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Full text of "The organization of trilobites, deduced from their living affinities; with a systematic review of the species hitherto described"

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HARVARD UNIVERSITY 




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OF THE 

MUSEUM OF COMPARATIVE ZOOLOGY 



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RAY SOCIETY 



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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. 



BIBLIOGRAPHY. 



1G98. Edw. L/iuytl iu the Pliilos. Transact., vol. xx, No. 24-1, August. Page 279. 
(First and oldest paper on Trilobites.) 

1699. Litliophylacii Britannici Ichnographia, seu lapid. etc. Londini (also Lipsise), 8vo, Ed. I, 

pag. 90, Ed. alt., O.von. 1760, 8vo. 
1700. Car. Leigh, A Natural History of Lancashire, Cheshire, and the Peak in Derbyshire. Oxt'ord, 1700, fol. 
1702. /. J. Scheuchzer, Specimen Lithologife Helvetise. Turici, 8vo. 
1708. C.N. Lange, Historia Lapidum Figuratorum Hclveti£e. Veuet. fol., p. 110. 

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). 
174;"). Linneeus, Oeliindska och Gothläudska Resa. Stockholm and Upsal, 8vo. 

1747. Wästgötha Resa. Stockh. 8vo. 

*1748. J.L. WoUersdorf, Systema Minerale, in Latin and German. Berhn, 4to, p. 42. 
*I750. Ch. Lijttelton, in the Philosoph. Transact., vol. xlvi. No. 496, Nov. and Dec, p. .")98. 
Ch, Mortimer, iu the same, p. 600. 
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.) 
*1826. Bar. v. Sehlotheim, in the Isis, page 315, Table I, Fig, 8-9. On Tril. Esmarkii and Tr. granura. 
* G. Be Razoumoivskij, Quelques Observations sur les Trilobites, in the Annales des Seienc. Natur, par. V. 

Audouiu and A. Brogniart, vol. viii, p. 186 seq. pi. XXVIII and XXIX. 
* E. W. Dalmann, on Palseaderna eller de sa kallade Trilobiterna. Stockh. 1826, 4. Translated into 

German by Fr. Engelhart. Nuremb. 1828, 4to, (with the original plates.) 

1827. Pay/on, On the Trilobites of Dudley. London, 4to. 

• 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. 
Stecheyloff, Journal für neue Entdeckungen im der Physiologie, Chemie, Naturgesch. und Technologie. 

(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 

Researches, extract by Bronn in Leonh. Journal ; Annual Series for 1828, p. 114. Note.) 

* A. Gold/nss, Oljservations sur la place qu'occupent les Trilobites dans le Regne Animal. Annales des Seienc. 

Natur, etc. tom. xv, p. 83, 8vo, pi. II. 
*1829. Fr. Jukes, on a new Trilobite from Great Barr in StaiFordshire (Bumasfes harrienses, March.) in Loudon's 
Mag. of Nat. Hist. vol. ii, p. 41, and in Silliman's Ametic. Journ. of Science and Arts, 1832, vol. xxiii. 
No. 1, p. 203. Also in Leonhard's Zeitschuh, 1833, 6. 
1830. E. Eichivuld, über die fossilen Podozoen und Cephalopoden, in den Russisch-Polnischen Provinzen (on the 
fossil Podozoa and Cephalopoda in the Russian-Polish provinces) ; from his Zool. Special. Russiee, &c. 
Wilnoe, 8vo, vol. i, p. 1, 323. (Nothing new ; some improved synonyms noticed in Leonh. Journal, 1832, 
122. Vol. ii contains the Vertebrata, 1831 ; likewise noticed in the above Journal, 1833, 708). 
*1830. C. II. Pander, Beiträge zur Geognosie des russischen Reichs. (Contributions to the Geology of the Rus- 
sian Empire.) St. Petersburg, 4to, Fig. c. (Leipzig, L. Voss, 1839.) 



BIBLIOGRAPHY. ix 

*]KW ITmiiujIiaus, in the Isis, p. 1)5, Table I, Fig. 2. a— c. on Cixl. macrophthahna. Also in Leonh. Jahrb. 1831, 

p. ;«i. 
* Gr. K. V. Sternheri), über die Gliederung und fiisse der Trilobitcn. (On the articulations and feet of 

Trilobites.) Isis, 1830, JUi, Table V, Fig. 1-3. 
1S31. Scolder, respecting Ediotea, in the Edinb. Journ. of Nat. Science, vol. iii. 
Hiiiicßlits Chemische Analyse der Deckeltheile der Entomostraciten oder Trilobiten. (Chemical Analysis 

of the erustaceous parts of the Eutomostracites or Trilobites. In Schweiger s Journ. of Nat. Science, 

and Isis, 1831, p. 341). 
J. D. Smverhy, i)u English Trilobites. In Loudon's Mag. of Nat. Hist., vol. iv, p. 53 seq. Also in Leonh. 

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). 
*1833. J. G. Zenker, Ueitriige zur Naturgeschichte der Urwelt. (Contributions to the Nat. Hist, of the Ancient 

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 *- 



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be S 



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"5 -2 



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~ 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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