1 839),  that  I  have  derived  my  conclusions.  The  animal,  according  to  the 
description,  possessed  a  head  which  appears  broader  than  the  glabella  of  the  Trilobites, 
because  it  was  softer  and  compressed,  but  otherwise  corresponds  with  it  in  form.  We 
recognize  in  it  two  large  lunate  eyes,  in  which  the  black  pigment  of  the  centre  may  be  very 
well  distinguished  from  the  glassy  spheres  and  lenses  extended  above  it,  as  the  figures  of 
Harlan  distinctly  show.  These  eyes  were  also  unquestionably  compound,  and  had  a  simple, 
smooth,  horny  membrane.  Three  pair  of  organs  seem  to  be  affixed  to  the  lower  surface  of 
this  head  ;  two  of  them  being  somewhat  small,  and  situated  at  the  anterior  margin,  and  the 
articulation  of  which  is  no  longer  recognizable,  although  the  long  bristles  with  which  they 
were  furnished  appear  quite  distinct.  1  take  these  for  the  antenujE,  and  suppose  them  to 
correspond  with  the  first  two  organs  of  locomotion  of  the  Phi/Uojioda.  The  third  pair  of 
organs  of  locomotion  of  the  head  were  longer  than  the  two  others,  thicker,  more  distinctly 
articulated,  free  from  bristles,  but  furnished  at  the  end  with  hooks ;  they  probably  formed 
the  accessory  pair  attached  to  and  forming  part  of  the  mouth,  and  were  useful  to  the  animal 
when  seizing  its  prey.  It  decidedly  appears,  from  Figure  2  of  Harlan's  Plate,  that  there 
followed  behind  these  three  pair,  and  at  the  first  thoracic  ring,  a  couple  of  large,  broad, 
articulated,  but  soft  fin-feet,  the  number  of  joints  of  which  appears  to  have  been  five. 
These  also  undoubtedly  bore  bristles  at  their  margin,  but  their  delicate  nature  prevented 
the  impression  from  being  retained.  Together  with  this  first  thoracic  ring,  I  recognize 
in  Harlan's  figure  (Fig.  1)  twelve  rings,  although  in  Fig.  2  there  are  only  ten  distinctly  to 
be  seen,  but  in  this  case  the  extremity  of  the  abdomen  is  injured ;  Fischer  has  represented 
fourteen  rings,  and  a  still  further  number  is  indicated  in  his  figure.  This  impression,  indeed, 
seems  generally  to  point  to  specific  differences,  on  account  of  the  sharp  lateral  prongs  of  the 
rings  of  the  body ;  but  we  might  also  take  these  lateral  lobes  for  the  extreme  ends  of 
the  fin-feet,  and  assume  at  the  same  time  that  they  were  much  smaller  than  the  first 
pair,  according  to  the  analogy  of  Jjms  (Table  VI,  Fig.  1).  I  am  myself  decidedly  of  this 
opinion,  and  consider  that  it  is  not  feet  that  are  visible  in  the  figures  of  Harlan  and  of 
Dekay,  the  animal  having  been  too  much  compressed  by  the  petrified  mass  during  its 
inclosure,  to  admit  the  possibility  of  the  extreme  ends  of  the  feet  projecting  in  this  manner. 
The  softer  abdominal  side  of  the  body,  together  with  the  feet,  may,  however,  have  been 
already  cast  off  in  these  very  specimens,  and  this  is  another  and  also  a  very  probable 
conjecture.  I  believe  in  other  respects  that  of  the  whole  number  of  the  rings  we  must 
reckon  nine  as  belonging  to  the  real  thorax,  the  remainder  being  abdominal.  The  great 
diminution  of  the  body  from  the  ninth  ring,  and  the  equal  breadth  of  the  succeeding  rings 
arc  reasons  in  favour  of  this  conjecture,  and  the  deviating  formation  of  these  first  rings   in 


TO  THE  EXISTING  ARTICULATA.  51 

Fischer's  figure  may  be  considered  as  another.  The  first  six  rings  certainly  here  appear  to 
be  much  more  peculiar  than  the  three  next  succeeding  ones ;  but,  considering  the  other 
points  of  identity  in  structure  between  this  species  and  the  North  American  one,  we  are 
probably  justified  in  assuming  that  they  must  have  had  an  equal  numerical  proportion,  so  far 
as  the  thorax  is  concerned.  According  to  this  view  three,  or  perhaps  six  rings  would  come 
to  the  abdomen,  and  this  proportion  would  correspond  with  the  prevalent  type  both  of  the 
Trilobites  and  Phyllojioda.  A  separation  of  both  divisions  of  the  body  in  six  and  six,  or  in 
six  and  nine  rings,  is,  however,  also  conceivable,  and  indeed  easily  to  be  accounted  for  by 
the  analogy  oi  Apus  and  also  of  the  species  oi  Pkacops  referred  to  the  second  division. 


SECTION  XXVII. 

Having  adduced  so  many  analogies  and  homologies  of  structure  between  the  Trilobites 
and  the  Pliyllopoih,  we  may  be  permitted  to  assume  some  similarity  also  in  the  habits  of  the 
two  groups,  and  I  now  propose  to  add  some  remarks  on  this  subject. 

The  PhyUopoda  live  in  stagnant  fresh  waters,  especially  in  ditches,  pools,  or  puddles, 
which  are  very  rapidly  produced  after  rain  in  the  early  part  of  the  year,  and  last  only  till 
the  middle  of  the  summer,  when  they  become  dried  up.  During  this  period  the  animals 
of  the  tribe  we  are  describing  are  usually  seen  in  numerous  companies  swimming  about  in 
the  water  at  various  depths,  the  species  of  BrancJiipus  being  most  frequently  close  beneath 
the  surface  of  the  water.  In  swimming  they  turn  their  back  downwards,  their  abdomen 
being  upwards,  so  that  the  feet  touch  the  surface  of  the  water,  and  accordingly  Branckipus, 
has  its  eyes  in  the  position  in  which  I  have  represented  it  in  Table  VI,  Fig.  3,  and  not 
proceeding  from  the  head  rectangularly.  This  position  of  the  eyes  enables  the  animal  to 
look  both  upwards  and  downwards.  Apus,  on  the  other  hand,  which  has  immoveable  eyes, 
can  only  look  downwards  while  swimming  on  its  back,  and  it  must  turn  itself  if  it  wishes  to 
look  upwards.  But  this  is  quite  natural,  since  in  each  case  the  animal,  when  in  its  usual 
position,  and  close  beneath  the  surface  of  the  water,  can  only  have  its  enemies  below,  and 
therefore  only  needs  to  be  secured  against  surprise  in  that  dii-ection.  These  creatures  are, 
however,  not  much  exposed  to  attack.  Their  prey,  which  consists  of  other  little  animals 
living  in  the  water,  they  obtain  during  their  constant  swimming  motion,  and  it  is  brought  to 
the  mouth  by  the  motion  of  the  water.  Owing  to  this,  the  region  and  cavity  of  the  mouth  in 
many  of  these  animals,  when  preserved  in  spirit  of  wine,  are  frequently  entirely  covered  or 
filled  up  with  extraneous  substances.  The  PhyUopoda  are  never  at  rest,  partially  because  they 
are  entirely  deficient  in  organs  by  which  they  could  keep  firm  hold  of  anything,  partially  also 
because  their  motion  of  swimming  produces  at  the  same  time  the  motion  of  the  respiratory 
organs,  which  being  independent  of  the  will  of  the  animal  does  not  cease.  I  have  not  yet 
had  an  opportunity  of  observing  Limnadia  and  Estheria  in  a  living  state,  but  both  genera 
undoubtedly  exist  in  the  same  manner  ;  I  am  not,  however,  aware  whether  they  swim  on 
their  back.  Considering  the  afiinities  of  the  Trilobites  with  the  PhyUopoda,  I  cannot  doubt 
for  a  moment  that  their  habits  during  life  and  their  mode  of  existence  were  similar,  and  I 
therefore  conclude — 


52  AFFINITY  OF  THE  TRILOBITES,  ETC. 

1.  That  these  animals  moved  only  by  swimming,  that  they  remained  close  beneath  the 
surface  of  the  water,  and  that  they  certainly  did  not  creep  about  at  the  bottom,  as  Mr. 
Klöden  supposed.* 

2.  That  they  swam  in  an  inverted  position,  the  belly  upwards,  the  back  downwards, 
and  that  they  made  use  of  their  power  of  rolling  themselves  into  a  ball  as  a  defence  against 
attacks  from  above. 

3.  That  they  lived  on  smaller  water-animals,  and  in  the  absence  of  such,  on  the  spawn 
of  allied  species. 

4.  That  they  most  probably  did  not  inhabit  the  open  sea,  but  the  vicinities  of  coasts, 
in  shallow  water,  and  that  they  here  lived  gregariously  in  vast  numbers,  chiefly  of  one 
species. 

.5.  That  the  number  of  species  could  never  have  been  very  great.  This  is  indeed 
proved  by  the  mode  of  their  appearance  in  the  fossil  state,  inasmuch  as  scarcely  more  than 
six  or  eight  species  have  been  found  together  anywhere  in  one  stratum. 

6.  Although  the  number  of  species  has  not  been  large,  the  number  of  individuals 
was  very  great  indeed ;  a  fact  likewise  observed  in  the  living  P/ii/Uopoda,  of  which  we  as 
yet  scarcely  know  a  dozen  species,  although  these  are  grouped  into  about  six  different 
genera.  « 

7.  The  great  differences  existing  in  the  dimensions  of  the  present  P^y/Zo/JOf/'?  according  to 
their  age,  justify  us  in  expecting  such  differences  also  among  the  Trilobites  ;  and  very  large 
individuals  of  the  latter,  therefore,  do  not  indicate  a  separate  species,  unless  other  differences 
are  presented. 

*  See  'Verst.  d.  Mark  Brandenburg,'  vou  H.  Klüdeii,  p.  104. 


CHAPTER  III. 

SYSTEMATIC  ARRANGEMENT  OP  THE  SPECIES. 

The  arrangement  of  Trilobites,  and  their  position  amongst  the  Crustacea,  now  no 
longer  offers  any  difficulties,  and  they  may  be  most  conveniently  described  in  the  following 
manner. 

If,  as  the  observations  already  offered  would  seem  to  demand,  we  arrange  the  genera 
Cytkerina  and  Euri/jjfcrus  with  the  Trilobites  in  a  single  division,  we  have  a  group  parallel  to 
the  existing  PhijUopoda ;  to  designate  which  we  may  employ  Dalman's  name  Palceudce*  and 
which  may  thus  be  described. 

The  Pal^ad^  are  crustaceous  Articulata,  belonging  to  the  second  order  of  the  class 
Crustacea  (divided  into  Ostracodermata,  Aspidoatraca,  and  Entomostraca),  characterized  by  the 
possession  of  two  large  compound  eyes,  by  the  absence  of  simple  secondary  eyes,  and  by 
having  short  undeveloped  feelers,  and  soft  leaf-formed  feet,  bearing  gills.  By  these 
characters  they  are  immediately  related  to  the  Phj/IIopoda,  and  might  perhaps  even  be 
united  with  the  latter  in  one  tribe.  Their  principal  difference  would  then  consist  in  the 
absence  of  the  constant  numerical  proportion  of  eleven  rings  of  the  thorax,  common  to  ail 
the  FhijUopoda,  which  must  be  expressed  by  the  formula  of  4  x  3 — 1.  Instead  of  this,  the 
Palceadce  exhibit  fluctuating  numerical  proportions  in  the  parts  of  the  thorax,  respecting  the 
reduction  of  which  to  a  constant  formula,  nothing  certain  can  be  said ;  because  we  neither 
know  the  number  of  the  accessory  parts  of  the  mouth,  nor  the  position  of  the  sexual 
openings.  These  animals  underwent  a  progressive  metamorphosis,  they  moved  by  swim- 
ming, probably  with  their  backs  downwards,  and  they  inhabited  the  ocean,  living  chiefly  in 
shallow  water.  The  whole  group  is  divided  into  three  families,  which  are  characterized 
according  to  the  nature  of  the  shelly  covering. 


First  Family— EURYPTERID.E. 

In  these  there  is  no  shell.  The  head,  whose  position  is  very  distinct,  bears  two  pair  of 
setaceous  feelers,  and  one  pair  of  accessory  parts  of  the  mouth.  There  are  probably  nine  (?) 
rings  in   the   thorax,  the   first  of  which  bears  a  pair  of  very  large   rudder-shaped   feet, 

*  See  the  article  written  by  me  on  the  Entomostraca,  in  Ersch  and  Gruber's  Encyclopiedia, 
sect,  i,  vol.  xsxv,  p.  134.  I  here  first  explained  the  relations  of  the  PalmadtE  with  the  existing 
Phyllopoda. 


54  SYSTEMATIC  ARRANGEMENT 

furnished  with  five  joints;  and  the  succeeding  rings  seem  to  have  borne  similar  leaf-Uke 
feet  of  an  equal  size.  The  abdomen  consisted  of  three  or  six  rings,  and  was  terminated  by 
a  pair  of  rudder-fins  (?). 

There  is  only  one  genus  belonging  to  this  family,  and  of  this  there  seem  to  be  three 
species. 


EuRYPTERUS,  D^kay. 

1.  E.  remipes :  Somewhat  slender,  the  terminal  joint  of  the  large  fin-feet  equal  in  length  to  the 
preceding.      Length  of  body  SYs",  breadth  at  the  upper  part  1)4". 

Reference. — D^kay,  Annals  of  the  Lyceum  of  Nat.  Hist,  of  New  York,  i,  12,  291,  Plate 
XIV;  and  375,  Plate  XXIX  (1826).  Froriep's  Notiz.  1827,  xviii,  1-3.  Holl, 
Petref  155.  Bronn,  Lethaa,  i,  109,  Table  IX,  Fig.  1.  Harlan,  Med.  and  Phi/s. 
Research.  297.  c.fff.     Mitchell,  Jm.  Month.  Magaz.  iii,  291. 

Locality. — Slate  rocks  of  Westmoreland,  Oneida,  and  New  York. 

2.  E.  lacustris :  Broader  than  the  former  species,  and  the  terminal  joints  of  the  large  rudder-feet 
much  smaller.      Length  of  body  almost  5",  breadth  2^". 

Bef. — Harlan,  as  above,  298.  c.fy. 

Loc. — The  grauwacke  rocks  at  Williamsville,  seven  miles  from  Buffalo,  U.  S. 

3.  E.  tetragonopfithahnus  .■  Eyes  placed  at  a  greater  distance  from  one  another,  quadrangular  (?), 
the  whole  of  the  structure  very  slender,  especially  that  of  the  abdomen,  the  joints  probably  acutely 
angled.      Length  nearly  two  inches,  breadth  %. 

Ref.—G.  Fischer,  Bullet,  de  la  Soc.  Imp.  d'Hist.  Natur,  de  Moscou,  1839,  ii,  127,  Plate 
VII,  Fig.  1 ;  and  his  Notice  sur  I'Eurypt.  de  Podolie,  etc.,  Moscow,  1839,  4. 

Loc. — The  transition  limestone  or  grauwacke  sandstone  of  Podolia,  at  the  village 
of  Zvilevy,  twenty  wersts  to  the  south  of  Kamenetz. 

It  is  probable  that  the  fossil  described  by  Scouler  under  the  name  of  Eidotea,  may 
belong  to  a  species  of  this  genus.  Fragments  of  it  only  are  known,  and  these  correspond 
with  the  head  and  the  commencement  of  the  thorax  of  Eurypterus,  but  certainly  belong  to  a 
different  species.  See  the  following  works  respecting  it:  Cheek's  Edinb.  Journ.  of  Nat. 
Science,  1831,  June,  N.  S.  iii,  352,  Plate  VII.  Leonhard  and  Bronn's  Jahrbuch,  1832, 
251.  Bronn,  Lethcea,  i,  109,  98,  Table  IX,  Fig.  2;  and  Hibbert,  Transact.  Roy.  Soc.  of 
Edinb.  1834.     This  latter  reference  I  have  not  had  the  opportunity  of  verifying. 


OP  THE  SPECIES.  55 


Second  Family— CYTHERINID.E. 

These  animals  were  contained  in  bivalve,  bean-shaped  shells,  which  are  the  only  parts 
preserved.  They  are  more  or  less  pointed  towards  the  external  wider  margin ;  at  the 
straight  or  dorsal  margin  they  are  rather  thickened.  They  vary  in  size  from  K"  to  ^",  or 
even  (though  rarely)  to  1". 

The  only  genus,  C}jth.enna,  which  belongs  to  this  family  requires  as  yet  a  more  accurate 
study,  as  there  seem  to  be  several  species  which  have  hitherto  been  confounded  with  one 
another.  The  specimens  from  the  mountain  limestone  are  probably,  however,  the  only  true 
representatives  of  the  geaus,  and  the  species  referred  to  Cyjiru,  and  found  in  the  wealden, 
cretaceous,  and  tertiary  formations,  probably  belong  to  a  different  and  peculiar  group. 
For  the  present  we  may  consider  as  belonging  to  it — 

1.  C.  haltica ;  HisiNGER,  Leth.  siiecica,  10,  Table  I,  Fig.  2,  and  Table  XXX,  Fig.  1. 

2.  C.  pkaseolus ;  Hisinger,  ibid.  Table  I,  Fig.   1,  and  the  Antechdng  i  P/ii/s.  och.  Geot/n. 

of  the  same  author,  V,  Table  8,  Fig.  3.     Klöden's  Verst.  d.  Mark  Brandenhury ,  102, 
Table  I,  Fig.  10-11. 

Third  Family— TRILOBIT^. 

The  body  covered  by  an  affixed  shell,  which  consists  of  as  many  rings  as  there  are 
joints  of  the  thorax  (?);  the  head  and  the  abdomen  each  similarly  included  in  a  large  united 
shield,  which,  like  the  rings  of  the  shell  of  the  body,  possesses  a  broad  border  that  freely 
projects  at  the  sides.  The  large  eyes  are  situated  in  the  lateral  portions  of  the  cephalic 
shield,  remote  from  the  true  head.  A  peculiar  suture  passes  through  the  cephalic  shield,  and 
divides  it  into  two,  three,  or  four  special  parts.  The  numerous  members  of  this  family,  which 
have  been  already  particularly  described  in  the  first  chapter,  admit  of  a  further  division 
into  natural  genera,  the  most  suitable  classification  of  which  may  perhaps  be  the  following : 

1.  Trilohites  incopahle  of  rolUng  themselves  ujj.  The  Trilobites  of  this  division  appear  to 
be  decidedly  of  more  ancient  geological  date  than  those  of  the  following  divisions,  and  are 
principally  found  in  the  lowest  Silurian  rocks,  but  are  there  accompanied  by  some  species 
of  the  other  group.  They  are  easily  recognized  by  the  structure  of  the  lateral  lobes  of  the 
body,  which  is  such  that  throughout  its  length  each  preserves  the  same  breadth,  and  never 
diminishes  on  the  upper  and  external  side  towards  the  margin,  a  peculiarity  observable  in 
the  members  of  the  second  group.  The  lateral  lobes  of  these  Trilobites,  therefore,  represent 
narrow  parallel  courses,  which  are  usually  divided  in  a  diagonal  direction  by  a  transverse 
fuiTow.  On  a  more  accurate  examination,  however,  we  find  that  two  different  types 
predominate  in  their  configuration,  which  present  new  differences,  the  details  of  which  we 
need  not  dwell  upon  in  this  general  description.  The  species  of  this  first  principal  group 
are  further  distinguished  by  the  smallness  of  their  eyes,  which  are  depressed,  and  have  a 
more  elongated  form  than  the  eyes  of  other  Trilobites.  Only  the  inner  surface  of  the  shell 
is  known,  the  upper  surface  being  absent  in  almost  all  the  specimens  hitherto  found,  ex- 
cepting those  belonging  to  the  genera  OdontopJeura,  Brontes,  and  Harpes.  This  is  especially 
the  case  in  those  found  in  grauwacke,  clayslate,  and  alum-slate.  As  already  mentioned,  this 
group  is  divided  into  two  sections,  according  to  the  characters  of  the  lateral  lobes. 


56  SYSTEMATIC  ARRANGEMENT 


GROUP  THE  FIRST. 

The  lateral  lobes  of  the  rings  of  the  body  are  situated  in  the  same  plane,  and  do  not  curve  or 
bend  downwards,  but  terminate  towards  the  posterior  part  in  a  more  or  less  prominent  point,  some- 
times very  long,  tchich  forms  a  somewhat  obtuse  angle  in  its  principal  direction  with  the  direction 
of  the  lobe. 

Of  this  group  there  are  further  subdivisions,  which  may  readily  be  distinguished  from 
one  another,  being  founded  on  the  presence  or  absence  of  a  large  caudal  shield. 

Division  A. 

Trilobites  with  a  simple,  large,  caudal  shield  {not  much  smaller  than  the  cephalic  shield), 
the  axis  of  which  is  many-jointed,  and  equals,  or  even  exceeds,  the  length  of  the  body.  Ogygiid^. 
To  this  group  belong  two  genera,  Trinucleus  (with  six  rings)  and  Ogygia  (with  eight  rings). 

Genus  1. — Trinucleus,  Murchison  (Cryptolithus,  Green). 

Cephalic  shield  almost  semicircular,  with  a  margin  which  is  dilated  all  round  and 
punctated,  and  with  posterior  angles  terminating  in  long  spines ;  the  central  glabella  very 
convex,  much  contracted  at  its  posterior  part  before  the  margin ;  without  lateral  lobes  or 
furrows. 

The  eyes  and  the  facial  suture  I  have  not  yet  myself  been  able  to  examine.*  The  body 
is  short,  the  six  rings  narrow,  scarcely  half  as  broad  as  the  lateral  lobes,  the  latter  with  a 
distinct  diagonal  furrow,  and  with  a  fine  short  angle. 

Caudal  shield  triangular ;  the  axis  articulated  in  six  or  more  jointed,  the  sides  without 
radial  furrows  ;  the  margin  reflexed  and  acutely  angular. 

Loccdity. — In  the  lower  and  middle  Silurian  strata. 

Remark. — Several  species  are  known,  from  the  lower  Silurian  strata  of  England,  North  America, 
Sweden,  and  Bohemia.  Some  authors  enumerate  only  five  body-riugs,  probably  by  mistake,  or  in 
consequence  of  the  defective  preservation  of  the  individual. 

1.  T.  Caractaci :  Limbo  scuti  cephalici  orbicular!,  conceutrice  punctato  ;  angulis  posticis  subrectis, 
longe  spinosis;  caudse  basi  annulata,  apice  scuti  acuto.      Long.  %-\]ii".      Plate  I,  Fig.  1. 

•    Ref—T.  Caractaci,  MuRCHisoN,  Sil.  Syst.  pt.  ii,  p.  659,  Plate  XXIII,  Fig.  I,  a,  b,  c,  d,  e. 

Brongn.   Crust,  foss.  Plate  IV,  Figs.  6,  7,  A,  B,  C,  p.  145.     Lhwyd,  Phil.  Trans. 

vol.  XX,  p.  243,  Plate,  Fig.  8.     Bigsby,  Jn/ials  of  the  Lye.  of  Nat.  Hist,  of  New  York, 

i,  214,  Plate  XV,  Fig.  1.      Emmr.  Diss.  51.  6.     Milne  Edw.   Crust,  iii,  331.  1. 

Portlock,  Report,  262,  Plate  I,  B,  Fig.  3-7. 

Cephalic  shield  nearly  semicircular,  broader  than  long,  the  enlarged  margin  covered 

with  five  to  six  concentrical  rows  of  little  pits,  from  which  rise  small  wart-like  prominences ; 

posterior  angles  oblique  and  oj)pressed,  each  terminating  in  a  long  pointed  spire  as  long  as 

*  Dr.  Loven  (Ofvers  of  Kongl.  Vetensk.  Ak.  Förh.  1845,  No.  4)  describes  the  facial  suture  as 
running  close  to  the  margin  of  the  cephahc  shield,  turning  inwards  at  the  posterior  angles,  and  inter- 
secting'' the  posterior  margin  of  the  shield  at  about  the  middle.  In  accordance  with  this  statement, 
such  an  arrangement  has  been  indicated  in  the  figure  of  Trinucleus  Caractaci. 


OF  THE  SPECIES.  017 

the  body ;  glabella  almost  twice  as  long  as  broad,  anteriorly  rather  hemispherical,  posteriorly 
contracted,  with  the  vestige  of  a  knob  at  each  side.  Six  distinct  rings  of  the  body,  the 
axis  of  each  scarcely  half  as  broad  as  the  lobes.  Caudal  shield  triangular,  with  a  slightly 
elevated  angle  at  the  exterior  margin ;  its  axis  only  articulated  to  a  little  beyond  the  centre 
with  six  rings,  afterwards  simple :  the  lateral  lobes  furnished  with  six  radiating  striae 
divided  towards  the  margin. 

Remark. — Described  from  specimcus  ia  the  IMuseum  at  Halle,  occurring  in  a  yellowisli  grau- 
wacke.  Found  also  in  the  lower  Silurian  strata  of  England,  North  America  (Montreal),  and  Bohemia. 
(Sternberg,  Verhandl.  d.  vat.  Mus.  1833,  Fig.  2,  b.) 

2.  T.  yranulatus  :  Limbo  scuti  cephalici  orbicul.u'i,  puuctato  ;  angulis  posticis  lobatoproductis,  brc\  e 
mucronatis ;  scuto  caudse  subsemich'culato,  rhachi  tota  annulata,  annulis  sex.      Long.  %".  • 

Jief. — Ei/t.  yranulatus,  Wahl.  «.  acf.   Ups.  VIII,  30.  5,  Table  II,  Fig.  4.     Asaph,  gran. 

Dalm.  Pal.  43.  4,  Table  II,  Fig.  6.     Brogn.   Cr.  f.  36,  PI.  Ill,  Fig.  7.     Milne 

Edw.  Cr.  Ill,  332.     Boeck.  Gaea  norm.  41.     Trinudeus  Lloydii,  MuRCH.  ^7.  Syst. 

Pt.  II,  GGO,  PI.  XXIII,  Fig.  4.     Emmr.  Biss.  .53.  9.     Milne  Edw.  /.  c.  4.     Loven, 

Ofcers  K.  V.  A.  Forhandl.  1845 ;   109,  Tab.  II,  Fig.  2. 

Cephalic  shield,  like  that  of  the  preceding  species,  but  the  posterior  angles  produced 

into  broad,  parallel,  punctated  lobes,  which  project  backwards  beyond  the  rings  of  the  body, 

and  finally  terminate  in  a  delicate  spine  rather  shorter  than  the  lobe.     Rings  of  the  body 

not  so  narrow  as   in  former  species,  and  more   than  half  as  broad  as  the  lateral  lobes. 

Caudal    shield,   a    segment   of   a   circle   smaller  than  a   semicircle ;    the    axis    indistinctly 

articulated  ;  the  sides  without  ribs. 

Occurs  in  a  black  limestone  belonging  to  the  upper  members  of  the  lower  Silurian 
series  in  Great  Britain  and  Scandinavia. 

3.  T.  fimbriatus  :  Limbo  scuti  cephalici  dilatato,  radiatim  granulate ;  angulis  posticis  irregulariter 
granulatis,  subrectis,  mucronatis;  cauda  tota  annulata,  annulis  12-13,  long.  1". 

Ä/.— MuRCH.  /.  c.  PI.  XXIII,  Fig.  2.     Luid.  Ic////oj/r.  p.  97,  Tab.  XXIII.    Emmr.  Diss. 

52.  7.     Milne  Edw.  /.  r.  2.     Portlock,  Bcporf,  ^-c. ,-  264,  PI.  I,  B,  Figs.  11,  12. 

Sars,  Isis,   1835;    Tab.  VIII,  Fig.  4,  d   (certainly  not   the  caudal  shield  of   an 

Ai//pt/,r). 

Cephalic  shield  shorter  and  broader  than  in  the  preceding  species  ;  the  mai'gin  furnished 

anteriorly   and   at  the  sides  with    radiating   pores  ;    the   posterior  angles    not   contracted, 

irregularly  granulated   with    pores,  with    a    long,  nearly  straight,   terminal    spine.      The 

glabella   but    little  diminished    posteriorly,   with    slight  traces  of  lateral  impressions,  but 

little  longer  than  broad.     Rings  of  the  body  indistinct ;  body  shield  oblong-triangular ;  the 

whole  axis  articulated  as  far  as  the  extremity,  long,  consisting  of  thirteen  or  more  rings ; 

the  sides  with  twelve  radiating  ribs ;  the  margin  acutely  angled. 

Remarks. — 1.  T.  nudiis^ CSlurch.  I.  c.  Fig.  5)  I  am  inclined  to  consider  the  same  species,  with 
the  margin  broken  off  at  the  cephalic  shield.      See  Emmerich,  Fig.  5.* 

*  Note,  by  the  Editors.  Trinudeus  nudus  is  really  a  species  of  Amjryx,  as  may  be  seen  by  con- 
sulting the  original  specimens  in  the  Museum  of  the  Geological  Society  of  London,  and  stiU  more 
perfect  ones  in  the  collections  of  the  Geological  Survey  of  Great  Britain. 


58  SYSTEMATIC  ARRANGEMENT 

2.  Asaphus  seticornis  (Hisinger,  Leth.  Suec,  second  supplement,  Tab.  XXXVII,  Fig.  2)  cannot 
be  identified  with  T.  fimbriatus,  as  figured  by  Portlock  (/.  c.  263,  PI.  I,  B,  Fig.  8),  and  Loven(  /.  c. 
107,  Tab.  II,  Fig.  1) ;  but  is  a  different  and  liighly  characteristic  species  allied  by  its  rounded  caudal 
shield  more  nearly  to  T.  gramdatus  than  T.  fimbriatus.  A.  cyllarus  (Hisinger,  /.  c.  Fig.  3)  is,  according 
to  Loveu,  the  same  species,  the  spine  of  its  cephalic  shield  being  broken  off. 


4.  T.  ornatiis :  Limbo  seuti  cephalici  antice  angusto,  estus  posticeque  lato,  sed  constricto ;  anguhs 
posticis  acimiinatis,  longe  spinosis. 

Tril.  oniatus,  Sternb.  Ver/t.  1833.  53.  Fig.  2,  a.  Trin.  radiatus,  Murch.  /.  c.  Fig.  3. 
Emmr.  Diss.  52.  8.     Milne  Edw.  /.  c.  3,  and  332.     Boeck,  Gaca  Norw.  42. 

Cephalic  shield  as  short  and  broad  as  in  the  preceding  species,  but  the  border  at  the 
anterFor  margin  smaller,  and  the  tubercles  not  radiated,  but  in  (four  to  five)  concentric  rows ; 
the  sides  very  much  enlarged,  with  five  to  six  rows  of  pores,  but  very  much  contracted  again 
towards  the  posterior  angle,  so  that  this  region  of  the  margin  assumes  the  form  of  the  letter 
S.  The  terminal  spine  is  long,  slender,  and  pointed.  The  glabella  is  oval,  higher,  more 
obtuse  at  the  anterior  part,  and  more  globose.  We  are  not  yet  accurately  acquainted  with 
the  rings  of  the  body  and  tail. 

Remurk. — The  statement  in  Murchison's  work,  that  the  enlarged  margin  in  this  species  has 
only  two  rows  of  tubercles,  I  must  consider  incorrect ;  Count  Sternberg  describes  from  four  to  five. 
Trin.  asaphoides  (Murch.  /.  c.  Fig.  6)  is  probably  a  specimen  of  T.  ornatus,  in  which  the  margin  of  the 
cephalic  shield  is  broken  away.  If  this  conjecture  be  correct,  the  caudal  shield  would  be  more  shortly 
triangulai',  but  the  axis  would  likewise  be  many-jointed,  having  perhaps  from  ten  to  eleven  lateral  ribs. 
Possibly,  however,  the  body  thus  referred  to  may  be  referable  to  the  species  last  described. 

N.B.  Both  the  former  species  and  the  present  occur,  but  rarely,  at  Builth  in  the 
Llandcilo  flags,  and  in  Bohemia.  Count  Sternberg's  specimens  were  found  in  a  rock  very 
much  loaded  with  pyrites,  in  the  district  between  Zebrak  and  Proskales,  in  Bohemia. 
Similar  fragments  have  been  found  in  the  calcareous  conglomerates  of  Carlshütten  and 
Beraun.  These  have  been  figured  by  Zenker,  (Beitr.  Table  IV,  Fig.  N,  5) ;  and  partly  from 
these,  partly  from  the  caudal  shields  of  quite  a  different  species,  the  author  has  composed 
his  Otarion  deffractum.     This  genus  Otario/i  must  be  banished  from  the  list  of  Trilobites. 


5.  T.  tessellatus :  Limbo  seuti  cephalici  parabolico,  tesselato-punctato ;  scuto  caudre  triangulari. 
Long.  }^". 

Cnjptol.  tesseU.  Green,  Mon.  73,  Fig.  4 ;  and  Model,  No.  28.  Bronn,  Lefli.  i,  117,  105, 
Table  IX,  Fig.  13.     Emmr.  Bisserf.  50.  2.     Harlan,  Zool.  Res.  304. 

To  judge  from  the  impression,  and  from  plaster  casts,  this  species  is  more  oblong  and 
smaller  than  the  others ;  the  form  of  the  cephalic  shield  more  parabolic,  the  lateral  lobes 
of  the  rings  of  the  body  more  arched,  the  caudal  shield  trilateral,  rather  acuminate. 

Occurs  .in  a  black  limestone  of  Trentonfalls  and  Glenfalls  in  New  York ;  also  on  the 
Island  of  Montreal. 

Remark. — Neither  representation  nor  description  indicate  any  more  definite  differences,  and  I 
therefore  consider  the  species  as  uncertain.  The  same  may  be  said  with  still  greater  reason  of 
T.  Bigsbyi  (Geology  of  the  Island  of  Montreal,  in  Lye.  of  Nat.  Hist,  of  New  York,  p.  214;  and 
Green,  /.  c.)  and  Nidtainia  concentricu  Eaton,  (Geolog.  Text -Book),  both  of  which  I  consequently 
jiass  over. 


OF  THE  SPECIES.  59 


Genus  2. — Ogygia,  Brongn. 


Cephalic  shield  semicircular  or  parabolic,  flat ;  the  glabella  moderately  convex,  con- 
tracted towards  the  posterior  part,  with  three  slight  lateral  impressions;  cheek -shields 
lengthened  into  a  more  or  less  extended  posterior  angle. 

Eyes  moderately  arched,  semicircular,  affixed  centrally  beside  the  glabella. 

Facial  suture  very  distinct,  running  in  an  arch  towards  the  left  and  right,  parallel  with 
the  anterior  margin,  between  the  latter  and  the  glabella;  then  turning  almost  at  a  right 
angle  towards  the  eye,  forming  the  well-known  plate  above  it ;  and  then  with  a  curve  in  the 
shape  of  the  letter  Sj  turning  towards  it  parallel  to  the  posterior  margin  in  the  principal 
direction,  and  terminating  there  at  about  three  fifths  of  its  extent  from  the  glabella. 

Body  certainly  composed  of  eight  joints,*  the  joints  short,  but  tolerably  broad,  yet 
less  by  one  half  than  the  lateral  lobes ;  the  latter  straight,  flat,  bent  strongly  backwards  at 
their  extremities,  and  pointed. 

Caudal  shield  corresponding  with  the  cephalic  shield,  its  axis  as  long  as  the  body, 
many-jointed,  its  sides  furnished  with  radiating  furrows,  the  interstices  of  which  are  again 
divided  by  smaller  half  rays. 

Locality. — In  the  oldest  fossiliferous  rocks. 

Remark. — This  genus  stands  in  so  remarkable  a  degree  of  affinity  to  the  preceding,  that  the 
circumstance  of  its  hitherto  hanng  frequentl}'  been  confounded  with  the  perfectly  heterogeneous  species 
of  Asaplms  is  truly  surprising.  It  is  elf  ar  that  even  acciu-ate  observers,  as  Emmerich  and  Boeck,  have 
not  always  estimated  correctly  tlie  zoological  position  of  these  fossils. 

1.  O.  Buchii :  Scuto  capitis  caudasque  semicLrculato ;  iUius  angulis  posticis  acuminatis.  Long. 
3-5".      Table  1,  Fig.  2. 

Lhwyd,  Phil.  Tr.  vol.  xx,  279,  tab.  add.  Fig.  15.     Iclm.  Brit.  Ep.  i,  Table  XXII,  Fig.  4, 

{see   Brunn.)      Tril.    dilatatus,  Brunn,   Kjobeuh.    Wiclcnsk.    Selsk.    Sriff.    1781,   i, 

393,  IV.     Parkinson,  0/y.  Bern,  etc.,  iii,  PI.  XVII,  Figs.  13,  15  (?).     As.  d.  Dalm. 

Palcead.  67.  8,  Tab.  Ill,  Fig.  1.     Emmr.  Diss.  28.  5.     Sars,  Ms,  1835,  336,  Table 

VIII,  Fig.  5.      Isot.  dilat.  Milne  Edw'ards,  Crm.  iii,  302.  9.      Ascqi/i.  de  Buchii 

Brongn.   Cr.  f.  20.  2,  Plate  II,  Fig.  2,  A,  B,  C.     Schloth.  Nachtr.   ii,  34.  8. 

Dalm.  Palcead.  68.  9.     Murch.  Sil.  Syst.  ii,  662,  Plate  XXV,  Figs.  2,  3  (young). 

Emmr.  Diss.  28.  5.     Milne  Edw.  Crust,  iii,  309.  5. 

Cephalic  shield  nearly  semicircular,  but  the  longitudinal  radius  a  little  shorter  than  the 

transverse,  furnished  at  each  side  with  three  slight  transverse  impressions,  by  which  two 

anterior  smaller   lateral   lobes,  and  a  third  posterior  broader  lateral  lobe   are  indistinctly 

bounded ;  the  posterior  margin  is  rather  distinctl}^  turned  up. 

Eyes  not  large,  semicircular,  corresponding  in  their  position  to  the  two  anterior  smaller 
lobes  of  the  glabella.  Cheek-shield  with  a  concentric  canal-like  groove  towards  the  exterior 
margin,  and  wdth  a  strongly  prominent  posterior  angle,  which  in  smaller  specimens  reaches 

*  Quenstedt  defends  the  se\  cn-jointcd  figures,  which  were  represented  from  defective  specimens ; 
but  all  the  well-preserved  specimens  that  I  have  seen  have  had  eight  rings. 


60  SYSTEMATIC  ARRANGEMENT 

to  the  third,  in  larger  to  the  sixth  abdominal  ring.  Body  distinctly  furnished  with  eight 
joints,  sometimes  owing  to  the  dislocation  of  two  successive  rings  appearing  to  be  limited  to 
seven  (see  Remark  2);  the  rings  narrower  than  the  half-lateral  lobes,  moderately  arched;  the 
lateral  lobes  quite  flat,  at  the  end  arcuated,  curved  towards  the  posterior  part,  with  a  strong 
diagonal  furrow,  which,  however,  does  not  quite  reach  to  the  terminating  angle.  Caudal 
shield  formed  like  the  cephalic  shield,  but  its  longitudinal  radius  larger  than  the  transverse, 
therefore  approximating  to  the  parabolic  form ;  the  axis  gradually  reduced  towards  the 
posterior  part,  rounded  off  at  the  end,  distinctly  articulated,  the  number  of  rings  in  it 
different  according  to  age  (usually  thirteen),  with  a  rather  longer  terminal  joint ;  in  younger 
specimens  the  number  is  eleven,  in  older  ones  as  many  as  seventeen ;  the  rays  beside  the 
axis  on  the  shield  usually  fewer  by  about  two  than  the  number  of  joints  of  the  axis  ;  thus, 
for  example,  when  the  number  of  joints  is  thirteen,  exhibiting  eleven  rays,  with  slight  traces 
of  a  twelfth,  besides  the  two  end  joints,  which  are  also  indistinctly  separated ;  the  intervals 
between  the  rays  again  divided  by  an  oblique  diagonal  furrow,  similar  to  the  lateral  lobes 
of  the  rings  of  the  body. 

Remarks. — 1.  Asaph,  dilatatus  and  A.  de  Buchii  of  authors  are  probably  the  same  species.  The 
figure  in  Dalman's  work  is  drawn  from  a  cast,  and  owing  to  tins  cii-cumstance  is  very  indistinct,  so 
that  I  have  preferred  the  latter  name,  the  species  having  been  fii-st  represented  distinctly  under  that. 
Parkinson's,  Brougniart's,  and  ^Nlurchison's  distinct  figures  leave  no  doubt  as  to  the  identity  of  the 
species.  Lliwyd's  figure  in  the  '  Philosophical  Transactions'  also  represents  this  species  tolerably  well,  for 
which  reason  it  has  been  quoted  by  Brunnich  from  the  '  Ichnographia  Britaunica.'  Individuals  vary 
very  much  in  point  of  size ;  I  have  a  caudal  shield  before  me  from  the  collection  at  Halle  (No.  639), 
wliich  is  scarcely  so  large  as  a  sixpence,  having  eleven  joints  in  the  axis,  a  pretty  long  undinded 
terminal  joint,  and  ten  rays.  The  number  increases  by  the  progressive  division  of  this  longer  terminal 
joint  with  increasing  age.  Another  specimen  of  the  same  rock  (a  blackish-gray  grauwacke,  locality 
unknown)  was  figured  by  me,  and  compared  with  perfect  specimens  in  the  Berlin  Museum  (Nos.  9.8 
and  9). 

2.  Quenstedt  adheres  to  the  view  that  these  Trilobites  are  seven-jointed,  and  founds  his  opinion 
on  the  figiu-es  given  by  Dalman  and  Brongniart  (3,  A),  as  well  as  on  original  specimens.  There  are 
certainly  two  well-preserved  fragments  in  the  Museum  at  Berlin  (Nos.  9.1,  and  9.5),  with  only  seven 
distinct  joints ;  but  there  are  also  others,  equally  distinct,  with  eight  joints  (Nos.  9.8,  and  9.9)  ;  and  the 
former  number  can  therefore  only  be  owing  to  a  dislocation  of  two  rings  one  under  another.  Con- 
sidering that  the  impressions  arc  merely  those  of  shells,  such  a  dislocation  is  very  conceivable,  and  the 
more  readily  so,  the  less  perfectly  the  shell  had  been  preserved.  The  same  remarks  hold  good  with  regard 
to  the  other  species. 

2.  O.  Guettardi:  Scuto  capitis  caud;cque  parabolico ;  illius  augulis  posticis  longissime  acuminatis. 
Long.  3-6  inch,  Table  I,  Fig.  3. 

Brogn.  Cr.fo.'^s.  28.  1,  Plate  III,  Fig.  1,  A,B.     Bronn,  Leth.  1.  119,  Table  IX,  Fig.  19. 

BucKLAND,Ä%.  Tr.  Plate  XLVI,  Fig.  9.    Milne  Edw.  Crust.  iii,337. 1.    Dalm. 

Palaad.  72.  I.     Emmr.  Diss.  27.   1.     Tril.  Gaett.  Schloth.  Petrf.  Nacldr.  ii,  93, 

and  35.  13.      0(iy(iia  MurcMsoni,  Murch.  Sil  Si/st.  664,  Plate  XXV,  Fig.  3,  a  (the 

lower  figure  h  does  not  belong  to  Of///f/ia,  but  to  an  Jsajj/ii/s).     Milne  Edw.  /.  c 

338.  3. 

Cephalic  shield  olilong  parabolic,  rather  pointed ;    the  glabella,  as   far  as  it  can  be 

recognized,  formed  as  in  the  preceding  species ;    the  eyes  oblong  elliptical ;    the  posterior 

angles  of  the  cheek-shield  as  long  as  all  the  rings  of  the  body  together,  or  even  longer. 

Eight  body  rings,  their  transverse  diameter  larger  than  half  the  breadth  of  the  lateral  lobes. 


OF  THE  SPECIES.  61 

both  of  which  are  relatively  longer  than  in  the  preceding-  species.  Caudal  shield  oblong 
parabolic,  rather  pointed,  with  a  broad  axis,  which  reaches  to  only  three  fourths  of  the  length 
of  the  shield,  and  consists  of  nine  rings ;  the  lateral  parts  furnished  with  eight  radiating 
furrows. 

Occurs  in  the  blackish-gray  clayslate  of  Angers,  in  specimens  in  the  Berlin  Museum 
(No.  10.  1). 

Renun-ks. — 1.  There  is  no  figiu-e  of  this  species  in  Gucttard's  'Treatise  on  the  Slate  of  Angers' 
(Mem.  fie  TAcad.  de  Scieuc.,  1757,  p.  82),  or  at  the  most  it  is  only  the  figure  marked  3,  in  Table  VII, 
(V),  that  could  be  considered  as  such. 

2.  Murchison  describes  several  Tiilobites  in  his  work,  which  have  been  taken  for  Ogtji/ia  by  other 
authors,,  but  which  do  not  belong  to  this  genus.  Asajikus  corndensis  (G63,  PI.  XXV,  Fig.  4)  certainly 
approximates  in  many  respects  to  O.  Buchii,  but  is  probably  a  genuine  Asajj/ius ;  at  least,  this  is  the 
case  if  the  lateral  lobes  of  the  rings  of  the  body  ha\e  been  con-ectly  represented.  A.  duplicatu.i, 
(ibid.  Fig.  8,)  on  the  other  hand,  is  probably  only  a  flattened  caudal  shield  of  Oijijgia  Buchii,  in  its 
young  state.  The  figui'es  of  Asaph,  tyrannus  (G62,  PI.  'XXIV  and  XXV,  Fig.  1)  do  not  belong  to 
Ogyyia,  but  are  also  to  be  referred  to  Asuphus. 

