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PRESENTED
The Trustees
THE BRITISH MUSEUM.
CATALOGUE
OF THE
CHAETOPO.DA
IN THE
*
BRITISH MUSEUM
(NATURAL HISTORY).
A. POTjYCHAETA:
PART I.— ARENICOLIDAE.
BY
J. H. ASHWOKTH, D.Sc,,
Lecturer on Invertebrate Zoology in the University of Edinbnrpti* ^ \j^ j (J A j
r^so,
LONDON :
PRINTED EY ORDER OF THE TRUSTEES
OF THE BRITISH MUSEUM.
SOLD BY
LONGMANS, GHEEN & Co., 39, PATERNOSTER Row, E.G.
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DULAU & Co., LTD., 37, SOHO SQUARE, W.
AND AT THE
BRITISH MUSEUM (NATURAL HISTORY), CROMWELL ROAD, S.W.
1912.
(All rights reserved.)
LONDON :
PRINTED BY WILLIAM CLOWES AND SONS, LIMITED,
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PREFACE
THE present work, which was undertaken at the suggestion of the
former Director, Sir E. Kay Lankester, K.C.B., F.R.S., covers but
a small proportion of the ground to be gone over in making a
Catalogue of the Chaetopoda or even of the Polychaeta.
Although the volume appears as " Part I " of a more general
catalogue, its selection for the first place was a fortuitous
circumstance, depending on the fact that Dr. J. H. Ash worth, the
author, had already devoted special attention to the Arenicolidae
when the idea was first projected. The Family in question was thus
not chosen because it was supposed to come naturally at the
beginning. But as circumstances have placed it there, it has been
thought advisable to devote some pages to an introductory survey of
the history and classification of the Chaetopoda, and in particular
of the Polychaeta. Morphological characters are largely em ployed
by the author in characterising the species.
Mr. F. Jeffrey Bell, whose official duties in the Museum include
the care of the specimens of Chaetopoda, has devoted much time to
the editing of this Volum,e.
The continuation of the series of volumes on Chaetopoda is not
at present provided for, but it is hoped that opportunities will
present themselves from time to time of continuing the series which
has been begun by Dr. Ashworth.
SIDNEY F. HAEMER,
Keeper of Zoology.
BRITISH MUSEUM (NATURAL HISTORY),
LONDON, S.W.,
November, 1912.
*<
TABLE OF CONTENTS
PAGE
LIST OF TEXT-FIGURES ......... vii
INTRODUCTION . . . . . . . . . . . xi
HISTORICAL ACCOUNT OF THE CHAETOPODA, WITH SPECIAL REFERENCE
TO THE POLYCHAETA AND THEIR CLASSIFICATION .... 1
ARENICOLIDAE ........... 25
ARENICOLA Lamarck, emend. . . . . . . .29
A General Account of the Genus Arenicola .... 32
External Characters ....... 33
External Apertures ........ 38
Chaetae . . . 39
Gills 55
Coelom and Coelomic Septa . . . . .61
Alimentary Canal : Burrowing ...... 63
Nervous System and Sense-Organs ..... 66
Nephridia ......... 71
Reproductive Organs ....... 72
Development ......... 73
Post-Larval Stages, with a Discussion of the Genus Clymenides . 75
Post-Larval Stages of A. marina ..... 77
,, ,, ,, A. cristata ..... 79
,, ,, ,, A. assimilis var. affinis ... 80
,, ,, „ A. ecaudata ..... 80
„ ,, ,, A. branchialis . . . , .81
Separation of the Genus Arenicola into Sections and Species . 82
The Caudate Section of the Genus Arenicola (with a Key to the
Caudate Species) * .- . . . . . .83
The Ecaudate Section of the Genus Arenicola (with a Key to
the Ecaudate Species) ....... 84
Arenicola marina (Linnaeus) . . . . . .86
Arenicola loveni Kinberg, emend. . . . . . 103
Arenicola cristata Stimpson . . . . . . 105
Arenicola glacialis Murdoch . . . . . . Ill
Arenicola pusilla Quatrefages . . . « . ^''iJA
Arenicola assimilis Ehlers, and var. affinis Ash worth. . £/' 123
Arenicola ecaudata Johnston . . . . . .132
Arenicola branchialis Audouin and Edwards . . . 138
BRANCHIOMALDANE Langerhans ....... 147
Branchiomaldane vincenti Langerhans ..... 147
THE INTER-RELATIONSHIPS OF THE MEMBERS OF THE FAMILY ARENICOLIDAE 156
THE AFFINITIES OF THE ARENICOLIDAE ...... 159