3.  Ogygia  Desmaresti,  Brongn.  I.  c.  28.  2,  PI.  Ill,  Pig.  1 ;  Schlote.  Nachtr.  23.  2,  and  35.  14 ; 
Dalm.  Palaad.  72.  2;  Milne  Edw.  Crust.  338.  2;  Emmr.  Dm.  27.  2.  The  impression  of  a  fragment  from 
the  lower  side  presents  too  few  characters  to  enable  one  to  found  a  separate  species.  The  specimen 
perhaps  only  belonged  to  a  very  large  specimen  of  the  Ogygia  Buchii,  the  rings  of  which  are  partially 
pushed  one  above  another,  and  for  this  reason  appear  small.  It  certainly  belongs  to  Ogygia. 
Guettard's  figures,  which  are  quoted  by  Milne  Edwards,  relate  to  quite  a  diflereut  species,  namely,  my 

Ilhenus  giganteus. 

Division  B. 

Trilobites  having  a  simjjle,  though  tolerabig  large  caudal  shield,  the  axis  of  which  consists 
of  but  few  joints,  and  is  always  .shorter  than  the  body. 

The  genera  belonging  to  this  division  may  be  divided,  according  to  the  number  of 
body  rings,  into  eight  jointed  and  ten  jointed. 

First  Subdivision   (a). 

Eight-jointed  Trilobites  with  a  short  articulated  caudal  a.xis,  incapable  of  rolling  them- 
selves up. — Odontopleurid.e. 

Genus  3. — Odontopleura,  Emmr.  (Acidaspis,  Murch. ;  Ceraurus,  Locke). 

This  remarkable  genus  is  closely  allied  in  habit  to  the  preceding,  and  is  highly  interest- 
ing in  a  zoological  point  of  view,  because  the  two  species  are  commonly  distinguished  from 
one  another  in  the  same  manner  as  the  species  of  the  preceding  genus. 

The  cephaHc  shield  is  subsemicircular,  the  longitudinal  radius  being  much  shorter  than 
the  other ;  the  moderately  convex  glabella  is  undivided  in  its  length,  contracted  towards  the 
posterior  part,  and  furnished  with  a  strong  articulating  varix  ;  it  enlarges  laterally,  and  at 
this  point  has  three  other  little  knobs  beside  it  in  two  rows. 

The  facial  suture  resembles  that  of  Ogygia,  forming  at  the  anterior  part  an  arcli  before 
the  glabella,  then  extending  inwards  to  the  eye  ;  thence  turning  to  the  posterior  margin, 
and  penetrating  it  at  about  one  fourth  of  the  distance  from  the  terminal  angle. 


62  SYSTEMATIC  ARRANGEMENT 

The  cheek-shields  are  therefore  broad,  thickened  at  the  entire  exterior  margin,  pro- 
minent, produced  beyond  the  anterior  part  of  the  central  shield,  and  furnished  with  very 
small  eyes  above  at  their  highest  point,  towards  the  posterior  part  beside  the  posterior 
margin  of  the  outermost  lobe  of  the  glabella. 

The  body-rings  (eight  in  number*)  are  small,  but  strongly  arched,  and  the  lateral  lobes 
are  situated  on  one  plane ;  each  has  an  elevated  transverse  ridge,  and  a  long  terminal 
spine  directed  obliquely  and  posteriorly. 

The  caudal  shield  has  a  short  two-jointed  axis,  only  one  elevated  lateral  rib,  but  large, 
strong,  marginal  spines  at  the  exterior  circumference.  The  surface  of  the  body  is  regularly 
covered  with  tubercles  and  knobs. 

Locdihj. — In  the  upper  Silurian  and  Devonian  strata  of  the  Eifel,  Silesia,  and  England. 

1.  0.  ovata  :  Corpore  ovate,  dilatato,  tmdique  fimbriatim  spinoso ;  lobis  trunci  bispinosis,  scuto 
caudae  duodecies  spinoso.      Long.  %  inch.  Table  II,  Fig.  11. 

Emmr.  Diss.  .53,  adj.  tab.  Fig.  3 ;  Batfics  tubercuhttiis,  Klöden,  Verst.  der  Mark 
Brcnidoihiirr/,  112,  Plate  I,  Fig.  16-23. 

This  remarkable  species  occurs  in  a  yellowish,  liver-brown  limestone,  found  as  a  boulder 
in  Silesia  by  M.  Bocksch  ;  the  only  known  specimen  was  presented  to  the  collection  at  Berlin 
by  M.  Dechen,  and  I  am  indebted  to  the  latter  gentleman  for  description  and  figure. 

The  circumference  is  a  broad  ellipse,  the  transverse  diameter  of  which  is  more  than 
two  thirds  of  the  longitudinal  diameter.  The  length  of  the  cephalic  shield  occupies 
rather  more  than  one  sixth  of  it ;  the  glabella  is  smooth  in  the  centre,  granulated  at  the 
sides ;  the  two  succeeding  smaller  tubercles  beside  it  are  minutely  granulated,  the  third 
external  one  has  three  more  considerable  eminences  before  the  region  of  the  eye,  and  many 
smaller  ones ;  the  cheek-shields  are  uniformly  granulated,  and  their  external  reflexed  margin 
is  also  ornamented  with  a  row  of  tubercles  and  spines,  which  are  visible  everywhere 
except  in  the  centre  of  the  anterior  extremity.  There  is  a  very  large  tubercle  on  the 
centre  of  the  articular  fold ;  beside  it  at  each  side  a  rather  smaller  one,  and  surrounding  the 
latter  several  very  small  ones.  The  axis  portions  of  the  rings  of  the  body  have  two  rather 
large  tubercles  beside  the  centre,  and  also  two  small  ones  externally  at  each  side.  An 
elevated  fold  is  seen  on  the  lateral  lobes,  which  terminates  at  the  margin  in  a  spine,  and 
which  is  covered  on  its  surface  with  seven  tubercles,  alternately  large  and  small.  Towards 
the  anterior  as  well  as  the  posterior  part  of  this  fold  we  perceive  a  transverse  row  of  other 
very  small  tubercles,  and  a  second  smaller  row,  corresponding  with  the  anterior  row,  occurs 
at  the  margin  before  the  spine.  These  small  spines  are  all  of  equal  length,  but  the  larger 
ones  become  gradually  longer  towards  the  posterior  part.  The  caudal  shield  is  rather 
smaller  than  the  cephalic  shield,  covered  by  larger  or  smaller  tubercles,  and  spiny  at  the 
circumference ;  the  spines,  of  which  there  are  six  at  each  side,  are  equally  long  and  equally 
broad ;  the  fold  which  proceeds  from  the  first  ring  of  the  axis  becomes  bent  at  the  third 
ring  from  the  centre. 

*  Emmerich  only  enumerates  seven,  but  has  omitted  to  notice  the  fact  that  both  lateral  lobes 
were  broken  off  from  the  fifth  joint,  and  that  thus  the  true  number  was  not  given.  Compai'c  his 
figure  and  mine. 


OF  THE  SPECIES.  63 

Remark. — Count  Miinster's  Tnnucleus  yibbosus  {Beitr.  Ill,  47,  Tabic  V,  Fig.  2")  is  probably  a 
fragment  of  tlic  cephalic  shield  of  this,  or  of  the  following  species. 

2.  0.  elUptica  :  Elongato  eUiptica,  lobis  trunci  unispinosis,  scuto  caudre  dccics  spinoso.  Long.  M". 
Table  I,  Fig.  4. 

Be/. — Faradoxides  quatuor  mucronatus,  MuRCH.  Sil.  S^st.  ii,  658,  Plate  XIV,  Fig.  10. 
Acidaspis  Brightii,  ibid.  Fig.  15.?  Arges  armatus,  jiw.  Goldf.  Nova  acta  Ph.  Med. 
Soc.  Caes.  Leop.  Car.  n.  c.  vol.  xix,  P.  I,  page  355,  Table  XXXIII,  Fig.  1,  d,  e. 

In  a  gray  limestone  of  the  Eifel,  according  to  a  specimen  in  Sack's  collection.  Of  the 
cephalic  shield  there  is  only  a  small  portion ;  but  this  resembles,  as  far  as  it  goes,  the  cor- 
responding part  of  the  preceding  species  ;  the  visible  part  of  the  anterior  margin,  however, 
is  covered  with  thicker  tubercles,  and  the  lobes  beside  the  forehead  appear  to  me  to  be 
smaller.  The  rings  of  the  body  (eight)  are  all  present,  but  only  the  last  two  are  perfect ;  on 
each  there  are  two  small  lateral  tubercles ;  the  lateral  lobes  are  smaller  than  the  double 
ring,  each  is  furnished  with  two  tubercles,  and  a  long  spine  which  issues  from  the  fold ;  I 
did  not  perceive  a  second  anterior  marginal  spine.  Caudal  shield  much  smaller  than  in 
the  preceding  species,  the  axis  furnished  with  two  rings.  The  first  sends  forth  a  lobe-like 
swelling  to  the  posterior  margin,  which  terminates  at  each  side  in  the  fourth  largest  marginal 
spine ;  the  three  preceding  ones  are  successivel)^  smaller  towards  the  anterior  part,  the  two 
most  central  ones  (the  fifth  of  each  side)  as  large  as  the  second. 

Remarks. — 1.  It  is  quite  certain  that  the  figui-e  given  by  Goldfuss  belongs  to  this  species;  and 
is  too  much  unlike  his  Aryes  armatus  to  allow  of  its  being  considered  the  same  species.  Murchison's 
Fig.  10  likewise  undoubtedly  represents  this  species,  but  it  must  still  remain  undecided  whether  Fig.  15 
is  the  cephalic  shield,  as  Emmerich  and  I  consider  it. 

2.  Several  authors  have  recently  described  Trilobites,  which  belong  to  this  group  of  Odoiitop/eum. 
First  of  aU,  Mr.  Locke  {Sillim..  Am.  Journ.)  has  described  a  Ceraurus  crassatus.  The  fragment  of 
Arges  radiatus,  copied  by  Goldfuss  [Leonh.  and  Bronn),  shows  a  great  similarity  with  the  maxillary 
shield  of  this  species ;  and  it  also  corresponds  with  the  maxillary  shield  of  another  species,  Ceraurus 
crenatus,  of  which  Dr.  Loven  (Ofveis,  &c.)  has  given  an  elaborate  description.  The  body  in  the  latter, 
however,  consists  of  niue  rings,  which  denotes  a  considerable,  and  even  generic  difference.  Ceraurus 
globiceps  (Portlock,  Geol.  Rep.  of  Londonderry ,  &c.)  can  with  less  certainty  be  identified  with  the 
genus  we  are  now  considering ;  it  seems  rather  to  have  affinit}'  with  Ceraurus  pleurexanthemus  (Green), 
a  species  which  is  supposed  by  myself  and  Dr.  Beyricli  not  to  be  connected  with  Odontopleura. 

Genus  4. — Arges,  Goldf.* 

As  I  am  not  acquainted  with  this  genus  from  actual  investigation,  I  shall  here  give  an 
abstract  of  Goldfuss's  description. 

Cephalic  shield  highly  arched ;  at  the  centre  of  the  glabella  there  are  two  very  high, 
reflexed,  diverging  spines ;  the  sides  behind  the  checks  are  hkewise  furnished  with  a  spine, 
the  margin  is  narrow,  the  posterior  part  prominent  in  an  angle,  rather  curved,  equal  in 
length  to  the  joints  of  the  body.  Below  there  is  a  prominent  mouth-plate,  much  turned 
downwards,  which  incloses  semicircularly  the  most  anterior  part  of   the  head  behind  the 

*  The  name  of  the  genus  is  not  well  chosen,  as  there  is  aheady  a  genus  of  Acori  described  by 
G.  Fischer  under  the  name  of  Aryas ;  other  names  of  the  same  author  arc  also  subject  to  similar 
objections.  Harpes  reminds  one  too  much  of  Harpa  or  Harpte,  and  Fabricius  had  already  used  Brontes 
for  a  genus  of  beetles. 


64  SYSTEMATIC  ARRANGEMENT 

margin  (the  Clypeus).  The  eyes  and  facial  suture  cannot  be  distinguished.  The  body  is  pro- 
bably furnished  with  eight  joints  (only  seven  rings  are  distinctly  represented  in  the  figure) ; 
the  rings  and  the  lateral  plates  are  highly  arched  and  broader  towards  the  posterior  part ; 
the  diagonal  diameter  of  each  ring  is  greater  than  the  width  of  the  lateral  lobes ;  the  latter 
terminate  at  the  margin  in  a  spine ;  the  separate  rings  are  successively  broader  and  larger 
towards  the  posterior  part. 

Caudal  shield  large,  with  an  almost  simple,  apparently  unarticulated  axis,  upon  which 
is  placed  a  long  spine,  bent  backwards  ;  the  external  margin  furnished  with  spines  alter- 
nately large  and  small,  the  sides  with  indistinct  radial  folds.  The  whole  surface  is 
finely  granulated,  there  are  large  tubercles  on  those  parts  of  the  circumference  whence 
spines  spring. 

Locality. — In  the  transition  limestone  of  the  Eifel. 

The  only  known  species  is 

A.  armatu»,  GoLDFUSS,  Nova  acta  Pki/s.  Med.  Soc.  Ca.s.  Leap.  Carol,  n.  cur.  vol.  xix,  PI.  I, 
p.  355,  Table  XXXIII,  Fig.  \,  a,  c.  Entire  length  two  inches,  the  body  about  ten  lines. 
The  granulation  appears  to  be  uniform,  it  forms  a  diagonal  row  of  larger  tubercles  on  the  rings 
and  lateral  lobes,  accompanied  also  by  smaller  ones.  The  caudal  shield  exhibits  radiating 
folds,  which  turn  towards  the  larger  spines  of  the  margin  of  each  side ;  between  the  first 
and  second  of  these  spines  there  is  one  smaller  spine,  between  the  three  following  there  are 
always  two  ;  the  two  most  central  principal  spines  immediately  at  the  end  have  no  smaller 
spines  between  them. 

Second  Sitbdivisio»  {h). 

Ten-jointed  Trilobites  with  a  short  articulated  caudal  axis.  Animal  not  able  to  roll 
itself  into  a  ball. 

Genus  5. — Bronteus,*  Goldf.  (Goldius  de  Koninck). 

The  caudal  shields  of  this  genus  are  common  enough,  but  all  the  other  parts  are  so 
rare,  that  I  have  never  had  an  opportunity  of  observing  them.  The  character  of  the  group 
may  possibly  therefore  be  defective. 

The  cheek-shields  are  always  broken  off  from  the  cephalic  shield,  whence  -Goldfuss 
inferred  their  actual  absence,  which  to  me,  however,  does  not  appear  probable ;  the  remain- 
ing part  has  a  highly  reflexed  margin  both  before  and  behind,  and  a  depressed  glabella 
joining  the  margin  anteriorly.  The  glabella  is  divided  by  lateral  bent  intersections  into 
four  lobes,  which  are  successively  smaller  from  the  antei'ior  to  the  posterior  part,  and  con- 
tracted at  the  third  and  fourth  lobe.  The  facial  suture,  which,  in  my  opinion,  borders  the 
cephalic  shield  on  both  sides,  issues  at  the  anterior  part  from  the  margin  near  the  angle  of 

*Dr.  Beyrich  has  recently  communicated  additional  information  concerning  this  genus,  in  his 
treatise  on  '  the  Trilobites  of  Bohemia,'  and  has  endeavoured  to  determine  the  distinction  of  the 
species  move  accurately.  He  proves  tliat  some  species  possess  a  granulated  and  others  a  lineated 
surface  of  shell,  and  further  distinguishes  them  according  to  the  number  of  furrows  at  each  side  of 
the  caudal  .shickl,  which  amount  to  either  six  or  seven. 


OF  THE  SPECIES.  C5 

tlie  glabella,  runs  on  both  sides  rather  cui-ved  towards  the  eye,  wliich  scorns  to  be 
situated  beside  the  narrowest  part  of  the  glabella.  It  then  forms  over  it  the  well  known 
covering-plate,  and  turns  itself  with  an  S-shaped  curvature  towards  the  posterior  margin, 
where  it  seems  to  terminate  not  far  from  the  external  angle. 

The  ten  rings  of  the  body  are  short,  almost  as  broad  as  their  lateral  lobes,  and  are 
diagonally  arched;  the  lateral  lobes  towards  the  exterior  part  are  flat,  with  a  strong 
curvature  backwards. 

The  caudal  shield  is  very  large,  circular,  or  slightly  parabolic ;  it  contains  at  the 
anterior  part  a  very  short  one-jointed  axis,  from  which  radiating  furrows  and  broad  ribs 
proceed  to  the  sides. 

Locality. — In  Devonian  and  upper  Silurian  strata. 

1.  Br.  flabellifer  :  Superficie  tota  graruilata;  costis  scutae  caudalis  quindecim,  sulcis  latitudine 
sequalibus,  serie  granvilorum  majorum  uotatis.      Long  W^-^Yi". 

Ä^— GoLDF.  /.  c.  361,  Fig.  3.  Leonh.  u.  Bronn.  JaJir/j.  1843,  349.  3.  Tab.  XYII, 
Fig.  3.     RoEMER.  Ferst,  d.  Harzes.  37.  1.  Tab.  XI,  Fig    1. 

The  granulation  on  the  cephalic  shield  consists  of  tolerably  large  tubercles,  between 
■which  there  are  some  very  small  ones  ;  the  rings  of  the  body  and  lateral  lobes  have  a 
diagonal  row  of  tubercles  ;  the  almost  circular  shield  exhibits  fifteen  elevated  ribs,  which 
are  divided  by  nearly  equally  broad  intervening  spaces,  and  on  each  rib  there  are  many 
nearly  equally  large  tubercles,  three  or  four  together,  the  central  being  largest  and  most 
prominent.  The  centre  of  the  entire  shield  is  convex  ;  it  becomes  flattened  towards  the 
margin,  and  expands  into  a  horizontal  border. 

Remarks. — Count  Münster  has  figured  [Beitr.  z.  Petref.  iii.  Tab,  V,  Fig.  13)  several  fragments 
which  belong  to  caudal  shields  of  Bronteus.  Fig.  13,  B.  radiutus,  Fig.  15,  B.  subradiaius,  appear  to 
me  hardly  to  differ  from  B.  flabellifer.  Fig.  14,  B.  costatus,  Fig.  16,  B.  Neptuni,  have  a  longer 
axis.  The  former  has  the  same  number  of  ribs  as  the  species  now  ])eforc  us,  but  is  very  different  in 
size  and  structui'e.  The  latter  [B.  Neptuni)  seems  to  approximate  to  Ent.  laticauda,  Wahl.,  in  its  nine 
flat  ribs. 

2.  Br.  laticauda:  Superficie  glabra,  transverse  lineata;  costis  scut»  caudalis  tredecim,  latis, 
planis.      Long.  ? 

Ä//.— Wahl.  N.  Act.    Ups.  viii,  28.  3.     Brong.   Crust,  fos.  24.  5,  PI.  Ill,  Fig.  8. 

ScHLOTH.  Petref.  Naehtr.  ii.  22.  5.  35.  12.      Dalm.  Paland.  52.  13.  and  71.  18. 

Beyrich,  Böhm.  Tril.  42.  4.  f.  8.  9. 

Wahlenberg  described  specimens  obtained  from  a  white  limestone  from  Osmundsberg, 

in  Dalecarlia,  and  the  fragments  which  I  examined  in  the  Berlin  Museum  (Nos.  7.  1-4.)  were 

heaped  together  in  a  ver)'  similar  deposit.     The   cephalic  shield  consisted  as  usual  of  a 

single  central  piece  having  an  anterior  and  posterior  strongl)'  reflexed  margin,  the  former 

being  narrow  and  strongly  curved,  the  latter  rather  broader,  but  less  strongly  arched.     The 

curvature  may  have  corresponded  with  the  rings  of  the  body.     A  stamp-shaped,  slightly 

lobed  glabella  occupied  the  whole  central  part,  and  became  broader  at  the  anterior  margin 

laterally.     Close  to  it  at  each  side  the  nearly  circular  cheek  portion  arched  itself,  and  at 

the  posterior  margin  of  this  a  covering  plate  for  the  eye  seemed  to  be  indicated.     I  did  not 

find  any  cheek-shields.     Tiic  caudal  shield  was  more    parabolic,  had  a  nearly  equilateral 

9 


66  SYSTEMATIC  ARRANGEMENT 

triangular  axis  and  thirteen  narrow  flat  radiating  ribs,  six  on  each  side  of  the  odd  central 
one.  Of  these  ribs  the  odd  one  only  (left  at  the  end)  is  straight ;  the  other  six  pair,  the 
symmetrical  lateral  ones,  are  somewhat  curved  in  the  shape  of  the  letter  S- 

Remarks. — 1.  Wahlenberg,  in  the  place  already  quoted,  has  figured  a  fragment  which  does  not 
belong  to  the  genus  Bronteus.  The  caudal  shield  also  does  not  resemble  accurately  the  one  I  have 
described,  for  it  has  only  nine  short  broad  ledges,  which,  however,  are  so  unsymmetrically  ai-ranged 
that  they  are  of  themselves  sufficient  to  convince  us  that  the  drawing  is  erroneous.  I  do  not  ventiire 
to  decide  whether  Count  v.  Miinster's  B.  Neptuni  (see  remark  on  the  last  species)  belongs  to  the  present 
form. 

2.  The  genus  Lic/ias  of  Dalman  [Palaad  53,  iv,  and  73.  Entomostr.  laciniahis.  Wahl.  /.  c.  34. 
8.  Tab.  II,  Fig.  2.  Brong.  /.  c.  35.  3.  PI.  Ill,  Fig.  3.  Schloth.  Nachtr.  ii,  36.  19.  Milne  Edw. 
Or.  iii,  344.  3),  which  appears  to  me  most  nearly  allied  to  Bronteus,  I  am  obliged  to  omit,  because 
the  fi-agments  that  have  come  under  my  obsei-vation  exhibit  nothing  to  characterize  it.* 

Division  C. 

Trilobites  havi/u/  a  simple  but  very  small  eaudal  shield,  the  ax-is  of  which  is  many-jointed,  hut 
vJiich  is  always  shorter  than  the  body.     OleniDjE. 

The  two  genera,  Paradoxides  and  0/e/ius,  belonging  to  this  division  have  been  hitherto 
united  by  the  authors,  but  are  distinguished  readily  and  safely  by  the  caudal  shield,  which 
in  Paradoxides  has  no  lateral  enlargement  at  the  base,  while  in  Olenus,  on  the  other  hand, 
it  is  enlarged  at  that  region,  and  thus  generally  assumes  a  trilateral  shape  ;  the  former  genus 
has  from  sixteen  to  twenty,  the  latter  fourteen  body-rings. 

Genus  6. — Paradoxides,  Brongniart  (Olenus,  Sect.  I,  Dalman). 

Cephalic  shield  lunate,  with  a  thickened  but  not  reflexed  mai-gin  ;  the  glabella 
clavate  or  oval,  moderately  convex ;  enlarged  anteriorly,  divided  into  four  portions  by 
three  curved  sutures,  of  which  the  posterior  is  the  margin  of  the  articulation  with  the 
body.  The  lower  part  of  the  head  (PI.  I,  Fig.  7,  Ent.  bucephalus — Wahl,  et  auct.)  has  a 
less  prominent  boss,  analogous  to  the  anterior  division  of  the  upper  part,  which  diminishes 
posteriorly,  and  is  terminated  by  a  convex  reflexed  margin,  having  at  each  side  an  oblique 
transverse  impression. 

The  facial  sutures  are  nearly  parallel  in  their  principal  direction,  commencing  at  the 
anterior  margin  on  a  line  with  the  eyes,  turning  towards  the  eye  with  an  S-shaped 
curvature,  forming  a  slightly  arched  lid,  and  returning  in  a  similar  S-shaped  curve  towards 
the  posterior  margin. 

Eyes  oblong,  lunate,  depressed,  corresponding  with  the  second  division  of  the  glabella, 
reaching  towards  the  anterior  part  nearly  to  the  centre  of  the  first  division,  and  towards 
the  posterior  margin  rather  beyond  the  commencement  of  the  second  ;  eyelid  rather  more 
convex  than  the  neighbouring  part  of  the  cheek. 

Cheek-shield  narrower  than  half  the  width  of  the  cephalic  shield,  having  a  curved 

*  Portlock,  Lovon,  and  Beyrich  have  since  published  descriptions  which  give  a  tolerably  perfect 
idea  of  this  form.  It  appears  from  their  accounts  that  Dalman's  Ampyx  ?  pac/iyrhynchus,  Green's 
Paradoxides  Bottom,  Castelnau's  Platinotus  and  Actinurus,  Eichwald's  whole  genus  Metopias,  and 
Portlock's  Nuttainia  Mbern'ira,  all  belong  to  one  genus,  which  ought  to  retain  its  earliest  name  of 
Lic/ias.      Dr.  BejTich  has  undertaken  to  describe  the  species. 


OF  THE  SPECIES.  67 

groove  before  the  lateral  margin,  which  ini])rcssion  is  continued  posteriorly,  and  returns  into 
itself  at  the  posterior  margin  of  the  cephalic  shield ;  the  external  border  is  slightly  convex, 
and  produced  at  the  posterior  part  in  a  long  slightly  incurved  spine. 

Body  many-jointed,  apparently  only  having  a  definite  number  of  joints  in  tlie  separate 
species  (16-20),  the  joints  towards  the  posterior  part  gradually  more  narrow  and  shorter, 
the  lateral  lobes  at  first  produced  diagonally,  and  in  this  part  almost  as  broad  as  the  rings 
of  the  body  ;  afterwards  projecting  in  a  long  angle  turned  outwards  and  backwards ;  a  deep 
diagonal  impression  on  the  transverse  portion,  which  extends  from  the  most  anterior  and 
innermost  angle  backwards,  to  the  origin  of  the  spine. 

Caudal  shield  circular  or  oval,  without  (?)  lateral  lobes  and  enlarged  sides  at  the  base, 
with  a  short  but  articulated  axis,  and  a  flat  border  to  the  posterior  portion. 

Localitij.  —  In  the  oldest  Palaeozoic  strata  (grauwacke,  clayslate,  and  alumslate)  ; 
hitherto  only  found  in  Bohemia,  Sweden,  and  near  St.  Petersburg. 

Remark. — I  know  onlj'  two  distinct  species  of  this  genus  from  my  own  observation,  and  confine 
myself  here  to  the  description  of  these  two,  but  in  so  doing  would  not  be  understood  to  question  the 
propriet}''  of  tlie  others  to  rank  as  species.  Naturalists  having  an  opportunity  to  investigate  perfect 
specimens  of  the  species  which  I  have  not  admitted,  will  be  able  to  decide  how  far  they  really  differ 
from  the  two  here  enumerated. 

1.  P.  Eohemictis :  Protuberantia  capitis  clavata ;  anguUs  scuti  cephalici  dimidio  corpore  longi- 
oribus  ;  trunco  \acies  annulate.      Long.  1-6." 

Vur.  juveii:   annulis  trunci  18;  lobo  lateral!  secundo  in  spinam  longissimam  extenso.   Tab.  I,  Fig.  6. 

Ref. —  Oleiiiis pi/mmidaUs,  Zenker,  Beifr.  etc.  41.  Tab.  IV,  Fig.  T.  U.  V.     Tril.  gracilis, 
BoECK,  Magaz.  f.  Naturw.  I,  Fig.  15.     Sternberg,   Verh.  d.   Vaterl.   Mm.   1825, 
Tab.  I,  Fig.  4,  C,  and  1833,  p.  47. 
yEfafe  paulo  provectiorQ)  Tril.  minor  Boeck,  1.  c.  f.  12,  14. 
Var.  senilis:   annulis  trunci  30;  lobo  lateral!  secundo  reliquis  aequali.      Tab.  I,  Fig.  5. 
Tril.  bohemicus,  Boeck,/.  c.f.  2.     Sternberg,/,  c.  1825,  83. Tab.  I, Fig.  4.  A.  B.  1833. 
46.     KiNSKY,  \nBoriis  Abha7icll.  etc.  I,  246,  Fig.  4,  5,  7.     ?'.  longicandatus,  Zenker, 
Beifr.  37,  Tab.  5,  Fig.  A  to  F.     Emmr.  Diss.  48.  4.      Milne  Edw.   Cnist.  iii, 
341.  2.     Olenus  Tessini,  Var.  1.  Dalm.  Palaad.  73. 
Central  part  of  the  cephalic  shield  rather  quadrate,  but  the   distance  between  the 
eye-plates  rather  greater  than  the  longitudinal  diameter  ;  the  anterior  round  lobe  of  the 
glabella  longer  than  the  three  others  together.     Spines  of  the  maxillary  shield  longer  than 
half  the  body ;  the  spine  of  the  second  ring  of  the  body  as  long  as  this  during  the  youth  of 
the  animal,  gradually  getting  shorter,  and  finally  reduced  to  the  same  length  as  the  spines 
of  the  other  body-rings.     Rings  of  the  body  less  numerous  during  youth  (sometimes  sixteen, 
usually  eighteen),  at  a  more  mature  age  probably  always  twenty  (at  least  I  have  never  seen 
a  greater  number  in  perfect  specimens).     Caudal  shield  quite  oval,  rather  broader  towards 
the  posterior  part,  almost  flattened,  the  axis  inarticulated  during  youth,  afterwards    one- 
jointed,  at  maturity  furnished  with  five  joints. 

Locality. —  In  a  blackish-green  grauwacke  of  Bohemia,  near  Horrowic  and  Ginec  ;  also  in 
Norway  and  Sweden,  in  the  latter  in  alumslate,  at  Olstrog,  Dämmen  and  Carlsfors. 

Remarks. — 1.  01. pyramidalis,  Zenker  {Tril.  gracilis,  Boeck)  I  can  only  agree  with  Count  Sternberg 
in  regarding  as  a  young  specimen  of  the  Tr.  lonyicavdufus  and  Tr.  bohemicus  of  the  same  author,  and 


68  SYSTEMATIC  ARRANGEMENT 

this  view  is  supported  uot  only  by  the  relative  proportions  of  the  body  which  perfectly  coirespond,  but 
also  by  the  delicate  nature  of  the  covering,  and  the  long  slender  spines.  The  remarkable  prolongation 
of  the  second  lateral  spine  (uot  the  third,  as  Boeck  and  Count  Sternberg  have  already  correcth'  shown 
while  controverting  Zenker)  indicates  some  peculiarity  relative  to  the  young  age  of  the  animal  (at  least 
so  far  as  it  seems  to  have  formed  a  pair  of  forceps  with  the  long  spine  of  the  cephalic  shield).  The 
length  in  this  case  gradually  decreases  as  the  others  increase,  but  is  still  distinctly  visible  in  individuals 
that  are  half  grown.  I  look  upon  Tril.  minor,  Boeck,  as  an  instance  of  this  kind.  That  the  rings  of 
many-jointed  Ciiistaceans  increase  in  number  as  the  animal  grows,  and  that  this  number  is  only  com- 
plete when  the  animal  is  fully  gro^v^l,  is  a  fact  too  well  known  to  the  natm'alist  to  require  proof  in  this 
place,  but  on  this  suljject  I  would  refer  to  my  own  investigation  of  the  Phyllopoda,  and  the  elaborate 
and  new  observations  of  Zaddack  and  Joly.      [Ann.  des  Sc.  n.  s.  1840  and  1842.) 

Olenus  latus  (Zenker  /.  c.  Figs.  W,  X.  Mune  Edw.  /.  c.  441,  3)  is  distin9tly  the  same  species  as 
the  one  above  described,  and  is  merely  flatly  compressed. 

2.  The  species  Paradoxides  seu  Olenus  Tessini  (Entom.  paradoxissimus,  Linn.  Mus.  Tess.  98,  Tab. 
Ill,  Pig.  1 ;  Wahl.  Nov.  act.  Ups.  viii,  34,  Tab  I,  Fig.  1  ;  Brongn.  Cr.f.  31,  PI.  IV,  Fig.  1 ;  Schlot. 
Pet.  Nacht,  ii.  23.  1.  35.  15;  Dalman,  Pal.  54.  1.  73.  1.  Tab.  VI,  Fig.  3;  Boeck,  May.  f.  Nat.  I.  26; 
Bucklaud,  B.  T.  PI.  XLVI,  Fig.  8;  Bronn.  Leth.  1,  120,  Tab.  IX,  Fig.  16;  Quenstedt,  Wieg.  Arch. 
1837,  348;  Emmr.  Diss.  48;  Milne  Edw.  Cr.  iii.  340,  1,  PI.  XXXIV,  Fig.  11 ;  Hising.  Leth.  suec.  18, 
Tab.  IV,  Fig.  1)  appear  to  me,  judging  from  the  representations  and  descriptions  enumerated  above, 
to  be  scarcely  different  from  P.  bohemicus  ;  at  least  I  find  no  certain  and  available  difference.  In 
Linnseus's  oldest  figure  there  have  been  indicated  at  most  seventeen  body-rings,  and  the  caudal  shield 
has  here  been  distinctly  represented  without  lateral  lobes.  Wahlenberg  represents  twenty-one  such 
rings,  and  twenty-two  lateral  lobes,  the  last  pair  of  which  is  affixed  to  the  caudal  shield  itself. 
Dalman's  figure  represents  a  similar  caudal  shield,  but  onlj'  twenty  body-rings  ;  and  both  authors  state 
that  they  have  only  examined  imperfect  fragments,  and  make  out  no  more  clearly  the  caudal  shield. 
Brongniart  copied  from  Wahlenberg ;  Bucklaud,  Bronn,  Milne  Edwards,  and  Hisinger  from  Dalman. 
I  consider  therefore  the  figure  given  by  Linna3ixs  of  tlie  caudal  shield,  and  Dalman's  enumeration 
of  the  body-rings  to  be  correct,  and  I  thence  infer  that  P.  Tessini  is  specifically  identical  with  P. 
bohemicus. 

3.  Wahlenberg  (Tab.  I,  Fig.  7)  has  figured  the  impression  of  the  under  side  of  a  cephalic  shield 
(the  hypostoma)  as  a  distinct  specific  form,  under  the  name  of  Entom.  bucephalus  (I.  c.  37.  10,  Tab.  I, 
Fig.  6).  Following  in  his  footsteps,  we  find  Dalman  {Pal.  55.  2),  Schlotheim  {Nacht,  ii.  37),  Boeck 
{Mag.f.  Nat.  I,  Fig.  16),  Milne  Edwards  {Cr.  iii,  341),  and  Hisinger  (/.  c.  18)  expressing  the  same 
view  more  or  less  doubtingly.  More  recently  Sars  {Isis  1835.  342),  Quenstedt  {Wieg.  Arch,  1837,  I. 
349),  and  others,  have  recognized  the  identity  of  the  structure  with  that  of  P.  bohemicus,  and  M.  v. 
Buch  has  shown  me  some  specimens  which  show  the  fact  in  a  very  instructive  manner.  I  have 
figured  such  an  under  cephalic  surface  in  Tab.  I,  Fig.  7.  The  concentric  lines  there  visible  may  be 
observed  in  all  under  surfaces  of  Trilobites,  and  have  ah-eady  been  alluded  to  by  Zenker,  in  the  work 
already  cited.  Figs.  C.  D. 

P.  spimdosus  :  Protuberantia  capitis  parabolica ;  augulis  scuti  ceplialici  dimidio  corpore  brevioribus, 
trunco  sedecies  annulato.      Long.  1". 

^,y._LiNN.  Jrf.  Holm.  1759,  22,  Tab.  I,  Fig.  2.     Wahl.  N.  a.  Vps.  viii,  38.  Tab.  I, 
Fig.  3.     Brong.  Cr.  /.  32,  PI.  IV,  Figs.  2.  3.     Schloth.  NacMr.  II.  25.  2.  36. 
16.     Dalm.  P«/.  56.  2.  73.  2,  Tab.  V,  Fig.  2.     Emmr.  Z»/.«*.  47.  5.     Quenstedt, 
Wiey.  Arch.  I.  c.  349.      Milne  Edw.  Cmsf.  iii.  342.  5.      Hising.  Ldh.  Suec.   19, 
Tab.  IV,  Fig.  2. 
I  have  seen  only  a  few  and  not  very  distinct  specimens  of  this  species,  but  these   cor- 
responded with  Walüenberg's  and  Brongniart's  figure  in  tlie  principal  points.     The  cephaHc 
shield  exhil)its  a  glabella  which  is  not  broader  anteriorly,  but  is  gradually  rounded  towards 
tliat  part,  with  three  slight  impressions  at  each  side.     I  counted  sixteen  rings  in  the  body. 


OP  THE  SPECIES.  69 

tlie  exact  number  which  seems  to  have  been  seen  by  Dahnan,  whilst  seventeen  have  been 
given  in  his  and  Wahlcnberg's  figure.  Brongniart's  very  excellent  figure  exhibits  also 
sixteen,  probably  the  correct  number.  The  lateral  lobes  of  the  first  body-rings  are  very 
broad,  broader  than  the  axis,  but  they  rapidly  get  smaller  posteriorly,  so  that  the  last 
become  narrower  than  the  axis.  The  caudal  shield  is  small,  roundish,  transversely  elliptical, 
and  has  no  lateral  lobes. 

Local  if  J/. — The  same  as  F.  bohemicus  and  P.  Tessini ;  and  also  in  the  clayslate  of  Angers, 
associated  with  Oyyc/ia  Gunttardi.  (Vide  Guettard,  Mem.  de  I' Acad  des  Sciences,  torn,  xiv, 
ann.  1757,  PI.  VI,  8,  Figs.  3.  4.  5.) 

Remarks. — Various  species  hitherto  impci'fectly  kuowu  appear  to  belong  to  this  genus.  Among 
these  are — - 

1.  A  figure  bv  Count  Razoumousky,  in  the  Annales  des  Sciences  (t.  viii,  PI.  XXVIII,  Fig.  11). 
While  possessing  a  similar  structure  with  0.  bohemicus,  this  specimen  is  distinguished  by  a  long  spine 
at  the  extremity  of  the  caudal  shield.  Locality. — In  Silurian  strata  between  St.  Petersburg  and  Lake 
Ladoga. 

2.  Paradox.  Boltoni,  Bigsby  (Green,  Mon.  60,  f.  5,  Joum.  Ac.  N.  S.  of  Phil.  vol.  iv,  p.  365, 
PI.  XXIII.  Harlan,  Zool.  res.  303.  Milne  Edw.  Crust,  iii,  314,  n.  1).  This  genus,  as  we  have 
already  seen,  belongs  to  the  genus  Lichas,  Dalman.      See  Remark  2,  under  Bronteus  laticauda. 

3.  Cahjm.  actinura  (Dalman,  K.  V.  Ac.  Hand.  1824,  370,  Tab.  lA^  Figs.  A,  B,  C.  Hising.  Leth. 
suec.  11,  Tab.  I,  Fig.  7.  Milne  Edw.  Crust,  iii,  321).  A  species  having  fifteen  (?)  lateral  lobes  and 
body-rings,  and  resembling  so  closely  in  every  respect  P.  Boltoni,  that  I  cannot  but  refer  them  to  the 
same  genus,  intermediate  between  Bronteus  and  Paradoxides,  the  chai'acters  of  which  canuot  yet  be 
determined  with  certainty. 

4.  Parad.  Harlani  (Green,  Silliman's  Am.  J.  of  Sc.  and  Arts,  vol.  xxv,  p.  336.  Harlan  and 
Milne  Edw.  as  before  cited). 

5.  All  the  other  species  hitherto  iucludcd  among  Paradoxides  or  Olcnits,  probably  belong  to  the 
following  genus. 

Gcii/fs  7.  — Olenus  (Paradoxides  p/Olenus  Aucfonim). 

Cephalic  shield  constructed  as  in  Paradomdes,  but  comparatively  bi'oader  and  shorter  ; 
the  glabella  parabolic,  not  broader  towards  the  anterior  part,  but  rather  more  narrow  and 
rounded,  at  each  side  furnished  with  three  slight  furrows,  which  separate  it  into  four 
divisions,  of  which  the  posterior  narrow  one  is  articulated  with  the  body. 

Eyes  oblong  curved.  The  facial  suture  originates  at  the  anterior  margin,  in  the  region  of 
the  eye.  It  is  there  bent  at  an  angle,  and  returns  nearly  parallel  to  its  former  direction 
towards  the  eye,  where  it  makes  a  bent  plate,  and  passes  in  an  S-shaped  curve  towards  the 
posterior  margin,  where  the  two  sutures  gradually  and  continually  diverge. 

Cheek-shield  tolerably  broad,  with  a  reflexed  margin,  and  with  a  pointed  but  not  very 
long  posterior  angle. 

Axis  of  the  body  many-jointed  (fourteen  ?)  ;  the  joints  more  narrow  tlian  the  lateral 
lobes,  short,  and  moderately  convex;  the  lateral  lobes  extended  in  a  straight  line,  only 
terminating  at  the  end  in  a  short  point  directed  backwards ;  each  furnished  with  a  diagonal 
furrow  from  the  anterior  and  internal  towards  the  posterior  and  external  part. 

Caudal  shield  much  broader  than  long,  semicircular,  straight  at  the  anterior  part, 
arched  or  obtusely  angular,  trilateral  posteriorly,  with  a  distinct  articulated  axis. 

Localifi/. — In  very  old  strata  with  species  of  the  preceding  genus. 


•70  SYSTEMATIC  ARRANGEMENT 

1.  O.  (jihbusiis :  Scuto  capitis  inter  suturam  facialem  et  umbonem  tuberculo  transverso  signato ; 
rhachi  coi-poris  quaterdecies  annulata,  caudae  quinquies.      Long.  1".     Table  III,  Fig.  9. 

Bef. — Tr.  truncatus,  Brunn.  N.  Act.  Hafn.  \,  391.     Modeer  in  Berl.  Gesellsch.  Schrift. 
vi,  Table  II,  Figs.  3-.5.     Entom.  gibhosm,  Wahlenb.  N.  A.  Ups.  viii,  39.  12,  Table  I, 
Fig.  4.     Brongn.  Cr.foss.  35,  PI.  Ill,  Fig.  6.     Schloth.  Nachtr.  ii,  26.  4.  36.  18. 
Dalm.  Palaad.  56.  4.  74.  4.     Boeck,  Mag.  f.  Nat.  i,  24.     Emmr.  Dissert.  45.  1. 
Milne  Edw.  Crust,  iii,  343.  4.     Hising.  Leth.  suec.  19,  Tab.  IV,  Fig.  3. 
Cephalic  shield  four  times  as  broad  as  it  is  long,  th&  axis  remarkably  narrow ;    an 
elevated  elliptical  prominence  both  to  the  left  and  right  at  the  anterior  extremity,  the  pro- 
minence extending  as  far  as  the  facial  suture.*     The  number  of  joints  in  the  axis  of  the 
body  is  fourteen ;  the  lobes  of  the  first  joints  are  twice  as  broad  as  the  axis ;  those  of  the 
last  only  a  little  broader. 

Caudal  shield  semicircular;  the  axis  five-jointed,  with    an  anterior  margin  of  articu- 
lation ;  the  lateral  portions  flat,  without  rays,  the  margin  rather  reflexed. 
Locality. — In  the  alumslate  and  stinkstein  of  Andrarum. 

Remarks. — 1.  The  cheek-sliields  of  the  head  are  absent  in  all  the  older  descriptions  and  figures, 
being  always  broken  off.  They  are  often  present,  however,  near  the  other  remains,  so  that  there  can 
hardly  be  a  doubt  about  theii-  existence.  I  counted  fourteen  body  joints  in  the  impressions  of  young 
and  perfect  indi\iduals. 

2.  Asaph,  tetragonocephahis  (Green,  Sill.  Am.  Jo.  vol.  xxv,  p.  336 ;  Emm.  Diss.  46.  4 ;  Milne 
Edw.  Cr.  iii,  330)  is  so  similar  to  01.  gibbosiis,  that  they  are  liable  to  be  confounded  with  one  another ; 
indeed  I  was  not  able  to  discover  satisfactory  specific  distinctions  in  the  plaster  model  which  I  examined 
at  Berlin.  I  counted  in  this  specimen  fourteen  body-rings,  and  certainly  three  caudal  rings,  but  the 
latter  were  indistinct  and  imperfect.      The  species  was  found  in  the  alumslate  of  Lockport. 

3.  Boeck,  in  Kielhaus's  Gcea  Norwegica  (see  Leonhard  and  Bronn,  Zeitshr.  1841,  p.  727),  has 
characterized  two  species  nearly  related  to  01.  gibbosus,  which  I  am  not  acquainted  with,  and  therefore 
give  them  here  according  to  his  statement. 

O.  alatus  (/.  c.  No.  38)  is  nearly  related  to  0.  gibbosus,  but  the  glabella  (which  is  the  only  part 
known)  is  proportionably  much  narrower,  and  the  transverse  prominence  which  issues  from  its  anterior 
extremity  does  not  extend  in  so  straight  a  #iue,  but  is  produced  more  backwards. 

O.  latus  (1.  c.  No.  39)  is  much  larger  than  01.  gibbosus,  and  the  piece  (probably  the  space)  between 
the  glabella  and  eyelid  is  considerably  broader. 

I  do  not  think  such  differences  in  imperfect  fragments  can  justify  us  in  founding  new  species. 

4.  Emmerich's  Pur.  acuminatus  (Dissert.  46.  2),  which  is  said  to  be  distinguished  from  01.  gibbosus 
by  a  more  developed  angularity  of  the  facial  suture  before  the  eye,  and  by  a  bending  of  it  inwards  at 
the  posterior  extremity,  also  appears  to  me  merely  to  indicate  an  individual  difference  caused  by  differ- 
ence of  preservation,  as  this  is  easily  accounted  for  in  the  impressions  of  tender  parts.  01.  gibbosus  in 
other  respects  varies,  like  its  allies,  very  considerably  in  size,  according  to  the  difference  of  age ;  I  have 
seen  specimens  of  Wi"  length,  and  others  scarcely  !^". 

2.    O.forficula. 

Sars,  Isis,  1835,  333,  Tab.  VIII,  Fig.  1.     Milne  Edw.  Crust,  iii,  .343.  1. 

According  to  the  figures,  this  species  most  nearly  resembles  Paracl.  spitiulosiis  in  the 
iiabit  of  the  head  {im  Habitus  des  Kopfes),  but  has  a  glabella  somewhat  broader  anteriorly, 
and  divided  by  two  furrows  into  three  nearly  equal  parts.  A  slight  longitudinal  impression 
appears  at  the  anterior  of  these,  and  on  the  third  there  is  a  small  tubercle.     Behind  it  the 

*  By  its  position  this  prominence  justifies  the  assumjrtion  that  a  small  tentacle  issuing  from  the 
glabella  has  existed  beneath  it  in  a  cavity  of  the  shield. 


OF  THE  SPECIES.  71 

swelling  of  the  margin  makes  a  fourth  division.  The  facial  suture  terminates  as  in  Olcnus, 
and  the  terminating  angle  of  the  check-shield  is  elongated. 

The  caudal  shield  is  semicircular,  straight  at  the  anterior  jjart,  bounded  by  a  curve  at 
the  posterior  part ;  the  axis  consists  of  five  to  six  rings,  and  a  fold  proceeds  from  it  towards 
the  posterior  margin,  which  there  projects  in  a  large  spine.  This  is  all  that  is  known  of  the 
animal. 

Locality.— k  calcareous  blackish-gray  alumslate  of  Rusielökbacken,  near  Christiania. 

Remarks. — 1.  According  to  Boeck  {Gcea  norw.  \,  No.  18),  tliis  species  is  not  properly  placed  here, 
but  forms  witli  Ceraurus  pleureocanthemus  (Green,  Mon.  84,  f.  10;  Bronn,  Let.  i,  117,  Tab.  IX,  Fig. 
12 ;  Milne  Edw.  Cr.  iii,  346)  a  distinct  genus.  It  is  very  probable  that  this  view  is  correct,  but  since 
I  have  not  myself  had  the  opportunity  of  examining  the  two  species,  I  must  leave  the  decision  to  others. 
No  doubt,  however,  Ceraurus  represents  a  form  closely  related  to  the  Olenides.  In  Green's  figure 
eleven  body-rings  and  a  broad  caudal  shield  are  represented,  the  latter  bearing  a  spine  on  one  side 
exactly  hke  that  of  O.  forficula.* 

2.  Murchison  [Sil.  Sys.  vol.  ii,  p.  (558,  Plate  XIV,  Fig.  8)  has  described  a  large  caudal  shield,  to 
which  he  gives  the  name  Paradoxides  bimucrotiatus,  and  this  in  many  respects  seems  to  hold  an  inter- 
mediate place  between  the  caudal  shield  of  the  last  and  of  the  next  succeeding  species.  It  is  straight 
at  the  anterior  part,  nearly  an  inch  in  width,  and  fiu-nished  with  a  three-jointed  axis,  over  which  there 
projects  forwards  one  of  the  articulation.  A  fold  proceeds  to  the  margin  from  each  ring,  and  the  three 
folds,  like  the  rings  themselves,  become  smaller  posteriorly,  so  that  the  free  semichcular  margin  is 
furnished  with  six  rather  bent  processes.! 

3.  O.  scarabeeoides  :  Scuto  capitis  convexo,  vertice  non  elevato  sublobato  ;  scuto  caudali  utrinque 
tridentato,  axi  biarticulata. 

i?p/._BROMEL,  Jcf.  lift.   Uj}.s.  1729.  521.  //.  3,  and  page  528.  6,  c  Fig.     Wahl.  iV.  J- 

ups.  viii,  41.   13,  Tab.  I,  Fig.  2.     Brongn.   Cr.  foss.  34.  3,  Plate  III,  Fig.  5. 

ScHLOTH.  Nac//f.  ii,  25.  3.  36.  17.     Dalm.    Palcead.  57.  5.     Emmr.  Bissert.  47.  6. 

Milne  Enw.   C/-.  iii,  344.   \,  Pelf iira  scarab.     Antltes  scarabcBoides,  GoiiD f.  Lecju/i. 

und  Br.  Jahrb.  1843,  p.  544. 
Of  this  species  I  am  only  acquainted  with  some  fragments  of  heads  and  perfect  caudal 
shields,  and  from  these  I  must  declare  it  to  be  a  species  with  which  I  am  too  little  con- 
versant to  judge  M'ith  certainty  respecting  its  systematic  position.  The  glabella  resembles 
that  of  the  first  described  species  of  this  genus,  but  is  relatively  shorter,  broader,  more 
convex,  and  the  indentations,  which  are  similarly  divided,  are  slighter.  The  existing  part 
of  the  cephalic  shield  beside  it  is  deeply  depressed,  and  thereby  indicates  a  very  great 
convexity  of  the  cheeks.  I  think  I  recognize  a  trace  of  the  eyelid  in  the  region  of  the  first 
anterior  sutui-e ;  a  distinctly  reflexed  margin  is  visible  at  the  posterior  part ;  but  I  have  never 
distinctly  seen  the  anterior  and  lateral  margin.  The  caudal  shield  has  a  short  two-jointed 
axis,  and  a  margin  of  articulation  before  the  first  joint ;  it  is  extended  on  both  sides  more 

*  A  new  species  of  Ceraurus  has  been  described  by  Portlock  {Rep.  257,  Plate  I,  Fig.  7)  as  C. 
globiceps. 

t  In  his  treatise  '  Ueber  einige  Böhmische  Trihbiten,'  Dr.  Beyrich  has  shown  that  this  species  of 
Murchison's,  together  with  Tril.  Sternberyi,  Boeck,  constitute  a  new  genus,  for  which  he  proposes  the 
name  Chirurus.  He  describes  four  Bohemian  species  of  this  genus,  and  includes  also  in  it  Cuhjmene 
Sternbergi,  C.  propinqua,  and  C.  articidata  of  Münster  [Beitr.  z.  Pet.  iii,  37,  Tab.  V)  ;  C.  speciosa, 
Dalman  (Pal.  74) ;  C.  ornala,  Dalm.  {Arsber.  am  nya  Zool.  Arbet.  134) ;  Amphion  gelasimsns,  Portlock 
[Rep.  289,  Plate  III,  Fig.  4)  ;  and  Arge.i  p/aiwspino.vi.t,  Portl.  (/.  c.  272,  Plate  Y,  Fig.  9) ;  the  two  latter 
being  probably  the  cephalic  and  caudal  shields  of  the  same  species  referable  to  this  genus  (Chinirm). 


72  SYSTEMATIC  ARRANGEMENT 

than  usual  posteriorly,  and  is  there  furnished  with  a  deep  transverse  furrow  before  the 
straight  margin,  and  is  drawn  out  at  each  side  into  three  pointed  marginal  processes,  which 
are  situated  lower  than  the  general  surface,  and  which  issue  from  the  deflexed  margin. 

Locality. — The  alumslate  of  Andrarum. 

Remarks. — ] .  Wablenberg,  who  states  that  he  has  seen  a  perfectly  preserved  individual  of  this 
species  at  Copenhagen,  describes  it  as  having  twelve  body-rings  with  very  short  lateral  lobes,  which  are 
pointed  towards  the  posterior  part ;  he  has,  however,  represented  the  glabella  and  the  caudal  axis  much 
too  broad,  and  for  this  reason  I  am  inclined  to  consider  the  body  axis  as  also  too  broad. 

2.  Harlan  [Med.  and  Phys.  Rev.  400  et  seq.)  describes  two  new  forms,  nearly  related  to  Par. 
scaratxcoides.  He  speaks  of  them  as  Parad.  triarttirus  (I.  c.  401.  1,  Fig.  5),  and  Parad.  arcuatus  (/.  c. 
403.  2,  Figs.  1,  2,  3).  Both  are  from  the  carboniferous  striita  (?)  of  Utica,  in  New  York.  They  are 
imperfect  heads,  which  certainly  resemble  the  fragments  of  01.  scarabaoides,  but  which  still  require  a 
further  investigation  as  to  their  true  organization.  The  author  compares  them  with  Triarttirus  Beckii 
(Green,  3Ion.  87,  Fig.  6),  with  which  they  certainly  seem  to  be  related. 

3.  I  shall  treat  more  particularly  in  the  Appendix  of  Triarttirus  Beckii  and  Trilobites  Slernbergi, 
which  probably  belong  to  the  Oleneides. 

4.  I  beg  once  more  to  remind  my  readers  that  I  have  mentioned  Paradoxides  spinulosus,  Olenus 
forficida,  and  Olen.  scarabceoides,  as  species  which  are  both  imperfectly  known  to  me,  and  the  correct 
arrangement  of  which  in  systematic  order  I  cannot  guarantee ;  this  is  still  more  the  case  with  the  other 
species  of  other  authors,  which  I  have  only  enumerated  here  hypothetically. 


GROUP  THE  SECOND. 

77te  lateral  lobes  of  the  hodt/-nngs  not  horizontally  extended  in  their  whole  length,  hut  turned 
downwards  from  the  centre,  and  not  terminatiny  in  a  point,  hut  with  an  arched  and  rounded 
extremity.     Furrowed  on  the  surface  alony  their  whole  lenyth.     C.\mpylopleuri.* 

I  am  only  perfectly  acquainted  with  the  first  two  of  the  three  genera  enumerated  in 
this  group ;  they  are  recognizable  by  their  smaller,  semilunar,  cephalic  shield,  by  their 
fewer  number  of  joints  (twelve  to  fourteen),  and  by  their  simple,  semicircular,  caudal 
shield.  The  one,  Conocephalus,  has  fourteen  rings ;  the  other,  EUipsocephahis,  twelve.  The 
third  genus,  Hmpes,  has  a  very  large  cephalic  shield,  shaped  like  a  horseshoe,  with  long 
posterior  angles,  and  is  stated  to  have  twenty-eight  rings. 

Genus  8. — Conocephalus,  Zenker. 

Cephalic  shield  not  unlike  a  half-moon,  but  the  posterior  internal  margin  only  slighth^ 
bent.  Glabella  separated  by  a  deep  furrow  from  the  lateral  lobes,  becoming  more  narrow 
towards  the  anterior  part,  divided  by  four  furrows  at  each  side  into  four  lobes,  and 
becoming  broader  from  the  anterior  to  the  posterior  part ;  behind  the  fourth  lobe  there  is 
a  reflexed  margin  of  articulation.  The  lateral  parts,  together  with  the  cheek-shield,  are 
highly  convex,  surrounded  by  a  furrow  and  by  a  thickened  margin. 

Eyes  small,  but  certainly  present ;  partly  fixed  at  the  anterior  part  beside  the  angles 
of  the  glabella,  partly  at  the  centre  of  the  sides. 

*  The  following  generic  names,  and  the  names  of  larger  groups  thence  derived,  have  been  alread}- 
made  use  of  to  designate  various  tribes  of  Locusts. 


OP  THE  SPECIES.  73 

The  facial  suture  couimenccs  at  the  anterior  margin  far  towards  the  outer  side,  turns 
inwards  with  a  curve  towards  tlie  eye,  forms  a  small  covering  plate,  and  then  runs  towards 
the  posterior  angle,  before  which  near  the  inner  part  it  penetrates  the  posterior  margin. 
The  angle  itself  is  furnished  with  a  short  straight  spine. 

Body  fourteen -jointed,  the  axis  narrower  than  the  lateral  lobes,  very  convex;  the 
lateral  lobes  quite  horizontal,  of  equal  breadth,  deeply  sulcated  in  their  whole  length ;  from 
the  centre  they  begin  to  curve  downwards  almost  at  a  right  angle,  and  are  rounded  at  the 
extremity ;  they  are  separated  at  the  base  from  the  axis  by  a  deep  furrow.* 

Caudal  shield  semicircular,  very  convex  anteriorly,  with  a  five-jointed  axis,  and  slight 
furrows  on  the  sides. 

Localiiy. — In  the  grauwacke  of  Bohemia,  at  Ginu. 

1.  C.  Sulzeri:  Oculis  juxta  apicem  tuberculi  frontalis.     Long.  VA-V .     Table  I,  Fig.  10. 

Ref. — KiNSKY,  in  Bom's  Ahh.  etc.,  I,  Figs.  1,  2,  3.     Triloh.  Sidz.  Schloth.  Nachtr.  ii, 

28.  1,  and  34.  5,  Table  XXII,  Fig.  1.     Dalm.  Palcead.  75.  I.     Sternb.  Verhandl. 

d.  Vaterland.  Mus.   1825.  81.  4,  Table  II,  Fig.  1,  A.     Boeck,  vI%.  for  Natur.  Sc. 

Figs.  20,  21,  Trilob.  Zippii.     Conoc.  costafus,  Zenk.  Beifr.  49.  15,  Table  IV,  Fig. 

G-K.     Milne  Edw.  Crust,  iii,  336. 
Syn.— Conoc.  Suheri,  Bronn,  Lethaa,   1.   121.   110,  Table  IX,  Fig.  15.     Emmr.  A'»?. 

43.  1.     QuENST.  in  Wieffm.  ArcJiiv.  1837,  i,  347. 
Glabella  very  much  contracted  anteriorly,  and  almost  rounded ;  before  it,  and  behind 
the  thickened  margin,  there  is  a  peculiar  transverse  fold. 

Eyes  small,  situated  on  tubercles  immediately  beside  the  anterior  angles  of  the  glabella, 
whence  the  facial  suture  continues  directly  across  the  sides,  dividing  the  narrow  cheek-shield. 
Body  rings  and  caudal  shield  not  remarkable. 

2.  C.  striatus :   Oculis  in  medio  partium  lateralium  scuti  cephalici.    Long.  lJ^-2".    Table  I,  Fig.  9. 
Äe/:— Emmr.  Diss.  43.  2,  C  fig.    Trilob.  Sulz.  var.  Sternb.  II,  I,  A,  and  Table  I,  Fig.  3. 

QUENSTEDT,  /.  C.  348. 

Similar  to  the  preceding  species  in  size,  habit,  and  structure ;  but  the  cephalic  shield 
totally  different.  The  glabella  at  the  anterior  part  is  broader,  straightly  truncated,  and 
merely  furnished  with  rounded  angles  ;  there  is  no  transverse  fold  in  front  of  it. 

The  eyes  are  more  distinct,  attached  to  the  centre  of  the  lateral  parts  of  the  cephalic 
shield,  and  bearing  the  same  proportion  to  the  facial  suture ;  but  a  sharp  ridge  extends  itself 
towards  them  from  the  angles  of  the  glabella. 

The  cheek-shields  are  not  narrow  and  elongated,  but  short  and  broad,  and  only  reach 
half  as  far  anteriorly  as  in  the  last  species. 

Boeck  was  the  first  to  point  out  the  differences  which  constitute  this  a  species,  although 
Count  Sternberg  had  previously  observed  it.      By  mistake,  however,  he  confounded  the 

*  Zenker  (/.  c),  and  after  bim  Quenstedt  and  Emmericb,  regard  tbis  furrow  as  the  indication  of  an 
articulation  or  suture ;  but  since  in  every  specimen  the  impression  is  merely  that  of  an  internal  shelly 
surface,  the  indentation  is  more  probably  the  impression  of  an  elevated  ridge,  -nhich  may  have  served 
for  the  insertion  of  the  muscles  of  the  legs.  The  analogy  of  all  other  Trilobites  is  against  the  existence 
of  a  suture. 

10 


74  SYSTEMATIC  ARRANGEMENT 

names,  regarding  the  true  C.  Siiheri  as  the  new  species.  Quenstedt  acknowledged  the 
points  of  specific  difference  without  noticing  what  had  been  done  before ;  and  Emmerich  at 
length  gave  the  name. 

Genus  9. — Ellipsocephalus,  Zenker. 

Cephahc  shield  similar  in  outline  to  that  of  the  preceding  genus,  but  quite  distinct  in 
construction,  being  flatter  and  without  posterior  prolonged  angles  ;  the  anterior  margin  also 
is  not  elevated.*  The  glabella  is  divided  from  the  shield  by  a  slight  indentation,  equally 
broad,  rounded  at  the  anterior  part,  without  transverse  furrows,  and  even  without  a  posterior 
articular  fold. 

Eyes  oblong  lunate,  very  narrow,  and  projecting  outwards.  Facial  suture  short,  com- 
mencing at  the  anterior  part  at  the  margin  before  the  eyes,  and  curving  over  them  towards 
the  posterior  angle.  Joints  of  the  body  twelve,  the  axis  nearly  as  broad  as  the  lateral  lobes, 
depressed.  The  lateral  lobes  at  first  horizontal,  rather  flat,  and  almost  without  furrow ; 
then  curved  downwards,  more  deeply  furrowed,  but  the  furrow  pointed  inferiorly ;  with  an 
anterior  surface  transversely  affixed,  indicating  a  deficiency  of  power  in  the  creature  to  roll 
itself  into  a  ball.  The  extremity  is  thus  rendered  obtuse-angled. 
Caudal  shield  small,  semicircular;  the  axis  one-jointed. 

Locality. — The  Palaeozoic  rocks  (grauwacke)  of  Bohemia.  The  only  known  species 
attains  a  length  of  about  1 M  inches,  and  is  E.  Hoßi.     Table  I,  Fig.  8. 

Ref. — KiNSKY  in  Bom's  Abhandl.  1.  246,  Fig.  6.  TrUohites  Hoff.  Schloth.  Nachfr.  ii, 
30.  2,  and  34.  6,  Table  XXII,  Fig.  2,  a,  h.  Count  Sternberg,  VerhancU.  d.  ratal 
Mus.  1825.  83,  Table  II,  Fig.  4,  and  1833.  50.  Dalm.  Palcead.  76.  2.  Boeck, 
Ma(/.f.  Naturv.  I,  Figs.  14,  17,  19. 
Syn. — ElUjjsocephalus  ambiguus,  Zenk.  Beitr.  51,  Table  IV,  Figs.  G,  K.  Milne  Edw. 
Cr.  iii,  344.  JEllips.  Hoßi,  Bronn,  Lethaia,  1.  122.  Ill,  Table  IX,  Fig.  18. 
Emmr.  Dissert.  44,  VI.  1.  Calymene  decipiens,  König, /co/^  sect,  i,  2,  Table  III, 
Fig.  32. 

Genus  10. — Harpes,  Goldfuss. 

Cephalic  shield  very  large,  in  the  shape  of  a  horseshoe,  very  convex  in  the  centre, 
flatly  expanded  at  the  whole  external  margin ;  the  posterior  angles  long,  and  projecting 
beyond  the  centre  of  the  body.  The  glabella  is  very  prominent,  oval,  and  does  not 
reach  to  the  anterior  margin ;  it  becomes  narrower  at  the  posterior  part  before  the  margin 
of  articulation,  and  is  furnished  with  a  double  impression,  which  separates  two  elliptical 
lateral  lobes  from  its  posterior  half;  by  the  side  of  it  externally  there  is  also  a  slight  trace 
of  a  third  arch-like  impression  and  lobe. 

Eyes  indistinct,  small,  appearing  in  the  shape  of  knobs  at  both  sides  beside  the  anterior 
half  of  the  glabella. 

*  The  impressious  occur  iu  two  kiuds  of  forms  ;  some  have  uo  elevated  mai-giu,  others  only 
exhibit  the  impression  of  it  as  an  indentation  in  the  matrix.  Accordiug  to  this,  there  seems  to  have 
been  a  reflexed  margin  only  at  the  lower  side  of  the  cephalic  shield.  This  appears  to  me  to  be  the 
case  also  with  regard  to  Conoceplialus. 


OF  THE  SPECIES.  75 

Facial  suture  indistinct ;  I  can  perceive  only  a  slight  indented  arch,  which  issues  from 
the  place  at  which  the  border  and  central  shield  meet  together.  This  line  turns  towards 
the  eye-tubercle,  and  separating  from  the  latter  at  the  posterior  part,  makes  another  turn 
with  a  sharper  curvature,  over  the  posterior  half  of  the  sides  to  the  angle,  which  is  formed 
by  the  open  posterior  margin  and  by  the  lobes  of  the  angle. 

Body  many-jointed  (above  twenty),  the  axis  very  convex,  narrowing  posteriorly,  but 
elsewhere  quite  as  broad  as  the  lateral  lobes ;  both  these  are  short,  the  latter  at  first  hori- 
zontal, slightly  furrowed,  bent  much  downwards  at  the  end,  and  obtusely  pointed. 

Caudal  shield  not  known. 

Zow//(y.— Upper  Silurian  and  Devonian  strata  of  the  Eifel,  the  Fichtelgebirge,  Bohemia, 
and  Ireland.* 

Remark.^. — 1.  Of  this  genus  I  have  before  me  only  a  single  cephalic  shield,  but  this  is  for  the 
most  part  well  preserved ;  it  lies  in  a  yellowish,  liver-brown  limestone,  probably  the  same  in  which  is 
also  found  Odontopleura  ovata,  and  has,  like  the  latter  Ti-ilobite,  preserved  its  real  shell,  partially  at 
least.  This  shell  is  punctated  with  little  indentations  at  all  parts  where  it  has  not  been  damaged,  but 
the  punctation  is  luieven,  so  that  the  largest  indentations  are  situated  immediately  at  the  circumference 
of  the  real  cephalic  shield,  where  the  flat  border  proceeds  from  it ;  and  they  decrease  in  size  from  this 
point  both  towai-ds  the  inner  and  outer  part.  A  fine  mai-ginal  ridge  runs  quite  round  the  open  margin 
of  the  border,  and  before  it  there  is  a  row  of  larger  indentations.  The  eyes  are  wanting  in  the  speci- 
men I  possess,  but  their  places  are  indicated. 

2.  Count  Sternberg  first  described  a  species  of  this  genus  as  TrUobiles  unyula  {Verhandl.  d.vaterl. 
Mus.  1833.  52,  Fig.  1),  in  which  at  least  twenty  body  rings  were  perfectly  distinct.  From  this  Goldfuss 
constituted  the  genus  {Nova  act.  Phys.  Med.  Soc.  Caes.  Leop.  Carol,  nat.  cur.  vol.  xix,  p.  1,  358,  Table 
XXXIll,  Fig.  2,  a,  b,  c),  and  gave  a  more  accurate  account  of  the  organization,  which  was,  howe\cr, 
ah-eady  known.  According  to  him  there  arc  twenty-eight  body  rings.  Count  Älünster  endeavoured  to 
enrich  the  genus  by  new  species  [Bcitr.  z.  Pctref.  Parts  III  and  V) ;  but  it  appears  to  me  that  he  has 
often  merely  taken  individual  differences  for  specific  characters.  This  is  the  more  likely  since  all  his 
specimens,  as  also  those  of  Sternberg,  probably  consist  of  mere  impressions,  without  any  remains  of  the 
shell.      At  present,  therefore,  I  can  admit  only  the  following  species  :t 

H.  tmgula  :  Limbo  scuti  cephalici  antice  latiori,  punctate  ;  punctis  internis  majoribus,  foraminulosis. 
Long,  sine  corp.  l>^-2",  cum  corp.  2-23^".      Table  I,  Fig.  11. 

Otarion  pygmaeum,  Münster  (/.  c.  V,  115,  Table  X,  Fig.  11),  appears  to  me  to  have  been  a  very 
young,  but  mutilated  indi-iddual;  Otar.  eleyans  (ibid.  I,  Table  X,  Fig.  2)  an  older  individual,  but  also 
mutilated;  Harpes  macrocephalus,  Goldf.  (/.  c.  359,  Table  XXX,  Fig.  2,  a,  b,  c),  and  the  figure  given 
in  this  work,  represent  full-grown,  perfect  individuals. 

Goldfuss's  description  is  detailed  and  correct ;  and  as  my  specimen  is  not  so  well  preserved,  I  will 
repeat  his  words  : 

"The  inverted  egg-shaped  body  is  depressed,  but  the  head  is  considerably  elevated,  and 
occupies  more  than  a  third  of  the  length  of  the  whole  animal.  Its  circumference  is  semi- 
circular, and  it  is  suiTounded  by  a  broad  margin,  which  at  the  anterior  part  is  horizontally 

*  Portlock  [vuh  Keport,  &c..  Tab.  V)  has  published  figures  which  prove  beyond  a  doubt  that  the 
genus  Harpes  belonged  to  that  group  of  Trüobites  capable  of  rolling  themselves  into  a  ball.  It  cannot 
therefore  be  brought  iuto  auy  near  relation  with  Trinucleus,  as  Portlock  supposes,  and  as  Loven  has 
endeavoiu-ed  to  prove  {Ofvers,  &c.  105). 

t  I  no  longer  hold  this  view,  and  am  now  much  rather  inclined  to  regard  both  Portlock's  species 
as  perfectly  distinct ;  and  I  also  am  willing  to  admit  at  least  two  of  Count  Miiuster's  species.  That 
represented  in  Table  V,  Fig.  19,  23,  is  one  of  these ;  and  the  other  is  that  marked  Fig.  20,  22.  The 
former  reminds  one  of  Harpes  Flanaganni,  of  Portlock  (/.  c.  268,  Plate  \,  Figs.  5-7) ;  the  latter,  of  his 
H.  Doranni  (ibid.  267,  Plate  V,  Fig.  4).  Count  Sternberg's  figure  more  resembles  the  former  than  the 
latter  species. 


76  SYSTEMATIC  ARRANGEMENT 

extended,  but  assumes  a  more  vertical  position  at  the  sides,  and  terminates  at  each  side  in 
a  point,  which  is  produced  posteriorly  for  three  fourths  the  length  of  the  animal.  Its  border 
is  rather  thickened,  and  forms  (both  on  its  upper  and  lower  reduplication)  an  elevated 
bordering  line.  From  this  horseshoe-formed  extension  of  the  margin,  the  head  rises  ante- 
riorly and  laterally  with  a  somewhat  steep  elevation,  and  in  the  middle  of  the  elevated  part 
it  has  an  oval  protuberance  in  the  manner  of  a  forehead,  which  is  surrounded  by  an  im- 
pressed furrow,  and  which  does  not  descend  to  the  expanded  margin.  It  forms  a  keel  (a 
very  slight  one,  Akc.)  at  its  highest  part,  and  exhibits  a  slight  fold  in  front  of  the  furrow  on 
the  summit.  A  small  semicircular  eye-tubercle  is  situated  on  each  of  the  large  cheeks, 
almost  at  the  anterior  extremity  of  this  fold,  and  close  to  it.  Even  with  the  naked  eye  one 
can  distinguish  a  somewhat  larger  round  protuberance  at  the  centre  of  this  eye-tubercle,  and 
two  oval  ones  of  the  same  size  on  both  sides.*  Behind  them  may  be  discovered,  with  the 
assistance  of  a  microscope,  other  small  tubercles  in  regular  rows. 

"The  head  terminates  posteriorly  in  a  small  protuberant  half-ring,  to  which  the  joints 
of  the  central  body  are  united.  The  protuberance  of  the  forehead  and  the  summit  of  the 
cheeks  above  the  eyes,  are  smooth  ;  and  it  is  only  upon  the  furrow  of  the  former  that  a  few 
small  granulations  are  perceptible.  The  rest  of  the  surface  of  the  head  is  thickly  granu- 
lated, so  that  the  boundary  towards  the  smooth  forehead  is  distinctly  marked,  f 

"  The  expansion  of  the  margin  is  prettily  ornamented  by  a  row  of  larger  granulations 
on  the  surface,  both  of  its  upper  and  lower  plate,  and  as  well  at  the  external  as  internal 
margin  (i.  e.  in  the  cast ;  in  the  true  shell  there  are  corresponding  indentations,  and  no 
granulations,  Auc) 

"  From  the  head  to  the  side  of  the  tail,  twenty-eight  segments  may  be  counted, 
becoming  gradually  and  uniformly  shorter  towards  the  posterior  part.  Whether  there  is 
also  a  small  simple  caudal  shield  without  ribs,  cannot  be  determined  from  the  specimens 
before  us.  The  high  convex  spine  (the  axis)  occupies  a  third  part  of  the  whole  breadth, 
and  its  segments  are  ring-shaped;  the  ribs,  however  (lateral  lobes),  have  only  a  fiat 
longitudinal  furrow,  are  closely  united,  and  form  a  flat  expansion  at  each  side.  Their  short 
ends  are  obtusely  pointed  and  bent  downwards  at  an  angle,  so  that  the  body  exhibits  a 
narrow  border.  The  anterior  ribs  (lateral  lobes)  increase  gradually  in  length^  as  far  as  the 
seventh  or  eighth,  and  the  rest  become  gradually  narrowed  again  behind  them.  The  spine 
is  granulated,  but  the  sides  are  quite  smooth." 

The  specimen  in  my  possession  has  no  trace  of  body  rings ;  but  I  suppose  from  the  analogy  of 
the  cephalic  shield  that  the  rings  of  the  axis  were  also  without  granules,  and  merely  ornamented  with 
punctiu'es,  Auc. 

*  These  parts  are  absent  in  the  specimen  which  I  possess ;  judging  from  the  figure,  I  should 
suppose  that  only  the  two  oval  spots  are  real  eyes,  and  that  the  warts  are  little  prominences  on  the 
shell.      This  genus  would  otherwise  be  characterized  by  four  eyes,  two  on  either  side. 

t  Goldfuss  is  here  describing  an  impression  without  the  shell,  in  fact,  a  cast  in  which  all  the 
indentations  of  the  real  shell  appear  as  protuberances  and  granulations.  In  the  same  way  Count 
Münster  describes  young  individuals  for  his  Trinuclens. 

X   The  breadth  is  from  left  to  right. 


OF  THE  SPECIES.  77 

II. 

Trilobites  having  the  poiücr  of  rolling  themselves  info  a  haU. 

The  distinctive  character  of  this  second,  more  numerous,  and  principal  group  of  Trilo- 
bites is  to  be  sought  for  in  the  structure  of  the  lateral  lobes  of  the  joints  of  the  body,  which 
at  first  are  continued  horizontally,  but  are  afterwards  more  or  less  curved  vertically  downward. 
At  the  point  of  curvature  there  appears  to  be  a  kind  of  articulation  between  two  successive 
joints,  or,  at  least,  there  is  a  very  accurate  insertion  of  one  into  the  other. 

The  lobe  from  this  point  becomes  broader  outwards  and  downwards,  ceases  to  be  con- 
nected with  the  adjacent  ones,  and  makes  a  turn,  its  anterior  edge  being  directed  obliquely 
inwards,  to  find  room  by  the  side  of  the  next  preceding.  It  thus  has  a  surface  somewhat 
turned  forwards,  obliquely  placed,  and  gradually  widening  below,  extending  hence  to  the 
posterior  margin  of  the  lobe,  and  only  leaving  a  very  small  space  for  the  true  upper  or 
external  side.  This  space  also,  the  true  external  surface,  gradually  diminishes  from  the 
point  of  articulation  of  the  two  lobes,  and  extends  to  the  posterior  margin ;  it  is  usually 
rather  strongly  arched,  and  divided  by  a  diagonal  furrow,  which  proceeds  from  the  anterior 
angle,  close  beside  the  rings  of  the  axis,  and  likewise  bends  towards  the  external  posterior 
angle.  The  anterior  sharper  margin  of  this  furrow  forms  at  the  same  time  the  edge,  at 
which  the  oblique,  but  always  flat,  anterior  surface  meets  with  the  posterior  or  upper  sur- 
face. When  the  animal  rolls  itself  up,  the  lateral  lobes  were  passed  one  under  another  from 
the  point  of  articulation,  each  preceding  lobe  covering  the  oblique  surface  of  the  next  so 
completely,  that  nothing  could  be  seen  of  the  roUed-up  animal  except  the  convex  posterior 
portion.  I  shall  henceforth  always  call  the  surface,  which  is  covered  during  the  rolling-up 
process,  the  anterior,  and,  on  the  other  hand,  the  one  which  remains  externally  visible,  the 
external  part;  the  former  being  manifestly  intended  to  be  concealed,  since  it  is  usually 
covered  by  the  parallel  punctured  furrows  which  are  found  in  all  Trilobites  at  the  lower 
surface  of  the  shell,  where  exposed. 

Such  punctures  are  never  absent  in  well-preserved  specimens ;  but  the  oblique  diagonal 
furrow  on  the  upper  side  of  the  rings,  on  the  other  hand,  is  deficient  in  some  genera  {lllanus 
and  Nileus).  The  boundary  between  the  rings  of  the  axis  and  the  lateral  lobes  is  also  more 
indistinct  when  such  is  the  case. 

There  are,  however,  other  characters  also  more  or  less  directly  connected  with  the 
power  of  the  animal  to  roll  itself  up.     As  such,  we  may  enumerate — 

1.  The  much  lai'ger  and  more  projecting  eyes,  a  character  which,  since  it  is  wanting  in 
the  previous  gi'oup,  has  led  to  the  assertion,  that  most  of  the  members  of  this  group  were 
blind  ;  I  have,  however,  recognized  the  eyes  in  almost  all  of  them  (except,  indeed,  Trinucleus), 
and  thus  refuted,  I  hope  satisfactorily,  the  notion  of  blind  Trilobites. 

2.  The  tougher  nature  of  the  horny  membrane.  It  is  at  least  remarkable  that  this  part 
is  preserved  in  a  fossil  state  in  almost  all  the  members  of  this  group,  while  in  the  members 
of  the  former  group  it  is  only  met  with  when  the  remains  are  found  in  limestones.  The 
Trilobites  of  this  second  group,  however,  occur  chiefly  in  limestone,  and  the  preservation 
of  their  shell  may  therefore  be  owing  to  that  circumstance. 


78  SYSTEMATIC  ARRANGEMENT 

3.  The  fact  that  the  size  and  shape  of  the  caudal  shield  correspond  pretty  nearly  with 
the  size  and  shape  of  the  cephalic  shield.  This  is  no  doubt  the  case  also  in  Ogyyki,  and 
partially  in  Trinudeus,  but  less  generally  than  in  the  present  group.  We  shall  rarely 
meet  with  forms  in  which  the  caudal  shield  is  much  smaller  than  the  cephalic  shield;  and, 
on  the  other  hand,  we  shall  find  some  species  in  which  the  former  is  the  greater  of  the  two. 
The  size  of  the  caudal  shield  can  scarcely  therefore  afford  any  safe  inference  with  regard 
to  the  power  of  the  animal  to  roll  itself  up. 

Since  most  of  the  members  of  this  group  are  found  in  limestones,  they  appear,  upon 
the  whole,  to  be  of  less  ancient  date  than  the  members  of  the  previous  group  ;  the  oldest 
forms  are  those  from  the  limestones  of  the  lower  Silurian  system,  as  are  also  the  genera 
Amjji/x,  Asaphim,  and  lUcenus,  taking  them  in  their  correct  limits ;  some  peculiar  species  are 
also  said  to  have  been  found  in  Tafel-schiefer. 

Calymene  and  Fhacops  follow  next,  but  the  different  species  range  through  all  the 
stages  of  the  Silurian  formation.  Certain  genera  furnished  with  nine  or  ten  body  rings  and 
a  highly  convex,  axis,  are,  however,  decidedly  more  modei'n,  and  seem  to  form  the  last  link 
in  the  series  of  creation  of  these  forms.  With  regard  to  the  division  of  this  very  natural 
group  into  subordinate  genera  there  appears  to  be  one  fact  which  has  hitherto  always  been 
overlooked  ;  namely,  the  nature  of  the  shell.  I  have  already  alluded  to  this,  and  have 
shown,  when  treating  of  general  considerations,  that  many  Trilobites  which  now  appear  to 
us  to  be  smooth,  were  furnished  during  life  with  a  peculiar  granulated  layer ;  that  others, 
on  the  other  hand,  had  a  peculiar  sculpture  and  punctation  in  the  shell  itself,  which  is 
incompatible  with  the  presence  of  a  special  upper  membrane.  Pursuing  this  idea,  we 
discover  that  Trilobites  with  distinct  granulations  always  possess  a  more  than  ten-jointed 
axis  of  the  body,  which  in  that  case  contracts  very  much  posteriorly ;  the  Trilobites 
without  granulation,  on  the  other  hand,  never  have  more,  and  usually  exhibit  less  than  ten 
joints,  of  equal  width  in  the  body.  Hence  I  believe  myself  justified  in  assuming  that  all 
Trilobites,  furnished  with  an  axis  of  ten  joints  which  gradually  becomes  smaller  towards 
the  posterior  part,  possessed  a  granulated  upper  membrane,  while  those  furnished  with  a 
fewer  number  of  joints  possessed  a  truly  punctated  or  sculptured  shell.  There  are,  however, 
in  both  groups,  genera  in  which  the  number  of  joints  is  ten. 

This  difference  becomes  yet  more  marked  when  we  consider  that  the  Trilolsitcs  not 
granvdated  occur  only  in  the  most  ancient  and  the  newest  Palfeozoic  strata,  while  those,  on 
the  other  hand,  which  are  granulated,  are  found  in  the  middle  beds  of  that  series.  I  have 
employed  this  structure  as  a  permanent  principle  of  classification,*  and  thus  form  two 
subdivisions  of  Trilobites  having  the  power  of  rolling  themselves  up. 

*  Dr.  Beyrich  lias  questioned  the  value  of  this  distinction,  because  in  the  genus  Bronteus  some 
species  have  a  granulated,  and  others  a  lineated  surface  of  the  shell.  But  this  genus  belongs  to  the 
group  of  Trilobites  not  rolling  themselves  up,  and  does  not  therefore  affect  the  question  with  regard 
to  the  other  group  in  which  we  make  use  of  the  principle.  A  more  important  objection  would  appear 
to  be,  that  certain  species  of  Archegonus  or  PhilHpsia  are  granulated,  and  others  lineated,  since  these 
genera  do  roll  themselves  up.  It  seems  that  in  this  genus,  the  last  effort  of  a  once  numerous  group, 
the  character  in  question  has  degenerated  into  a  mere  specific  distinction,  although  once  distinctive  of 
the  main  divisions  of  the  genera, 


OF  THE  SPECIES.  79 


Trilohifes  having  the  poiccr  of  rolling  t/icnwelves  into  a  ball,  with  the  axis  of  the  body  contracted 
posteriorh/,  the  shell  (/ranulated,  and  generally  more  than  ten  body  rings*     Calymenid^E. 

This  natural  section  I  formerly  subdivided  according  to  the  number  of  body  rings  into 
three  genera,  having  respectively  thirteen  joints,  eleven  joints,  and  ten  joints.  There  have 
since,  howe\er,  been  found  forms  which  render  this  method  of  grouping  unadvisable,  and  I 
now  prefer  taking  the  course  of  the  facial  suture  as  the  basis  of  arrangement. 


Trilobites  capable  of  rolling  themselves  up,  and  whose  facial  suture  terminates  exactly  in 
the  angles  of  the  cephalic  shield. 

It  appears  that  there  arc  but  two  genera  that  can  be  included  in  tiiis  subdivision,  and 
for  these  I  retain  the  names  of  Calymene  and  Ilomalonotus.  They  are  distinguished  from  one 
another  by  the  cephalic  shield,  which  in  Calymene  is  furnished  with  a  reflexed  margin,  over 
which  the  anterior  extremity  of  the  facial  line  extends ;  whilst  a  flat  expanded  margin  is 
found  in  Homalonotus,  the  anterior  ends  of  the  facial  line  meeting  in  the  centre  of  the 
margin  of  the  forehead,  before  the  glabella.  Other  differences  accompany  this  principal 
one,  and  justify  the  separation  of  the  genera. 

Genus  11. — Calymene,  Brongniart,f  (Amphion  and  Zethus,  Pander). 

Cephalic  shield  semilunate,  rather  strongly  convex,  furnished  with  a  margin  which  is 
reflected  all  round,  the  largest  and  anterior  division  usually  broken  ofl'.  The  glabella, 
which  is  always  rather  contracted  towards  the  anterior  part,  has  a  high,  much  reflected 
margin  of  articulation,  and  besides  this  always  two  or  three  sulcations  at  each  side,  by 
which  it  is  divided  into  three  or  four  lobes.  If  only  two  sulcations  are  present,  then  it  is 
the  anterior  one  which  is  wanting.  The  hindermost  lobe  of  each  side  is  the  largest,  and 
considerably  arched  ;  the  second  from  the  posterior  extremity  is  next  in  point  of  magnitude  ; 
the  third  is  usually  the  smallest,  and  frequently  very  imperfectly  separated  from  the  last  or 
anterior  one,  especially  in  the  most  common  species,  C.  Blumenbachii.  The  cheeks  extend 
by  the  side  of  the  glabella  as  independent  convex  plates,  and  bear  strongly  projecting  but 
not  very  large  eyes,  the  horny  membrane  of  which  is  either  wanting  or  pressed  in.  They 
are  placed  sometimes  on  the  centre    (C  Blumenbachii),    sometimes  on  the  anterior  half  of 

*  As  additional  characteristics,  it  may  be  stated  that  the  members  of  tliis  group  ahvays  exhibit  a 
highly  arched  caudal  axis,  with  distinct  rings  and  radiated  lateral  furrows  proceecUng  from  it.  These 
furrows  are  absent,  if  not  in  both,  at  least  iu  the  second  group  of  the  second  division.  The  glabella 
likewise  has  (with  only  two  exceptions)  lateral  fuiTows  and  lobes. 

t  If  Murcbison's  figure  of  C.  variolaris  {Sil.  Syst.  PI.  XIV,  Fig.  1)  be  correct,  the  animal  had 
thirteen  body  rings,  and  l)elongs  to  this  division.  Preceding  authors,  as  Parkinson  (Org.  Rem.  iii,  PI. 
XVII,  Fig.  16)  and  Brongniart  {Cr.fos.  PI.  I,  Fig.  3,)  enumerate  only  eleven,  indicating  an  affinity 
with  Phacops. 


80  SYSTEMATIC  ARRANGEMENT 

the  cheeks,  and  are  in  that  case  either  more  or  less  pushed  inwards  (C.  Trisfnni)  or 
outwards.  The  facial  line  projects  forwards  at  the  level  of  the  eyes  over  the  anterior 
margin  of  the  head ;  it  is,  however,  connected  at  the  side  of  the  latter,  which  is  turned 
under  or  anteriorly  downwards  by  a  diagonal  suture  running  parallel  with  the  margin 
itself,  with  its  neighbour  at  the  other  side.  From  the  point  where  both  enter  over  the 
margin,  they  run  almost  parallel  with  each  other  towards  the  eye,  form  over  it  the  covering 
plate,  and  turn  from  its  posterior  boundary  in  an  S-shaped  diagonal  direction  over  the 
sides  of  the  cheeks,  continuing  their  course  towards  the  posterior  corner  of  the  cephalic 
shield,  which  they  divide  exactly  in  its  angle.  The  cheek-shield  thereby  assumes  a  narrow 
form,  which  is  obtuse  at  the  anterior,  and  pointed  at  the  posterior  part.  The  posterior 
angle  of  the  cephalic  shield  is  always  obtuse,  rounded,  and  not  projecting. 

The  thirteen  body  rings  have  a  very  convex  axis,  the  separate  members  of  which  are 
very  convex  :  they  become  gradually  more  narrow  towards  the  posterior  part.  The  lateral 
lobes  are  abruptly  separated  from  the  axis,  are  very  convex,  and  their  oblique  impression  is 
very  strong,  but  short. 

The  caudal  shield  is  always  narrower,  but  sometimes  longer  than  the  cephalic  shield, 
and  is  embraced  during  the  doubling-up  process  by  the  reflexed  margin  of  the  latter;  it  has  a 
distinct,  prominent,  seven,  nine,  or  eleven-jointed  axis,  Vv'hich  is  narrowed  towards  the  posterior 
part,  and  rounded,  and  has  the  same  number  of  lateral  protuberances,  or  perhaps  one  less, 
which  from  the  centre  appear  to  be  furcated.  The  free  margin  of  the  cephalic  shield  is 
only  slightly  enlarged. 

The  upper  side  of  the  whole  of  the  back  was  covered  during  life  with  a  tolerably  strong, 
unequally  granulated,  membrane,  which  in  well  preserved  individuals  can  still  be  seen  quite 
distinctly ;  it  is,  however,  more  frequently  absent.  The  granulation  appears  to  have  been 
most  distinct  on  the  cephalic  shield,  and  on  the  axis  of  the  body. 

Species  are  found  in  clayslate  {Ccdymene  Trisfani),  in  the  very  oldest  limestones  (C. 
poli/foma,  Dalm.),  and  in  the  whole  Silurian  system  to  its  uppermost  strata.  The  most 
common  species,  C.  BhimenbacJiii,  has  a  very  wide  range,  and  is  found  in  Europe,  in  South 
Africa,  and  North  America. 

1.  C.  Trist  am :  Limbo  scuto  cephalici  antico  valde  reflexo,  integro,  oculis  altissimis  iuternis  ; 
tuberculo  capitis  utrinque  quadrilobato.      Long.  3-3."  Table  II,  Pigs.  7,  8. 

Bef. — Tristan,  Jour»,  des.  Mines,  tom.   xxiii,  page  21.     Brongn.    Or.  foss.    12.  PI.  I, 

Fig.  2,  A-K.     ScHLOTH.  jYac/ifr.  ii,   14.   2.  23.   2  and  40,  Tab.  XXII,  Fig.   5. 

Dalm.  Falcead  62.  3.      Emmr.  Dissert.  39.  4.     Milne   Edw.    Crust,   iii,  320.   5. 

Zethus   verrucosus,   Pander,    Beitr.    etc.    139,   Tab.  IV,  C,  Fig.  4,   and   Tab.  V, 

Fig.  6. 
Cephalic  shield  strongly  granulated  when  the  shell  is  well  preserved ;  furnished  with 
tubercles,  or  smooth ;  the  glabella  contracted  anteriorly,  with  an  extremity  which  is  rather 
straightly  truncated  and  slightly  curved :  at  each  side  there  are  three  distinct  furrows, 
which  divide  it  into  four  almost  equal  lobes,  becoming  somewhat  narrower  towards  the 
anterior  part ;  the  lateral  portions  are  very  convex  ;  the  eyes  are  placed  close  to  the 
glabella,  and  affixed  beside  the  second  lobe  ;  the  enlarged  margin  of  the  head  is  remarkably 
prominent,  the  centre  of  the  anterior  margin  is  erected  or  reflexed,  the  lateral  lobes,  on  the 


OF  THE  SPECIES.  81 

other  h.and,  are  more  strongly  turned  downwards ;  wlien  the  animal  is  rolled  up  they 
embrace  the  caudal  shield,  so  that  the  latter  fits  into  tlie  wide  gap  between  tliem  and  the 
raised-up  centre.  The  rings  of  the  back  are  highly  arched,  but  without  peculiarities  in 
other  respects.  Caudal  shield  oblong,  triangular,  the  extremity  prominent,  and  projecting 
considerably  beyond  the  axis  ;  the  latter  seven-jointed,  and  furnished  with  an  indistinct 
terminal  joint ;  the  sides  furnished  with  elevated,  radial  protuberances,  which  are  furcated 
as  far  as  beyond  the  centi'e. 