SYSTEMATIC INDEX TO THE ARENICOLIDAE ...... 163
GENERAL INDEX ........... 165
DESCRIPTION OF PLATES I-XV . . . 171
LIST OF TEXT-FIGURES
Fig. 1. — Arenicola loveni. Anterior end, dorsal aspect
Fig. 2. — A. pusilla. Anterior end, dorsal aspect ..... 33
Fig. 3. — A. brancJiialis. Anterior end, dorsal aspect .... 34
Fig. 4. — A. assimilis var. affinis. Anterior end, dorsal aspect . . 39
Fig. 5. — A, ecaudata. Outline of the posterior end of a post-larval
specimen, 8 nim. long, to show the chaetae .... 40
Fig. 6. — A. ecaudata. Crotchet from one of the posterior notopodia of
the same specimen ........ 40
Fig. 7. — A. cristata. Outline of a larva, about '7 mm. long, to show
the chaetae ......... 41
Fig. 8. — A. pusilla. Notopodial chaetae of larvae .... 41
Fig. 9. — A. marina. Notopodial chaetae of a post-larval specimen,
4'3 mm. long ......... 42
Fig. 10. — A. ecaudata. Distal halves of notopodial chaetae, from post-
larval specimens about 7 mm. long ..... 42
Fig. 11. — A. loveni. Distal third of a notopodial chaeta, from a specimen
335 mm. long ......... 44
Fig. 12. — A. cristata. Tips of unworn and worn notopodial chaetae
(adult) . . . .' 45
Fig. 13. — A. marina. Distal fourth of a notopodial chaeta (adult) . . 46
Fig. 14. — A. assimilis var. affinis. Distal third of a notopodial chaeta
(adult) . .' ... ..' .... 46
Fig. 15. — A. pusilla. End of a fractured chaeta (adult) . ... 47
Fig. 16. — A. ecaudata and A. branchialis. Distal portions of notopodial
chaetae (adult) . . - . . . .47
Fig. 17. — A. marina. Crotchet from a post-larval specimen, 5 mm. long 48
Fig. 18. — ,, Crotchet from a young adult, 17 mm. long . . 49
Fig. 19. — ,, Crotchets from a specimen, 125 mm. long . . 49
Fig. 20. — ,, Ventral end of the neuropodial chaetal sac of a
specimen 250 mm. long, showing the formation of crotchets . 50
Fig. 21. — A. assimilis var. affinis. Crotchets from a post-larval specimen,
7 "6 mm. long ......... 50
Fig. 22. — A. assimilis var. affinis. Crotchets from specimens 136 mm.
and 208 mm. long ........ 51
viii List of Text-figures
I'AQK
Fig. 23. — A. glacialis. Crotchets, in three phases of growth ... 52
Fig. 24. — A. pusilla. Crotchets from the type specimen, and from
specimens 17 and 160 mm. long ...... 53
Fig. 25. — A. cristata. First crotchet of a larva '25 mm. long . . 53
Fig. 26. — „ Crotchets from specimens 48, 130, 250 and
330 mm. long . . 54
Fig. 27. — A, loveni. Crotchet from the type specimen, and from a
specimen from Saldanha Bay ...... 56
Fig. 28. — A. ecaudata. Crotchet from a post-larval specimen, 8 mm. long 56
Fig. 29. — ,, Dorsal and ventral crotchets of a neuropodium
from a specimen 200 mm. long . . . . . .57
Fig. 30. — A. branchialis. Crotchet from a specimen 230 mm. long . 57
Fig. 31. — A. marina (from Wood's Holl). Dorsal axis of gill . . 59
Fig. 32. — A. pusilla (from Unalaska). Dorsal axis of gill ... 59
Figs. 33, 34.— A. glacialis. Gills 60
Fig. 35. — A branchialis. Gill 61
Fig. 36. — A. ecaudata. Dorsal gill-stem ...... 61
Fig. 37. — A. marina. Statoliths, and cuticular lining of statocj'sts of
specimens from Jersey and Trieste ..... 68
Fig. 38. — A. assimilis var. affinis. Statoliths, and cuticular lining of
statocysts of specimens from Otago Harbour and the Falkland
Islands 68
Fig. 39. —A. glacialis. Statoliths, and cuticular lining of statocyst . 69
Fig. 40. — A. cristata. Statolith, and cuticular lining of statocyst . . 70
Fig.. 41. — A. branchialis. Statoliths, and cuticular lining of statocyst . 70
Fig. 42. — A. marina. Eipe spermatozoon and ripe ovum ; A. bran-
chialis, ripe ovum .... ... 72
Fig. 43. — A. loveni. Anterior end, dorsal aspect ..... 103
Fig. 44. — ,, Type specimen ; a portion of the nineteenth
chaetiferous segment, the extra (twentieth) segment and
notopodium, and a portion of the tail ..... 104
Fig. 45. — A. cristata. Anterior end, dorsal aspect .... 106
Fig. 46. — A. glacialis. Anterior end, dirsal aspest . . . .112