Locality. — The  clayslate  of  Angers  {Bed.  Mus.),  Nantes,  the  Cotentin.  Found  also  at 
Valognes  and  Cherbourg ;  in  the  transition  limestone  of  Esthonia,  near  Revel,  and  Zarskoe 
Selo,  also  in  boulders  ( Collection  at  Halle) . 

Remarks. — 1.  There  is  no  doubt  whatever  that  Zetfius  verrucosus  of  Pander  is  identical  with 
Cahjmene  Tristam ;  the  structm-e  of  the  glabella  is  quite  the  same. 

2.  The  caudal  shield  represented  by  Schlotheim  {ante  cit.)  probably  belongs  to  this  species. 

2.  C.  Polytoma :  Limbo  scuti  cephalici  antico  crenato  ;  tuberculo  capitis  antice  latiori,  in  apice 
quadrilobato.      Long.  2-3." 

Äp/.— Dalm.  Palcead.  37,  Tab.  I,  Fig.  1,  a-c.     Emmr.  Bissert.  38.  2.      Milne  Edw. 

Crust,  iii,  321.  6.      L.  v.  Buch,  Bcitr.  4.5.      Asapkus  Fischeri,  Eichwald,  Dissert. 

52,  §  58.  Tab.   Ill,   Fig.  2,  a.  b.      Calymene  frmitiloba,  Stschegloff.      Amphion 

frontiloha,  Pander.  Beitr.  139,  Tab.  IV,  Fig.  1  ;  Tab.  IV,  B,  Figs.  5,  6,  7 ;  Tab.  V, 

Figs.  3,  ff,  h,  and  8. 

Cephalic  shield  less  convex  than  in  the  preceding  species,  and  the  lateral  lobes  less 
turned  downwards ;  the  glabella  broader  towards  the  anterior  part,  furnished  with  two 
lateral  sulcations,  dividing  it  into  three  lobes,  that  are  broader  anteriorly ;  between  the  two 
anterior  lobes  there  are  three  radiating  furrows  directed  towards  the  centre  of  the  head, 
which  separate  two  smaller  central  lobes  from  the  external  ones.  The  enlarged  border  at 
the  anterior  margin  is  divided  by  eight  furrows  into  nine  rather  acute  notches  or  teeth, 
which  very  readily  break  oS",  and  are  therefore  wanting  in  many  specimens.  Eyes  of  a 
moderate  size,  placed  in  the  line  of  the  posterior  lateral  sulcation,  projecting  very  far 
outwards,  and  inclosed  by  the  indented  facial  line.  Beneath  them  there  seems  to  be 
another  marginal  concentric  furrow.  Body  rings  strongly  arched,  rather  short.  Caudal 
shield  long,  trilateral,  rather  acuminate  ;  the  axis  many-jointed  (eleven-jointed  according  to 
Dalman's  figure  and  Eichwald's  enumeration),  and  reaches  almost  as  far  as  the  end ;  the 
lateral  folds  probably  not  furcated  (at  least  the  figures  indicate  no  such  division). 

Loc. — The  red  transition  limestone  of  East  Gothland  and  Esthonia ;  I  have  not  myself 
seen  a  specimen. 

Remark. — The  specimen  represented  by  Dalman  was  deficient  in  the  margin  of  the  head,  and  so 
also  was  that  figui-ed  by  Pander,  Table  V,  B,  Fig.  3.  The  presence  of  this  notched  margin,  and  the 
somewhat  different  structure  of  the  glabella,  scarcely  justify  the  constitution  of  a  peculiar  genus,  as 
suggested  by  Pander  (who,  however,  seems  to  think  his  species  different  from  Dalman's).  His 
enumeration  of  the  body  rings  (twenty  in  the  body,  four  in  the  tail)  is  erroneous  ;  Eichwald  had 
already  enumerated  them  correctly. 

3.  C.  Blumenhacliii  :  Limbo  scuti  cephalici  antico  integro  ;  tuberculo  capitis  subquadrilobo  antico 
sive  ultimo  maxima,  penultimo  appeudiculato.      Long.  1)4-3".     Table  II,  Figs.  1-3. 

Bef. — Ch.   Lyttelton,   P/til.    Trans,    vol.  xlvi,  p.    598,  PI.    I,  II.       C.  Moktimeh, 

II 


82  SYSTEMATIC  AKRANGEMEXT 

ibid    600.      Em.   Mendez    da    Costa,  Phil.  Trans,    vol.   xlviii,   p.     286.      I. 

ToRRUBiA,   Jpp.   P-   L.    Hist.    N.    Espan.    pp.   83,    13,   n.    96,   Com.   iii,   n.   4. 

GuETTARD,  Mem.  de  V Acad.  Poy.  des  Sei.  torn,  xv,  PI.  IX  (VII),  Fig.  2.     Wilkens, 

Stralsund  Magas.  i,  4,  Tab.  I,  Figs.  A-2.      Klein,  Sjwc.  Descr.  j)etrpf.  Gedan.  Tab. 

XV,  Fio-s.  5-7.      J.  J.  Walch,  Text  zu  Knorrs  Abbild,  d.    Fersfein,  vol.  iii,  p.  222, 

Tab.  IX,  Figs.  1-5.      Beckmann,  Nov.   Conim.   Soc.   Peg.   Göttingen,  torn,   iii,  pp. 

101-2.     Tril.  fuberculatus.  Brünnich,  Nga.  Sand.  etc.  i,  389.  1.     Gehler,  Progr. 

&r.    6.   Fio-s.   I-V.      Blumenbach,   Abbild.    ?iaturk.    Gegenst.  i.  Tab.   L.   Entom. 

paradoxus,  Parkinson,  Org.  Bern,  iii,  PI.  XVII,  Figs.  11,  13,  14.      Schlotheim, 

Petref.  p.  39.  2.      Wahlenberg,  iV.  A.  f^«.  viii,  31.  6.  Ent.  tuber culattis,  Calymene 

Blumenbachii,  Brongn.  Or.  foss.  11.1.  PL  I,  Fig.  8,  A-C.     Schloth.  Nachtr.  ii, 

13.  1.  and  33.  1.     Dalm.  Palcead.  35.  1,  Tab.  I,  Figs.  2.  3.  a-c.     Payton,  Tril.  of 

Dudley,  Fig,  14.   Cal.  Blumenb.  Green,  Mon.  28.  KLÖDEN.Fe/'sA  d.  Mark  Brand.  105. 

Harlan,  Med.  and  Pliys.  Research.  300.    Murchison,  Silur.  Syst.  ii,  653.  PI.  VII, 

Figs.  5-7.     BuCKLAND,  Bridg.  Tr.  p.  46.   Figs.    1-3.     Bronn,  Lethaa,  i,  110.  99, 

Tab.  IX,  Fig.  3.    Hisinger,  Leth.  Suec.  10,  Tab.  I,  Figs.  3-4.    Boeck,  Gaea.  Norw.  i, 

710.  16.     Quenstedt,    Weigmamis  Archiv,   1835,  i,  342.     Emmr.  Dissert.  39.  3. 

L.  V.  Buch,  Beitr.  z.  Geog.  Bussland,  47.     Milne  Edwards,  Crust,  iii,  318,  1. 

Cephalic  shield  lunate,  the  margin   strongly  reflexed  but  simple,  thickened  beneath ; 

o-labella  indistinctly  four-lobed,  the  first  anterior  lobe  larger  than  the  second,  which  is  not 

so  much  separated  from  it  as  from  the  third ;  the  latter  highly  convex,  but  smaller  than  the 

fourth  and  posterior  one.     Eyes  at  the  centre  of  the  cheeks,  not  very  prominent,  placed  on 

a  line  with  the  third  lobe  ;  posterior  margin  of  articulation  much  more  narrow  than  the  lobe 

preceding  it.      Thirteen   rings    in  the  body,  which  become  successively  smaller,  without 

presenting  any  peculiarities.     Caudal  shield  considerably  smaller  than  the  cephalic  shield, 

the  axis  short,   broad,  seven-jointed,   the  two  last  joints   indistinctly  separated,  the  sides 

furnished  with  six  radiating  furrows,  with  intermediate  ones  along  the  whole  length  of  the 

four  central  ones.     The  whole  surface  finely  granulated  in   well-preserved  fragments  (var. 

pulchella,  Dalman,  /.  c.  Fig.  3),  but    more  generally  smooth,  owing  to   the  uppermost  layer 

of  the  shell  being  absent. 

Remarks. — 1.  I  have  compared  all  the  authors  quoted,  as  far  as  tliey  were  accessilile  to  me,  and 
conv-inced  myself  that  they  all  treat  of  this  species.  The  figures  of  Brongniart  marked  A,  B,  and  of 
Murchison,  are  the  only  ones  sufficiently  accurate  ;  in  all  the  others  the  boundaries  between  tail  and 
body  cannot  be  recognized  with  sufficient  distinctness.  Dalman's  figure  with  ten  body  rings  is 
erroneous,  and  as  erroneously  copied  by  Hisinger. 

2.  Zet/ius  verrucosus  of  Pander,  which  M.  v.  Buch  considers  as  belonging  to  this  species,  I  have 
preferred  enumerating  under  Cal.  Tristani ;  his  Z.  uniplicatus  (Beitrage  z.  Geogn.  d.  lluss.  Reus.  138, 
Tab.  V,  Fig.  7),  with  which  the  representation  of  Razoumowsky  (Ann.  Sc.  Nat.  viii,  PL  XXVIII,  Fig.  4) 
seems  to  correspond,  has  as  little  relation  to  this  species.  The  glabella  differs  too  much  in  both 
figures  to  permit  of  their  being  referred  to  Calymene  Blumenbachii,  even  supposing  it  to  have  been 
imperfect  iu  the  specimens  that  were  examined  by  the  authors  cited.  The  species  must  therefore  be 
regarded  as  distinct. 

3.  C.  platijs,  Green,  Mon.  32,  Milne  Edw.  Cr.  I.  c.  320.  4,  I  take  to  be  a  large  specimen  of  C. 
Blumenbachii,  with  perfect  granulations. 

4.  The  numerous  references  above  given  sufficiently  prove  that  this  species  is  ^ddely  extended  ; 
it  i.s,  however,  only  found  in  limestones,*  and  if  its  relation  in  this  respect  in  England  can  be  assumed 

*  Not  so  in  England. — Editors. 


OF  THE  SPECIES.  83 

as  general,  it  belongs  especially  to  the  upper  and  middle  Silurian  strata  {Ludlow,  Dudley,  IVenlock). 
In  Sweden  it  is  only  found  in  the  limestone  of  Gothland,  which  is  wanting  in  Esthonia.  In  Germany 
it  seems  to  occur  in  only  travelled  fragments,  and  appears  to  have  been  transported  from  the  Scandi- 
navian mountains.  Torrubia  found  it  in  Spain,  on  the  frontier  of  Pardos,  two  leagues  from  Molina 
de  Arragon.  In  North  America  it  is  found  in  difl'erent  places,  especially  near  Lebanon,  in  the  state 
of  Ohio,  and  at  Trenton  Falls,  in  New  York.  JSIurchison  also  mentions  specimens  from  the  Cedar 
Mountain  at  the  Cape  of  Good  Hope. 

4.  C.  caHlcephata  :  Limbo  scuti  cephalici  incrassato,  oculis  altis  extemis,  marginem  superantibus ; 
tuberculo  capitis  utrinque  trUobo :  lobis  posticum  versus  majoribus.     Long.  2}i.     Table  II,  Figs.  9-10. 

Be/. — Green,  Mon.  30.     Milne  Edw.  C'rmi.  iii,  319.  2. 

More  nearly  allied  to  tlie  preceding  species  in  habit,  but  the  cephalic  shield  is  com- 
paratively shorter  and  broader,  the  sides  more  strongly  curved,  the  posterior  angles  more 
turned  backwards.  The  reflexed  margin  is  not  very  strong,  at  least  not  at  the  anterior 
part,  where  it  is  usually  highest.  The  eyes  are  rather  small,  but  are  remarkably  prominent, 
so  that  they  project  from  above  over  the  external  margin  of  the  shield ;  they  are  situated 
at  the  anterior  part  beside  the  front  lobe  of  the  glabella.  This  lobe  is  small  and  very 
narrow ;  the  second  certainly  less  broad,  but  projecting  more  outwards ;  the  third  is 
remarkably  broad,  large,  semicircular,  and  separated  for  the  greater  part  not  only  from  the 
preceding  lobe,  but  also  from  the  axis  of  the  head  by  a  furrow  (as  in  Cal.  Trisfani).  I  have 
not  seen  the  body  and  tail ;  according  to  Green,  the  two  together  consist  of  fourteen  rings, 
in  which  case  only  one  would  belong  to  the  tail ;  the  axis  of  the  latter  is  almost  of  equal 
breadth,  therefore  very  obtuse  at  the  posterior  part,  and  the  lateral  lobes  are  not  furcated. 

Loc. —  Ixi  North  America,  it  occurs  in  Hampshire,  Virginia;  on  the  shores  of  the 
Miamis,  at  Cincinnati ;  and  in  Indiana ;  in  a  blackish  gray  limestone.  This  species  is  not  found 
at  Trenton  Falls,  where  Cal.  Blumeiihacliii  is  so  frequent.  I  saw  a  plaster  cast  of  the  head 
(No  2,  Green)  in  the  Berlin  Natural  History  Cabinet. 

Remarks. — The  other  species,  considered  as  belonging  to  Calymene,  are  arranged  by  me  under 
other  groups. 

1.  Cal.  bellahda.  Dalm.,  and  Cal.  concMm«,  Dalm.,  are  the  representatives  of  two  particular  genera; 
C.  actinura.  has  been  already  mentioned  (p.  69)  and  C.  sclerops  is  a  Phacops.  Of  C.  punctata,  I  know 
only  the  caudal  shield ;  it  forms  according  to  Boeck  (Gaea  Norweg.  13)  a  particular  genus,  including 
also  Cal.  variolaris. 

2.  1  can  give  the  following  explanations  respecting  Green's  various  species :  oi  C.  selenecephala 
(p.  31  ;  Milne  Edw.  320,  3 ;  Emmr.  Diss.  40,  fi)  I  have  seen  a  plaster  cast  (No  3  of  Green),  but 
owing  to  the  badly  preserved  state  of  the  specimen  from  which  it  had  been  taken,  I  could  not  arrive  at 
any  sure  specific  characters.  C.  microps,  Green  (p.  34,  Model  6),  is  a  Phacops,  and  will  be  alluded  to 
more  particularly  under  this  genus.  C.  anchiops  (p.  35,  Model  7)  likewise  belongs  to  the  genus 
Phacops,  but  not  C.  diops,  which  forms  a  separate  genus  with  Cal.  concinna,  Dalm.  C.  macrophthahna 
(p.  89)  is  a  Phacops,  and  C.  Bu/o  (p.  41)  likewise.  C.  odontocephala  (Gr.  Suppl.  p.  9,  Milne  Edw. 
322,  8)  is  likewise  a  Phacops,  but  a  distinct  species. 

3.  Murchison's  Calym.  Downinigice  [Sil.  Syst.  ii,  655,  PI.  XIV,  Fig  3)  and  Cal.  tuberculata  (A  c. 
Fig.  4)  belong  to  Phacops ;  his  Fig.  5,  PI.  XIV,  is  perhaps  the  caudal  shield  of  a  species  of 
the  latter  genus,  and  in  that  case  is  identical  with  Ph.  latifrons,  to  which  C.  tuberndata  decidedly 
belongs.* 

4.  Milne  Edwards's  species  (pp.  318-328)  have  been  already  explained,  with  the  exception  of  Cal. 
Stokesii  (p.  324,  No.  13),  (not  Asaph.  Stokesii  of  Älurchison — Sil.  Syst.  PI.  XIV,  Fig.  6),  which  is  my 
Phacops  latifrons. 

*  The  figure  referred  to  represents  the  tail  of  a  Proetiis. — Editors. 


84  SYSTEMATIC  ARRANGEMENT 


Genus  12. — Homalonotus,  König,  (Trimerus,  Green,  Murchison  ;  Dipleura,  Green.) 

Cephalic  shield  hyperbolic,  the  anterior  angle  rather  acute,  the  lateral  margins  gently 
arched,  the  posterior  margin  tolerably  straight,  without  the  angles  being  extended  back- 
wards ;  the  whole  nppcr  surface  gently  arched,  but  the  region  at  the  external  margin 
and  the  border  at  the  posterior  margin  rather  flatly  expanded ;  the  latter  separated  by  a 
furrow,  slightly  arched.  The  glabella  undivided,  broader  towards  the  posterior  than  at  the 
anterior  part,  and  occupying  about  two  thirds  of  the  posterior  margin.  It  then  conti'acts 
a  little,  and  assumes  a  round  shape  towards  the  anterior  part ;  without  lateral  lobes  and 
sutures,  but  there  is  a  trace  of  a  furrow,  which  issued  from  the  region  where  the  e3'es  are 
situated  beside  the  glabella.  This  furrow  is  produced  backwards  towards  the  central  line, 
and  may  sometimes  be  perceived  with  tolerable  distinctness.  Both  furrows  correspond 
with  the  posterior  furrows  of  the  glabella  of  the  preceding  genus,  and  separate  the  anterior 
cerebral  region,  the  forehead,  from  the  posterior  or  branchial  region. 

Eyes  placed  near  the  centre  of  the  glabella,  just  in  the  centre  of  the  lateral  parts  of  the 
shield,  or  a  little  behind  it,  depressed,  corapai'atively  smaller  than  in  Cahjniene ;  usually 
similarly  excavated. 

Facial  suture  parallel  anteriorly  with  the  margin  of  the  cephalic  shield,  but  apart  from 
the  latter ;  acutely  angular,  terminating  on  the  flat  extension  of  the  cephalic  shield  ;  thence 
turning  in  the  form  of  an  arch  towards  the  eye,  over  which  it  forms  the  well-known  covering 
plate,  and  then  bends  itself  with  an  S-shaped  curvature  towards  the  posterior  lateral  angle, 
which  is  divided  into  two  halves,  either  in  the  angle  itself,  or  before  the  point  towards  the 
outer  side. 

Axis  of  the  body  thirteen-jointed,  decidedly  narrower  towards  the  posterior  part ;  the 
axis  itself  but  slightly  arched,  owing  to  which  the  lateral  lobes  (the  transverse  diameter  of 
which  is  smaller  than  the  transverse  diameter  of  the  axis)  are  not  as  strongly  separated  from 
it  as  usual ;  the  posterior  margin  of  each  separate  ring  of  the  axis  is  produced  forwards, 
acutely  angular,  sometimes  (in  Diplriira)  even  rather  turned  up ;  the  anterior  or  articular 
portion  separated  by  a  more  or  less  impressed  transverse  furrow,  proceeding  from  the 
posterior  part  of  the  ring.  This  character  does  not  belong  to  any  other  genus  of  the  Trilo- 
bites,  and  on  that  account  appears  to  me  a  most  important  and  peculiar  one.* 

Caudal  shield  hyperbolic,  longer,  but  much  more  narrow  than  the  cephalic  shield,  and 

*  In  interpreting  the  fragments  of  tliis  genus,  we  ought  to  be  very  particular  in  obserriug 
whether  the  impressions  of  the  rings  originate  from  the  upper  exposed  surface  of  the  back,  or  from  the 
inner  surface,  which  is  turned  towards  the  soft  part  of  tlic  animal.  lu  the  former  case  the  transverse 
ftirrow,  which  separates  the  articulating  portion  from  the  ring  itself,  appears  as  a  fine  line,  and  thus  it 
has  also  been  represented  in  Murchison's  Figures  (Tables  VII  and  "N'lII,  as  far  as  Figs.  1,  2) ;  in  the 
latter  it  forms  a  deep  broad  furrow,  which  originates  from  a  horny  process  of  the  ring  that  hangs 
downwards  towards  the  inner  part,  and  owing  to  this  process  being  thick,  it  is  also  broadly  and  deeply 
impressed  into  the  matter  inclosing  it.  Thus  appear  Mm-chisou's  Figures  3  and  4  in  Table  VII. 
Hence  it  follows  that  impressions  differing  from  each  other  in  the  manner  described  do  not  indicate 
different  species,  but  different  sides  of  the  shell  of  the  same  species.  My  Figures,  Table  IV,  Figs.  10 
and  11,  show  the  difference  in  the  rings  of  the  shells  of  Homalonotus  and  Calymene  more  particularly, 
and  respecting  their  significance  I  refer  the  reader  to  the  explanations  of  the  plates. 


OF  THE  SPECIES.  85 

proportionalily  smaller ;  its  axis  has  either  no  articulation  at  all,  or  a  distinct  one,  very 
rapidly  narrowed  posteriorly  and  even  at  the  commencement  rather  narrower  than  the  last 
ring  of  the  hody ;  the  external  terminal  angle  more  or  less  prominent. 

Remark. — The  species  of  this  genus  are  amongst  the  largest,  but  also  the  rarest  Trilobites,  and 
seem  to  be  peculiar  to  the  upper  or  central  Silurian  strata.  I  regret  to  say  that  I  have  only  been 
able  to  examine  casts  or  imperfect  specimens.  I  recognized  the  granulation,  however,  iu  botli  most 
distinctly,  where  there  were  any  remains  of  shell;  the  specimens  deficient  in  shell,  on  the  other  hand, 
always  appear  quite  smooth.  According  to  the  proportion  of  axis  and  lateral  lobes,  they  furnish  us 
with  two  subdirisions,  which  most  authors  enumerate  as  distinct  genera. 

A.  BipJeura,  Green.  —  The  outer  end  of  the  facial  suture  cuts  in  half  the  posterior 
angle  itself.  The  joints  of  the  axis  are  not  broader  than  the  lateral  lobes,  and  very  distinctly 
separated  from  the  latter ;  the  latter  have  a  process  at  the  lower  and  outer  extremity,  with 
which  they  passed  beneath  the  open  margin  of  the  cephalic  shield  during  the  rolling-up 
process.  The  posterior  margin  of  each  ring  of  the  axis  is  strongly  reflexed,  and  the  ring  in 
itself  alone  is  highly  arched. 

Caudal  shield  slightly  pointed  or  produced  forwards,  the  axis  without  joints,  the  sides 
even  and  ribless. 

1,  H.  Decaji :  Scuto  capitis  dilatato,  dimidio  latitudine  vix  longiori ;  oculis  ellipticis ;  annulis 
trunci  convexis,  iu  margine  postico  reflexo  dilatatis.      Long.  2K". 

Rpf. — B'qüeum  Dekai/i,  Green,  Moh.  79,  Figs.  8,  9.  Bronn,  Letluea,  i,  1 13.  101 ,  Plate 
IX,  Figs.  6,  7.  Harlan,  Med.  and  PJii/s.  Research.  304.  Emmr.  i)m.  42,  IV. 
RIiLNE  Edw.  Crust,  iii,  316.    Bronn,  Leonh.  and  Br.  Jahrbuch.  1840,  pp.  447  et  seq. 

Found  in  different  parts  of  North  America ;  amongst  other  places  at  Lockport,  Madison, 
Steuben,  Cazenovia,  Rochester,  all  situated  in  the  state  of  New  York ;  also  at  Northumber- 
land, in  Pennsylvania,  and  Mount  Hope,  in  the  vicinity  of  Baltimore.  I  have  only  had  an 
opportunity  of  examining  the  two  plaster  casts  (Nos.  30  and  31)  of  Green's  fragments,  and 
cannot  therefore  give  an  accurate  description.  The  distinct  granulation  and  the  acute 
margins  of  the  body  rings  render  it  certain  that  the  calcareous  shell  remained  in  the  actual 
specimens,  which  fact  agrees  very  well  with  the  absence  of  joints  at  the  caudal  axis.  These 
joints  are  probably  wanting  only  at  the  upper  surface,  and  are  visible  on  the  inner  surface, 
as  is  shown  by  the  smooth  individuals  without  a  calcareous  shell.  Green's  statement  of 
there  being  fourteen  rings  is  based  upon  an  error,  as  the  models  have  only  thirteen ;  for  that 
which  appears  to  be  the  first,  is  the  thickened  posterior  margin  of  the  cephalic  shield. 

B.  Trinierus. — The  outer  extremity  of  the  facial  suture  meets  the  margin  rather  before 
the  angle  of  the  cephalic  shield,  externally.  The  joints  of  the  axis  are  broader  than  the 
lateral  lobes,  very  slightly  separated  from  the  latter,  and  not  reflexed  at  the  posterior  margin; 
a  distinct  transverse  furrow,  which  also  continues  over  the  anterior  surface  of  the  lateral 
lobes,  divides  the  margin  of  articulation  from  the  true  ring. 

Caudal  shield  very  prominent  at  the  end,  the  axis  distinctly  jointed,  the  sides  furnished 
with  ribs. 


86  SYSTEMATIC  ARRANGEMENT 


j_ — Species  without  spines  a)id  tubercles.     Trimerus,  Green  ;  Homalonotus,  König. 

2.  H.  Knightii:  Scuto  caudie  acuminato,  annulis  rhachis  8-9,  costis  lateralibus  6.    Long.  corp.  3-4". 
Re/.—Kö'üiG,  Icones  Sectil.  i,  4,  Plate  VII,  Fig.  85.     Bronn,  Letltaa.  i,  119.  107,  Table 

IX,  Fig.   14.     MuRCHis.  Sil.  Syst.  n,  651,  Plate  VII,  Figs.  1,  2.     Milne  Edw. 

Cr.  iii,  315.     Homalon.  Z?<6?raOT5,  Murch.  ibid.  Figs.  3,  4.     Emmr.  i)me?-;'.  41.  8. 

Bronn,  Leonh.  Jahrb.  1840,  445. 
Found  in  the  grauwacke  strata  of  the  Eifel  at  Daun  (according  to  specimens  in  Sack's 
collection),  and  in  the  upper  Silurian  strata  of  England. 

I  have  examined  only  two  caudal  shields  of  this  species ;  they  are  comparatively  shorter 
and  broader  than  that  of  the  following  species,  the  axis  is  more  flatly  arched,  and  more  dis- 
tinctly pointed  at  the  end,  owing  to  a  furrow  which  surrounds  it.  We  can  recognize  in  it 
seven  distinct  rings,  besides  the  margin  of  articulation ;  there  is  also  an  eighth,  and  indeed, 
even  a  ninth  ring,  but  very  slightly  marked ;  after  which  follows  the  short  triangular  pointed 
extremity.  There  are  six  strong  broad  ribs  on  the  sides.  The  point  of  the  shield  is  broken 
off  in  the  specimen,  but  it  must  have  been  prominent. 

3.  H.  delphinocephalus :  Scuto  caudse  acuminate,  in  apice  reflexo,  annulis  rliachis  11-12,  costis 
lateralibus  8.      Long.  corp.  3-6". 

Bef. — Trim,  delph.  Green,  Mon.  82,  Fig.  1  (Model,  No.  32).  Emmr.  Dissert.  41.  7. 
Bronn,  Lethcea,  i,  112.  100,  Table  IX,  Fig.  5.  Homalon.  delphino-cephalus,  Murch. 
Sil.  Si/st.  ii,  651,  Plate  VII,  to  Figs.  1,  2.  Milne  Edw.  Crust,  iii,  314.  1.  Homalo. 
Ahrendi,  RoMER.  Verst.  des  Harzes,  39.  1,  Tab.  XI,  Fig.  5. 

Found  in  a  yellow  grauwacke  from  the  Eifel,  containing  a  considerable  quantity  of  iron 
(according  to  specimens  in  Sack's  collection) ;  also  in  the  transition  limestone  of  North 
America  (Williams ville,  Niagara,  New  York),  and  of  England  (Wenlock,  Dudley). 

The  rich  collection  of  Mr.  Sack  contains  perhaps  a  dozen  caudal  shields  of  different  size 
(varying  from  half  an  inch  to  two  inches  in  length),  besides  fragments  of  all  parts  of  the 
head,  and  some  joints  of  the  body,  all  belonging  to  this  species.  They  correspond  in  the 
principal  points  with  Murchison's  very  accurate  figure.  The  caudal  shield,  which  appears 
to  me  to  present  the  best  specific  character,  is  comparatively  shorter,  more  acutely  triangular, 
very  prominently  pointed  at  the  end,  and  is  here  rather  flatly  extended.  The  axis  is 
certainly  more  convex,  but  not  so  strictly  defined  as  in  the  preceding  species ;  its  rings  are 
decidedly  shorter  but  higher,  and  separately,  with  a  much  sharper  edge.  I  have  counted 
eleven  distinct  rings,  and  a  very  indistinct  twelfth  ring,  besides  the  margin  of  articulation  ; 
eight  equally  distinct  ribs  are  perceptible  on  the  sides,  which  are  situated  less  towards  the 
external  part,  and  more  posteriorly. 


OF  THE  SPECIES.  87 


B. — Species  with  thick,  si/mmetrical  spines  on  the  whole  surface  of  the  back. 
HoMALONOTus,  Murcli. 

4.  H.  armatus :  Tuberculo  capitis  octies  spinoso,  lateribus  scuti  ceplialici  bispinosis;  annulis  trunci 
bispinosis,  rliachi  caudse  mutica.      Long.  corp.  3-6". 

Be/. — H.  Greeiiii,  Goldf.  in  Bronn  n.  Jahbr.  1843.  560.  5. 

Found  in  the  grauwacke  strata  of  the  Eifel  at  Daun.  The  collection  already  alluded 
to  contains  some  fragments  of  this  species,  from  which  I  have  constituted  it,  and  which  I 
shall  now  describe  more  particularly.  It  is  comparatively  broader  than  the  other  species,  the 
cephalic  shield  is  hyperbohc,  slightly  reflexed  at  the  circumference  ;  the  glabella  is  furnished 
with  eight  spines,  namely,  six  larger  ones  in  two  rows,  three  on  each  side,  and  two  smaller 
ones  close  to  each  other,  in  the  centre  before  the  two  posterior  ones.  The  cheek-shield  has 
a  large  high  spine  at  the  sides,  and  rather  behind  the  eyes ;  besides  this  there  is  one  spine 
at  each  side,  on  the  elevated  part  of  the  posterior  margin,  and  one  on  its  centre.  The  body 
rings  are  each  armed  with  two  spines,  one  at  each  side,  immediately  before  the  front, 
where  they  become  transformed  into  the  lateral  lobes. 

Caudal  shield  short  and  small,  the  axis  six-jointed,  unarmed ;  each  of  the  sides  furnished 
with  three  ribs,  of  which  the  first  bears  a  spine  at  each  side ;  the  end  of  the  sliield  is  oblong 
pointed,  in  the  form  of  a  spine. 

5.  H.  HerscJielii :  Annulis  trunci  quadrispinosis,  lobis  lateraliljus  unispinosis  ;  rhachi  caudse  in  basi 
4  spinosa,  lateribus  miiticis. 

i?^/._MuRCHis.  Sit.  S?/sf.  ii,  652,  Plate  VII,  to  Fig.  2.     Milne  Edw.  Cri/st.  iii,  315. 

Found  in  the  upper  Silurian  strata  of  the  Cedar  Mountains,  Cape  of  Good  Hope,  asso- 
ciated with  Cat.  Bliiment)acliii  and  C.  TristaniQ:). 

According  to  Murchison's  figure,  the  caudal  axis  of  this  species  consists  of  fourteen 
joints,  the  two  first  bearing  a  spine  at  each  side  ;  the  sides  seem  to  possess  a  number  of  ribs 
equal  to  the  number  of  joints,  but  no  spines.  Of  the  body  rings  we  find  seven  ;  they  appear 
to  be  furnished  with  four  spines,  two  on  each  side,  approximating  to  the  lateral  lobes ;  and 
besides  these  there  is  probably  another  one  on  the  lateral  lobes  themselves. 

The  cephalic  shield  is  wanting. 

B. 

Tritot)ites  having  the  power  of  rolling  themselves  up,  whose  facial  suture  terminates  in  the 
external  lateral  margin  of  the  cephalic  shield. 

This  section  of  Trilobites,  originally  established  by  Quenstedt,  and  confirmed  by 
Emmerich,  includes  only  the  genus  Phacops,  and  appears  not  to  require  the  generic  sub- 
divisions proposed  by  Milne  Edwards  and  Goldfuss. 


88  SYSTEMATIC  ARRANGEMENT 


Genus  13. — Phacops,  Emmerich.    (Calymene,  Audonim;  Pleuracanthus,  and 
Peltura,  Milne  Edw. ;  Asaphus,  Acaste,  and  Phacops,  Goldfuss.) 

Cephalic  shield  semicircular,  or  somewhat  parabolic  (when  the  posterior  angles  strongly 
project)  ;  lunate  ;  acutely  angular,  or  rather  extended  at  the  external  margin,  and  thickened 
at  the  posterior  margin ;  the  glabella  highly  convex,  in  some  simple,  in  others  divided  into 
several  lobes  by  lateral  sections ;  always  broader  at  the  anterior  than  at  the  posterior  part, 
and  at  the  latter,  broader  than,  or  as  broad  as  the  distance  of  both  eyes  from  each  other. 
The  facial  suture  extends  in  a  circle,  concentric  with  the  posterior  margin,  round  the  glabella, 
turns  towards  the  eye,  forms  the  covering  plate,  and  then  runs  in  an  S- shaped  curve  from 
the  posterior  corner  of  the  eye  to  the  lateral  margin,  which  it  divides  at  a  considerable 
distance  in  advance  of  the  posterior  angle. 

Eyes  remarkably  large,  very  prominent,  forming  a  segment  of  a  cone,  and  having  large 
semicircular  lenses  in  considerable  but  varied  number.  Posterior  angles  of  the  cephalic 
shield  either  obtuse,  or  longitudinally  extended. 

Body  rings  always  eleven,  the  axis  rather  smaller  than  the  lateral  lobes,  both  separately 
convex,  the  extremities  of  the  latter  either  rounded  off,  or  pointed  in  the  shape  of  a  spine  ; 
the  joints  of  the  axis  distinctly  contracted  towards  the  posterior  part. 

Caudal  shield  partly  obtuse,  partly  acute,  parabolic,  the  axis  distinctly  jointed ;  the 
sides  strongly  ribbed. 

The  upper  surface  in  all  well-preserved  individuals  is  granulated,  but  is  smooth  in  those 
which  have  lost  their  natural  shell ;  the  body  rings  also  are  frequently  smoothed  by  friction, 
even  when  the  shell  is  present. 


Group  A. — Species  with  a  simple,  undivided,  trapezoidal  glabella,  which  at  the  poste- 
rior part  is  provided  with  a  short  peduncle,  and  has  beside  it  two  small  tubercles.  Angles 
of  the  head  obtuse,  the  caudal  shield  rounded  at  the  end. 

1.  Ph.  latifrons  :  Lateribus  tubercvili  capitis  rectis ;  rhachi  caudse  7-9  annulata,  costis  lateribiis 
5-7.      Long.  1-3".      Table  II,  Figs.  4-6. 

fief. — Cali/mcnc  macrojilithalma,  Brongn.  Crust,  fuss.  PI.  I,  Fig.  5,  A-C.  Schloth.  Petref. 
Nachtr.  ii,  15.  34.  KNORRandWALCH,  Natur(/cschichte  der  Verstein.  Suppl.  Table  I, 
Figs.  4,  5.  Zeno,  Neue  Phi/s.  Bell.  Table  I,  Fig.  2.  Honinghaus,  Noggsreautli  s 
Bheinb.  und  Weslph.  291,  with  figures.  The  same  author,  in  the  Isis,  1824,  pp. 
464,  534,  986;  Table  V,  Figs.  1,  4.  and  1830.  95.  Table  I,  Fig.  2,  a.  c. 
Count  Sternberg,  Fer/i.  d.  Vnterl.  Mus.  1825.  75.  I,  Table  I,  Fig.  1,  A,  D. 
Dalm.  Palcead.  63.  8.  Bronn,  Leih.  i.  111.  2,  Table  IX,  Fig.  4,  a.  b.  Green, 
Mon.  of  Trilob.  39.  Murchison,  Sil.  Si/st.  ii,  655,  PI.  XIV,  Fig.  2.  Buckl. 
Bridff.  Tr.  PI.  XLVI,  Fig.  4.  Emmerich,  Dissert.  19.  1.  Cal.  latifrons  and 
SMothemii,^ViO'&-(i,Leonh.  Zeit  sehr,  f  d.  Miner.  1825.  317,  Table  II,  Figs.  1-8., 
Dalm.  Palcead.  64.  10.  11.     Römer,  Rhein.   81.  68.     Cal.   bufo,  Green,  Mon.  of 


OF  THE  SPECIES.  89 

Tril.  41.  Milne  Edwards,  Cmsl.  iii.  327.  19.  CaJ.  taherculata,  Murch.ü.  65G, 
PI.  14,  Fig.  4.  Milne  Edw.  Crust,  iii,  325.  14.  Portlock,  Bei).  284,  PI.  II, 
Fig.  10.  Cal.  (jramdaia.  Count  v.  Münster,  Beiir.  iii,  36.  3,  Tab.  V,  Fig.  3, 
a-d,  and  Cal.  Icems,  ibid.  Fig.  4.  Cal.  Stokesn,  Milne  Edw.  Crust,  iii,  324.  13 
Trinucleus  {.^)  leevis,  Coxs-!!ii:  v.  Münster,  i?«7/-«y(',  N.  116.  1,  Tab.  X,  Fig.  6.  (?) 
Cal.  Jordani,  Romer,  Verst  d.  Harz.  37.  1.  PI.  XI,  Fig.  4. 
Loc. — The  transition  limestone  of  the  Eifel,  the  Hartz,  the  Fichtelgebirge,  Bohemia, 
England,  and  North  America. 

This  common  Trilobite  is  rarely  well  and  perfectly  preserved,  hence  the  many  designa- 
tions that  have  been  given  to  it.  Perfect  specimens  with  the  shell  are  always  strongly 
granulated,  as  I  have  represented  it.  The  granulation  is  most  distinct  on  the  glabella  and 
on  the  eyelids  less  so  on  the  body-rings,  and  slighter  everywhere  on  the  sides,  where 
indeed  it  is  usually  altogether  wanting.  It  is  likewise  not  seen  when  the  true  shell  is 
absent.  Brongniart,  Bronn,  and  Murchison  have  figured  such  individuals  as  the  normal 
state.  The  axis  of  the  tail,  in  specimens  without  a  shell,  has  only  seven  rings  and  five  ribs  ; 
two  more  rings  and  ribs  are  seen  when  the  shell  is  present,  but  the  two  latter  are  very 
slightly  marked,  and  sometimes  can  scarcely  be  recognized.  The  eye,  according  to  an 
accurate  calculation,  has  from  99  to  i  04  lenses,  many  of  which  are  frequently  wanting  in  the 
centre  at  the  upper  margin  in  some  individuals,  but  are  present  in  others.  There  are  five 
lenses  at  the  anterior  part,  and  two  at  the  posterior,  in  the  first  row ;  the  rows  then  increase 
at  each  side  by  from  one  to  five  lenses  in  the  vertical  row,  upon  which  rows  of  six  and 
seven  lenses  alternate  several  times  with  one  another  ;  there  are  usually  from  sixteen  to 
eighteen  of  such  rows  forming  each  eye. 

Remarks. — 1.  Brongniart  described  as  Cal.  macrophthahna  a  species  quite  different  from  this,  ^-ith 
a  glabella  divided  in  lobes ;  and  not  only  has  the  present  species,  but  also  the  C.  iiiacrophthalma  of 
later  authors,  been  described  as  belonging  to  various  individuals  resembling  his  species.  The  latter, 
however,  is  much  more  common  than  the  former  or  Brongniart's,  and  has  been  almost  always  mistaken 
for  it,  although  totally  distinct.  Honinghaus  and  the  natm'alists  of  Bonn  seem  afterwards  to  have 
repeated  the  error  committed  by  Brongniart  himself,  and  Count  Stei'nberg  followed  in  their  footsteps. 
Bronn,  who  at  first  correctly  considered  his  Cal.  Schlotheimii  and  C.  latifrons  as  different,  subsequently 
returned  to  the  error  of  his  predecessors.  Murchison  and  Emmerich  recognized  the  difference  of  fig. 
5  and  fig.  4  of  Brongniart's  representation,  but  suffered  the  name  erroneously  given  by  Brongniart  to 
remain,  as  referring  to  the  really  undescribed  figure  marked  5.  Milne  Edwards  was  the  first  who 
announced  Brongniart's  error  [Crust,  iii,  323,  note  2),  and  who  restored  its  original  name  to  C.  macronh- 
tlialma,  although  the  introduction  of  a  new  name  for  the  second  species  was  superfluous,  since  it  had 
already  received  two  from  Bronn.  I  therefore  i-etain  the  name  originally  given  by  this  careful  in- 
vestigator. 

2.  In  the  first  and  second  chapter,  I  have  mentioned  the  species  here  described  as  /-"/;.  latifrons 
under  the  name  of  Phacops  maci-oplitlialmiis,  not  choosing  to  difi'cr  from  the  prevailing  custom,  and  I 
therefore  called  the  species  as  it  had  hitherto  usually  been  called.  This,  however,  must  not  be  done 
for  the  future. 

2.  Ph.  protuberans  :  Lateribus  tuberculi  capitis  subangulatis  sive  arcuatis ;  oculis  miuutis,  externis. 
Long.  2".     Table  III,  Fig.  6. 

Ar/.— Emmr.  Dissert.  19.  2.  Sternb.  T'er/i.  d.  Valerl.  31us.  1825.  77,  Tab.  I,  Fig.  2, 
a.  c.      Cal. proluh.  Dalm.  Pahead.  63.  9. 

Loc. — A  gray  limestone  of  the  Branikberg,  near  Prague,  (Nos  2,  18  of  the  Berlin 
Museum).     It  is  said  bv  Count  Sternberg  to  occur  also  in  Westphalia. 

12 


90  SYSTEMATIC  AREANGE^iIENT 

This  species  approximates  very  nearly  to  the  preceding,  but  can  be  readily  distinguished 
from  it.  The  glabella,  which  in  other  respects  is  similar,  is  not  quite  so  broad  at  the 
anterior  part  as  in  Ph.  lafifrons,  and  its  sides  are  rather  angular,  or  at  least  bent  in  this,  but 
extend  in  quite  a  straight  line  in  the  former ;  the  eyes,  which  are  small,  are  situated  beside 
the  anterior  part  of  the  angle,  close  to  the  margin  of  the  head,  and  have  only  few  lenses 
(from  two  to  three  rows) ;  the  circumference  of  the  cephalic  shield  is  more  broadly  reflexed, 
and  does  not  present  quite  so  acute  an  edge ;  the  posterior  margin  seems  to  be  less  produced 
The  body  and  caudal  shield  are  not  yet  known  ;  the  individual  which  I  examined  was 
without  a  shell,  and  therefore  quite  smooth. 


Group  B.  Species  with  a  glabella  divided  into  lobes ;  the  isolated  little  tubercles  on 
the  posterior  angles  are  wanting,  and  instead  of  them  there  is  a  transverse  protuberance. 

Remark. — The  glabella  in  this  group  has  always  three  lateral  lobes  between  the  large  trapezoidal 
front  lobes  and  the  posterior  margin  of  articulation,  therefore  four  lobes  in  all  (including  the  anterior 
and  chief  protuberance).  Of  these  the  third  is  sometimes  very  small,  and  on  that  account  appears 
occasionally  to  have  been  overlooked. 

Sub-Groiijj  {a).     The  posterior  extremity  of  the  caudal  shield  rounded  or  obtuse.* 

3.  Ph.  anchiops :  Tuberculo  capitis  elevato,  lobis  lateralibus  obsoletis  (s.  mutilatis);  oculis  maximis; 
rhachi  caudse  12  anuulata,  costis  decern.      Long.  2-4". 

Bef. — Calt/m.  ff«r/<.  Green,  J/o».  o/ yn7o(5.  3.5,  Mod.  7.  Emmr.  Z)m«-^.  22.  8.  Milne 
Edw.  Or.  iii,  ,325,  15.    Var.  minor.  Asajjh.  Wetlimlli,  Green,  Mod.  20. 

Locality. — In  a  black  limestone  of  North  America,  at  Ulster  and  Murron  (New  York). 

The  plaster  cast  which  I  examined,  and  which  is  in  the  Berlin  Museum,  reminds  one 
of  the  preceding  species,  and  the  present  is  principally  distinguished  by  a  longer  urn-shaped 
glabella,  sulcated  posteriorly,  in  which,  however,  I  could  not  perceive  any  distinct  lateral 
lobes,  with  an  acute  outline  as  usual.  On  the  other  hand,  there  is  only  an  im])erfect  lobe, 
which  is  isolated,  and  projects  near  the  tubercle  of  the  eye  at  the  glabella ;  and  instead  of 
the  peduncle,  I  notice  before  the  margin  of  articulation  a  short  transverse  prominence 
scarcely  disconnected.  The  original  from  which  the  cast  had  been  taken  was,  however, 
evidently  impei-fect.  The  body  has  distinctly  eleven  joints ;  there  are  twelve  joints  of  the 
caudal  shield,  and  ten  lateral  ribs  towards  the  posterior  part,  but  rather  indistinct.  Green, 
owing  to  this,  enumerates  only  twenty  rings  in  all,  which  would  leave  nine  for  the  tail. 

Remark. — Asaph.  Wetherilli,  of  which  I  examined  a  plaster  cast  at  Berlin,  appeared  to  me  to  be 
a  smaller  individual  of  the  species  described  by  Green  as  Cal.  anchiops.  The  head  is,  however,  so  in- 
distinct, that  accurate  determination  is  impossible ;  I  was  able  to  recognize  the  eleven  body  joints  with 
certaintv. 


*  From  observations  which  I  have  made  on  Phacops  sclerops  and  P.  procerus,  and  which  I  shall 
subsequently  make  known  more  in  detail,  I  believe  myself  justified  in  inferring  that  elongated  pointed 
angles  at  the  cephalic  shield  existed  in  most  of  the  species  of  Phacops  liaAnng  a  lobed  glabella,  but  were 
broken  off  with  the  calcareous  shell.  These  species  therefore  can  no  longer  be  grouped  according  to 
the  form  of  the  cephalic  shield. 


OF  THE  SPECIES.  91 

4.  Ph.  srierops  :  Protubcriuitiie  frontalis  lobo  antico  maximo  rcnlfoniii,  lobo  quarto  minuto,  rcliquis 
abrupte  augustiori ;  rliachi  cauthe  H  aiuuilata,  costis  latcralibus  sex.  Long.  114-2."  Table  IV,  Figs. 
5-6. 

R(f. —  Ca/j/m.  sclerops,  Dalm.  Palcead,  39.  5.  Milne  Edw.  Crust,  iii,  322.  9.  Phac. 
sderops,  Emmr.  Dmert.  22.  8.  Pander,  Beitr.  138,  Tab.  XLVIII,  Fig.  9,  Tab.  V, 
Fig.  4,  Tab.  VI,  Fig.  10. 

Zoc.— Swedish  limestone  at  Husbj'fjol,  in  East  Gothland;  in  gray  limestone  near 
Skarpasen  ;   in  red  limestone  near  Furudal ;   in  Dalecarlia  in  red  limestone. 

This  distinct  species  can  readily  be  known  by  the  peculiar  form  of  its  glabella,  which 
consists  of  five  lobes,  of  which  the  anterior  and  largest  is  singularly  wide,  and  projects 
laterally  over  the  eyes  ;  the  second  is  narrower  and  posteriorly  smaller,  the  eye  corresponds 
with  it ;  the  third  is  a  very  small  narrow  lobe,  and  the  fourth  has  pretty  much  the  same 
size  as  the  margin  of  articulation  following  it.  The  eyes  are  large  and  prominent,  the 
facial  suture  is  distinct  (Dalman  was  the  first  who  described  the  facial  suture  in  this  species 
as  terminating  in  the  lateral  margin)  ;  the  posterior  cephalic  angles  are  obtuse.  The  axis 
of  the  tail  consists  of  four  distinct,  and  four  rather  more  indistinct  rings,  and  has  from  six  to 
seven  lateral  ribs ;  its  extremity  is  obtuse,  and  so  also  is  the  front  of  the  cephalic 
shield. 

Remark. — From  examining  a  great  number  of  specimens,  I  have  had  an  opportunity  of  convincing 
myself  that  this  species  does  possess  long  projecting  angles  at  the  cephalic  shield,  and  thereby  approxi- 
mates so  near  to  Ph.  conophthalmus  of  Boeck,  that  I  am  inclined  to  doubt  their  specific  distinctness. 


5.  Pli.  cunuphtliulinus  :  Protuberantia  frontali  antice  latissima,  posticum  versus  valde  coarctata  ; 
oculis  minutis  ;  rhachi  caudae  7  annulata,  costis  laterahbus  9.      Long.  2K". 

Ref. — Emmr.  Dissert.  21.7.     Boeck,  Gaea  Norm,  i,  4. 

Loc. — The  yellowish  gray  limestone  of  Revel,  and  Ladegaards  Oen  at  Cliristiania  ;  found 
likewise  in  boulders  at  Gussow,  in  Mecklenburg  (Berlin  Museum). 

This  singular  species  resembles  the  preceding  one  in  the  formation  of  the  glabella, 
but  is  readily  distinguished  by  the  pointed  angles  of  the  cephalic  shield.  The  anterior 
large  lobe  of  the  glabella  has  an  oblique  rhombic  form  with  rounded  angles ;  the 
second  is  obtusely  trilateral,  rather  truncated  towards  the  posterior  part ;  the  third  is  the 
smallest,  and  is  rather  narrower  than  the  margin  of  articulation  which  follows  it.  The  eyes, 
which  are  not  large,  correspond  merely  to  the  second  lobe  of  the  head.  The  facial  suture 
is  very  distinct.  The  cephalic  shield,  which  is  very  broad  at  the  sides  and  rounded  off  at 
the  anterior  part,  is  rendered  conspicuous  by  a  sharp  point  at  the  posterior  extremity, 
which  point  is  about  as  long  as  the  four  first  body  rings ;  the  caudal  shield  has  a  ten- 
jointed  rounded  axis,  obtuse  at  the  posterior  part,  and  nine  diagonally-furrowed  latei-al  ribs ; 
it  is  much  smaller  than  the  cephalic  shield,  and  not  pointed  at  the  end,  but  perceptibly 
incurved.  When  rolled  up,  this  incurvation  is  closely  embraced  by  the  under  margin  of  the 
cephalic  shield. 

Remarks — 1 .  The  cephalic  shield  from  the  transition  limestone  of  llevel,  figured  by  ScLlotheim  in 
Leonhard's  Taschenbuch,  1810,  Table  I,  Fig.  6,  I  consider  as  most  decidedly  belonging  to  this  species. 

.2.  Cahjmene  microps  (Green,  Mon.  p.  34;  Milne  Edw.  Crust,  iii,  326.  17)  is  very  nearly  allied  to 
the  species  just  described,  and  may  perliajjs  be  the  same. 


92  SYSTEMATIC  ARRANGEMENT 

6.  Ph.  odontocephalus ;  Protuberantia  frontali  antice  ovata,  lobo  sccuudo  coustricto ;  limbo  ante 
protuberantiam  octies  dentato.      Table  IV,  Fig.  4. 

Ee/. — Calym.  odontocephala,  Gkeen,  Sill.  Am.  Jourii.  vol.  xxv,  p.  334.  Harlan,  Med. 
and  Pliys.  Res.  30 1 . 

Loc. — In  a  gray  sandstone  at  Ulster,  New  York,  U.  S.  I  saw  the  plaster  cast  of  a 
cephalic  shield  of  this  species  at  Berlin. 

The  glabella  is  short  at  its  anterior  extremity,  ovate,  moderately  convex ;  the  second 
lobe  is  reniform,  almost  isolated,  only  connected  with  the  central  axis  by  a  short  peduncle  ; 
the  third  is  a  narrow  transverse  protuberance,  behind  which  there  follows  a  fourth  broader 
one,  perfectly  resembling  the  margin  of  articulation.  The  large  eyes  correspond  with  the 
kidney-shaped  prominence ;  they  reach  neither  to  its  anterior  nor  to  its  posterior  extremity, 
and  are  far  removed  from  the  external  margin.  A  broad  flat  border  encircles  the  latter,  in 
which  may  be  distinguished  anteriorly,  and  placed  in  front  of  the  glabella,  eight  obtuse 
indentations,  inclosed  by  an  impressed  furrow  (?  of  the  facial  suture).  The  posterior  angles 
of  the  specimen  were  indistinct,  but  appeared  to  be  obtuse ;  body  and  caudal  shield  are 
wanting. 

Sub-group  (i.)     The  extremity  of  the  pygidium  sharply  angulated. 

7.  Ph.  macrophthahnus  ;  Lobo  autico  capitis  acutangulo,  lobis  sequentibus  sequalibus  ;  rliaclii  caudse 
10-12  articulata,  scuto  in  apice  acuminato.      Long.  1-1J4". 

Bef. — Cahjmene  macr.  Brongn.  Crust,  foss.  14,  PI.  I,  Fig.  4,  A,  B.     Milne  Edw.  Crust. 

iii,  323.     Pander,  Beitr.  138,  Tab.  IV,  B,  Fig.  8  ;  Tab.  V,  Fig.  5  ;  Tab.  VI,  Fig. 

9.     C.  Bowningi(B,  Murchison,  Ä7.   Sgst.  ii,  655,  PI.  XIV,  Fig.  3.      Buckl. 

Bridg.  Tr.  PI.  XLVI,  Fig.  5.     Milne  Edwards,  Crust,  iii,  324.  12. 

Loc. — The  older  transition  limestone  of  Huraandiere  in  Brittany,  and  in   the  Petersburg 

hüls. 

This  species  approaches  very  near  to  C.  sderops  in  point  of  habit,  but  is  much  more 
slender  ;  the  glabella  is  similarly  four-lobed,  and  the  eyes  are  much  larger,  almost  as  large 
as  in  Ph.  rotundifrons.  The  anterior  lobe  of  the  glabella  is  obliquely  rhombic,  rather 
acutely  angular  at  the  anterior  part ;  the  three  following  lobes  between  it  and  the  margin 
of  articulation  become  successively  rather  smaller,  and  the  posterior  lobe  is  the  most 
strongly  arched  among  them.  The  prominent  eyes  reach  from  the  anterior  margin  of  the 
cephalic  shield  to  the  posterior.  The  caudal  shield,  according  to  Pander,  has  from  ten  to 
twelve  joints  in  the  axis,  slight  lateral  ribs,  and  a  sliort  but  acute  termination. 

8.  Ph.  rntundifrons  :  Tuberculo  capitis  antico  ovato,  lobis  sccuiulis  triangularibus,  tertiis  minutis 
spii-ajformibus  ;  oculis  maximis ;  rhacbi  caudali  7-8  anuulata,  costis  lateralibus  sex.  Long.  2".  Table 
IV,  Pig.  2. 

Bef. — Emmr.  Dissert.  23.  10,  c,  Fig.  Pleur.  laciiiiatus,  Romer,  d.  Blieiu.  Uebergmigstel 
83.  69.  2,  Tab.  II,  Fig.  8 

Loc. — Described  from  an  impression  in  plaster  in  the  Museum  at  Berlin  ;  tlie  original 
was  found  at  the  Kalauerberg  (in  the  Dietzhatze,  in  the  Westerwald  near  Dillenburg). 

Exactly  similar  to  the  preceding  species  in  its  entire  habit ;  but  the  anterior  large  lobe 
of  the  glabella  rather  more  oblong  and  of  a  short  egg-shaped   form  ;  the   second  has  the 


OF  THE  SPECIES.  93 

form  of  a  triangular  lobe  ;  the  third  of  a  narrow  transverse  protuberance,  the  margin  of 
articulation  exceeding  it  in  point  of  width.  The  eyes  are  enormously  large,  and  occupy 
the  entire  sides  of  the  cephalic  shield  from  the  anterior  to  the  posterior  margin.  There  are 
eleven  body  rings. 

Caudal  shield  oblong,  trilateral,  rather  narrow,  the  axis  furnished  with  seven  distinct 
rings,  the  sides  with  six  short  ribs,  and  the  extremity  acutely  angular. 

Remark. — According  to  the  researches  of  Römer  {d.  Rhein,  uhergamjsgel ,  83.  G9.  2),  this  species 
possesses  not  merely  elongated  cephalic  angles,  but  also  dentations  to  the  caudal  shield,  and  belongs 
therefore  to  the  last  group,  called  by  Milne  Edwards  Pleur acanthus.  I  have  therefore  indicated  tlie 
ceph.alic  angles  and  caudal  points  according  to  Romei-'s  drawing  in  the  former  figure,  which  represented 
mere  impressions  in  stone.      Römer  calls  it  Pleur.  laciniatus. 


9.  Ph.  proeevtts :  Tuberculo  capitis  antico  rhombeo,  secundo  et  tertio  sensim  minoribus,  hoc  a 
spire  articulatoria,  longius  distante ;  rhachi  caudali  8  annulata,  costis  lateralibus  septem.  Long.  2". 
Table  IV,  Fig.  3. 

Be/.—EuMR.  Dissert.  25.  14. 

Loc. — The  Bohemian  grauwacke  of  Ginec. 

Comparatively  shorter  and  broader  than  the  preceding  species ;  the  anterior  lobe  of 
the  glabella  forming  a  highly  convex,  granulated,  oblique,  rhombic  plate,  to  which  the 
second  wedge-shaped  lobe  is  as  closely  joined  as  the  third  and  narrower  one,  which  is 
contracted  laterally,  is  to  this.  The  margin  of  articulation  then  follows  posteriorly  at  a 
somewhat  greater  distance. 

The  eyes  not  large  in  proportion.  They  correspond  entirely  to  the  second  lobe  of  the 
head,  beyond  which  they  do  not  project  at  all  anteriorly,  and  but  little  posteriorly.  I  have 
not  seen  the  body.  The  caudal  shield  is  trilateral,  heart-shaped,  convex,  pointed  at  the 
end,  and  has  eight  rings,  successively  becoming  narrower,  besides  an  ovate  terminating 
joint ;  seven  broad  ribs,  rather  impressed  longitudinally,  are  visible  on  the  sides.  The 
smaller  anterior  margin  of  articulation  has  been  left  out  in  this  calculation ;  if  we  count  it 
likewise,  it  would  increase  the  number  of  rings,  including  the  terminal  joint,  to  ten. 

Remark.- — I  have  recently  had  opportunities  of  examining  many  specimens  from  the  ^Mineralo- 
gical  ^Museum  of  the  University  of  Halle.  In  many  of  them  there  are  distinct  traces  of  long  processes 
on  the  cephalic  shield,  and  of  a  spine  at  the  extremity  of  the  caudal  shield,  which  suggests  the  idea 
that  Phacops  proavus  may  perhaps  be  identical  with  Ph.  mucronatus. 

Siih-(/roup  (c).     The  caudal  shield  is  pointed  at  the  extremity,  and  has  no  lateral  spines. 

10.  Ph.  Hausmanni :  Oculis  maximis,  usque  ad  limbum  scuti  cephulici  cxtensis  ;  rhachi  candie 
19-20  annulata,  costis  latei'alibus  15.      Long.  3-5". 

Re/. — Jsaj)/i.  Hausmaimi,  Broügü.   Cr.  Joss.   21.  3,  PI.   II,   Fig.  3,  A,  B.      Schloth. 
Naclitr.  ii,20.  35,  Tab.  XXII,  Fig.  7.     Sternb.  VerhancU.   1825,  77,  Tab.   II,  Fig. 
3,  A-C.     Dalm.  Palcead.  GG.  4.     Phac.  Hausmanni,  Emmr.  Dissert.  24.  13. 
Loc. — The  gray  transition  limestone  of  Bohemia,  on  the  left  shore  of  the  Beraun,  near 
Karlstein,  and  at  the  shores  of  the  Moldau,  near  Kosorz  and  Brauik. 

The  largest  species  of  the  genus,  and  particularly  distinguished  by  its  very  large  eyes, 
the  lenses  of  which,  however,  are  remarkably  small.     The  glabella  is  shorter  and  broader 


94  SYSTEMATIC  ARRANGEMENT 

than  in  the  other  species  of  this  group ;  the  three  central  lobes  are  nearly  of  an  equal  size, 
and  the  eye  reaches  not  only  beyond  the  second,  but  even  beyond  the  fourth,  and  almost  as 
far  as  the  broad  flat  margin.  The  posterior  angle  is  moderately  pointed,  probably  as  long 
as  four  or  five  articulations.  The  large  trilateral  caudal  shield  has  an  a.xis  of  from  nineteen 
to  twenty-two  joints,  and  from  fourteen  to  fifteen  lateral  ribs.  It  is,  however,  moderately 
convex,  and  extended  in  a  flat  border  at  the  circumference,  which  forms  a  carinated  angle, 
|)ointed  at  the  extremity.  The  surface  is  finely  granulated  wherever  the  shell  is  preserved, 
but  smooth  when  it  is  absent ;  the  lateral  ribs,  in  the  latter  case,do  not  appear  to  be 
grooved,  but  merely  flattened,  but  they  have  a  double  granulated  I'idge.  of  unequal  height, 
when  the  shell  is  present. 

Remarks. 1.   Brongniart,  who  knew  this  species  b}'  fragments  only,  represented  the  caudal  shield 

as  beino-  rounded  at  the  posterior  part,  which  probably  may  be  in  consequence  of  the  defective  state  of 
his  specimen.  I  therefore  do  not  consider  this  caudal  shield  different  from  that  represented  by 
Sternberg  and  Schlotheim,  as  Milne  Edwards  supposes  (see  p.  312  of  his  work). 

2.  The  angles  of  the  cephalic  shield  are  wanting  in  Count  Sternberg's  figure ;  they  are,  however, 
present  in  the  perfect  specimens  which  I  saw  at  Berlin.      A  well-preserved  head  is  very  rare. 

3.  Asaph,  auriculatus,  Dalm.  [Paltead.  6.  6.  3),  which  is  based  upon  Count  Sternberg's  unknown 
individual  (see  his  work,  p.  80,  Table  II,  Fig.  2),  is  beyond  a  doubt  a  smaller,  younger  specimen  of 
Ph.  Haii.mumni,  and  therefore  cannot  be  admitted  as  a  species. 

11.  Ph.  caudatti.'s :  Ocuhs  miuorihus,  nee  anticum  nee  posticum  limbum  scuti  cephalici  attiugen- 
tibus ;   rhachi  cauda;  14  annulata,  costis  lateralibus  octo,  limbo  in  apice  acuminato.      Long.  2-3". 

Uef.—Triloh.  caudat.  Brunn,  Kjob.  Scllsk.  Skrift.  N.  S.  i,  392.  3.  Parkinson,  0/y. 
Bern.  PL  XVII,  Fig.  7.     Schloth.  Nachtr.  35.  11  (or  21.  4). 

Asaph,  ccmd.  Brongn.  Crust,  foss.  22.  4,  PI.  II,  Fig.  4,  a-c ;  PI.  Ill,  Fig.  9.  Dalm. 
Palcead.  42.  2,  and  65.  2,  Tab.  II,  Fig.  4.  Green,  Mon.  of  TrU.  50.  Buckl. 
Bridg.  Tr.  PL  XLV,  Figs.  9-11,  and  PL  XLVI,  Figs.  11,  12.  Murchis.  Sil.  Sj/sf. 
ii,  654,  PL  VII,  Fig.  8,  a. 

Asajih.  tuberoilato-caudatim,  Murchis.  Sil.  Si/st.  ii,  654,  PL  VII,  Fig.  8,  b.  Milne  Edw. 
Crust,  iii,  308.  2  (specimens  with  the  granulation  well  preserved). 

l,oc. In  a  gray  limestone  in  England  (Dudley,  Ludlow),  in  Sweden  (Gothland),  and  in 

North  America  (Lockport). 

This  species  is  nearly  allied  to  the  following  one,  but  has  characteristic  distinctions ; 
the  anterior  tubercle  of  the  head  is  very  large,  and  laterally  very  much  produced  forwards, 
by  which  the  eyes  are  thrown  back;  the  latter  are  smaller  than  in  P.  Ilausmanni. 
They  do  not  reach  beyond  the  anterior  margin  of  the  second  lobe  of  the  head,  and  only 
just  reach  the  front  at  the  posterior  part ;  the  posterior  angles  of  the  cephalic  shield  reach 
to  the  centre  of  the  body  rings,  the  latter  are  gradually  more  pointed  towards  the  posterior 
part.  The  caudal  shield  has  an  axis  with  about  fourteen  joints,  which  is  distinctly  rounded 
at  the  posterior  part,  and  does  not  pass  into  the  spine  at  the  extremity  ;  there  are  eight  ribs 
on  the  sides,  each  divided  by  a  diagonal  furrow ;  the  broad  expanded  margin  is  lengthened 
into  a  moderately  long  point  at  the  posterior  part,  which  is  usually  nearly  as  long  as  one 
half  the  length  of  the  axis. 


OF  THE  SPECIES.  95 

13.  Ph.  nmcronatus :  Oculis  mediis,  lobo  capitis  sccundo  ct  tcrtio  aiquantibus,  caudic  iliaclii  10-1 1 
articulata,  costis  hiteralibus  8-9,  scuti  apice  mucronato.      Long.  8-4". 

Ecf. — Asaph.  )Hncro)iatu-<t,  Brongn.  C'r.fo.ss.  24,  PL  III,  Fig.  9.  D.xlm.  Pulcrad.  42.  1.  05, 
Tab.  II,  Fig.  3,  a-h.     Schloth.  Nachtr.  \\,  37.  24.     Milne  Euw.  Crust,  iii,  308.  4. 

Eiüommtr.  caudattts,  Wahlenb.  N.  A.  Upsal.  viii,  28.  4,  Tab.  II,  Fig.  3 ;  Journ.  d.  Phys. 
V,  91,  p.  34,  Fig.  4. 

Phacops  mucronatus,  Emmr.  Dissert.  24.  11. 

Asaph,  hngkatidatus,  MuRCH.  <S'/7.  Si/.^t.  656,  PI.  XIV,  Figs.  11-14.  Milne  Edw.  Cr. 
iii,  308.  3. 

Loc. — The  Silurian  limestones  of  England  (Dudley,  Wenlock),  of  Sweden  (Ostgothland  at 
Borensliult,  Schonen  at  Rostanga),  in  the  clayslate  of  Mosseberg;  likewise  in  the  grauwackc 
rocks  of  the  Eifel  at  Daun  (Sack's  collection)  associated  with  Tlomahnotus  armatns. 

This  species  resembles  the  tenth  in  point  of  structure  of  the  head,  and  the  eleventh 
with  regard  to  the  caudal  shield,  and  thus  forms  an  intermediate  link  between  them. 
According  to  Murchison's  figure,  its  cephalic  shield  is  pointed  in  the  centre  of  the  anterior 
margin,  and  has  a  glabella  which  is  not  so  broad  anteriorly  with  the  first  lobe,  decidedly 
smaller  than  iu  the  preceding  species,  but  which  in  front  penetrates  with  a  slight 
point  into  the  marginal  point  of  the  shield.  The  eye,  rather  smaller  than  in  Ph. 
caitdatiis,  but  much  smaller  than  in  Ph.  Hnifsmanni,  neither  projects  beyond  the  second, 
nor  at  the  posterior  part  beyond  the  third  lobe  of  the  head ;  the  long  spines  of  the 
posterior  angles  are  more  acutely  prominent,  and  reach  beyond  the  centre  of  the  body. 
The  lateral  lobes  of  the  body  joints  are  pointed.  The  caudal  axis  is  longer  and  more 
slender  than  in  Ph.  mudatiis,  and  consists  of  from  ten  to  fourteen  rings,  the  last  four  being 
more  or  less  distinctly  separated ;  at  the  sides  there  are  only  eight  ribs,  of  which  the  first 
six  behind  the  foremost  marginal  rib  exhibit  a  deep  diagonal  transverse  furrow,  which 
is  particularly  distinct  in  specimens  without  the  shell ;  the  margin  is  much  narrower  than 
in  Ph.  caudatiis,  and  not  broader  towards  the  posterior  part,  owing  to  which  the  long  spine 
of  the  extremity  usually  issues  more  suddenly  from  the  margin  of  the  shield  ;  the  spine 
extends  itself  in  the  shape  of  a  convex  protuberance  as  far  as  towards  the  end  of  the  axis, 
and  becomes  as  long  as  all  its  joints. 

Remarks. — 1.  Though  I  only  know  this  species  from  the  descriptions  of  the  authors  eniuiierated, 
aud  tlie  cephalic  shield  alluded  to  in  Sack's  collection,  I  am,  however,  convinced  of  its  distinctness. 
Formerl}'  I  attributed  to  it  fourteen  lateral  ribs  on  the  caudal  shield ;  but,  owing  to  the  diagonal 
transverse  fuiTow,  I  am  now  aware  tliat  I  counted  the  anterior  five  twice  over ;  there  are,  in  fact,  only 
eight  lateral  ribs. 

2.  A  number  of  species  occur  in  Green's  Monograph  aud  its  appendices,  which  do  not  seem 
to  be  different  from  Ph.  caudatus  or  Ph.  mucronatiis ;  I  content  myself  here  by  enumerating  them; 
they  are  founded  for  the  greater  part  upon  caudal  shields.  Ä.i(ipli.  crypt urus.  Green  (Transact,  of  tlie 
Geolog.  Soc.  of  Pennsylvania,  i,  37,  Plate  \1),  Harlan  {Med.  et  Pliys.  Res.  .303),  !Milne  Edwm-ds  (iii, 
313),  a  caudal  shield  with  twelve  rings  of  the  axis,  and  ten  ribs ;  judging  from  the  form,  appears  to 
belong  to  Homalonotus.  Asaph,  limuliiriis  [Mon.  48),  Milne  Edwards's  species  (iii,  307,)  appears  to  be 
identical  with  Ph.  mucronatvs.  Asaph,  pleuropiya  [Mon.  55)  belongs  either  to  the  latter  mentioned 
species,  or  perhaps  to  Ph.  Hausmanni.  Asaph,  mio-'irus  {Mon.  56)  is  likewise  a  Phacops  with  a  pointed 
caudal  shield,  the  specific  characters  of  which  cannot  be  more  accurately  ascertained,  and  which  probably 
belongs  to  one  of  the  three  species  here  described. 

Rather  more  diflcrent  from  each  other  are  some  caudal  shields  with  two  eud-poiuts,  which  probably 
also  belong  to  this  genus ;    I  saw  plaster  casts  of  them,  or  at  least  of  the  second  species,  at  Berlin. 


96  SYSTEMATIC  ARRANGEMENT 

Asaph,  selenurus,  Green  {Mon.  46),  Eaton  {Geol.  TcrZ-iJooA,  31),  Harlan  [Med.  and  Phys.  Research. 
302),  Milne  Edw.  [Crust,  iii,  309). 

Asaph,  laticosiatus,  Green  [Mon.  45).  The  caudal  shield  resembles  that  of  Ph.  conophthalmus 
(No.  6),  and  may  possibly  belong  to  Ph.  odontocephalus ,  or  to  a  similar  species  ;  it  has  twelve  short 
joints  in  the  rounded  caudal  axis,  and  nine  lateral  ribs,  of  which  the  two  last  run  towards  the  obtuse 
end-points. 

Asaph,  myrmecoides,  Green  [SiU.  Joiirn.  vol.  xxxii,  p.  397),  Harlan  [Med.  and  Phys.  Res.  303), 
still  more  resembles  the  caudal  shield  of  Ph.  conophthalmus,  being  equally  short,  broad,  and  diverging 
at  the  end,  but  it  is  much  larger,  being  upwards  of  three  inches  in  width.  The  obtuse,  but  comparatively 
not  very  broad  axis,  consists  of  from  seventeen  to  eighteen  rings,  and  on  the  sides  we  remark  thirteen 
ribs ;  both  are  covered  with  large  round  tubercles. 

Asaph,  astragalotes,  Green  [SUl.  Journ.  vol.  xxv,  p.  325),  Harlan  (/.  c),  I  consider  the  caudal 
shield  of  a  large  individual  of  Pliacops  latifrons,  or  Calym.  biifo,  Green  ;  it  has  from  seven  to  eight 
rings  at  the  axis,  and  five  lateral  ribs. 

3.  I  am  equally  imable  to  interpret  distinctly  Asaph.  Powisii,  Murch.  [Sit.  Syst.  ii,  661,  PI.  XXIII, 
Pig.  9,  a,  b),  which  certainly  is  a  decided  Phacops,  and  belongs  to  the  same  group,  together  with  Ph. 
anchiops  or  Ph.  sclerops,  but  has  reraai-kably  small  eyes.  The  body  appears  to  me  to  fit  but  little  to 
the  cephalic  shield,  the  rings  are  much  too  broad  towards  the  margin  of  articulation  of  the  cephalic 
shield.  According  to  Emmerich  [Leonh.  and  Bronn,  Jahrbuch.  1845,  p.  53),  the  head  is  identical  with 
Ph.  sclerops  (No.  4) ;  according  to  Portlock,  on  the  other  baud  [Rep.  of  Geol.  297),  the  body  belongs 
to  Asaphus.* 

Suh-grmip  [d).     The  caudal  shield  having  long  spines  on  its  whole  circumference. 

13.  Ph.  urachnoides  .-  Scuto  capitis  in  medio  marginis  antici  acuto,  angulis  posticis  valde  productis; 
limbo  scuti  caudalis  decies  spinosa.      Long.  1-1  ^i".      Tab.  IV,  Fig.  7. 

j{,ef. — Asaph,  arachnoides,  Goldf.  Leoiih.  and  Bronn  sn.  Jahrb.  1843,  561.  13,  Tab.  V, 
Fig.  3.  Paradox,  gratet ,  Rom.  Verst.  d.  Hertz.  39,  Tab.  XI,  Fig.  11.  Pleuracanthits 
pimctatus,  Rom.  Rhein.  TJberg.  82.  Olenus pimctatus.  Steinung,  Mem.  de  Soc.  Geol. 
Fr.  i,  356.  Honinghaus,  Epist.  Cref.  1835.  Emmr.  Dissert.  55.  Plenra- 
canthus  arachn.  Milne  Edw.  Cnist.  iii,  329. 
Lqc_ — In  an  ash-gray  limestone  of  the  Eifel,  according  to  specimens  in  Honinghaus's 
and  Sack's  collections. 

Cephalic  shield  oblong,  parabolic,  the  centre  of  the  anterior  margin  pointed,  and 
rather  curved  upwards ;  the  anterior  lobe  of  the  head  very  large,  the  three  following  suc- 
cessively smaller;  eyes  high,  strongly  arched,  exactly  equalling  the  length  of  the  three 
posterior  lobes  of  the  head,  each  single  eye  furnished  with  162  lenses;  posterior  angles  of 
the  cephalic  shield  very  much  lengthened,  reaching  as  far  as  the  ninth  ring  of  the  body.  The 
latter  gradually  becomes  rather  broader  as  far  as  the  fifth,  afterwai'ds  again  more  narrow  ; 
the  lateral  lobes  considerably  broader  than  the  rings,  and  lengthened  at  the  end  into  a  spine, 
which  at  each  successive  joint  is  larger  than  at  the  preceding.  Caudal  shield  parabolic, 
rather  flattened  ;  the  axis  slender,  thirteen-jointed,  the  sides  furnished  with  five  elevated 
ribs,  which  issue  from  the  arched  circumference,  and  at  each  side  five  spines,  which  become 
shorter  from  the  anterior  to  the  posterior  part,  and  correspond   with  the  ribs ;    the  first 

*  The  head  and  tail  figured  by  Sir  Roderick  jNIm-chison,  under  the  name  of  Asaphus  Powisii,  are 
now  known  to  belong  to  difi'erent  Trilobites.  The  name  Asaphus  Powisii  is  retained  for  the  tail,  whilst 
the  head  is  the  cephalic  shield  of  a  Pliacops,  named  by  Mr.  Salter,  who  has  met  with  the  tail  of  tlie 
species,  Phacops  felinns. — Ed. 


OF  THE  SPECIES.  97 

spine  is  twice  as  long  as  the  spine  of  tlie  last  joint  of  the  body.     The  wliole  upper  surface 
is  granuhitcd. 

Remark. — The  lateral  angles  of  the  cephalic  shield  are  wanting  in  Ilfhiiughaus's  otherwise  very 
beautiful  figure,  and  the  hody  appears  to  be  thirtcen-jointed ;  but  the  perfect  specimens,  which  were 
intrusted  to  me  for  examination  by  my  colleague  M.  Germar,  had  the  proportions  I  have  stated.  I 
likewise  recognized  in  them  their  identity  with  three  fragments  in  Sack's  collection. 


14.  Pit.  stellifer :  Scuto  capitis  in  medio  margiuis  antiei  acuto,  angulis  posticis  longissime 
productis ;  scuto  caudie  undecies  radiato.      Long.  IH".     Tab.  IV,  Fig.  8. 

Zoc.  — An  ash-gray  hmestone  of  the  Eifel,  according  to  specimens  in  Sack's  collection. 

The  cephalic  shield,  of  which  I  have  a  pretty  perfect  specimen  before  me,  resembles 
perfectly  that  of  the  preceding  species,  but  the  arjterior  lobe  of  the  glabella  is  comparatively 
larger,  and  the  entire  shield  therefore  a  little  longer  ;  the  proportions  of  both  species  seem 
to  be  the  same  in  other  respects.  I  am  only  acquainted  with  fragments  of  the  joints  of  the 
body,  and  can  therefore  onl}^  state  it  as  probable  that  they  terminate  in  lateral  spines.  Of 
the  caudal  shield  I  have  three  specimens  before  me,  which  admit  of  being  generally  charac- 
terized. It  is  comparatively  smaller  than  in  the  preceding  species,  the  axis  is  only  divided 
into  five  distinct  joints  at  the  anterior  part,  the  joints  afterwards  are  certainly  still  visible, 
but  the  articulation  is  indistinct  (at  the  sides  we  may  still  distinguish  six  segments).  Five 
ribs  issue  from  the  anterior  joints  to  the  circumference,  which  is  upturned  much  as  in 
the  preceding  species,  but  the  spines  issuing  from  it  are  all  of  equal  length,  compa- 
ratively much  shorter  and  thicker,  and  they  meet  together  at  their  bases,  and  between  the 
two  most  posterior  ones  there  is  another  but  odd  eleventh  spine,  which  exactly  fills  up 
the  gap. 

Remarks. — 1.  The  caudal  shields  represented  by  Wahlenberg  (Nov.  act.  Ups.  viii,  30,  5,  Tab.  II 
Fig.  4)  and  by  Brongniart  [Crust,  fossil.  PI.  Ill,  Fig.  7)  perhaps  also  belong  to  this  species  ;  Dalman  had 
before  suggested  that  these  did  not  belong  to  the  head  represented  with  them  {Palaad.  66,  5). 

2.  Peltura  BucMandi,  Milne  Edw.  [Cr.  iii,  345,  1,  PI.  XXXIV,  Fig.  12),  which  perfectly  cor- 
responds with  Brongniart's  figure  {Cr.  fossil.  PI.  IV,  Fig.  9),  perhaps  likewise  belongs  to  this  species; 
I  cau  certainly  count  eleven  rings  at  the  left  side  of  both  figures,  and  almost  thirteen  at  the  right 
side ;  the  central  terminal  spine  decidedly  seems  to  be  in  favour  of  its  affinity  with  Phac.  stellifer. 


Trilobifes  capable  of  rolling  themselves  up,  having  the  axis  of  the  body  diminishing  posteriorly, 
and  their  facial  suture  extending  to  the  piosterior  margin  of  the  cephalic  shield. 

The  Trilobites  of  this  group  are  rare,  and  belong  to  the  middle  and  newer  Palceozoic 
strata,  more  particularly  to  the  Devonian  rocks,  but  extending  as  far  upwards  as  the 
carboniferous  limestone.  The  number  of  the  body  rings  varies  from  nine  to  twelve, 
and  may  vary  in  the  species  of  one  genus.  The  glabella  is  very  convex,  but  divided 
only  into  indistinct  lobes  or  furnished  with  slight  lateral  furrows.  The  axis  of  the 
body  is  very  gibbous,  and  furnished  with  short  articulations  ;  the  caudal  shield  likewise 
possesses  a  distinctly  articulated  axis,  and  radiated  lateral  furrows  or  lobes. 

13 


98  SYSTEMATIC  ARRANGEMENT 


Genus  14.— Cyphaspis  (Calymene,  Roemer  ;  Phacops,  Goldfuss). 

The  cephalic  shield  is  almost  semicircular,  but  not  quite  so,  the  sides  very  much 
produced,  the  margin  thickened  all  round  (and  therefore  excavated  in  casts) ;  the  glabella 
very  convex,  resembling  the  half  of  an  egg,  without  furrows,  but  furnished  with  two 
longitudinal  protuberances  close  to  the  narrower  posterior  extremity.  The  surface  of 
specimens  in  which  the  shell  is  absent  is  smooth,  or  very  slightly  granulated,  but  the  shell 
when  preserved  is  thickly  and  strongly  granulated. 

Eyes  rather  small,  situated  on  high  protuberances  close  to  the  glabella.  The  facial 
suture  intersects  the  anterior  margin  on  a  line  with  the  eyes,  thence  proceeds  in  an  almost 
straight  line  towards  the  eye,  from  the  posterior  part  of  which  it  proceeds  outwards, 
and  penetrates  the  posterior  margin  very  near  the  external  angle  ;  the  latter  is  elongated 
into  a  spine. 

Body  rings  eleven  (or  twelve  ?)  smooth  and,  in  well-preserved  specimens,  finely 
granulated ;  the  first  five  ai*e  either  furnished  with  a  very  pointed  posterior  angle,  or 
are  rounded  off ;  the  whole  axis  becomes  gradually  narrower  towards  the  posterior 
part. 

Caudal  shield  very  small,  with  a  short  articulated  axis,  indistinct  ribs,  and  a  remarkably 
depressed  circumference,  which  is  not  reached  by  the  ribs. 

Remarlis. — 1.  The  specimens  upon  wliicli  this  genus  is  founded,  are  rare  aud  well  preserved. 
The  high  glabella  is  usually  entu-cly  wautiug,  but  iudications  of  it  may  easily  be  discovered  where  it 
was  brokcu  off. 

2.  Dr.  Loveu  has  described  a  Trilobite  under  the  uame  ot  Proeius  eleyantuhis  {Ofvers  K.  V.  A. 
Foerh.  1845,  p.  51,  Tab.  I,  Fig.  4),  which  seems  to  belong  to  the  genus  Cyphaspis,  or  at  least  possesses 
many  of  its  characters ;   it  is  said,  however,  to  have  twelve  body  rings. 

C.  ceratophthalma :  Scuto  capitis  antice  rotuudato,  glabella  vakle  iuflata,  grosse  granulosa ; 
.annuUs  tiuuci  luulecim,  anticis  spinosis,  oculis  altissimis,  couoideis.  Loug.  1-1^".  Tab.  Ill,  Figs. 
3-4. 

S/f. — Phacops  ceratojjhthalmus,  GoLDF.  Leonh.  and  Bronn.  n.  Jahrbuch.  1843.  365. 
Tab.  V,  Fig.  2.  Calymene  hydrocephcda,  Römer,  Verst.  d.  Harzi/ehir(/es,  38.  4,  Tab. 
IX,  Fig.  7. 

The  cephalic  shield  is  rather  less  than  a  semicircle,  everywhere  inclosed  by  a 
thick  margin,  and  elongated  into  a  spine  at  the  posterior  angles.  Immediately  before  the 
spine  a  deep  indentation  is  perceptible,  the  granulation  then  commences,  and  continually 
increases  towards  the  middle,  so  that  the  highest  tubercles  are  placed  in  the  centre  of  the 
glabella.  The  latter,  in  point  of  form  and  convexity,  may  be  compared  to  the  larger  half 
of  an  egg.  It  rises  from  the  cephalic  shield,  and  is  furnished  at  the  posterior  part  with  two 
elliptical  protuberances.  The  raised  eye-tubercles  correspond  with  the  anterior  extremities 
of  these  protuberances,  upon  which  the  conical  eyes  are  placed.  The  body  rings  are 
very  gibbous  and  finely  granulated ;  each  of  the  latei'al  lobes  has  a  small  indentation  at 
its  extreme  angle,  and  the  first  five  appear  to  me  to  be  acutely  pointed.  The  short  caudal 
axis  is  three-jointed. 

Remarks. — 1.   ^My  figures  were  made  up  from  five  imperfect  specimens,  of  which  two  are  iu  the 


OF  THE  SPECIES.  99 

University  collection  and  three  in  Sack's  museum.      The   body   rings   appear  smooth,  or  at   least   the 
lateral  lobes  are  so  ;   the  caudal  shield,  on  the  contrary,  exhibits  a  distinct  fine  granulation. 

2.  I  formerly  included  in  this  group  Cahjmene  clavifmns,  Dalm.  [Pahi-ad.  75.  2,  Sar-i  his,  1835. 
339,  Tab.  IX,  Fig.  8),  Tril.  sphd'ricns,  Boeck  (Gaea  norw.  i,  14),  P/mcops  xp/ia-ricus,  Emmr.  {Dissert. 
20.  3),  and  erroneously  connected  with  it  Asaph,  diibiiis,  Münster  [Beitr.  v,  113,  Tab.  X,  Fig.  12). 
The  latter  is,  as  Dr.  Beyrich  has  shown,  the  hypostoma  of  a  Ckierurus  ;  the  former,  however,  is  a  fragment 
of  a  peculiar  Trilobite,  which  Dr.  Beyrich  includes  in  his  new  genus  Sp/ia>re.vochus. 

3.  Cahjmene  bellatula,  Dalm.  {Paheud.  3G.  2,  Tab.  I,  Fig.  4,  Rising.  Leth.  Stiec.  ii.  Tab,  I,  Fig.  5, 
Milne  Edwards,  Ciiist.  iii,  321.  7,  Emmr.  Dissert.  31.  8),  likewise  does  not  belong  to  my  genus 
Cyphaspis,  as  I  formerly  supposed,  judging  from  a  damaged  specimen,  but  must  be  referred  to  a 
peculiar  genus  which  Dr  Löven  {ante,  p.  1 10)  calls  Cyhele,  and  in  which  he  also  includes  the  Calym. 
verrucosa,  Dalm.  {Arsber,  etc.  1827.  52),  together  with  Trilob.  velutus,  Schloth.  {Petref.  supplement  ii, 
40,  Tab.  XXII,  Fig.  5),  found  at  Revel.  I  must  refer  to  Dr.  Löven's  treatise  for  the  characters  of 
this  new  genus,  which  has  been  very  thoroughly  described  by  him.* 


Genxs  15. — Proetus,  Steiningcr,  (^Eonia,  Burmcister;  Gerastos,  Goldfuss.) 

Cephalic  shield  semicircular,  surrounded  by  a  thickened  margin ;  the  posterior  angles 
do  not  project  perceptibly;  the  glabella  is  very  convex,  parabolic,  rounded  at  the  anterior 
part,  undivided,  without  any  lateral  lobes  ;  at  the  posterior  part  it  is  as  broad  as  the  margin, 
to  which  it  is  immediately  joined.  The  facial  suture  projects  over  the  anterior  cephalic 
margin  on  a  line  with  the  eyes,  is  thence  directed  towards  the  eye,  forms  the  covering  plate, 
and  runs  at  first  straight,  afterwards  in  an  S- shaped  curve,  to  the  posterior  margin,  which 
it  penetrates  beyond  the  centre,  in  an  oblique  direction  towards  the  external  part. 

Eyes  of  moderate  size,  very  prominent,  smooth,  joined  rather  closely  to  the  glabella. 

Body  axis  ten-jointed,  the  joints  gradually  more  narrow  towards  the  posterior  part, 
strongly  arched,  abruptly  separated  from  the  lateral  lobes  by  a  peculiar  furrow,  these  lobes 
having  an  oblique  indentation. 

Caudal  shield  corresponding  with  the  cephalic,  but  smaller,  the  axis  highly  arched, 
short,  distinctly  articulated,  the  sides  furnished  with  slight  furrows  or  obsolete  ribs, 
the  margin  even,  but  having  a  very  acute  angle.  The  surface  of  the  shell  almost 
smooth,  but  with  distinct  traces  of  granulation  on  the  glabella,  and  on  the  cheeks  beneath 
the  eye. 

Remark. — Prof.  Goldfuss  described  species  of  this  genus  under  the  name  of  Gerastos,  but  con- 
nected with  them,  as  I  also  did,  other  Trilobites  which  do  not  belong  to  the  group.  Mistakes  of  this 
kind  would  have  happened  less  frequently,  if  former  authors  had  furnished  us  with  as  distinct 
illustrations  as  we  have  at  present  in  my  Monograph,  and  in  the  works  of  Goldfuss,  Löven,  Beyrich, 
and  others. 

P.  Cuvieri :  Protuberantia  verticis  latissima,  longitudine  vix  angvistiori,  obsoletissime  granulata  ; 
angulis  scuti  cephalici  obtusis.      Long.  1".     Tab.  Ill,  Figs.  1,  2. 

*  The  following  are  the  characters  given  by  Professor  Löven  for  his  genus  Cyhele : — Caput  breve 
latum.  Scutum  centrale  sublunatum,  latum.  Sutura  pone  oculum  subrecta,  ad  angulum  ducta. 
Oculi  minuti  arcu  infraorbitali  elevato,  angusto.  Thorax  articulis  (in  una  specie)  duodccira.  Terga 
convexa.  Pleuraa  sulco  longitudinal!  in  partem  anticam  dins»  syndesmalem  breviorem,  et  posticam, 
magis  minusve  productam.  Pygidium  thoraci  ex  parte  conforme,  minutum,  ex  articulis  numerosis 
coalitis,  quorum  basales  aliquot  majores,  pleuris  prrediti,  reliquis  in  caudam  lauceolatam  arctius  connatis. 
Oversii/t  af  Kongl.  Vetenskap.   Arnd.  Fork.  1815,  No  4,  p.  110. — EniTORS. 


100  SYSTEMATIC  ARRANGEMENT 

Jlpf-  Steininger,  Bemerk,  ii.  d.  Vorst.  d.  Eifel.  Trier,  1831.  4,  No.  52.     3Iem.   de  la 
Soc.  Geol.  de  France,  i,  359,  No.  52,  PI.  XXI,   Fig.  6    (1834).     Gerastos  hevif^afns, 
GoLDF.  Leonh.  and  Bronn.  n.  Jahrb.  1843.  557,  Table  IV,  Fig.  3. 
Locality. — A   yellowish-gray  limestone  of  the  Eifel,   near  Blankcnheim,  according  to 
specimens  in  Sack's  and  the  Academy  collections. 

Glabella  not  very  convex,  without  distinct  granulation ;  it  does  not  reach  the  anterior 
maro-in,  which  is  reflexed :  eyes  rather  behind  the  centre,  surrounded  externally  by  an 
indented  I'ing,  the  cheeks  beneath  them  distinctly  granulated,  their  angles  rounded.  Body 
rings  not  remarkal^le  ;  the  caudal  shield  rather  small,  and  flat  like  the  axis,  the  latter  nearly 
eight-jointed,  but  the  last  joints  indistinctly  separated ;  the  sides  furnished  with  six,  more  or 
less  deeply-marked,  furrows. 

Remarks. 1 .  The  Trilobite  above  described  I  formerly  considered  to  belong  to  Calymene  conchma, 

Dalm.  iPalmad.  40.  7,  Tab.  I,  Fig.  5  ;  Milne  Edw.  Crust,  iii,  325.  16  ;  Asap/i.  cone.  Emmr.  Dissert. 
35  19).  Dr.  Löven,  however,  has  since  published  a  very  accurate  description  of  Dalman's  species 
(49  Tab.  I,  Fig.  2),  and  proved  that  it  is  not  identical  with  Proetus  Cuvieri.  But  he  is  of  opinion 
that  both  Trilobites  belong  to  the  same  genus,  which  I  cannot  admit.  I  prefer  separating  Dalman's 
species  from  the  species  of  Steininger,  giving  the  new  genus  my  former  designation  of  Jeoiiiu,  and 
distinguishing  it  from  Proetus  by  the  following  characters  : 

Glabella  (which  is  shaped  like  a  violin)  has  at  each  side  three  slight  furrows,  is  contracted  behind 
in  a  pedunculated  stape,  and  furnished  with  two  little  tubercles  close  to  the  peduncle.  The  angles  of 
the  cephalic  shield  terminate  in  long  spines. 

The  eyes  are  oblong,  lunate,  and  flatter  than  in  the  other.  The  axis  of  the  body  is  comparatively 
narrower,  but  likewise  ten-jointed. 

The  caudal  shield  is  not  so  obtuse,  its  axis  longer  and  narrower,  and  its  sides  have  deeper  radi- 
ations. 

The  following  species  belong  to  this  new  genus  : 

1.  Ae.  concinna  [Proetus  concinnus,  Löven  1,  1;  Calymene  cone.  Dalm.).  The  cephalic  shield  I 
have  copied  from  Löven's  figiu-e.      Tab.  V,  Fig.  8. 

2.  Ae.  Stokesii  [Asap/i.  Stokesii,  Murch.  Sil.  Syst.  ii,  625,  PL  XI Y,  Fig.  6;  Löven  50,  Tab.  I, 
Fio-.  3).      From  the  figure  by  Löven  I  have  copied  the  cephalic  shield.      Tab.  V,  Fig.  5. 

3.  Ae.  verticuUs,  Mihi,  Tab.  V,  Fig.  9  (Gerastos  cormitvs,  Goldf.  558.  3,  Tab.  Y,  Fig.  1).  This 
species  is  nearly  related  to  the  former,  and  perhaps  identical.  I  have  formerly  described  it  from  an 
imperfect  specimen  as  Trilobites  verticalis,  and  therefore  did  not  recognize  it  properly ;  the  present 
fio-ure  is  more  correct.  The  glabella  is  flat  and  fiddle-shaped,  becomes  gradually  narrower  towards  the 
anterior  part,  and  exhibits  at  each  side  three  oblique  sulcations,  of  which  the  posterior  rans  in  a  curve 
towards  the  posterior  margin,  nearly  reaching  it.  Traces  of  granulation  may  be  seen  on  its  summit. 
The  oblong,  lunate  eyes  correspond  to  the  two  posterior  cephalic  lobes ;  they  are  externally  surrounded 
at  their  base  by  a  furrow.  The  margins  of  the  cephalic  shield  form  a  protuberance,  which  passes  over 
at  the  angle  into  the  long  powerful  spine,  but  is  sulcated  at  the  upper  part.  The  body  joints  are 
short  but  rather  broad,  uarrower,  however,  than  the  lateral  lobes.  The  caudal  shield  is  rather  less 
than  a  semicircle,  its  axis  acutely  pointed,  seven-jointed ;  the  sides  have  five  flat  elevated  ribs,  their 
extremities  gradually  becoming  broader  and  indented  by  an  additional  radiated  furrow. 

Occurs  in  the  Eifel  near  Bensberg  (Sack's  collection). 

2.  Calymene  diops,  Green  [Mon.  37,  Fig.  2 ;  MontJily  Amcr.  Journ.  of  Geol.  559,  Tab.  XXII, 
Fig  2;  Milne  Edwards,  Crust,  iii,  323.  10;  Harl.  Med.  and  Plnjs.  Res.  301).  The  figure,  Tab  III, 
Fi^.  5,  is  copied  from  the  specimen  in  plaster  of  Paris  of  the  Berl.  Museum ;  this  species  seems  rather 
to  belong  to  the  new  genus  Aeonia  than  to  Proetus,  and  I  shall  therefore  not  attempt  a  further  description 
of  it  until  I  have  accurately  examined  original  specimens.      The  figure  is  sufiSciently  recognizable. 

3.  Gerastos  granulosus,  Goldf.  (558.  2,  Tab.  V,  Fig.  4),  belongs  decidedly  to  Proetus.  It  is 
distinguished  from  Pr.  Cuvieri  by  its  more  elongated  and  more  strongly  granulated  glabella,  and  by 
the  more  pointed  angles  of  the  cephalic  shield. 


OF  THE  SPECIES.  101 


GeiiKs  16. — Archegonus,  (Phillipsia  and  Griffitiiidrs,  Portl.) 

The  cephalic  shield  is  rather  large,  parabolic,  moderately  convex,  with  a  niarcrin  but 
slightly  thickened,  the  glabella  is  evident,  but  not  so  distinct  as  in  the  former  genera, 
its  form  is  different,  its  sections  and  lobes  not  very  depressed.  The  postci-ior  angles  of 
the  cephalic  shield  are  either  pointed  or  obtuse. 

The  facial  suture  commences  at  the  anterior  margin  of  the  cci)halic  shield,  turns  thence 
somewhat  inwards  towards  the  eye,  forms  the  covering  plate,  and  extends  in  a  curve  to 
the  posterior  margin,  which  it  intersects  near  the  middle. 

The  eyes  are  small,  particularly  low,  but  frequently  long,  lunate,  and  of  a  finely  trans- 
parent lattice-work. 

The  axis  of  the  body  consists  of  nine  short,  highly  arched  rings,  and  is  only  very  slightly 
narrowed  towards  the  posterior  part ;  the  lateral  lobes  are  as  broad  as  the  axis,  and  have 
only  a  distinct  oblique  furrow. 

The  caudal  shield  is  but  very  little  smaller  than  the  cephalic,  its  form  parabolic  ; 
it  is  highly  arched  at  the  axis,  and  less  so  at  the  sides ;  the  axis  is  distinctly  articulated,  and 
consists  of  twelve  or  more  joints ;  the  sides  are  furnished  with  radiated  furrows. 

The  surface  of  the  shell  is  granulated  in  most  of  the  species,  but  in  some  it  is  finely 
lineated. 

Localifi/. — The  carboniferous  limestone  and  other  contemporaneous  beds. 

Remark. — WLeu  I  first  described  this  genus  (which  I  did  contemporaneously  with  Portlock), 
I  knew  accurately  only  one  species,  and  owing  to  the  shell  of  this  species  possessing  a  lineated  surface, 
I  placed  Archegonus  in  the  next  group  of  Trilohites.  This  genus,  however,  has  become  better  known 
since,  and  it  has  been  proved  that  the  shell  of  most  species  presents  a  granulated  siu-face.  I  have 
therefore  been  obliged  to  alter  its  systematic  position.  The  occurrence  of  two  different  kinds  of 
mai'kings  in  the  same  genus  is  a  remai'kable  circumstance,  but  less  enigmatical  in  this  instance  when 
we  take  into  consideration  that  this  genus  represents  the  last  type  of  the  Trilobites,  and  therefore 
naturally  would  bring  together  characters  which  hitherto  had  been  distributed  over  different  contemporary 
genera.      A  similar  combination  takes  place  filso  in  Brontcus. 

The  species  may  probably  be  grouped  best  in  the  following  manner : 

I.  Those  in  which  the  glabella  has  three  lateral  furrows,  which  obliquely  extend 
towards  the  posterior  part,  and  become  gradually  larger;  the  posterior  and  largest  separates 
a  lobe  which  is  more  strongly  arched  and  more  projecting  ;  and  the  elongated  eyes  corre- 
spond with  the  latter  in  position.  The  posterior  angles  of  the  cephalic  shield  are  elongated 
in  a  granulated  manner. — Phillipsia,  Portlock. 

A.  The  glabella  not  broader  towards  the  anterior  part,  but  of  the  same  breadth, 
and  commencing  from  the  eyes,  afterwards  parabolically  rounded.  The  shell  has  a  tuber- 
cular granulation,  particularly  at  the  axis. 

To  this  belong  the  species,  Phill.  Kcllii,  Portl.  {Rep.  of  Geol.  etc.,  307,  Table  II,  Fig.  1) ; 
Pliill.  oniata,  Portl.  (/.  c.  307,  Fig.  2) ;  the  figure  in  the  same  work  marked  Figs.  4.  10.  11.  12  ; 
the  caudal  shield  in  Brongniart's  Crust,  foss.  Table  IV,  Fig.  12;  Phill.  gemmulifera, 
De  Koninck,  {Mem.  de  VAcad.  Poy.  de  JBruxelles,  torn,  xiv.  Fig.  3 ;  Ej.  Anim./oss.  de  la  Belyiq. 
603.   4,  Table    LlII,  Fig.  3.)      Perhaps  we  may  also   include   among  this  group  Amph. 


102  SYSTEMATIC  ARRANGEMENT 

duh'uix,    Münster   {Bei fr.    112,    Table   X,    Figs.    1,   4,   5),    togetlier   with    Cal.   furcnfa   (ibid. 
Fig.  9.) 

B.  The  glabella  a  little  broader  towards  the  anterior  part,  or  at  least  broadly  rounded, 
and  more  strongly  arched  at  the  extremity.  The  shell  has  a  finer  granulation,  the  eyes  are 
very  much  elongated,  and  reach  to  the  posterior  margin  of  the  cephalic  shield. 

To  this  group  belong,  PhiUqma  Jonesii,  Portl.  (30.  8,  Table  II,  Figs.  3  and  5) ; 
Asaphus  Balmanni,  Emmr.  {Dissert.  36.  21,  Gold/,  in  Lconh.  and  Bronn.  n.  Jahrb.  1843, 
.561.  12)  ;  PJiiUipsia  dnrlai/ensis,  De  Koninck  {Anim.  fossile,  etc.,  601.  2,  Table  III,  Fig.  2)  ; 
Cnlpnene  ?  cecjnalis,  v.  Meyer  {Nova  Acta  Phijs.  Med.  Soc.  Cues.  Leop.  Carol,  n.  cur.  ,xv, 
2.  100,  Table  LVI,  Fig.  3). 

II.  The  glabella  with  only  one  lateral  furrow,  which  separates  one  indistinct  lobe  before 
the  margin  of  articulation.  The  eye  shorter,  but  higher,  more  remote  from  the  glabella, 
and  not  projecting  so  far  towards  the  posterior  part. — Griffithides,  Portlock. 

a.  The  cephalic  shield  with  horny,  elongated  angles,  the  surface  of  the  shell  at  least 
partly  granulated  (e.  g.  on  the  cheeks). 

To  this  belongs  Phillipsia  (/lohieeps,  De  Koninck  (599.  2,  Table  LIII,  Fig.  1),  and 
probably  also  Grißthides  lonpsjnnm,  Port).  312.  Table  XXIV,  Fig.  12). 

b.  The  cephalic  shield  not  elongated  into  processes,  the  surface  of  the  shell  without 
granulation,  but  with  a  lineated  sculpture. 

To  this  belong  two  species:  1.  A.  ylobiceps,  Mihi  {Griff,  glohiceps,  Portl.  311.  Plate  II, 
Fig.  9  ;  Asaph,  r/lob.  Phill.  Geol.  ofYorhh.  1,  Table  XXII,  Figs.  16.  20  ;  Emmr.  Dissert,  35.  20). 
2.  A.  daviceps,  scuto  capitis  caudoeque  subparabolico,  angulis  illius  rotundatis  ;  axi  caudae 
duodecies  annulata,  sulcis  scuti  lateralibus  octo.     Long.  1",  Table  V,  Fig.  3. 

Archegonus  ipqindis. 

Locality. — A  grayish-brown  grauwacke  near  Altwasser,  in  Silesia ;  received  (from  the 
same  locality)  from  M.  Bocksch  through  M.  de  Charpentier ;  in  the  Berlin  Museum. 

The  cephalic  shield  is  somewhat  broader  than  long,  the  glabella  very  convex, 
moderately  thickened  towards  the  anterior  part,  marked  by  deep,  transversely  corrugated 
lines,  contracted  in  the  region  of  the  eyes,  and  there  provided  with  a  slight  sulcation, 
which  separates  an  indistinct  lobe  before  the  margin  of  articulation.  The  posterior 
extremity  of  the  eye  corresponds  with  this  furrow.  The  margin  of  articulation  projects 
somewhat  at  the  posterior  part ;  the  cephalic  shield  has,  however,  no  reflexed,  but  only  a 
slightly  indicated  marginal  fold.  The  nine  body  rings  are  short,  their  lateral  lobes 
rather  broader  than  the  axis,  and  very  distinctly  separated  from  it ;  the  oblique  transverse 
furrow  is  very  visible.  The  caudal  shield  is  parabolic,  rather  convex,  especially  the  axis, 
and  obtusely  rounded.  We  distinguish  in  it  from  ten  to  twelve  rings,  separated  according 
to  their  size,  and  about  eight  more  depressed  lateral  furrows,  between  which  there  may  also 
be  perceived  the  more  shallow  diagonal  furrows. 


OF  THE  SPECIES.  103 


SECTION    II. 

TrUohites  possessing  the  eapacifi/  of  rollhif/  themselves  up,  the  bochj  axis  not  shortened 
posteriori!/,   the  shell  finely  lineated,   the  caudal  shield  not  having    radiated  lateral  farrows. — 

AsAPHin.E. 

I  have  already  made  some  necessary  remarks  respecting  the  structure  of  the  shells  of 
this  group ;  an  additional  common  characteristic,  however,  seems  also  to  exist  in  the 
glabella,  which  is  always  simple  and  destitute  of  lobes,  indistinct  traces  only  of  lateral 
lobes  being  occasionally  recognized  at  its  posteiior  contracted  part.  The  caudal  axis 
likewise  has  frequently  no  joints,  but  generally  has  thera  indistinctly  marked,  whilst  the 
ribs  on  the  sides  of  the  shield  are  always  entirely  wanting,  and  are  at  the  utmost  only 
indicated  by  fine  ridges  or  lines.  With  regard,  however,  to  the  width  of  the  body  rings 
I  must  remark  that  the  central  rings  become  rather  broader  than  the  anterior  and  posterior 
ones,  and  the  axis  has,  therefore,  only  an  equal  width  at  the  anterior  and  posterior  part. 

A. 

Tlie  body  axis  consisting  of  ten  equal  rings. 
Genus  17. — Ill^nus,  (Ill^nus  and  Bumastes.) 

The  cephalic  shield  may  be  best  compared  to  the  fourth  part  of  a  sphere,  and  is, 
therefore,  bounded  by  curves  on  the  posterior  and  anterior  margins,  and  strongly  arched 
between ;  at  the  posterior  margin  we  recognize  the  glabella  as  a  slight  convexity  on  the 
surface ;  the  anterior  margin,  on  the  other  hand,  is  acutely  angular,  rather  produced, 
and  depressed. 

The  facial  suture  projects  obliquely  over  the  flattened  margin,  rises  with  a  gentle 
curvature  upwards  to  the  eye,  forms  the  covering  plate  over  the  latter,  and  thence  turns 
again  with  a  gentle  curvature  towards  the  posterior  margin,  which  it  intersects  not  far 
from  tlie  axis.  Both  sutures  are  connected  on  the  flattened  anterior  margin  by  a  transverse 
suture. 

The  eyes  are  semilunate,  depressed,  and  smooth. 

The  body  consists  of  nine  or  ten  short  but  broad  rings,  which  are  not  furnished  with  an 
oblique  transverse  furrow  on  the  lateral  lobes. 

The  large,  almost  semicircular,  caudal  shield  is  highly  arched,  and  furnished  with  an 
indication  of  a  short  axis,  as  in  Brontes. 

The  surface  of  the  shell  has  fine,  concentric,  irregular  lines  or  ridges,  between  which,  as 
also  on  the  parts  which  are  not  striated,  there  are  impressed  punctures. 

Division  A. — Axis  of  the  body  not  broader  than  the  lateral  lobes,  and  distinctly  sepa- 
rated from  them. — Illj^inus,  auctorum. 

The  species  occur  in  the  lower  strata  of  the  grauwacke  formation. 

1.  ///.  crassicauda :  Oculis  margiui  postico  scuti  ceplialici  approximatis.  Long.  1-3".  Tab.  V, 
Fig.  2. 

Entom.  cr.  Wahlenb.  N.  A.  Ups.  viii,  27.  2,  Tab.  II,  Figs.  5,  G.    Dxhyi.  Pal^ad.  51.  12, 
Tab.  V.  Fig.  2,  «,/.    Bronn,  lefh.  i,  ll',,  C.  3,  Tab.  IX.  Fig.  9,  a,  b.     Boeck, 


104  SYSTEMATIC  ARRANGEMENT 

Gaea  Norw.  i,  34.     Emmr.    Diss.  34.   17.     Pander,  Bcitr.    137,  Tab.    V.    Figs. 
9,    10.     L.   V.    Buch,  Beitr.  43.     Triloh.  Esmurkii,  Schloth.   Ms,    1826,   315, 
Tab.  I,  Fig.  8. 
Crjjpionymus  Biidnljj]iü,^\cw.'W.  Observ.  etc.  50.  ^  56,  Tab.  II,  Fig.  1,  a,  h.  Cr.    Mosenhergii, 
ibid.  48,  Tab.  Ill,  Fig.  3,  a,  b.    Or.  Parkimonii,  ibid.  51.  ^  57,  Tab.  IV,  Fig.  \,a,b. 
Cr.  Wahlenhergii,  ibid.  50,  Fig.  3,  a,  b. 
Isotdes  crassicauda,  Milne  Edw.  Cr.  iii,  300.  6. 
The  following  seem  to  be  young  individuals  of  the  same  species. 
Elanus perovali.'i,  MuRCHis,  Sil.  Syst,  iii,  661.  PL  XXIII,  Fig.  7. 

Localiti/.  — Occurs  in  the  transition  limestone  of  Sweden  ;  at  Husbyfjol,  in  East  Gothland  ; 
at  Osraundsberg,  in  Dalecarlia  ;  in  Esthonia,  at  Revel,  and  at  St.  Petersburgh  ;  in  England, 
in  the  Caradoc  sandstones  of  Shropshire  and  Montgomeryshire. 

This  common  Trilobite  is  easily  to  be  recognized  by  its  peculiar  habit,  and  is  distin- 
guished from  the  following  species  by  the  eyes,  which  are  situated  far  towards  the  posterior 
part,  close  to  the  borders  of  the  head. 

2.  ///.  giganteus  :   Oculis  in  medio  latere  scuti  cephalici.      Long.  3-6".      Tab.  Ill,  Fig.  10. 
GUETTARD,  Mem.  do  TAcad.  Boy.  etc.  1757,  torn,  xv.  Tab.  VII,  Fig.  2  ;  Tab.  VIII,  Fig.  \; 

Tab.  IX,  Fig.  1. 
Occurs  in  the  clayslate  of  Angers ;  according  to  a  specimen  in  the  academical 
collection  at  Halle.  This  species  seems  rare,  and  not  to  have  been  found  by  any  observer 
since  Guettard's  time ;  it  is,  however,  as  distinct  as  any  other  species  of  Trilobite.  The 
splendid  specimen  in  the  collection  above  named,  of  which  I  give  an  accurate  figure,  shows 
only  the  cast  of  the  animal ;  but  exhibits  all  the  characteristics  of  Ulanus,  together  witli 
the  peculiarity  which  mai'ks  it  as  a  distinct  species  :  this  is  seen  in  the  position  of  tlie  eyes,  and 
is  very  manifest.  The  covering  plate  at  each  side  of  the  cephalic  shield  is,  however,  only 
visible  on  the  latter,  the  maxillary  shield  and  the  eye  itself  are  wanting  ;  I  have  endeavoured 
to  indicate  its  position  by  a  dotted  line. 

Division  B. — The  axis  of  the  body  comparatively  broader,  and  only  imperfectly  sepa- 
rated from  the  lateral  lobes  by  a  slight  longitudinal  sulcation. — Bumastes,  Murch. 

3.  IJl.  (Bit.)  burrieims ;  Oculis   margini  postico  scuti  cephalici  approximatis.      Long.  2-3". 
MuRCH.    Sil.    System,  ii,  656,  PI.  VII,  Fig.  3,  «,  b,  c,  PI.   XIV,  Fig.   7.      Jukes    and 

Sowerby,  Zoitd.  May.  of  Mit.  History,  ii,  41.  Silliman,  ^'/ww.  Journ.  of  Science, 
1832,  vol.  xxiii,  I.  p.  203.  Emmr.  Dissert.  33.  Milne  Edw.  Cr.  iii,  295. 
Locality — The  middle  Silurian  strata  of  England,  at  Barr,  in  Staffordshire,  at  Brandlodge, 
and  Presteign.  This  Trilobite  resembles  so  much  the  ///.  crassicauda,  with  the  exception  of 
the  body,  the  broad  axis  of  which  is  not  strictly  separated  from  the  lateral  lobes,  that  I 
hesitated  for  some  time  before  I  could  decide  upon  its  being  a  different  species.  Isolated 
cephalic  and  caudal  shields  can  scarcely  be  distinguished  from  the  former. 

Remar/c. — Nilens  glomerinus,  Dalm.  [Arsberatt,  1828,  p.  136 ;  Hising.  Letli  Sitec.  16),  seems  to  be 
the  same  species. 


OF  THE  SPECIES.  105 


B. 


The  body  axis  cotmstinr/  of  nine  rings. 
Genus  18. — Dysplanus. 

Cephalic  shield  highly  arched,  large,  semilunar,  the  posterior  angles  elongated  into 
pointed  processes,  the  glabella  not  more  strongly  arched,  and  no  posterior  j)roniinent 
margin  of  articulation. 

The  facial  suture  describes  in  front  a  semicircle,  bends  towards  the  eyes,  and  extends 
with  a  gentle  curve  from  the  latter  to  the  posterior  margin  ;  between  its  extremity  and  the 
glabella  there  is  at  each  side  a  furrow. 

Eyes  small,  slightly  convex,  scarcely  rising  above  the  level  surface  of  the  head,  placed 
still  further  towards  the  exterior  part  than  in  Ulanns,  lunate,  transparently  reticulated. 

Body  axis  rather  convex,  but  the  rings  are  short ;  the  lateral  lobes  rather  broader 
than  the  axis,  strongly  bent  downwards,  without  diagonal  furrows. 

Caudal  shield  broad,  semicircular,  slightly  arched,  with  a  short,  slightly  indicated  conical 
ixis,  without  rings  or  lateral  furrows. 

The  only  known  species  is : 

D.  centrofiis  ;  Asaph  {Illesnus)  centrot.  Dalm.  Pahead.  51.  11,  Tab.  V,  Fig.  1,  a.  c. 
BoECK,  Gaea  Norm.  I,  No.  35.  Emmr.  Dissert.  34,  18.  Isotcles  centr.  Milne 
Edw.  Crust,  301.  7. 

LocaUti/. — The  transition  lime  of  Eastgothland,  near  Husbyfjöl,  but  of  rare  occurrence ; 
found  also  at  Christiania. 

C. 

The  axis  of  the  body  consisting  of  eight  equal  rings. 

Genus  19. — Asaphus,  Brong.    (Asaphus  et  Nileus,  Dalm. ;  Isoteles,  Dekay ; 
Hejucrypturus,  Green.) 

This  genus  embraces  a  widely  extended  group,  if  we  define  it  according  to  the  number 
of  the  rings  of  the  body  ;  but  in  addition  to  these  it  only  exhibits  one  other  generic  character, 
derived  from  the  course  of  the  entire  facial  suture,  on  the  upper  side  of  the  cephalic  shield. 
Intersecting  the  margin  at  the  posterior  part,  in  the  centre  of  the  lateral  lobes,  this  suture 
turns  with  the  usual  S-shaped  curve  towards  the  eye,  forms  over  it  the  covering  plate,  and 
thence  extends,  describing  an  arch  to  the  centre  of  the  anterior  margin.  The  two  angles 
pass  into  one  another,  describing  a  semicircle,  if  the  anterior  margin  is  obtuse,  and  they 
form  an  angle  with  one  another  if  the  latter  is  pointed.  The  eyes  themselves  are  large, 
high,  and  exceedingly  prominent,  although  not  quite  so  elevated  as  in  Thacops ;  the  thick 
horny  membrane  is  smooth,  but  the  lenses  are  not  unfrequently  seen  through  it. 

The  axis  of  the  body  is  of  equal  breadth,  rather  broader  perhaps  towards  the  centre, 
and  usually  distinctly  separated  from  the  lateral  lobes  ;  the  oblique  transverse  furrows  are 
then  visible  likewise. 

The   caudal  shield   resembles  the  cephalic,  either  wholly  or  very  nearly  in   point  of 

14 


106  SYSTEMATIC  ARRAXGEMENT 

outline  and  shape,  and  has  not  always  a  projecting  axis,  but  this  axis,  when  visible,  is  usually 
articulated.  Several  subdivisions  may  be  established  in  this  large  genus,  and  we  may  consider 
these  as  so  many  subgenera. 

Group  A.  The  lateral  lobes  not  separated  by  any  furrow  from  the  axis  of  the  body 
and  with  no  transverse  furrows ;  the  trace  of  an  axis  wanting  in  the  caudal  shield,  and  the 
indication  of  the  glabella  in  the  cephalic  shield.  The  facial  suture  describes  a  circle,  the 
eyes  are  large,  lunate,  but  not  very  prominent. — Nileus,  Dalman. 

1.  AsapJms   [Nileus)  armadillo:    Scuto   capitis   caudfeque   convexo  brevi  dilatato ;  angulis  capitis 
-posticis  obtusis:  thoracis  axi  lobis  lateralibus  latiori.      Loug.  1-2". 

Mef.—D^iM.  Palcead.  49.  10,  Table  XIV,  Fig.  3,  a-e.  Milne  Edw.  Crust,  iii,  294.  1, 
PI.  XXXIV,  Figs.  1,2.  P.\ND.  Beitr.  132,  Tab.  V,  Fig.  2.  L.  v.  Buch,  Beitr.  50. 
HisiNG.  LetJi.  Suae.  16,  Tab.  Ill,  Fig.  3.     Asaph,  armed.  Emmr.  D'mcrf.  33,  15. 

Var.  Minor :  Nileus  chiton.  Pander,  Beitr.  132,  Tab.  V,  Fig.  I.  Milne  Edw.  Crust. 
iii,  295,  2. 

Locality.— '^\^&  transition  limestones  of  Eastgothland,  Husbyfjöl,  and  Skarpasen ;  in 
Dalecarlia,  at  Rathwick  ;  in  Esthonia,  at  St.  Petersburgh. 

Cephalic  shield  short,  scarcely  half  as  broad  as  long,  uniformly  convex,  with  rather 
acute  margins  ;  the  eyes  separated  far  from  one  another,  reaching  almost  to  the  anterior  and 
posterior  cephalic  margins,  but  depressed,  and  with  a  large  covering  plate. 

The  rings  of  the  body  short,  without  any  division  between  axis  and  lateral  lobes  ;  the 
former,  however,  is  indicated,  and  is  almost  twice  as  broad  as  the  latter,  which  has  no  trans- 
verse furrows. 

Caudal  shield  short,  broad,  curved  at  the  basis,  without  a  vestige  of  an  axis. 

Remarks.^1.  It  is  easily  distinguished  from  Bumastes  (like  which,  however,  it  has  an  axis  not 
separated  from  the  lateral  lobes)  by  the  number  of  body  rings,  and  not  less  so  by  the  position  and  size 
of  the  eyes,  and  the  comparatively  inferior  size  and  less  convex  shape  of  the  glabelhi.  It  stands, 
however,  in  the  same  relation  to  the  following  group  as  Bumastes  does  to  Iltcenus,  and,  as  in  the  latter 
case,  there  are  analogous  forms. 

2.  Nil.  gJomerinus,  Dalm.  (Arsberatt  1828.  136;  Risinger,  Let h.  Siiec.  16).  Nil.  glaberrimus 
(Milne  Edw.  Cr.  iii,  295),  with  small  eyes  and  ten  body  rings,  may  probably  be  identical  with  Bumastes 
barriensis.     Dalman's  specimens  were  found  at  Husbyfjöl. 

Group  B.  The  lateral  lobes  of  the  rings  of  the  body  separated  from  the  axis  by  a 
depressed  longitudinal  furrow.  The  diagonal  furrows  of  these  lobes  seem  to  be  always 
present.* 

Subdivision  A. — The  facial  suture  describes  an  arch  anteriorly,  but  is  not  angular. 

a  a.  The  glabella  and  caudal  axis  distinctly  indicated,  the  latter  not  articulated  and  very  short  (?). 
The  eyes  are  also  flatter  and  depressed,  lunate,  and  supported  at  the  lower  part  by  a  portion 
of  the  cheek-shield,  upon  which  they  are  borne ;  the  diagonal  furrows  of  the  lateral  lobes 
appear  to  be  slight. — Symphysurds,  Goldfuss. 

*  They  have  not  been  indicated  in  Dalman's  figure  in  Asaph,  palpebrosus  and  A.  Imviccps,  but 
are  mentioned  in  the  description  as  being  slight. 


OF  THE  SPECIES.  107 

2.  As.  palpebrosiis  :  \'crticc  tumido,  uiargiuem   crassum   scuti  ccphalici  superantc  ;   oculis  longis- 
simis.      Long.  IK-li'i  ". 

Dalm.    Falaad.  48.  9,  Tab.  IV,  Fig.  1,  a-c.     Emmr.  Dimcrt.  32.  14.     Milne   Edw. 
Crust,  iii,  299.  4.     Hising.  Ldh.  Sure.  1.5,  Tab.  Ill,  Fig.  l.ajj. 
Localily. — The  transition  limestone  of  Eastgothland,  at  Husbyfjül.     Having  had  no  oppor- 
tunity of  examining  a  specimen  of  this  or  the  following  species,  I  must  refer  the  reader  to 
Dalman's  detailed  description. 

3.  As.  l<Bviceps :  Scuto  capitis  caudreque  in  marginc  dilatato,  acutangulo,  axin  siiperante  ;  oculis 
brevioribus.      Long.  2". 

Dalm.  Fa/aad.  47.  8,  Tab.  I,  Fig.  1,  a-d.      Emmr.  Bissai.  32.    13.     Milne   Edw. 

Cn/st  iii,  305.  5.     Rising.  Lef/i.  Suee.  Tab.  II,  Fig,  8,  a,  b. 
Loeality. — The  transition  limestone   of  Eastgothland,  at  Husbyfjöl ;  but,  like  the  pre- 
ceding species,  of  rare  occurrence. 

h  b. — The  glabella  and  tbe  caudal  axis  project  distinctly  as  defined  and  convex  portions,  circum- 
scribed by  sulcations ;  the  latter  is  also  articulated.  The  eyes  are  elevated,  but  short 
protuberances,  which  reach  only  at  the  posterior  part  to  the  fiuTow  at  the  maxillary  shield. 
The  angles  of  the  cephalic  shield  are  rounded.  The  axis  of  the  body  is  narrower  than  the 
lateral  lobes,  and  the  latter  have  distinct  diagonal  fiu'rows.  Hemicrypturus,  Green,  Cryp- 
tonynnis,  Goldf.  Eichw.* 

4.  A.  exjwnsus :  Protuberantia  verticis  postice  coarctata,  utrinque  juxta  spiram  articulatoriam 
nodosa ;  angulis  scuti  cephalici  caudseque  obtusis.      Long  3-3 ".      Tab.  V,  Fig.  1,  a,  c. 

Eef. — Entomol.  paradoxus  a,  crpansus,  Linn.  8.  Nat.  iii,  160.  It.  vel.  147.  e.  Fig. 
RoBERG,  Dissert,  de  Jstac.  pp.  19,  20.  Klein,  Spec.  Petr.  Gedan,  Tab.  XV, 
Figs.  3,  4.  ScHLOTH.  Leonliard's  Taschenb.  1810.  1.  Tab.  I,  Figs.  1,  3.  Razou- 
MOWSKY,  Annal.  de  Scienc.  Nat.  tom.  viii,  PI.  XXVIII,  Figs.  2, 3,  5,  6,  7.  Entomostr. 
expans.  Wahlenberg,  N.  A.  Ujjs.  viii.  25.  I.  Asapih.  expans.  Dalm.  Palcead.  45.  6, 
Tab.  Ill,  Fig.  3,  a,  d.  Klod,  Verstein.  der  Mark  Brandeni).  108.  Bronn,  Letli  i, 
114.  1,  Tab.  IX,  Fig.  7.  Emmr.  Dissert.  30.  10.  Hising.  Leth.  Suec.  Tab.  II, 
Fig.  6.     L.  V.  Buch,  Beitr.  41. 

Asaph.  corni(/erus,  Brongn.  Cr.foss.  18,  PI.  II,  Fig.  1,  a,b;  PI.  IV,  Fig.  10.  Pander. 
Beitr.  135,  Tab.  VI,  Figs.  1,  4,  7  ;  Tab.  VII,  Figs.  3,  4;  Tab.  VIII,  Figs.  2-6. 

Trilob.  cornif/er.  Schloth.  Petref.  38.  1,  NacJdr.  vi,  16.  34.  Trilob.  Schroeteri,  ibid. 
35.  10,  Tab.  II,  Fig.  3  (large  caudal  shield). 

Cryptonymus  Lichtensteinii,  EiCHW.  47,  §  53,  Tab.  II,  Fig.  3,  a,  b.  Cr.  Panderi,  ibid.  47. 
§  52,  Tab.  Ill,  Fig.  1,  a,  b.  Cr.  Schlotheimii,  ibid.  45,  Tab.  IV,  Fig.  2,  «,  b.  Isoteles 
expans.  Milne  Edw.  Crust.'m,  304.  12.  Isot.  Lichtensteinii,  ibid.  303.  11,  Hemi- 
crypturus  Basoumowskii,  Green,  Mon.  of  Trilob.  20. 

Locality. — The  transition  limestone  of  Sweden,  at  Husbyfjöl,  and  Oeland ;  in  Esthonia, 
at  Revel  and  Petersbui-gh ;  in  Norway,  at  Christiania ;  in  boulders  in  Northern  Germany. 
Wilken's  figure  in  the  Stralsund  Mag.  (I,  Tab.  II,  Fig.  5, Tab.  Ill,  Fig.  II)  seems  to  belong  to 
this  species. 

Cephalic  shield  at  the  posterior  part  tw  ice  as  broad  as  long,  the  entire  external  margin 


108  SYSTEMATIC  ARRANGEMENT 

suddenly  deflexed,  not  produced.  The  glabella  distinctly  defined,  broadest  at  the  anterior, 
narrowing  towards  the  posterior  part,  contracted  in  the  shape  of  a  peduncle  before 
the  margin  of  articulation,  and  there  elevated  in  the  centre  into  a  protuberance  ;  beside 
it,  at  each  side,  another  more  level  protuberance,  which  extends  to  the  eye.  A  deep  fur- 
row separates  the  margin  of  articulation  from  the  cephalic  axis,  and  the  posterior  half  of 
the  lateral  surfaces  from  the  other  surface ;  it  disappears,  however,  towards  the  obtuse, 
rounded,  posterior  angle.     Eyes  short,  but  prominent. 

Axis  of  the  body  moderately  arched,  broader  towards  the  centre  than  at  either  end,  the 
separate  rings  strongly  arched. 

Caudal  shield  at  the  base  broader  than  long,  rather  obtuse  at  the  end,  moderately  con- 
vex, the  axis  even  at  the  commencement  rather  narrower  than  the  last  ring  of  the  body^ 
obtuse  at  the  posterior  part,  articulated  anteriorly,  but  more  or  less  distinctly  so,  (which 
depends  on  the  size  of  the  individual,)  eight  distinct  rings  in  all, rarely  more;  the  sides  with- 
out ribs.  The  whole  upper  surface  of  the  shell  is  not  smooth,  but  covered  with  elevated 
fine  ridges,  which  run  obliquely  towards  the  external  and  posterior  part ;  between  them 
are  impressed  points  or  dots,  which  are  occasionally  united  into  spiral  lines;  there  are 
usually  from  seven  to  eight  larger  striae  on  the  sides  of  the  caudal  shield,  which  correspond 
to  the  joints  of  the  axis.  Badly-preserved  specimens  are  so  worn  that  they  appear  to  be 
smooth. 

Remark. — Perfect  specimens  are  seldom  more  than  three  inches  long,  but  caudal  shields  of  much 
larger  individuals  have  lieen  fouud,  especially  in  boulders  (as  in  the  collection  at  Halle).  These  {Tril. 
Schrosteri  seems  to  be  the  same  species)  must  have  attained  the  length  of  six  inches.* 

5.  Asaphus  tyr annus  :  Protuberantia  capitis  ovata ;  angulis  scuti  cephalici  posticis  caudEeque  acutis 
vel  acuminatis.      Long.  6-10".      Tab.  V,  Fig.  4. 

i?(/.— MuRCHis.  Sil.  Syst.  ii,  662,  PI.  24.  Emmr.  Dissert.  29.  6.  Milne  Edw.  Cr. 
iii,  310.  7. 

Locality. — The  Llandeilo  flags  of  England,  in  Caermarthenshire,  Pembrokeshire,  and  in 
boulders  in  a  red  limestone  in  the  collection  at  Halle. 

The  cephalic  shield  is  not  yet  sufficiently  known ;  but  Murchison's  figure  leaves  no 
doubt  that  the  facial  suture  described  a  circle  at  the  anterior  part,  and  that  the  posterior 
angles  were  much  produced. 

The  large  caudal  shield,  which  I  have  represented,  belongs  undoubtedly  to  this  species, 
and  shows  that  Murchison's  figure  of  its  extremity  represents  it  as  rather  too  pointed.  The 
sculpture  of  the  upper  surface,  according  to  Murchison's  figure,  appears  to  be  exactly  the 
same  as  in  the  preceding  species,  only  less  delicate  ;  it  is  wanting  in  my  specimen  ;  I  have 
copied  Murchison's  figure  in  this  respect. 

SuMirisioH  B. — The  facial  suture  describes  an  angle  at  the  anterior  part,  and  is  not 
semicircular. 

a  a. — The  caudal  axis  projects,  and  is  distinctly  separated  by  a  furrow  in  the  shield. — 
Asaphus. 

*  Tlie  large  caudal  shields,  of  which  I  am  here  speaking,  belong  to  Isoteles  Powisii,  Portl.  {Rep. 
of  Geo/.  297,  PI.  YI,  Fig.  1),  and  must  not  therefore  be  identified  with  Asaphus  ex'jiansus.  I  now  very 
much  doubt  whether  Tri/.  Schrceteri,  Schloth.  belongs  to  it. 


OF  THE  SPECIES.  109 

6.  Asaphus  raniceps  :  Scuto  capitis  parabolico,  acuto,  angulis  posticis  subacutis  ;  rLaclii  cauda; 
subarticulata.      Long.  3-4". 

Be/.—BAhM.  Palcead.  Table  III,  Fig.  4.  Crypton.  Weissii,  Eichw.  Ohscrv.  AG,  §  51. 
Table  II,  Fig.  2,  a,  b.  Milne  Edw.  Crunt.  iii,  304.  13.  Razoumowsky,  An.  des 
Sc.  Kaf.  viii,  PL  XXVIII,  Fig.  1.  Pander,  Beifr.  Table  IV,  C,  Fig.  3  Table  VI, 
Fig.  XXIII.    Table  VII,  Figs.  1,  5,  6.    Table  VIII,  Fig.  7. 

Occurs  in  company  with  A.  e.vjjansus.  This  species  has  been  taken  for  a  variety  of 
A.  expansus  by  many  authors,  but  is  certainly  a  different  species. 

The  whole  cephalic  shield,  and  especially  the  glabella,  is  much  more  depressed,  the 
external  margin  produced  and  acutely  angular,  the  anterior  angle  pointed.  The  eyes  at  the 
same  time  are  always  higher,  the  rings  of  the  body  comparatively  flatter,  the  caudal  shield 
parabolic,  certainly  not  acutely  angular  at  the  posterior  part,  but  much  more  lengthened  ; 
it  is  also  more  flatly  arched,  and  the  a.xis  has  only  very  slight  indications  of  rings. 
Even  if  all  these  diS"erences  were  to  be  considered  as  merely  relative,  and,  therefore,  as 
mere  characters  of  variation,  yet  the  remarkably  acute,  angular,  facial  suture,  which  is 
curved  by  the  side  of  the  angle,  would  constitute  a  good  positive  distinction. 

The  eyes  are  also  situated  rather  more  close  to  each  other. 

7.  Asaphus  extemiatus  :  Scuto  capitis  parabolico,  acuto,  angulis  posticis  in  cornua  productis  ;  rbachi 
caiidse  subarticulata.      Long.  4-10". 

Bef. — Entom.  extemiatus,  Wahlenb.  N.  Act.  Ups.  viii,  295,  Table  VII,  Fig.  4. 

Asaph,  exten.  Dalm.  43.  3,  Table  II,  Fig.  3.  Hising.  Leth.  Suec.  13,  Table  IL  Fig.  3. 
Isoteles.  exten.  Milne  Edw.  Cr.  iii,  301.  8. 

Individiia  maxima :— Asaph,  grandis,  Sars'  Isis,  1835,  338,  Table  IX,  Fig.  6,  a,b. 
Milne  Edw.  Crust  m.,  311.  9. 

Found  in  a  gray  limestone  of  Eastgothland,  at  Husbyfjol  and  Hela  ;  in  the  black 
limestone  at  Aggersbakken,  near  Christiania. 

The  peculiar  lengthened  form  of  the  cephalic  shield,  its  greatly  produced  posterior 
angles,  and  the  long,  parabolic,  but  not  actually  pointed  caudal  shield,  conspicuously 
distinguish  this  beautiful  and  rare  species.  The  arch  of  the  glabella  is  moderate,  the 
furrowing  between  the  eyes  not  very  strong,  and  the  thickened  margin  of  articulation 
slightly  developed.  The  rings  of  the  axis  are  much  more  narrow  than  the  lateral  lobes, 
and  very  short,  compared  with  the  size  of  the  caudal  shield.  The  latter  has  a  long  parabolic 
form,  and  a  slightly  elevated  axis,  on  which  the  rings  are  indicated  in  the  horny  shell  as 
in  Asaph,  tyrannus,  by  little  elevated  transverse  ridges,  similar  fine,  radiating,  minute  ridges 
also  appear  at  the  sides.  This  I  could  perfectly  distinguish  in  Sars'  large  individual,  of 
which  I  found  a  plaster  cast  in  the  Berlin  Museum.  The  latter  appears  to  me  to  be  difl'erent 
only  in  size ;  the  specimens  of  Dalman  and  Wahlenberg  appear  to  have  lost  their  shell, 
or  at  least  the  sculptured  surface,  but  this,  according  to  all  analogy,  would  be  less  consider- 
able in  small  than  in  large  individuals. 


no  SYSTEMATIC  ARRANGEMENT 

b  h. — The  caudal  axis  does  not  project,  or  projects  but  very  little  from  the  shield. 

8.  As.  {Isot.)  platycephalus :  Scuto  capitis  caudaeque  parabolico,  acuto ;  tlioracis  axi  lobis  latera- 
libus  latiori,  axi  caudae  obsoleta.      Long.  2-6".      Tab.  II,  Fig.  13. 

Jief. — Asaph,  platyceph.  Stokes,  Trans,  of  the  Geol.  Soc.  of  London,  i,  8.  208,  PI.  27. 
Isoldes  gigas,  Dekay,  Annals  of  the  Lye.  of  Nat.  His.  of  New  York,  i,  176,  PL  12,  13. 
Fig.  1.  Dalm.  Palcead.  70.  13.  Green,  Mon.  of  Tril.  67.  Bronn,  Leth.  i,  115, 
PI.  IX,  Fig.  8.  Emmr.  Dissert.  32.  12.  Milne  Edw.  Crmt.  iii,  298.  1.  Brong- 
niartia  isoleta,  Eaton,  Geol.  Text  Book,  PI.  II,  Fig.  19. 

Found  in  a  black  limestone  of  Trenton  Falls,  in  the  state  of  New  York  ;  at  Cincinnati, 
in  the  state  of  Ohio,  and  at  other  places.  My  figure,  which  is  perfectly  accurate,  represents 
the  impression  of  the  lower  surface  of  the  shell,  and,  therefore,  exhibits  traces  of  lobes  on 
the  glabella  and  articulations  in  the  tail,  which  are  not  recognizable  in  the  upper  surface. 
I  convinced  myself  of  the  presence  of  a  peculiar  sculpture,  consisting  of  dots,  from 
remnants  of  it  in  the  specimen  from  which  my  drawing  is  taken,  which  therein  indicates 
a  near  affinity  with  Asajjhns  expansvs.  The  acute  shape  of  the  posterior  cephalic  angles  and 
of  the  lateral  lobes  of  the  body  distinguishes  Isoteles  from  the  group  of  Asaplms  marked  B  a, 
even  if  the  shape  were  not  distinct. 

Remarks. — 1.  Asajj/iiis  angitstifrons,  Dalm.  {Palcead.  44.  5,  Tab.  Ill,  Fig.  2,  a,  b),  of  wbicb  I  have 
seen  a  plaster  cast  at  Berlin,  seemed  to  me  to  be  a  member  of  this  group,  but  the  caudal  axis  projected 
rather  more  from  the  .shield,  and  was  not  narrower  than  the  bodj'  at  the  anterior  part.  This  shortening, 
which  seems  to  be  indicated  by  furrows  and  little  punctations  at  the  lower  side  of  the  shell,  is  a  peculiar 
feature  of  Asaphus  platycephalus. 

2.  Green's  Isoteles  planus  [Mon,  p.  68),  stegops  (71),  and  Isot.  megalops  are  indi\'iduals  in  different 
states  of  preservation,  and  of  diflerent  sizes,  but  all  belong  to  Isot.  gigas.  The  same  author's  Isot. 
Cyclops  (p.  69),  on  the  other  hand,  seems  to  belong  to  a  peculiar  species,  nearly  related  to  Asapti.  angus- 
tifrons,  if  not  identical  with  it.  Isotel.  megalops  is  based  upon  individuals  which  most  nearly  correspond 
with  the  one  I  have  represented. 


D. 

Six-joi?ited  TriloMtes,  capable  of  rolling  themselves  up,  and  having  the  axis  of  the  body  equally 
broad  throughout. 

Genus  20. — Ampyx,  Dalman. 

I  am  acquainted  neither  with  original  specimens,  nor  with  casts  of  this  genus,  and 
cannot,  therefore,  give  a  sufficient  explanation  of  it ;  judging  from  the  figures  and  the 
descriptions  of  authors,  it  seems  to  be  most  nearly  allied  to  those  species  of  Asaphus  which 
have  a  pointed  cephalic  shield.  It  has  much  produced  angles,  which  are  generally  broken 
off,  but  it  is  distinguished  from  the  species  alluded  to  by  its  higher  and  more  prominent 
glabella,  and  more  projecting  eyes.  According  to  Dalman,  the  axis  consists  of  six  body 
rings  (according  to  Sars,  of  five  only),  which  are  short,  but  have  broad  lateral  lobes,  on  which 
(according  to  Sars)  the  transverse  furrows  can  be  seen.  The  caudal  shield  resembles  the 
cephalic  shield,  and  has  a  distinctly  projecting,  obtuse  axis,  in  which  six  or  eight  rings  are 
usually  indicated ;  the  ribs  on  the  sides  appear  to  be  wanting. 


OP  THE  SPECIES.  Ill 

Occurs  in  very  old  strata  of  tlic  transition  limestone  ;  three  different  species  are  known, 
respecting  which  I  beg  to  refer  to  the  authors  quoted. 

1.  A.  nasutiis,  Dalm.  Palmad.  .'34.  1  ;  Emmr.  Dins.  49.  1  ;  Milne  Edw.  Cr.  iii,  296.  1  ; 
BoECK,  Gaea  None.  1,  No.  47. 

In  a  gray  limestone  of  Eastgothland,  at  Skarpasen  and  HusbyfjiJl ;  occurs  also  in  a  red 
limestone  of  the  Billinger  Mountain  at  Skofda. 

2.  J.  mammillatus,  Sars'  Ms,  1835,  335.  3,  Table  VIII,  Fig.  4,a-c  (the  caudal  shield  d 
probably  belongs  to  a  Trinudeus) ;  Emmr.  Diss.  49.  2 ;  Milne  Edw.  /.  c.  3 ;  Boeck,  /.  c. 
No.  46. 

Occurs  in  the  transition  limestone  of  Loadegaarts  Ocn,  and  Hjortnaestangen,  near 
Christiania. 

3.  J.  rosfratus,  Sars,  ibid.  334.  2,  Table  VIII,  Fig.  3,  a-c;  Emmr.  Diss.  49.  3;  Milne 
Edw.  ibid.  2;  Boeck,  ibid.  No.  5. 

Found  at  the  same  places  with  the  preceding  species,  but  more  rarely. 


APPENDIX. 


1. 

The  following  species  are  enumerated  in  works  which  I  could  not  obtain,  for  which 
reason  they  have  not  been  referred  to. 

Ampyx  incertiis,  Delongchamps,  Mem.  de'Ja  Soc.  Zimieefine  de  Calvados,  ii.  316,  PI.  XX, 
Fig.  5.     Milne  Edw.  Crust,  iii,  297. 

Asaphis  Brongniartii,  ibid.  PI.  XIX,  Figs.  1-5.     Milne  Edw.  ibid.  313. 

AsapJnts  quadrilimhatus,  Philips,  Geol.  of  Yorkshire,  vol.  ii,  p.  239,  PI.  XXII,  Figs.  1,  2. 

AsajjJnis  obsoletus,  Phil.  ibid.  Figs.  3-6. 

Asaphus  gramdiferus,  Phil.  ibid.  Fig.  7. 

Asaphus  semimferus,  Phil.  ibid.  Figs.  8-10. 

Asaplmsgemmuliferus,VniL.\hiA.  Fig.  II.  Buckl.  Br.  Tr.  PI.  XLVI,  Fig.  10.  Ac- 
cording to  Buckland's  figure,  this  is  probably  the  same  species  as  that  represented  by 
Brongniart  in  the  Cr.  foss.  PI.  IV,  Fig.  12,  and  which  I  have  mentioned  when  treating  of 
Archegonus  cequalis. 

Asaphus  truncntidus,  Phil.  ibid.  Figs.  12,  13. 

Asaphus  megalophthalmm,  Troast,  Mem.  de  la  Soc.  Geol.  de  France,  iii,  94,  PI.  XI,  Fig.  1. 

Asaphus  heros,  Dalm.  Arsberätt  om.  nya.  zool.  Arbcten  135,  Stockholm,  1828.  Hising. 
Leih.  Suec.  13.  Milne  Edw.  Cr.  iii,  309.  The  author  places  this  species  beside  Bhac. 
caudatus. 

Asaphus  plat ynotus,  Dalm.  ibid.  135.  W\?.\^g.  Leth.  Suec.  15.  Milne  Edw.  Crust. 
iii,  304. 

Calymene  ornata,  Dalm.  ibid.  p.  134.  Hising.  Leth.  Suec.  11.  Milne  Edw.  Crust,  iii, 
304.  According  to  Milne  Edwards,  it  is  nearly  related  to  Calym,.  Blumenbachn,  but  distin- 
guished from  it  by  the  structure  of  the  glabella.  According  to  Dr.  Beyrich  {Bohem.  Tril. 
18),  the  species  belongs  to  Cheinmis.     See  also  Löven,  Of  vers  K.  V.  A.  1844,  68. 

Calymene  verrucosa,YSK\M..S!ü\A.  134,  and  Balaad.  76.  Brongn.  Crust,  foss.  PI.  IV,  Fig. 
11.  Hising.  Leth.  Suec.  11.  Dr.  Loven  enumerates  this  species  in  his  new  genus  Cybele. 
[Ofvers.    K.  V.  A.  Forh.  1845.  109.) 

Entomolithus  dcrbicnsis,  Martin.  Betrifcata  derbiensia,  PI.  XLV,  Fig.  1.  Identical  with 
Asaphus globiceps,  Phil,  (my  Archegonus globiceps),  according  to  a  conjecture  of  Milne  Edwards' 
CrtiM.  iii,  313.     Poktlock  {Rep.  p.  312)  seems  to  doubt  the  correctness  of  this  reference. 

Calymene  phlytctanoides.  Green,  Sill.  Americ.  Journ.  of  Science  and  Arts,  1837,  vol,  .\x.\ii, 
I.  p.  167.     Leonh.  and  Bronn, /a/^ri.   1838,  363. 

Trimerus plal ypleii rus,  Green,  as  above,  p.  168. 

Trimerus  Javksonii,  Green,  /.  c.  pp.  347,  364. 


APPENDIX.  113 

Cn/]jlupi(s  (perhaps  the  sub-group  B  fi  oi  Pliacojjs)  Boothii,  Green,  /.  c.  pp.  344,  3G3. 
Cryplueiis  callilchis,  Green,  pp.  346,  365. 
Asaphiis  Trimbii,  Green,  pp.  348,  365. 


I  have  now  to  add  some  remarks  on  species,  wliich  could  not  with  any  degree  of  cer- 
tainty be  inchided  in  my  regular  arrangement,  partly  because  I  liad  no  opportunity  of 
examining  specimens,  and  partly  also  because  the  species  themselves  are  not  sufficiently 
known.  Their  characters,  as  far  as  hitherto  ascertained,  I  now  therefore  place  here  at 
the  conclusion  of  my  work. 

Asaphis  frontalis,  Dalm.  Pahmcl.  46.  7.  Emmr.  Dlasert.  29.  7.  Milne  Edw. 
Cr.  iii,  3)1.  Angulis  scuti  cephalici  posticis  rotundatis,  protuberantia  capitis  bis  bi- 
impressa,  oculis  distantibus ;  scuto  caudse  rotundato,  costis  utrinque  sex  radiantibus. 
Found  in  the  red  limestone  of  East  Gothland,  at  Ljung.  The  author  compares  this  species 
with  0(/i/gia  Buchii,  and  places  it  next  to  As.  erpansus.  The  impressions  of  the  lower  side  of 
the  shell  are  said  to  exhibit  no  strife,  as  in  As.  expansus ;  but  this  probably  refers  only  to 
the  inner  wall  of  the  upper  surface  of  the  shell,  and  that  is  smooth  everywhere.  These 
striae  are  found  in  all  Trilobites  on  the  free  under  surface  of  the  dorsal  shell.  This  species, 
according  to  Qucnstedt,  is  identical  with  Asaph,  angiistifrons.  (J.  Wiegman's  Archiv,  1837, 
1,  345.) 

Asaphiis  Fulcatii,  Murchis.  Sil.  Si/st.  ii,  663,  PI.  XXV,  Fig.  5.  Milne  Edw.  Cr.  iii, 
314.  I  do  not  quite  understand  this  species.  I  should  not  hesitate  to  associate  it  with 
Cali/mcnc  aqualis,  H.  v.  Meyer's,  and  to  bring  it  under  Archeyoaus,  if  it  really  has  nine 
rings. 

Asaphm  conidensis,  Murchis.  Sil.  Si/sl.  ii,  663,  PL  XXV,  Fig.  4.  Emmr.  Dissert. 
27.  3.  MiLNE  Edw.  Crust,  iii,  310,  has  already  been  mentioned  (p.  70  of  the  original), 
but  has  not  yet  been  properly  placed.  It  certainly  is  not  an  Opi/yia,  as  Emmerich  considers  ; 
for  it  is  clear,  from  the  angularly-shaped  diagonal  furrows  of  the  lateral  lobes,  and  their 
rounded  form,  that  the  animal  possesses  the  power  of  rolling  itself  up,  which  is  not  the  case 
in  Oyygia.  I  am  rather  inclined  to  take  this  species  for  a  young  individual  of  Asaphus  tyrannus, 
accounting  for  the  evidently  shorter  structure  of  the  caudal  shield  by  the  youth  of  the  indi- 
vidual, it  being  well  known  that  many  of  the  acute-angular  parts  of  the  living  Crustacea  are 
more  obtuse  during  youth  than  at  an  advanced  age.  Doubts  certainly  might  arise  against 
the  correctness  of  this  conjecture,  from  the  much  longer  terminating  angle  of  the  cephalic 
shield;  but  if  we  bear  in  mind  that  the  spines  of  the  young  Paradoaitles  hoheiuicas  [Olenus 
yracilis,  Zenk.)  are  very  long,  this  lengthened  form  of  the  cephalic  angles  might  be  the  type 
of  3'outh. 

Asaphis  tyrannus  (ibid.  PI.  XXV,  Fig.  1)  I  have  already  mentioned  (see  ante,  p.  108)  as 
not  belonging  to  the  typical  form,  see  Plate  XXIV;  and,  indeed,  it  almost  appears  to  mc 
not  to  be  an  Asaphus  at  all,  for  I  do  not  know  any  other  species  of  that  genus  possessing 
such  strongly  projecting  lateral  lobes  on  the  caudal  shield,  and  such  a  broad  axis  of  the 
body.     We  might  be  tempted  to  bring  this  form  under  Asaphus  cdienualus,  with  the  entire 

15 


114  APPENDIX. 

contour  of  which  it  harmonizes  best,  if  we  might  venture  to  assume  that  the  two  portions 
have  been  incorrectly  represented  in  the  drawing. 

CuJfjmene  variolaris,  Brongn.  Crust,  fosn.  14. 3,  PI.  I,  Fig.  3,  a,  c,  Parkins.  Organ,  rem.  iii, 
PI.  XVII,  Fig.  IG.  Dalm.  Pß/^«f/.  61.  1.  Buckl.  Brid(/.  Tr.  Pl.XLVI,  Fig.  6.  Münster, 
Bdtr.  iii,  34.  1,  Table  V,  Fig.  1.  Murchis.  Sil.  Sj/stem,  655,  Plate  XIV,  Fig.  1.  Milne 
Edw.  Cr.  iii,  326.  Trilob.  variolar.  Schloth.  Nachtr.  ii,  34.  3.  Phacops  variol.  Emmr. 
Dissert.  20.  4.  This  species  has  already  been  mentioned  (see  ante,  p.  83)  as  a  form  with 
■which  I  am  unacquainted.  It  has  a  semicircular  cephalic  shield  with  a  very  convex 
glabella  which  is  undivided  and  broader  at  the  anterior  part,  and  with  terminating  angles 
which  are  suddenly  produced  into  long  points.  The  eyes  are  situated  in  the  centre  beside  the 
glabella,  on  the  surface  of  the  cheek-shields,  nearly  as  in  Cahjmeiie  Blunienhachii,  presenting 
also  the  form  of  the  latter.  The  body  becomes  more  narrow  towards  the  posterior  part,  and 
has  distinctly  thirteen  rings  in  Murchison's  figure,  but  only  eleven  in  Brongniart's.  The 
caudal  axis,  according  to  the  reckoning  of  the  latter,  consists  of  twelve  rings,  and  there  are 
nine  lateral  ribs  on  the  shield ;  in  Murchison's  figure  I  can  only  count  seven  lateral  ribs,  and 
from  eight  to  nine  joints  in  the  axis.  In  addition  to  this,  the  whole  upper  surface  of  the 
body  is  covered  with  large,  strong  protuberances,  which  are  almost  entirely  wanting  on  the 
body  in  Murchison's  figure,  but  are  represented  in  several  rows  upon  the  caudal  axis,  whilst 
Brongniart's  figure  also  shows  strong  protuberances  on  the  body,  and  only  one  central  row 
on  the  caudal  axis.  Buckland's  figure  agrees  with  Brongniart's,  and  is  probably  copied 
from  it.  The  species  is  found  in  the  middle  Silurian  rocks  of  England,  and  also  in  the 
Fiehtelgebirge,  on  the  authority  of  Count  v.  Minister.  The  Count's  figure  agrees  better  with 
Murchison's  than  with  Brongniart's ;  the  long  pointed  angles  of  the  cephalic  shield  are 
wanting  in  it,  as  in  the  one  figured  in  the  Silurian  System.* 

Judging  from  these  statements,  I  am  almost  inclined  to  consider  the  different  forms  as 
being  specifically  different,  and  to  call  Murchison's  species  a  true  Calymene,  Brongniart's 
and  Parkinson's  a  Phacops.  Boeck's  assertion,  however,  that  Calymene  variolaris  forms  a 
distinct  genus,  to  which  the  Cal.  jmnctata,  AuCT.  also  belongs,  is  opposed  to  this  assumption. 
(See  Keilhaus,  Gaea  Norv.  I.  Trilob.  No.  13.)  The  following  authors  treat  of  the  last- 
named  species. 

Tril. punctatus,  Brunn,  Kjöhenh.  Selkk.  Skrivt.  mje.  Saml.  i,  394.  5.  Schloth.  Nachtr. 
ii,37.  23.  Entomostr.punct.  Wahlenb.  N.  J.  Ups.  viii,  32.  7.  Linn^eus,  Act.  Beg.  ac.  Holm. 
1759.  22.  24,  Table  I,  Fig.  2.  Lehmann,  Nov.  Comm.  Petropol.  x,  Table  XII,  Fig.  10. 
Beckm.  Nov.  Comm.  Göthing.  iii,  102.  Wilck,  Strals.  Magaz.  iv,  St.  Table  III,  Fig.  12. 
Cahjm.punct.  Brongn.  Cr.foss.  36.  'Dk.-LU.Palaiad.  64. 12.  Murchis.  /.  c.  ii,  661,  PI.  XXIII. 
Fig.  8.     Milne  Edw.  Cr.  iii,  327. 

All  of  them  merely  describe  caudal  shields,  with  the  exception  of  Wahlenberg,  who 
also  figures  the  central  piece  of  the  cephalic  shield,  which  bears  distinct  marks  of  being  a 
Calymene,  especially  in  the  thickened  anterior  margin  of  the  head,  and  a  peculiar  structure 
of  the  lobes  of  the  glabella,  which  reminds  us  of  Cal.  Blumenhachii.     But  I  doubt  whether 

*  Cal.  intermedia,  Münster  (35.  2,  Table  V,  Pig.  2),  is  said  to  Lave  foiu-  sulcations  on  each  side 
uf  the  glabella,  but  resembles  C.  variolaris  so  perfectly  in  other  respects,  that  I  must  yet  doubt  whether 
it  forms  a  distinct  species. 


APPENDIX.  1 1 5 

it  reall}'  belongs  to  this  species.  The  caudal  shield,  according  to  all  the  authors  (juotcd, 
has  a  many-jointed  axis,  the  rings  of  which  bear  a  row  of  protuberances  in  the  centre,  and 
from  seven  to  eight  lateral  ribs,  of  which  each  also  has  a  protuberance  on  the  centre.  The 
ten  rings  of  the  body,  represented  by  Dalman  next  to  it,  appear  to  be  smooth.  Such 
caudal  shields  are  not  uncommon  in  a  pure  whitish-gray  limestone  found  in  Gothland,  a 
specimen  of  which,  in  my  collection,  contains  two  individuals,  which,  unfortunately,  have 
the  inner  surface  of  their  shell  turned  upwards,  and  the  external  surface  so  firmly  flexed  in 
the  stone,  that  it  is  impossible  to  detach  them.  I  can,  however,  distinctly  recognize  six 
central  protuberances  on  the  axis,  which  is  the  number  that  Dalman  describes  it  to  have, 
and  on  each  side  of  them,  the  impressions  of  from  twenty-eight  to  thirty  rings,  whilst  the 
central  region  is  surrounded  by  rings  where  the  protuberances  are  situated.  One  ring 
corresponds  to  each  protuberance,  and  I  can  count  two  rings  between  the  first  and  the 
second  protuberance,  three  between  the  second  and  third,  two  again  between  the  third  and 
fourth,  three  between  the  fourth  and  fifth,  and  four  between  the  latter  and  the  sixth,  after 
which  there  are  still  six  or  seven  behind  the  last  tubercle ;  a  greater  number,  however,  may 
be  existing  at  the  upper  side,  where  the  rings  are  always  more  distinct.  I  can  only  find  eight 
lateral  ribs  in  my  imperfect  specimens,  and  no  traces  of  protuberances,*  which,  indeed,  can 
probably  only  be  recognized  on  the  external  surface  of  the  shell.  The  caudal  shield  of 
Calymeiie  variolaris,  according  to  Brongniart's  and  Buckland's  figures,  so  perfectly  corresponds 
•with  the  structure  above  described  (Parkinson's  figure,  I  regret  to  say,  I  no  longer  have  in 
my  possession),  that  I  do  not  believe  I  am  wrong  in  stating  the  ordinary  Cali/mene 
punctata  to  be  identical  with  Cal.  variolaris  of  the  last-named  authors.  I  propose,  however, 
to  retain  the  name  of  Cal.  variolaris  for  Murchison's  species  so  called,  this  being  probably 
distinct ;  but  I  shall  transfer  the  still  older  name  of  C.  punctata  to  the  Calym.  variolaris  of 
Brongniart,  which,  at  an  earlier  period,  was  certainly  known  by  that  name.  Not  having 
been  able  to  examine  specimens  myself,  I  must  leave  the  question  undetermined,  whether 
this  Calymene  punctata  really  belongs  to  a  distinct  genus,  or  is  a  PJiacops ;  Calymene  variolaris, 
in  my  opinion,  corresponds  most  nearly  with  the  genus  whose  name  it  bears,  and  approxi- 
mates very  closely  to  those  species  of  Phacops  in  which  there  is  an  undivided  glabella,  just 
as  C.  Bluiiienbachii,  C.  Triistani,  &c.,  are  analogous  to  those  with  a  lobed  glaliella.  The 
latter  might  still  further  be  grouped  according  to  the  number  and  form  of  the  lobes, 
as  in  the  species  of  Phacops,  were  such  subdivisions  required  by  a  large  number  of  subgcneric 
forms. 

Trilohltcs  Stcmbcryii  was  so  named  by  Bocck,  in  the  ^Fay.  für  NaturridensJ,-,  which  I  am 
not  acquainted  with.  (See  Sternberg,  Verliandl.  d.  vaterl.  Mus.  etc.,  1833,  51.)  Count 
Sternberg's  figure  in  the  work  just  cited  (1825,  Table  I,  Fig.  5)  belongs  to  this  species, 
and  is  briefly  described  at  the  conclusion  of  his  treatise  (p.  85.)  My  figures  (Table  III, 
Figs.  7,  8)  agree  perfectly  with  that  given  by  him,  and  were  sketched  from  Sternberg's 
plaster  casts.  Sternberg  says  of  the  cheeks,  that  they  are  prominent.  I  have  only  been 
able  to  recognize  impressions  in  the  cast.  The  eye  was  broken  ofl"  in  Sternberg's 
specimen,  but  its  position  and  size  are  by  no  means  left  doubtful.  The  whole  circumference 
visible  has  a  rcflcxed,  rounded  margin.     The  black  limestone  of  the  Branikberg,  in  which 

*  This  is  tbe  true  structure,  tlie  promiueut  ends  of  the  lateral  ribs  look  like  a  row  of  tul)ercles. — Edit. 


116  APPENDIX. 

Phacops  lafifrons  is  found,  contains  also  isolated  cephalic  shields  of  this  rare  species. 
Dalman,  we  know,  has  referred  Stemherg's  figure  to  \\is' CaJi/mcne  speciosa  {PalcBud.  76.  3), 
which,  however,  according  to  Beyrich,  is  a  Cheirurus,  as  may  be  seen  from  Hisinger's  figure 
{Leth.  Suec.  mippJ.  Talkie  XXXIX,  Fig.  2),  but  the  two  anterior  furrows  of  the  glabella  do 
not  traverse  it  entirely,  and  the  third  is  bent  down  at  each  side  of  the  centre,  which  is 
not  the  case  in  TrU.  Sfernhergil.  It  is  also  possible  that  Count  Miinster's  Calym. 
Sternhergii  {Beifr.  iii,  37.  5,  Table  V,  Fig.  5)  and  Cali/m.  propinqua  (ibid.  38.  6,  Fig.  6),  if 
the  furrows  of  the  head  do  not  really  unite  across,  correspond  with  Phacops  speciosus,  whilst 
Calgm.  articidafa  (ibid.  7,  Fig.  7),  with  furrows  of  the  head  that  do  traverse,  but  which  are 
badly  drawn,  is  more  immediately  referrible  to  Trihhites  Sternhergii.  Dr.  Beyrich 
enumerates  all  these  species  in  his  new  genus  Cheirurus. 

I  am  not  yet  acquainted  with  anything  further  respecting  the  natural  position  of  this 
species  in  the  system.     It  I  have  already  mentioned,  and  the  next  (see  ante,  p.  72). 

Triarthrus  Beclii,  Green,  3Ion.  of  Tril.  86  et  seq.  Monthly  Americ.  Journ.  p.  560. 
Harlan,  Med.  and  Physic.  Pes.  305.  Brongniartia  carcinoidea,  Eaton,  Geol.  Text-Book. 
Bronn.  Leth.  i,  117,  Table  IX,  Fig.  10.  Paradoxides  triarthrus,  Harl.  3Ied.  and  Physic. 
Besearches,  401,  i,  Fig.  5.  Parad.  armatus,  ibid.  402.  2,  Figs.  1,  3.  Milne  Edw.  Criist.  iii, 
345.  Of  these  Trilobites  we  only  know  the  central  piece  of  the  cephahc  shield  with  the 
short  parabolic  glabella,  on  which  the  margin  of  articulation  is  indicated  by  a  transverse 
furrow ;  laterally,  however,  there  are  two  sulcations,  produced  in  a  diagonal  direction 
towards  the  posterior  part,  which  separate  three  nearly  equal  lobes.  In  this  it  entirely 
corresponds  with  the  head  of  01.  scarabaoides  (see  ante,  p.  71).  Nothing  satisfactory  can 
be  said  or  conjectured  with  regard  to  the  systematic  position  of  this  species,  as  the  maxillary 
shields  are  wanting  in  all  the  specimens  that  have  been  examined,  the  rings  of  the  body  are 
merely  known  by  fragments,  and  the  caudal  shield  has  not  yet  been  found.  Its  affinity  with 
Olen.  scarahcBoides,  as  shown  by  Harlan,  is  very  readily  seen ;  but  the  latter  form  also  is  as 
yet  not  sufficiently  known  to  enable  us  to  draw  any  inference  from  it  in  regard  to  the 
species  at  present  under  discussion.  Harlan  assumes,  however,  four  body  rings  in  Parad. 
triarthrus,  and  a  short  caudal  shield,  which  is  rounded  at  the  circumference :  he  represents 
the  lateral  lobes  of  all  the  joints  of  the  body  as  being  more  narrow  than  the  axis;  the 
latter  is  about  equal  to  them  near  the  head,  but  the  lateral  lobes  rapidly  become  shorter 
towards  the  posterior  part. 

In  the  last  respect,  the  new  genus,  Bemojileurides,  established  by  Portlock  [Eep.  255, 
PI.  I  Fio-s.  1-6),  in  some  measure  approaches  it.  It  appears  also  to  have  affinity  with  Olenus 
scarabesoides,  and  to  belong  to  the  group  of  Olenida. 

Agnostus  s.  Battus.  The  discovery  of  several  complete  specimens  of  this  singular 
genus  of  Trilobites  has  confirmed  the  view  taken  by  Wahlenberg  and  Dalman  {Palaad. 
p.  33),  viz.  that  both  the  known  forms  of  it  belong  to  one  and  the  same  animal  in  the 
relations  of  cephalic  and  caudal  shield.  Dr.  Beyrich  has  described  a  perfect  specimen  of 
a  new  species  from  Bohemia,  and  proved  from  the  analogies  of  the  latter  with  previously 
known  shields,  that  the  shields,  which  are  usually  rather  larger,  and  furnished  at  the  margin 
with  two  points,  belong  to  the  pygidium,  and  that  the  shields  undefended  at  the  margin  and 
rather  more  convex,  the  axis  being  more  narrow  towards  the  front,  belong  to  the  head. 
According  to  this  the  genus  might  be  characterized  as  follows  : — 


APPENDIX.  117 


Genus  Agnostus,  Brongn.     (Battus,  Dalman.) 

Cephalic  shield  (Tal)le  V,  Fig.  7)  equally  large  as,  or  a  little  smaller  than  the  caudal 
shield,  similarly  formed,  very  convex,  margin  elevated,  or  uniformly  declining  at  the  circum- 
ference, the  axis  more  or  less  distinctly  marked,  narrower  towards  the  front,  provided  the 
extremity  be  not  very  much  enlarged,  as  it  is  in  a  new  species  Agn.  Rex,  Barr.  This 
extremity  is  usually  marked  by  a  distinct  transverse  furrow  ;  the  basal  part  is  not  divided,  or 
if  so,  at  the  utmost  only  by  two  small  lateral  lobes. 

Facial  suture  and  eyes  not  perceptible. 

Body  two-jointed,  the  axis  of  the  joints  depressed,  broader  than  the  furrowed  lateral 
lobes. 

Caudal  shield  (Tab.  V,  Fig.  6)  usually  rather  broader,  although  not  longer  than  the 
cephalic  shield,  the  lateral  margin  rather  less  elevated,  frequently  ornamented  with  two 
marginal  points;  the  axis  considerably  prominent,  distinctly  divided,  usually  furnished 
with  an  elevated  longitudinal  callosity,  and  two  oblique  lateral  furrows,  which  extend 
towards  the  axis,  and  separate  its  rather  broader  extremity  in  the  manner  of  a  glabella.  At 
the  commencement  of  the  axis  there  is  a  distinctly  projecting  marginal  articulate  fold. 

Their  power  of  rolling  themselves  up  has  not  yet  been  ascertained. 

Locality. — In  the  lower  Silurian  strata.  The  species  have  not  yet  been  satisfactorily 
established,  but  there  appear  to  be  several. 

1.  A.  pisiformis,  Tab.  V,  Fig.  7,  cephalic  shield;  Fig.  6,  caudal  shield.  Brongn. 
Crust,  foss.  38,  PI.  IV,  Fig.  4,  a,  B.  Bronn.  Letkaa  geogn.  i,  123,  Tab.  IX,  Fig.  20. 
MuRCHis.  m.  Syst.  ii,  664,  PI.  XXV,  Fig.  3.  Milne  Edw.  Crust,  iii,  348.  1.  Gr.  v. 
Münster,  Contrib.  111,47.  1.  Goldf.  Leonh.  and  Bronn.  Neio  Annual,  1843,  542.  1. 
Trihh.pisif.  ScHLOTH.  Petr.  Suppl.  II,  36,  21.  26,  1.  Battus pisif.  Dalm.  Palaad.  57.  IV.  1  ; 
75.  V.  1.  HisiNG,  Leth.  Suec.  19,  Tab.  IV.  Figs.  5,  6.  Linn,  ä  Nat.  iii,  160,  161. 
(ed.  12).  Bromell,  Act.  lit.  Ups.  1729,  526.  4.  e  Fig.  Wilkens,  Verst.  75.  Tab.  VII, 
Figs.  38,  39.     Modeer,  Schrift  d.  Naturf.  Freunde  s.  Berlin,  14,  248.  Tab.  II,  Figs.  1,  2. 

Locality. — In  the  alumslate  and  stinkstone  of  Andrarum,  at  the  Kinnekulle,  etc.,  and 
in  similar  strata  in  England. 

2.  A.  IcBvigatus.  Dalm.  Arsberäth.  1828.  136.  Hising.  Leth.  Suec.  20.  2.  Goldf.  /.  c. 
542.  2.     At  the  Kinnekulle,  near  Hönsater. 

3.  A.  integer.  Baltics  integer,  Beyr.  on  Bohemian  Trilobites,  44,  1,  Fig.  19.  In  the 
lower  Silurian  strata  of  Bohemia. 

4.  A.  nudus.     Battus  nudus,  Beyr.  as  above,  46.  Fig.  20. 

Remark. — ]My  figures  of  A.  pisiformis  (Tabic  V,  Figs.  6,  7),  owing  to  the  fault  of  the  artist, 
were  not  formerly  quite  true  to  nature,  and  they  have  therefore  been  somewhat  altered,  so  that  they 
now  certainly  appear  different,  but  decidedly  more  correct,  although  even  now  the  shades  of  the 
furrows  may  perhaps  be  rather  too  deep.  The  smaller  forms  (formerly  Figs.  5  and  8)  do  not  deviate 
so  materially  as  to  render  a  particular  representation  of  them  necessary,  and  they  have  therefore  been 
set  aside  to  make  room  for  other  figures  of  more  consequence. 


118  APPENDIX. 


3. 


The  descriptions  and  representations  of  the  following  species  appear  to  me  to  be  wholly 
unavailable  for  systematic  arrangement;  I  merely  enumerate  them  for  the  sake  of  com- 
pleteness, and  will  not  venture  upon  any  conjectural  construction. 

AsapJms  Camclori,  Murchis.  Sil.  Si/st.  ii,  655,  PI.  VII,  Fig.  9.  Münster,  Beitr.  iii, 
38.  1,  Tab.  V,  Fig.  8. 

Amphis  subcaudatus,  Murchis.  ibid.  Fig.  10;  probably  only  a  larger  individual  of  the 
preceding  species. 

Asaphm  diuriis,  Green,  Sill.  Americ.  Journ.  1839,  vol.  xxxvii,  p.  40.  A  species  related 
to  As.  selenwrus,  therefore  a  Phacops,  with  a  double -pomted  end  of  the  caudal  shield.  (See 
ante,  p.  95.) 

Asaplms pmillm,  Münster,  Beiir.  iii,  39.  2,  Tab.  V,  Fig.  9. 

Asaphus  brevis,  ibid.  39.  3,  Fig.  10. 

Asaplms  grandis,  ibid.  39.  4,  Tab.  IX,  Fig.  1  ;  a  fragment  of  a  caudal  shield,  which  is 
probably  different  from  Sars'  species  of  the  same  name.     (See  p.  109.) 

Paradoxides  brevimucronaius,  [hid.  40.  1,  Tab.  V,  Fig.  12,  seems  to  he  a.  Zic/ias  laciniatus  ; 
but,  according  to  Dr.  Beyrich  {Bohn:tr.  16),  it  is  a  Cheiruriis. 

Bumastes  franconicus,  ibid.  42,  Tab.  V,  Fig.  7.  Cephalic  and  caudal  shield  without  any 
specific  characters.  • 

Bumastes  planus,  ibid.  43.  2,  Fig.  18,  a  larger,  more  compressed  individual  of  the 
preceding  species.  Trinucleus  (?)  Nillsoni,  ibid.  46., 5,  Tab.  V,  Fig.  25;  Tmucl.  (?) 
Otarion,  Tab.  VI,  Fig.  26,  and  Trinucleus  intermedins,  ibid.  V.  116,  Tab.  X,  Fig.  10,  are 
fragments  that  cannot  be  distinctly  recognized,  but  they  are  hardly  Trinuclei.  According 
to  Dr.  Beyrich,  they  are  parts  of  the  cephalic  shield  of  Bronteus  {Calymene)  furcata, 
Münster,  Beitr.  V,  113.  2,  Tab.  X.  Fig.  9;  it  has  a  semicircular,  granulated,  caudal 
shield,  with  a  many-jointed  axis,  and  seven  lateral  ribs  that  are  slit  to  one  half  of  their 
length. 


APPENDIX.  119 


After  I  had  brought  my  work  to  a  conclusion,  and  was  engaged  in  preparing  the  index, 
I  received  the  second  series  of  the  '  Magazin  für  Naturvidenskaberne,'  (second  series  from 
1S32,  vols,  i  and  ii.)  This  series  contains  some  remarks  by  Esmark  on  the  following  five 
TrUobites ;  see  vol.  i,  p.  268,  Tab.  VIII. 

1.  Tril.  Asellm,  a  ten-jointed  Trilobite,  incapable  of  rolling  itself  up  (Fig.  V),  with 
a  large  caudal  shield,  the  axis  of  which  is  wanting,  but  which  nevertheless  seems  to  be 
many-jointed.  Boeck  represents  this  species  in  Keilhau's  Gaea  Noncegica  (1  Tril.  No.  36), 
placing  it  next  to  Illcenm  cculrofiis,  Dalm.,  but  between  this  and  Esmark's  figure  there  is  no 
resemblance. 

2.  Tril.  ellijüifrons,  p.  269,  Figs.  6,  7,  a  Phacops,  with  an  undivided,  narrow  glabella, 
which  seems  most  nearly  to  resemble  that  of  Ph.  lati/rons,  but  which,  perhaps,  differs 
from  it  specifically  in  the  narrow  shape  of  the  glabella,  if  the  figure  be  correct.  Boeck, 
who  treats  of  this  species  (/.  c.  No.  1),  likewise  distinguishes  it  from  Ph.  lutlfrons,  his  Tril. 
elcgans ;  Sars  (ibid.  No.  2,  "  by  the  wide  (long  ?)  elliptical  glabella."  Both  arc  found  at 
Malmöekalven. 

3.  Tril.  spharicus,  Fig.  8,  according  to  Boeck,  (/.  c.  sub  No.  14,)  is  identical  with  Tril. 
clavifrons,  Sars,  concerning  which  I  have  already  expressed  my  opinion  (see  ante,  p.  99), 
connecting  it  with  Dalman's  species  of  the  same  name.  But  Esmark's  figure  exhibits 
three  furrows  on  the  glabella,  and  I  am  therefore  still  in  doubt  whether  Tr.  spharicm  can 
really  be  Sars'  Tr.  clavifrons.  If,  however,  this  be  the  case,  it  would  belong  to  Ctjphaspis 
clavifrons. 

4.  Tr.  semilunaris,  Fig.  9,  according  to  Boeck's  conjecture,  (/.  c.  sub  No.  10,)  is  only  a 
small  individual  of  Phacops  caudatus.     (See  ante,  p.  94.) 

5.  Tr.  dentatus.  Fig.  10,  is  a  large  caudal  shield,  with  a  many-jointed  axis,  and  three 
large  lateral  ribs  curved  backwards  (the  figure  indicates  15  rings,  and  an  oval  terminal 
joint) ;  the  ribs  project  over  the  margin  of  the  shield  in  the  shape  of  obtuse  spines.  Boeck 
adds  (/.  c.  sub  No.  7),  that  the  semicylindrical  glabella,  which  is  rounded  at  the  anterior 
part,  has  three  lateral  furrows,  and  that  the  posterior  angles  of  the  shield  terminate  in 
spines  like  the  lateral  lobes  of  the  body  rings.  This  species,  therefore,  is  decidedly  a 
Phacops  of  the  division  B  d,  and  approximates  to  Pliac.  arachnoides.  From  these  state- 
ments there  appears  now  to  be  scarcely  a  doubt  that  it  belongs  to  Dr.  Loven's  new 
genus   Ci/helc. 

I  likewise  only  received  the  work  of  F.  A.  Römer,  mentioned  at  the  conclusion  of  the 
bibliography,  very  recently.     The  author  describes  in  it  the  following  Trilobites  : 

1.  Brontes flabellif er,  p.  37,  Tab.  II,  Fig.  1. 

2.  Br.  signatus,  ibid.  p.  37,  Figs.  2,  3 ;  citing  also  Phillips,  Paleozoic  fossils.  Tab.  LVII, 
Fig.  255  ;  a  caudal  shield  of  a  shorter,  more  circular,  form. 

Br.  (?)  glahratus,  ibid.  Fig.  G.  The  central  piece  of  a  cephalic  shield  possessing  the 
shell,  but  otherwise  without  satisfactory  characters. 

4.  Calymene  Jordani,  ibid.  Fig.  4,  certainly  only  a  specimen  of  Phacops  latifrons.  -  I  have 
a  well-preserved  specimen  of  this  species  lying  before  me  (from  the  collection  at  Halle), 
which  was  found  in  the  ground  of  the  monastery  at  Michelstein,  near  Blankenburg.  Römer 
also  refers  to  this  specimen  (p.  xviii  of  his  work). 


120  APPENDIX. 

5.  Cd.  Sclmsteri,  p.  38,  Tab.  XII,  Fig.  42.  The  caudal  sliield  of  a  small  individual  of 
Phacops  latifrons. 

6.  Cal.  subornata,  ibid.  Figs.  40,  41.  It  can  hardly  be  that  both  these  fragments  belong 
to  the  same  species.     The  species  cannot  be  recognized  from  these  figures. 

7.  Cal.  hi/drocephala,  ibid.  Tab.  XI,  Fig.  7.  Beyond  a  doubt  the  central  piece  of  a 
cephalic  shield  of  Ci/phaspis  ceratopJMalma.     (See  p.  98.) 

8.  Asaphus  Zinkenii,  ibid.  Fig.  8.  The  central  piece,  ■without  a  shell,  of  the  cephalic 
shield  of  Ph.  latifrons. 

9.  Paradoxides  Grotei,  ibid.  p.  39,  Tab.  XI,  Fig.  \\,a,b.  Distinct  fragments  of  P//acops 
araclinoides. 

10.  Homalonotus  Ahrendii,  ibid.  Fig.  5,  a,  h.  Certainly  not  different  from  Horn.  Knightii, 
Murch. ;  for  the  distinctions  enumerated  originate  from  the  changeable  cur\'ature  of  the  rings 
towards  each  other,  and  merely  relate  to  individual  peculiarities. 

11.  Horn,  pundatus,  ibid.  Fig.  9,  and  Horn,  y  ig  as.  Fig.  10,  are  probably  only  fragments 
of  other  individuals  of  the  same  species;  the  punctation  distinctly  indicates  the  granulation 
originally  present. 

A  notice  of  rather  older  date,  which  I  have  just  received,  occurs  in  SilJim.  Americ. 
Journ.  of  Sciences  and  Arts,  vol.  xlii,  p.  366.  1842.  Mr.  J.  Locke  describes  there  a  new 
species  of  Trilobite  as — 

Isofeles  meffistos  (there  is  a  figure  in  Plate  III  of  the  same  work).  This  drawing,  nearly 
a  foot  in  length,  is  nevertheless  very  imperfect,  since  no  oblique  transverse  furrows  are 
indicated  on  the  lateral  lobes  of  the  rings  of  the  body,  and  all  positive  characters  are  wanting 
on  the  posterior  half  of  the  cephalic  shield.  In  addition  to  this,  the  figure  has  exactly  the 
proportions  of  Asaph.  plati/cepJialns  {Isot.giyas),  but  has  short,  terminating  spines  at  the  lateral 
ano-les  of  the  cephalic  shield.  From  this  it  certainly  seems  to  be  a  distinct  species, 
distinguished  from  As.  plafi/ceplialm  by  the  last-mentioned  character,  from  As.  ajir/iisfifrons  by 
its  broad  forehead,  if  transverse  furrows  exist  on  the  lateral  lobes;  it  would,  however, 
belong  to  Nileus  if  the  latter  are  wanting,  which  I  doubt.  The  anterior  extremity  of 
the  facial  suture  describes  an  angle,  and  indicates  a  similarity  with  the  division  B  ä  of 
Asaphis. 

M.  de  Castelnau  has  communicated  to  the  French  Institute  (1842,  p.  74)  some  observa- 
tions respecting  the  feet  of  Trilobites,  which  he  states  he  has  observed  in  rolled-up  indi\'iduals 
in  North  America.  As  his  statements  coincide  entirely  with  the  results  which  I  have  arrived 
at  from  analogy,  his  observations  seem  to  deserve  every  credit;  but  nevertheless  I  can 
scarcely  help  doubting  their  correctness. 


SUPPLEMENTARY    APPENDIX. 


BY  THE  EDITORS. 


In  order  to  render  this  work  more  readily  complete  and  consultable  for  the  student  of 
British  fossils,  the  Editors  have  added  the  following  catalogue  of  published  British  Trilobites. 
It  consists  of  the  list  of  Trilobites,  in  alphabetical  order,  given  by  Mr.  Morris  in  his  valuable 
Catalogue  of  British  Fossils,  with  a  concordance  showing  their  names  or  the  places  where 
they  are  referred  to  in  this  edition  of  Professor  Burmeister's  Monograph ;  also  a  list  of  such 
new  Ti'ilobites  as  have  been  described  by  Mr.  M'Coy  since  the  publication  of  Mr.  Morris's 
Catalogue.  Through  the  kindness  of  Mr.  Salter  they  are  enabled  to  add  the  names  of  the 
new  species  described  by  him  in  Professor  Sedgwick's  forthcoming  work  on  the  '  Geology 
of  Wales  and  Westmoreland.' 

They  have  also  appended  some  useful  extracts  from  recently  published  foreign  works 
on  Triloliites. 


I.  Alphabetical    List  of  British    Trilobites,   with    their    Synonymes    in    this    work,    or 
references  to  the  pages  wherein  they  are  mentioned. 


AciDASPis,  Murchison 
Brightii,  Murchison. 
p.  63. 


Odontopleura  elliptica  ? 


Amphion,  Pand. 

frontllobus,  Pand.     Calymene  polytoma,  p.  81. 
gelasinosus,  Portl.     Cheirurus  sp.  p.  71,  note, 
multi-segmentatus,  Portl. 
pseudo-articulatus,  Portl. 


Am  PYX,  Dalman 
Austinii,  Portl. 
baccatus,  Portl 
rostratus,  Sars. 
Sarsii,  Portl. 


See  p.  111. 


Agnostus,  Brong. 

pisiformis,  Brong.     See  p.  117. 
tuberculatus  March.     See  Odontopleura   ovata, 
p.  6-2. 

A  RUES,  Goldf. 

])lano-spinosus,  Portl.  Cheirurus  sp.  p.  71,  note. 


As  A  Pilus,  Brong. 

astragalotes.  Green.     See  p.  9R. 

Buchii,  Brong.     Ogygia  Buchii,  p.  59. 

caudatus,  Brong.     Phacops  caudatus,  p.  94. 

Cawdori,  Murch.     See  p.  118. 

Corndensis,  Murch.    See   remarks,  p.    61,  and 

p.  113. 
•  cornigerus,  Brong.    Asaphus  expansus,  p.  107. 
dilatatus,  Dalm.     Under  Ogygia  Buchii,  p.  59 

(but  distinct. — Ed.) 
duplicatus,  Murch.     See  remarks,  p.  61. 
?  gemmulifcrus,  Phil.     Archegonus  aequalis,  p. 

101. 
?  granuliferus,  Phil.     Appendix,  p.  112. 
latifrons,  Portl. 
longicaudatus,   Murch.     Phacops  mucronatus, 

p.  94. 
marginatus  Portl. 
Mj'ops,  König, 
quadrilimbatus,  Phil.      Appendix,  p.  112. 


Asaphus. 

Stokesii,  Murch. 


Proetus  Stokesii,  p.  100. 

16 


122 


SUPPLEMENTARY  APPENDIX. 


ASAPHUS. 

subcaudatus,  Murch.     Appendix,  p.  118. 
tuberculato-caudatus,  Murch.  Phacops  caudatus, 

p.  94. 
Tj-rannus,  Murch.     Ibid.  p.  108,  and  p.  113. 
Vulcani,  Murch.     Appendix,  p.  1 13. 

Bkoxtes,  Goldf. 

llabellifer,  Goldf.     p.  f>5. 

signatus,  Ph.     See  Appendix,  p.  119. 

Bu.MA.STES,  Murch. 
■  Barriensis,  Murch.     Iltenus  barriensis,  p.  104. 

C.ALYMEXE,  Brong. 

Blumenbachii,  Brong.     Ibid.  p.  81. 

brevicapitatus,  Portl. 

Downingife,  Murch.   Phacops  macrophthalmus, 

p.  92. 
granulata,  Munst.     Phacops  latifrons,  p.  87. 
laevis,  Munst.     Phacops  Itevis,  p.  89. 
Latreillii,  Stein, 
multisegmentatus,  Portl. 
pulchella,  Dalm.    Calymene  Blumenbachii,  var. 

p.  82. 
Sternbergii,  Munst.    Cheirurus  sp.  p.  71,  note, 
tuberculata,  Murch.     Phacops  latifrons,  p.  89. 
variolaris,    Brong.      See   p.    83,    note,   and   p. 

114. 


Ceraurus,  Green 
globiceps,  Portl. 

EuRYPTERUS,  Harlan. 
Scouleri,  Hibbert.     Se 

Griffithides,  Portl. 
globiceps,  Portl. 
longiceps,  Portl 
longispinus,  Portl. 
platyceps,  Portl. 


54. 


See  Archegonus,  p.  101 
and  Appendix,  p.  1 12. 


Harpes,  Goldf. 

Doranni,  Portl.     See  p.  75,  note. 
Flanaganni,  Portl.     See  p.  75,   note, 
macrocephalus,  Goldf.     See  p.  75. 

HOMALONOTUS.       Kouig. 

delphinocephalus,  Murch.     Ibid.  p.  56. 

Ilerschelii,  Murch.     Ibid.  p.  87. 

Knightii,  König.     Ibid.  p.  86. 

Ludensis,  Murch.     Under  II.  Knightii,  p.  56. 


Ill^f,nu.s,  Dalm. 

centrotus,  Dalm.  Dj-splanus  centrotus,  p.  105. 

crassicauda,  Dalm.     Ibid.  p.  103. 

?   perovalis,   Murch.      I.   crassicauda  junr.  ? 

p.  104. 
quadrato-caudatus,  Portl. 

IsoTELEs,  Dekay. 
arcuatus,  Portl 

gigas,  Dekay.     Asaphus  platycephalus,  p.  110. 
intermedius,  Portl. 
lasviceps,  Portl. 
ovatus,  Portl. 

palpebrosus,  Dalm.  p.  107. 
planus,  Dekay. 

Powisii,  Portl.     See  note   p.  96  (includes  Pha- 
cops felinus,  Salter), 
rectifrons,  Portl. 
sclerops.  Green. 

NuTTAiNiA,  Eaton. 

Hibernica,  Portl.     Lichas  sp.  p.  66,  note. 
?  obscura,  Portl. 

Ogygia,  Brong. 

Murchisoniae,  Murch.  Ogygia  Guettardi,  p.  60. 
rugosa,  Portl. 

Paradoxides,  Brong. 
?  Bucephali,  Portl. 
bimucronatus,    Murch.      Chirurus   sp.    p.    71, 

note, 
quadrimucronatus,  Murch.   Odontopleura  ellip- 

tica,  p.  63. 

Olenus,  Dalm. 
punctatus.     Stein. 

Phacops,  Emmerich. 

Brongniartii,  Portl.     Phacops  latifrons,  p.  88. 
Dalmanni,  Portl. 
Jamesii,  Portl. 
Murchisonii,  Portl. 
truncato-caudatus,  Portl. 


Phillipsia,  Portl. 
Jonesii,  Portl. 
Kellii,  Portl. 
Maccoyii,  Portl. 
obsoleta,  Phil, 
ornata,  Portl. 
raniceps,  Phil, 
seminifera,  Phil. 


See  Archegonus,  p.    101, 
and  Appendix,  p.  112. 


SUPPLEMENTARY  APPENDIX. 


123 


REMOPLEuiiinr;s,  Portl.     p.  llö. 
Colbii,  Portl. 
dorso-spinifcr,  Portl. 
lateri-spinifcr,  Portl. 
longi-capitatus,  Portl. 
longi-costatus,   Portl. 

Trinucleu.s,  Lhwyd. 

?  Asaphoides,  Murch.     Sec  remarks,  p.  58. 
Caractaci,  Murch.     Ibid.  p.  öö 


TuiXUCLEUS 

elongatus,  Portl. 

fimbriatus,  Murch.     Ibid.  ]).  .5". 

latus    Portl. 

Lloydii,  Murcli.     T.  granuiatus,  p.  .57. 

nudus,  Murcli.  an  Am/ii/i-.   (uote,  p.  57). 

'!  punctatus,  Murch. 

radiatus,  Murch.     Trinuclcus  ornatus,  p. 

seticoriiis,  Portl.     p.  58. 


58. 


II.  To  the  above  List  of  British  Trilobites  must  be  added  tliosc  species  described  since 
the  publication  of  Mr.  Morris's  Catalogue,  and  wliicii  have  not  come  under  the  inspection  of 
Professor  Burmeister. 

In  Mr.  M'Coy's  '  Synopsis  of  tlic  Carboniferous  Fossils  of  Ireland,'  the  following  new 
species  are  described  and  figured  :  ■" 


Griffithldes  calcaratus. 
Phillipsia  coelata. 
Phillipsia  Colei. 


Phillipsia  (?)  discors. 
Phillipsia  mucronata. 
Phillipsia  quadriserialis 


In  Mr.  M'Coy's  '  Synopsis  of  the  Silurian  Fossils  of  Ireland,'  collected  by  Mr.  Griffith 
(Dublin,  1846),  the  following  new  genera  and  species  are  described  and  figured : 

TiRESiAS.  New  genus.  "  Cephalo-thorax  semioval,  longitudinal ;  glabella  very  gibbous, 
pyriform,  rounded  in  front,  contracted  into  a  narrow  neck  posteriorly  (obscure  traces  of  two 
small  cephalo-thoracic  furrows  on  each  side)  ;  neck  furrow  very  strong;  cheeks  triangular, 
gibbous,  prolonged  backwards  into  long  flattened  spines;  eyes  none?" 

"  This  remarkable  Trilobite  agrees  nearly  in  form  with  the  carboniferous  genus 
Griffithides,  Portl.,  except  in  being  apparently  Wind."  (Loc.  cit.  p.  43.)  One  species, 
T.  imculptus,  in  the  limestone  of  the  Chair  of  Kildare. 

FoRBESiA.  New  genus.  [From  the  description  and  figures  this  genus  would  appear 
to  be  synonymous  with  Proetus.]    F.  latifrom. 

PoRTLOCKiA.  New  gcnus.  Cephalo-thorax  truncato-orbicular,  lateral  angles  not 
produced  into  spines ;  glabella  large,  clavate,  widest  in  front,  reaching  to  the  margin, 
contracting  to  a  narrow  neck  behind ;  neck  fuiTow  strong ;  cheeks  rather  small,  triangular, 
convex ;  eyes  large,  reniform ;  abdomen  of  thirteen  segments,  rounded  at  their  extremities, 
anterior  margin  sharpened  for  contraction ;  pygidium  semi-elliptical,  of  seven  simple 
segments  ;  margin  entire,  smooth. 

The  genus  includes  CuJymene  fubercuhtla  and  C.  marroj)IifIiahiia  of  the  Silurian  S3'stem  ; 
Fhacops  tuhercuJaia  of  Captain  Portlock's  report ;  Calymene  nvpera,  Hall ;  Calymene  hufo. 
Green,  &c. 


*  In  the  same  work  are  described  and  figured  the  following  allied  Crustacea  from  the  cai'bouifcrous 
limestone  of  Ireland :  Dithyrocaris  (Scoular)  Scouleri ;  Entomoconchus  (new  genus,  M'Coy)  Scouleri ; 
Cytherina  Phillipsiana  of  De   Koninck;    Daphnia    primjEva;    Bairdia   (new   genus,    M'Coy)     curtus. 

B.  gracilis ;   Cythere  amygdalina,    C.  arcuata,  C.  bituberculata,  0.  costata,  C.  cornuta,  C.  elongata, 

C.  excavata,  C.  gibberula,  C.  Hibbertii,  C.  impressa,  C.  inflata,  C.  inornata,  C.  oblonga,  C.  orbicularis, 
C.  pusilla,  C.  scutulum,  C.  spinigera,  C.  trituberculata. 


124  SUPPLEMENTARY  APPENDIX. 

Trinodus.  New  genus.  Cephalic  shield  truncato-elliptical ;  glabella  convex,  nearly 
cylindrical,  sharply  defined  ;  cephalo-thoracic  furrows,  one  on  each  side  confluent  with  the  next 
furrow,  and  with  that  defining  the  glabella,  rctroflexed  to  fonn  a  small  flattened  tubercle  on 
each  side  of  the  base  of  the  glabella ;  neck  segment  small,  narrow,  convex,  surrounding  the 
glabella  in  front,  the  portion  in  front  of  the  glabella  as  wide  as  that  at  the  sides  ;  cheeks 
surrounded  by  a  thick,  flattened,  entire  margin,  of  equal  width  all  round ;  eyes  none,  facial 
suture  (?  none) ;  caudal  shield  equal,  and  similar  in  form  to  that  of  the  head ;  axal  lobe 
semicylindrical,  very  convex,  divided  by  three  segmental  furrows,  and  having  usually  a 
prominent,  lengthened  tubercle  extending  down  the  middle,  and  which  is  not  cut  by  the 
segmental  furrows ;  lateral  lobes  almost  equal  to  the  axal,  very  convex,  not  marked  by  the 
segmental  furrows ;  portion  encircling  the  obtuse  apex  of  the  axal  lobe  about  equal  to  that 
of  the  sides,  surrounded  by  a  flattened  margin,  less  than  the  side  lobes  in  width." 
T.  agnosiifonnis. 


Remopleurides  laticeps. 

Acidaspis  bispinbsus. 

Sphffirexochus  calvus.    [Calymene  clavifrons  of 

Dalman.] 
Encrinurus   Stokesii.     [Calymene  variolaris   of 

authors.] 
Calymene  arenosa. 


Calymene  ?  forcipata  (a  Lichas?). 

Portlockia  sublaevis. 

Lichas  laxata. 

Lichas  pumila 

Ilomalonotus  ophiocephalus. 

Otarion  obtusum. 

Harpes  ?  megalops. 


Mr.  M'Coy,  in  the  same  work,  has  placed  the  Balfiis  tubercidafus  of  Kloden  among  the 
Entomostraca,  in  a  genus  which  he  names  Beyrichia,  and  defines  as  follows  : 

"  Gen.  Char.  Shell  bivalve,  rotundato-quadrate,  ventral  margin  slightly  concave,  ends 
very  nearly  equal,  obtusely  rounded ;  sides  equal,  very  gibbous,  deeply  impressed  by  a  strong 
and  wide  sulcus,  which  extends  fi'om  the  ventral  margin  nearly  to  the  dorsal,  giving  a  bilobed 
or  reniform  appearance  to  each  valve  ;  sulcus  slightly  nearer  to  the  anterior  end  ;  within  this 
sulcus  on  each  valve,  and  close  to  the  anterior  (or  smaller)  side,  is  a  lengthened  oval 
tubercle,  nearly  at  right  angles  with  the  ventral  margin,  and  reaching  about  two  thirds 
of  the  distance  from  thence  to  the  dorsal  margin  ;  surface  smooth. 

"  On  first  examining  some  specimens  from  the  Irish  Silurian  sandstones,  of  what  I 
considered  to  be  the  Aynostus  {Batfus)  tuheradotiis,  Klod.,  of  the  Silurian  System,  I  perceived 
that  the  vertical  sulcus  was  very  slightly  nearer  to  one  end  than  to  the  other,  and  that  the 
lengthened  tubercle  forming  the  so-called  mesial  lobe  was  not  precisely  in  the  middle,  as 
figured  and  described  by  authors ;  this  deviation,  though  very  slight,  was  important,  as 
showing  that  we  could  not  be  really  looking  at  the  back  of  a  symmetrical  animal,  as  was 
previously  supposed,  and  that  the  creature  could  not  be  an  Agnosim.  I  also  perceived  that 
some  of  the  specimens  had  the  tubercle  nearest  the  right,  and  others  nearest  the  left  end, 
and  that  consequently  I  had  got  the  two  valves  of  an  entomostracous  shell.  I  therefore 
doubted  the  correctness  of  the  reference  to  the  English  species  until,  on  examining  the 
original  specimens  in  London,  I  found  that  they  too  were  unsymmetrical ;  I  am  now  therefore 
certain  that  my  observations  apply  equally  to  the  Irish  fossil  and  the  Agnosius  tuherculafus  of 
Wales,  but  should  still  have  doubted  the  reference  to  Kloden's  Brandenburg  species,  had  not 
an  author  well  acquainted  with  the  continental  fossil  published,  a  few  months  ago,  a  Memoir, 
in   which   he   incidentally    alludes   to  this    subject,    and  expresses  an  opinion  of  Kloden's 


SUPPLEMENTARY  APPENDIX.  125 

continental  fossil,  similar  to  that  I  had  already  formed  of  the  English  and  Irish  specimens, 
and  which  though  I  cannot  advance  as  a  discovery,  I  can  yet  confirm  so  far.  To  o-ive 
Herr  Beyrich  full  credit  for  his  penetration,  I  subjoin  his  remarks  (loc.  cit.  p.  47),  and 
have  great  pleasure  in  naming  the  genus  after  him.  '  Baftus  tubcradalus,  Klöden,  welchen 
Burmeister  als  synonym  zu  Odontoplciira  omtu  citirt,  ist  weder  ein  Battus  nocht  überhaupt 
ein  Trilobit.  Er  hat  ein  zweiklajjpige  Schale,  deren  Oberfläche  mit  ganz  unsymmetrisch 
geordneten  Lappen  und  Tuberkeln  bedeckt  ist,  und  muss  eine  besondere  Gattung  neben 
Cytherma  bilden.' 

"  The  Af/nostus  Mus  of  the  American  geologists  from  their  '  Clinton  group,'  also  belono-s 
to  this  genus.  The  species  I  propose  naming  after  its  original  discoverer,  Bcijrichia 
Klodeniy  (Loc.  cit.  p.  58.) 

The  Cythere  jjliaseolus  of  Hisinger  is  enumerated  among  Irish  Silurian  fossils  in  the 
same  work. 

IV.  The  following  new  Trilobites  and  Entomostraca  are  described  and  figured  by  Mr. 
Salter  in  the  work  of  Professor  Sedgwick,  already  mentioned.* 


Cheirurus  juvenis. 
Cybele  sexcostata. 
Calymene  tuberculosa. 


llhenus  Davisii. 

Bowmanni. 
Asaphus  elevatus. 

Homalonotus  bisulcatus.  parvifrons. 

rudis.  Lichas  (nodulosus) 

?  Cephalaspis.  Ogygia  radiata. 

Dahuannia  aifinis.  Agnostus  trinodus. 

obtusicaudata  Beyrichia  complicata. 

Phacops  apiculatus  Beyrichia  plicata, 

felinus.  Cythere  umbonata. 

alifrons.  Cypridina  strangulata 


V.  From  the  treatise  '  Ueber  einige  böhmische  Trilobiten,'  by  Dr.  Ernst  Beyrich  (1845), 
referred  to  by  Professor  Burmeister  more  than  once,  we  have  extracted  the  following  generic 
characters  of  Cheirurus,  Sph.erexochus,  Lichas,  and  Trochurus. 

Cheirurus.  Caput  ambitu  semi-orbiculari,  limbo  prsecinctum,  testa  tectum  granulosa 
in  glabella,  scrobiculosa  in  genis.  Suturse  faciales  ab  oculis  postice  ad  marginem  exteriorem, 
antice  sejunctse  ad  marginem  ductae.  Oculi  parvi.  Sulcus  occipitalis  profundus,  prope 
angulos  cum  sulco  marginali  confluens.  Glabella  magna,  lata,  usque  ad  limbum  marginalem 
porrecta,  frontem  versus  dUatata.  Sulci  laterales  glabella;  tres  distincti ;  posteriores  versus 
ad  sulcum  vertiealem  retrorsi ;  medii  et  anteriores  ssepius  conjuncti,  recti  vel  parum 
retroversi.     Alse  occipitales  scuti  centralis  latae  ;  scuta  marginalia  parva. 

Thorax  ex  articulis,  undecim.  Rhachis  arcuata,  versus  pygidium  coarctata,  trans- 
versim    annulata.       Pleurse  sulco  transversal!  in  partem  interiorem  minorem   et  exteriorem 

*  In  the  forthcoming  (the  second)  volume  of  the  Memoirs  of  the  Geological  Survey  of  England  and 
Wales,  now  in  the  press,  a  new  species  of  Olcints  is  described  by  Professor  Phillips,  under  the  name  of 
O.  Iiumi/is,  and  a  new  A»ipi/x,  named  by  Professor  E.  Forbes,  A.  purvuhm. 


126  SUPPLEMENTAEY  APPENDIX. 

majorem  dmsse ;  pars  interior  sulco  longitudinali  oljliquo  cxarata,  pars  exterior  Integra 
recurva. 

Pygidium  breve,  latum^  digitato-fissum,  compositum  ex  articulis  tribus  completis  et 
articulo  quarto  tcrminali  pleuris  carente.  Pleurae  majore  ex  parte  liberse ;  anteriores  sulco 
brevi  longitudinali  exaratte  seque  ut  tlioracis  pleuras. 

(Three  new  species,  C.  insiffnis,  C.  damyer,  and  C.  r/ibhus.) 

Sph^rexochus.  Caput  ambitu  semi-orbiculari  (limbo  praecinctum?)  testa  tectum 
undique  granulosa.  Suturae  faciales  ab  oculis  postice  ad  mai-ginem  exteriorem  prope  angulis, 
antice  sejunctse  ad  marginem  ductse.  Oculi  cornea  rotundata  distinctae  granulosa  (Loven.) 
Sulcus  occipitalis  latus  profundus.  Glabella  magna,  antice  usque  ad  marginem  producta,  inde 
a  sulco  verticali  turgida,  suliliemispliasrica.  Sulci  laterales  onmes  sejuncti,  posteriores  reversi, 
saepius  cum  sulco  verticali  confluentes ;  anteriores  et  medii  recti,  sejuncti,  saepius  obscuri. 

Thorax  ex  articulis  undecim. 

Pygidium  breve,  latum,  digitato-fissum,  compositum  ex  articidis  tribus  completis,  quonmi 
postremus  in  rhachi  penitus  implicatus  est  cum  articulo  terminali.  Pleurae  elevatse;  sulcis 
profundis  sejunctse,  apicibus  liberis. 

{Sphmrexochus  mirns. ) 

LiCHAS.  Caput  testa  tectum  undique  dense  granulosa.  Suturae  faciales  ab  oculis  antice 
sejunctae  ad  marginem  ductae  ;  postice  (?)  Glabella  lata  usque  ad  marginem  porrecta,  fronte 
plerumque  tumida  margini  imminente.  Sulci  laterales  anteriores  retroversi,  longissimi, 
sejuncti  proximo  ad  sulcum  verticalem  retroducti ;  medii  saepius  obsoleti,  posteriores  breves, 
retroversi,  cum  sulco  verticali  confluentes. 

Thorax  ex  articulis  undecim,  pleuris  planis,  falcatis,  sulco  longitudinali  usque  ad 
apicem  acutum  exaratis. 

Pygidiiun  ambitu  laciniato,  compositum  ex  articulis  tribus  completis,  quorum  postremus 
in  rhachi  obscure  distinctus  est  a  medio  et  penitus  implicatus  cum  articuli  terminali.  Pleurae 
sulcis  sejunctae  et  sulcis  longitudinalibus  exaratae,  apicibus  anteriorum  et  mediarum  (in 
quibusdam  speciebus  posteriorum  quoque  ?)  liberis. 

(Two  new  species,  LwJias  scahra  and  L.  dissidens.) 

Trochurus.  Caput  ambitu  semi-orbiculari,  testa  tectum  undique  granulosa.  Suturae 
faciales  ab  oculis  postice  ad  marginem  exteriorem  prope  angulos  ductae ;  antice  ?  Oculi  ? 
Glabellae  pars  anterior  (frons)  valde  dilatata,  turgida,  subhemisphaerica,  usque  ad  marginem 
porrecta ;  pars  posterior  angusta,  semicylindracea,  sulcis  dorsalibus  parallelis  definita, 
stipitem  quasi  frontis  exhibens.  Sulci  laterales  posteriores  et  medii  obsoleti,  anteriores 
conjuncti ;  sulcus  occipitalis  profundus. 

Thorax  ex  articulis  undecim  f 

Pygidium  ambitu  semi-orbiculari ;  lateribus  planis ;  rachi  convexa,  versus  marginem 
angustata  et  attenuata  ;  margine  spinis  sex  tenuibus  pendulis  aucto.  Rhachis  antice  annulos 
articulorum  duos  praebet,  sulcis  profundis  sejunctos.  Pleurae  utrinque  tres  distinguendas  ; 
anteriores  et  mediiE  costis  definitas,  rectis,  radiantibus,  ad  spinas  marginis  ductis ;  posteriores 
costis  carentcs,  cum  rhachi  coalitae,  prope  rhachim  spiniferae.  Testa  granulis  inaequalibus  scabra. 

(One  species  Trochurus  sjjeciosus.) 

VI.    M.  Joachim    Barrande    has    very   recently    (1S46)  published  a  memoir,    entitled 


SUPPLEMENTARY  APPENDIX. 


127 


'  Notice  Preliniinaire  sur  le  Systeme  Siluricn  ct  les  Trilobites  dc  Boheme.'  In  this  paper  a 
very  great  number  of  new  species  of  Trilobites  are  briefly  described,  but  not  figured,  and 
several  new  genera  noticed.  With  a  view  to  prevent  over-multiplication  of  synonyms,  and  to 
render  this  enumeration  as  complete  as  possible,  we  .extract  the  new  names  given  in 
M.  Barrande's  treatise,  and  refer  the  reader  to  the  work  itself  for  the  descriptions.  In  the 
following-  list  the  names  of  the  new  genera  are  printed  in  small  capitals. 


Aretiiu.sa  Koninckii 
Abiox  ceticephalus 
Asaphus  ingcns 

nobilis 

(Nileus)  Bouchardi 

Battus  bibullatus 
granulatus 
Orion 
af&nis 
rex 

cuneifer 

tardus 

Bronteus  Brongniarti 

porosus 

pustulatus 

formosus 

angusticeps 

Zippei 

Partschii 

Haidingeri 

ambiguus 

Caphyra  radians 
Calymene  pulclira 

parvula 

incerta 

diademata 

Bayleii 

Beaumonti 
Cheirurus  Beyrichii 

Quenstedti 

corda 
Conocephalus  Emmerichii 

coronatus 
Cyphaspis  Burmeisteri 

depressa 

Cerberus 

DioxE  Formosa 

Egle  rediviva 
Ellipsoccphalus  nanus 
tumidus 

Harpes  tenuipunctatus 


Hydrocephalus  Saturnoides 
carens 

Lichas  propinqua 
pahuata 
simjjlex 
Haueri 
parvus 

MoNADlNA  distincta 
micron 

Odontopleura  Prevosti 
Dufrenoyi 
mira 

Verneuili 
Leonhardi 
minuta 
tricornis 
direlicta 
Hornesii 
lacerata 
Buchii 
primordialis 

Proetus  Ryckholtii 

intermedius 

decorus 

venustus 

lepidus 

luberculatus 

Myops 

inasquicostatus 

sculptus 

gracilis 

Lovenii 
Phaeton  membranaceus 
striatus 
Archiaci 
Paradoxides  Linnei 

rotundalus 
pusillus 
Phacops  fecundus 

bulliceps 

trapeziceps 


128 


SUPPLEMENTARY  APPENDIX. 


Phacops  Glockeri 

intercostatus 
spinifer 
Reussii 
Bi'onnii 
socialis 
Hawlei 
elongatus 
'dubius 
Philiipsii 
intermedius 
breviceps 


Phacops  laivigatus 

Sao  hirsuta 
Staürocephalus  Murchisoni 

Trinucleus  Goldfussii 

Bucklandii 

Trilobites  heteroclytus 

orbitatiis 

desideratus 

decipiens 

Lindaueri. 


DESCRIPTION    OF    THE    PLATES. 


TABLE  I. 

Fig.   1.  Triimdcus  Caractaci. 

2.  0()i/(jia  Biichii. 

3.  Guettardi. 

4.  Oclontopk'ura  elUptica. 

5.  Paradoxides  hohtnücm,  old  specimen. 

6.  Bo.  do.         young. 

7.  Bo.  do.         under  part  of  cephalic  shield  (irtc/^a/as). 

8.  EUijJsocephalm  Hoßi. 

9.  CoHOcephahis  driatas. 

10.  Sulzeri. 

11.  Harpcs  ungula. 

11«.  A  portion  of  the  sculptiu'c  of  the  margin  magnified. 


TABLE  IL 

Fig.   1.  CulymeHc   Bhtmenbachii,    rolled    up,     vie\Aed     from    the   side,    drawn    from    a 
perfectly-preserved  specimen  in  M.  E.  Anton's  collection. 

2.  The  same,  extended,  seen  from  above. 

3.  The  same,  a  front  view. 

4.  Phacojjs  lafifrons,  rolled  up,  side  view. 

5.  The  same,  extended,  from  above. 

6.  The  same,  front  view. 

7.  Cephalic  shield  of  Calymene  Tristani,  from  above. 

8.  The  same,  from  the  side. 

9.  Cephalic  shield  of  Calymene  calliccpliala,  from  above. 

10.  The  same,  from  the  side. 

11.  Odoniopleura  ovata. 

12.  Asapkm  p)latycephalus.  17 


130  DESCRIPTION  OF  THE  PLATES. 


TABLE  III. 

Fig.  1.  Proetus  Cuvieri,  Gerastos  lavigatus,  Gold!".,  rolled  up,  side  view. 

2.  The  same,  extended,  from  above. 

3.  Ci/phmpis  ceratopldhalma,  rolled  up,  side  view. 

4.  The  same,  extended  from  above. 

5.  Aeonia  diops  {Calj/mene  diops.  Green). 

6.  Phacops  protuberans. 

7.  Tril.  Sternhergii,  cephalic  shield  from  the  side. 

8.  The  same,  from  above. 


9.      Olctms  (jihhosus. 
10.     lUanus  ijigantem. 


TABLE  IV. 


Fig.  1 .     Homalonofiis  armatus. 

2.  Phacops  rotundifrons. 

3.  Phacops proavus,  cephalic  and  caudal  shield. 

4.  odonfocephaliis,  head. 

5.  conophihalmus. 

6.  The  same,  rolled  up. 

7.  Phacojjs  arachnoides. 

8.  stell  if  er. 

9.  caudal  us. 

10.  Four  body  rings  of  Homalonotus  as  seen  in  a  transverse  section. 

11.  Four  body  rings  of  Calymene  as  seen  in  a  transverse  section. 

Remark. — The  anterior  smaller  segment  in  these  two  transverse  sections, 
represents  the  articular  fold;  the  posterior  larger  segment  indicates  the 
true  ring,  beneath  which  the  articular  fold  is  hidden  when  the  body  is  ex- 
tended. In  Catymene  we  merely  perceive  an  acute  angle  at  the  place 
where  the  two  segments  meet ;  in  Homalonotus,  on  the  other  hand,  a 
thick,  perpendicularly-descending  ridge. 

12.  The  eye  of  Phacops  latifrons,  without  a  horny  membrane,  enlarged  to  twice  its 

natural  size. 


TABLE  V. 


Fig.   1.     Asaphns  cxpansus. 

a.  Extended. 

b.  Rolled  up,  and  seen  in  front. 

c.  Do.  lateral  view. 
2.     nianus  crassicauda. 

a.  Extended. 

Ij.  Rolled  up,  front  view. 


DESCRIPTION  OF  THE  PLATES.  131 

Fig.  2.     c.  Rolled  up,  side  view. 

Eemark. — Particular  attention  has  been  paid  to  the  sculpture  in  both  figures, 
and  the  body  has  therefore  been  represented  only  in  outhne. 

3.  Arcliegonus  claviceps. 

4.  Caudal  shield  of  Asaphws  Tijrannus. 

5.  Aeonia  Slokesii,  cephalic  shield. 

6.  ^/^»o.y/««  jöM{/bn«/s,  cephahc  shield. 

7.  The  same,  caudal  shield. 

8.  Aeonia  concinna. 

9.  Aeonia  verticalis,  Gerastos  cornutus,  Goldf. 
10.     Pkacojjs  Ilaiismanni. 

Remark. — Two  forms  of  the  caudal  shield  of  this  species  occur  in  the  grau- 
wacke  hmestone  of  Bohemia,  of  which  the  one,  which  is  the  rarer  species, 
is  more  elongated,  and  has  21  joints  of  the  axis,  upon  which  two  larger 
tubercles  are  placed  near  the  centre.  The  lateral  lobes,  1 5  in  number,  are 
broader,  more  depressed  at  the  upper  part,  less  distinctly  impressed  longi- 
tudinally, and  the  granulation  of  the  siu-face  is  more  scattered.  The 
other  form  (represented  here)  is  shorter,  broader,  and  more  obtuse;  has 
only  from  IS  to  19  rings  in  the  axis,  and  13  more  convex  and  narrower 
lateral  ribs,  which  are  distinctly  furrowed  at  the  angle,  and  very  finely, 
and,  on  the  axis,  uniformly  granulated.  I  suspect  that  the  former  form 
may  have  been  the  male,  the  latter  the  female  individual. 


TABLE  VI. 

Fig.  1.  AjMS  cancriformis,  viewed  from  below,  natural  size,  very  old. 

2.  Serolis paradoxa,  from  above,  fuU  grown. 

3.  Brancldpus  stagnalis,  from  below,  enlarged  to  six  times  its  diameter. 

4.  Structure  of  the  eyes  oi  BrancMjMs. 

a.  Cornea  extern,  laivis. 

b.  Cornea  ai-eolata. 

c.  Lens. 

d.  Corpus  vitreum. 

e.  Commencement  of  the  black  pigment. 
/.  Nervus  opticus. 

5.  Parts  of  the  mouth  of  Avus. 

A.  The  jaw. 

B.  1  P.  The  accessory  parts  of  the  mouth. 

C.  2  P.  Do.  do. 

D.  Rudiment  of  the  first  foot. 

6.  Parts  of  the  mouth  of  Brancldpus. 

A.  The  jaw. 

D.  Rudiment  of  the  fijrst  foot. 


132  DESCRIPTION  OF  THE  PLATES. 

Fig.  7.     Imaginary  transverse  section  of  an  Amphus. 
a.  Lateral  lobes  of  the  shell. 
h.  The  gül. 

c.  The  most  external  fin  lobe. 

d.  Interior  do. 

8.  View  of  an  Amphm  cornigcrm,  from  below. 

a.     Clj'peus. 
hh.    Lobi  antennigeri. 
cc.    Lobi  laterales. 
d.     Labrum. 
pp.    Mandibular. 
ff.    The  indentations   into   which  the    lower  ends    of  the    lateral    lobes    are 

placed  when  the  animal  rolls  itself  up. 
h.  Rectum. 

9.  Foot  of  an  Apus  cmicriformis,  from  the  body  region,  \ery  nuicli  enlarged. 

10.  Foot  of  the  same  species,  from  the  central  region  of  the  tail,  very  much  enlarged. 

11.  The  last  foot  of  Apiis  cancrifonnis,  very  much  enlarged. 

12.  Foot  oi  BranchijJiis  stcif/naUs,  very  much  enlarged. 

The  designation  of  each  of  the  feet  is  as  follows  : 

A.  Basis,  where  it  is  aifixed  to  the  body. 

B.  Basis  interna  libera. 
1 — 5  Fin  lobes. 

K.  Gill. 

L.  Lobe  protecting  the  gill. 
/.  Second  protecting  lobe. 
.     13.     A  young  Apus. 

a.  Small  feelers. 

b.  Large  feelers. 

c.  Jaw. 

d.  Rudiments  of  the  feet. 

14.  Young  Branchipus :  parts  as  in  the  last. 

15.  Linniadia  mauritiana,  enlarged. 

B.  Foot  of  Limnadia,  parts  as  above. 

16.  Branchipus,  with  a  Trilobite  shell,  viewed  from  above. 


INDEX   OF   GENERA   AND   SPECIES 

ENUMERATED  BY  THE  AUTHOR. 


AcASTE,  Goldfus«,  88. 

AciDASPis,  Murcli.  61. 

Brightii,  63. 

AcTINURUS,  66 

Aeonia,  Biimi.  99,  100. 

coneinna,  100. 

Stokcsii,  100. 

verticalis,  100. 

diops,  100. 
Agnostus,  116. 

pisiformis,  117. 

laevigatus,  117. 

integer,  117. 

nudiis,  117. 
Amphion,  Pand.  79. 

froutilobus,  SI. 

gelasinosiis,  71. 
Ampyx,  Dalm.,  110. 

incertus,  112. 

mammillatus.  111. 

nasutus,  110. 

?  pachyrhyuchus,  66. 

rostratus.  111. 
Anthes,  72. 
Apcs,  41. 
Archegonüs,  101. 

centrotus,  I0.>. 

seqvialis,  102. 

globiceps,  102. 
Arges,  Goldf.  6.3. 

armatus,  63,  64. 

radiatus,  63. 

planospinosus,  7 1 . 
.\btemia,  41. 
AsAPHüs,  Brong.  10.). 

angustifrons,  110. 

ai-achnoides,  96. 


ASAPIIIS, 

armadillo,  lOti. 
astragolites,  96. 
aiiriculatus,  94. 
breyis,  US. 
Brongniartii,  112. 
Buchii,  59. 
caudatus,  94. 
Cawdori,  117. 
centrotus,  105. 
claviceps,  102. 
corndeusis,  61,  113. 
cornigeriis,  107. 
crypturus,  95. 
Cyllarus,  58. 
Dalmanni,  102. 
dilatatus,  59. 
diurus,  118. 
dubius,  99,  102. 
duplicatus,  61. 
expansus,  107. 
exteniiatus,  109. 
Fisclieri,  81. 
frontalis,  113. 
gemmuliferus,  1 12. 
gigas,  110. 
globiceps,  102,  112. 
grandis,  Sars,  107,  118. 

Munster,  111. 
granulatus,  57. 
granulifems,  1 1 2. 
Hausmanni,  93. 
heros,  112. 
laciuiatus,  66. 
Ifpviccps,  107. 
laticauda,  65. 
laticostatus,  95. 


ASAPHUS, 

limulurua,  95. 

longicaudatus,  Oö. 

megalophthalmus,  1 1 2. 

micrui-us,  95. 

mucronatus,  94. 

myimecoides,  96. 

obsoletus,  112. 

palpebrosus,  107. 

platycephalus,  110. 

platynotus,  112. 

pleuroptyx,  95. 

Powisii,  96. 

pusUlus,  118. 

quadrilimbatus,  112. 

raniceps,  109. 

selenurus,  95. 

seminiferus,  1 12. 

seticornis,  58. 

Stokesii,  100. 

subcaudatus,  1 18. 

tetragonoeephalus,  70. 

Trimbii,  113. 

truncatulus,  112. 

tuberculato-caudatus,  94. 

Tyrannus,  108,  113. 

Vulcani,  113. 

Wetherillii,  90. 

Zinckenii,  120. 
Battus,  117. 

pisiformis,  117. 

integer,  117. 

nudus,  117. 

tuberculatus,  62. 
Beanchipus,  41. 
Brongniartia,  110. 

carcinoidea,  1  lU,  116. 


i;34 


INDEX  OF  GENERA  AND  SPECIES. 


Bromtes, 

Goldfuss,  64. 

costatus,  65. 

flabeUifer,  65,  119. 

fiireata,  118. 

glabratus,  119. 

laticauda,  65. 

Neptuni,  65. 

radiatus,  65. 

signatus,  119. 

subradiatus,  65. 
Bum  ASTES,  Murcb.  104. 

bamensis,  104. 

franconicus,  118. 

planus,  118. 
Calymene,  79. 

sequalis,  102. 

actinura,  68,  83. 

anchiops,  83,  90. 

articulata,  71,  116. 

aracbnoides,  96. 

bellatiüa,  83,  99. 

Blumenbachii,  81. 

bufo,  83,  88. 

caUicephala,  83. 

clavifrons,  99. 

concinna,  83,  100.  > 

decipiens,  74. 

diops,  83,  100. 

Downingise,  83,  92. 

frontiloba,  81. 

furcata,  118. 

granulata,  89. 

hydrocephala,  98,  120. 

intermedia,  112. 

Jordani,  89,  119. 

lievis,  89. 

latifi'ons,  88. 

macrophthalma,  83,  88,  92. 

microps,  83,  91. 

odontocephala,  83,  92. 

ornata,  112. 

phlyctsenoides,  112. 

platys,  82. 

polytoraa,  81. 
propinqua,  71,  116. 

protuberans,  89. 

punctata,  83,  114. 
Scblotheimii,  88. 
Schuster!,  120. 
sclerops,  83,  91. 


Calymene, 

selenecepbala,  83. 
speciosa,  71. 
Sternbergii,  71,  116. 
Stokesii,  83,  89. 
subornata,  120. 
Tristan!,  80. 
tuberculata,  83,  89. 
variolaris,  79,  83,  114. 
verrucosa,  99,  112. 
Ceraukus,  Green,  61. 
crenatus,  63. 
Crosotus,  63. 
globiceps,  63,  71. 
pleurexanthemus,  63. 
Cheirurus,  71. 
Conocephalus,  Zenk.  72. 
costatus,  73. 
striatus,  73. 
Sulzeri,  73. 
Cryph.eus,  Green,  113. 
callitelus,  113. 
Boothii,  113. 
Cryptolithus,  Green,  56. 
Bigsbü,  58. 
tesselatus,  58. 
Cryptonymus,  Eich. 
Lichtensteinii,  107. 
Panderi,  107. 
Parkinsonii,  104. 
Eosenbergii,  104. 
Eudolphii,  104. 
Scblotheimii,  107. 
Wahlenbergii,  104. 
Weissii,  109. 
Cypuaspis,  98. 
clavifrons,  99. 
ceratoplithalma,  98. 
Cyprts  faba,  50. 
Cybele,  Löev.  99. 
beUatula,  99. 
verrucosa,  99. 
Cytherina,  55.     . 
baltica,  55. 
phaseolus,  55. 
DiPLEURA,  Green,  85. 

Dekayi,  85. 
Dysplanus,  105. 

centrotus,  105. 
EiDOTEA,  Scouler,  54. 


Ellipsocephalus,  Zenk.  74. 

ambiguus,  74. 

Hoffii,  74. 
Entomolitiu's,  Linn. 

Derbiensis,  112. 

expansus,  107. 

paradoxissimus,  68. 

paradoxus,  82,107. 

pisiformis,  117. 

tuberculatus,  82. 
En'tomostracites,  Wahl. 

actinurus,  69. 

bucephalus,  68. 

caudatus,  94. 

crassicauda,  103. 

expansus,  107. 

exteuuatus,  109. 

gibbosQS,  70. 

granidatus,  57. 

laciniatus.  66. 

laticauda,  65. 

paradoxissimus,  68. 

pisiformis,  117. 

punctatus,  114. 
Estheria,  Strauss,  41. 
EuRYPTERUs,  Dekay,  54. 

lacustris,  54. 

remipes,  54. 

tetragonophthalraus,  54. 

Scouleri  (Eidotea),  54. 
Gerastos,  Goldf.  99. 

cornutus,  100. 

globiceps,  102. 

granulosus,  100. 

Isevigatus,  100. 

sphisericus,  100. 
GoLDius,  65,   120. 

flabeUifer,  63. 
Griffitiiides,  102. 

globiceps,  102. 

longispinus,  102. 

claviceps,  102. 
Harpes,  Goldf.  74. 

macrocephalus,  75. 
speciosus,  75. 
ungula,  75. 
Flanaganni,  75. 
Doranni,  75. 
Hemicrypturus,  Green,  105. 
Rasoumowskii,  107. 


INDEX  OF  GENERA  AND  SPECIES. 


135 


HoMALüNOTVS,  König.  84. 

Alirendü,  86,  120. 

armatus,  8". 

Dckayi,  88. 

delpbinoccplialus,  86. 

gigas,  120. 

Greenü,  87. 

Herschelii,  87. 

Knightii,  86. 

ludensis,  86. 

punctatus,  120. 
Ill.knus,  103. 

barriensis,  104. 

centrotus,  106. 

crassicauda,  103. 

giganteus,  104. 

perovalis,  104. 
IsoTELEs,  Dekay,  lOä. 

angustifrons,  1 10. 

centrotus,  105. 

crassicauda,  104. 

Cyclops,  1 10. 

dilatatus,  59. 

expansus,  107. 

extenuatus,  109. 

gigas,  110. 

Iseviceps,  107. 

Liclitensteinii,  107. 

megalops,  1 1 0. 

megistos,  120. 

palpebro.sus,  107. 

planus,  HO. 

Powisii,  108. 

stegops,  1 10. 
Lepidurus,  41. 
LiCHAS,  Dalm.  66. 

laciniatus,  66. 
LiMNADIA,  41. 

LiMULUS,  35. 
Metopias,  66. 
Nileos,  Dalm.  11)6. 

armadillo,  106. 

chiton,  106 

glaberrimus,  106. 

glomerinus,  104,  106. 
NuTTAiNiA,  Eatou,  58. 

concentrica,  58. 

Hibernica,  66. 
Odontopleur.v,  Em.  61. 

elliptica,  63. 

ovata,  62. 


Ogygia,  Brongn.  59. 
Bucbii,  59. 
Desmarcsti,  60. 
Gucttardi,  60. 
Murchisonii,  CO. 
Olenus,  Dalm.  69. 
alatus,  70. 
Bohemicus,  69. 
bucephalus,  68. 
forficula,  70,  72. 
gibbosus,  70. 
gracilis,  67. 
latus,  67,  70. 
pyramidalis,  67. 
punctatus,  96. 
scarabseoides,  72. 
spinulosus,  68. 
Tessini,  67,  68. 
Otarion,  Zenk.  58. 
diffractum,  58. 
elegans,  75. 
pygmaeum,  75. 
Pauadoxides,  66. 
acuminatus,  70. 
alatus,  70. 
arcuatus,  72. 
armatus,  116. 
bimucronatus,  71. 
Boltoni,  66,  68. 
bobemicus,  67. 
brevimucronatus,  1 18. 
bucephalus,  68. 
forficula,  70,  72. 
gibbosus,  70. 
gracilis,  67. 
Grotei,  96,  120. 
Harlani,  68. 
latus,  67,  70. 
longicaudatus,  67. 
pyramidalis,  67. 
quadrimucrouatus,  63. 
scarabseoides,  72. 
spinulosus,  68,  72. 
Tessini,  67,  68. 
triarthrus,  72,  116. 
Peltura,  M.  Ed.  88. 
Bucklandi,  97. 
scarabseoides,  71. 
Phacops,  Emm.  88. 
anchiops,  90. 
arachnoides,  96. 


PlIACOPS, 

caudatus,  94. 
ceratoplithalmus,  98. 
clavifrons,  71. 
conophthalraus,  91. 
Hausmanni,  93. 
latifrons,  88. 
macrophthalmus,  92. 
miicrouatus,  94. 
odontocephalus,  92. 
proasvua,  93. 
protuberans,  89. 
rotundifrons,  92. 
selerops,  91. 
sphairicus,  99. 
stcllifer,  97. 
Tariolaris,  114. 
Phillipsia,  Porti, 
derlayensis,  102. 
gemmulifera,  101. 
globiceps,  102. 
Jonesü,  102. 
Kellii,  101. 
oruata,  101. 
Platinotus,  66. 
Pleuracanthus,  M.  Ed.  88. 
arachnoides,  96. 
laciniatus,  92. 
punctatus,  96. 
Proetus,  Stein. 

elegantulus,  98. 
Cuvieri,  99. 
concinuus,  100. 
granulosus,  100. 
Remopleurides,  Porti.  116. 
Serolis,  Leacb,  35. 
Sph.erexochus,  99. 
Symphysürus,  106. 
Triarthrus,  Green,  116. 

Beckii,  72,  116. 
Trilobites. 

Aaellus,  119. 
Blumenbachii,  81. 
bobemicus,  67. 
Buchii,  59. 
bucephalus,  68. 
caudatus,  94. 
cnrnigcrus,  107. 
crassicauda,  103. 
dentatus,  119. 


136 


INDEX  OF  GENERA  AND  SPECIES. 


Trilobites, 

Desmaresti,  60. 
dilatatus,  59. 
elliptifroDs,  119. 
elegans,  119. 
Esmarkii,  104. 
gibbosus,  "0. 
gracilis,  67. 
Guettardi,  60. 
Hausmanni,  93. 
Hoffii,  74. 
laciniatus,  66. 
latieauda,  6.T. 
latifrons,  88. 
longicaudatus,  67. 
macrophthalmus,  83. 
minor,  67. 
mucronatus,  94. 
omatus,  58. 
parado.xus,  82. 
pisiformis,  117. 
punctatus,  114. 


TaiLOBITES, 

scarabseoides,   72. 
Schroten,  108. 
semilunaris,  119. 
sphaericus,  99,  119. 
ephaerocephalus,  Schloth.  (an 

indeterminable  fragment.) 
spinulosus,  68. 
Sternbcrgii,  71, 116. 
Siilzeri,  73. 
Tessini,  67. 
Tristani,  80. 
truncatus,  70. 
tuberculatus,  82. 
ungula,  75. 
variolaris,  114. 
velatus,  99. 
verticalis,  100. 
Zippii,  73. 
Trimerus,  Green,  85. 

delpbinocepbalus,  86. 
Jacksonii,  112. 


Trimervs, 

platypleurus,  112. 
TEtNUCLEUs,  Green,  56. 


Bigsbyi,  58. 
Caractaci,  56. 
ellipticus,  89. 
fimbriatus,  57. 
gibbosus,  63. 
granidatus,  .')7. 
intermedius,  118. 
Isevis,  89. 
Lloydii,  57. 
Nillsoni,  118. 
nudus,  57. 
omatus,  58. 
otarion,  58. 
radiatus,  58. 
tessellatus,  58. 
Zethus,  79 

verrucosus,  80,  82. 
uniplieatus,  82. 


ERRATA. 

Page  5,  11  lines  from  bottom, /oc  Torrnbia,  reud  Torrubia. 
17,  note,  for  Triarthrus  Breki,  read  Triarthus  Bcckii. 
In  the  table,  p.  34,  for  Crophyropoda  read  Lophyropoda  ;  and 
for  Arthrostaca,  read  Arthrostraca,  also  in  note  to  p.  35. 


C.  AND  J.  ADLARD,  PRINTERS,  BARTHOLOMEW  CLOSE. 


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