Fig. 47. — ,, Diagram of a dissection of the anterior portion . 113
Fig. 48. — A.pusilla. Anterior end, dorsal aspect ..... 116
Fig. 49. — ,, Anterior aspect ... . . . . . 116
Fig. 50.— ,, Type specimen, right aspect of tenth chaetiferous
segment . . . . . . . . . .117
Figs. 51, 52. — A. pusilla. Type specimen, antero-ventral and dorsal views
of the anterior end ........ 118
Figs. 53, 54. — A pusilla. Specimen from California, antero-ventral and
dorsal views of anterior end . . . . . . 118
List of Text-figures ix
PAGE
Fig. 55. — A. assimilis. Anterior end, dorsal aspect .... 125
Fig. 56. — A. assimilis var. affinis. Anterior end, dorsal aspect . . 125
Fig. 57.— „ „ „ „ . 125
Fig. 58,— „ ,, „ „ . . 125
Fig. 59. — Brancliiomnldane vincenti. Anterior end, dorsal aspect . . 149
Fig. 60. — ,, ,, Notopodial chaetae . . . 149
Fig. 61. — ,, ,, juv. (" Clymenides incertus").
Notopodial chaeta . . . 150
Fig. 62. — ,, ,, Distal portions of three notopodial
chaetae . . . .150
Fig. 63. — „ „ juv. (" Clymenides incertus ").
Neuropodial crotchet . . 151
Fig. 64. — ,, ,, Adult. Neuropodial crotchet . 151
Fig. 65. — ,, „ juv. (" Clymenides incertus ").
Crotchet from one of the pos-
terior notopodia . . . 151
Fig. 66. — ,, ,, Diagram of the nephridia . . 153
Fig. 67. — ,, ,, Transverse section . . . 154
Fig. .68.— „ .„ Young stages of development
(after Mesnil) . '. .154
THE family Arenicolidae, though small in the number of its genera
and species, holds an important place in the literature of Polychaeta.
One of the members of this family — Arenicola marina, the common
lugworm — is the most abundant and most readily accessible Poly-
chaete of northern and western Europe. Probably no other marine
worm has been so frequently observed, collected and dissected, and,
consequently, the records and descriptions of which it is the subject
form a very extensive series. Twenty years ago the anatomy of the
other species of Arenicola was almost unknown ; the accounts of the
internal organs, given in descriptions of the genus Arenicola, referred
only to A. marina, j,nd it seemed to be taken for granted that all the
other species agreed in structure with this. Several of the internal
organs, notably the statocysts, oesophageal caeca, nephridia and septal
pouches have, however, been found to exhibit well-marked differences,
in form or number, in the various species, and to afford considerable
help in systematic work. In preparing the diagnoses, I have made
full use of the internal characters, the value of which will be
especially appreciated in those cases where it is necessary to deter-
mine defectively preserved or incomplete examples, which, as
experience has shown, can seldom be diagnosed safely by examination
of their few and imperfect external features. By means of the keys
and diagnoses provided, the identification of the members of the
family Arenicolidae will, it is hoped, be accomplished with certainty
and with comparative ease.
Questions of synonymy have received careful consideration and
full treatment in the text. I have examined all the extant types of
the species of Arenicola, and, in the case of those species the types
of which are no longer preserved, I have analysed the published
descriptions, and have compared them, with the long series of speci-
mens at my disposal, with the result that I can confidently state
my conviction that all the known forms fall into the eight species
described in this Catalogue.
In addition to the British Museum Collection, the entire
xii Introduction
Collections of Arenicola in the Museums of Berlin, Paris, Cambridge
(Mass.) and the Smithsonian Institution, together with interesting
examples from the Museums of Copenhagen, Dublin, Hamburg,
Eeykjavik, St. Petersburg, Stockholm and Vienna, have been sent to
me for examination. I am much indebted to the authorities of theste
institutions for placing their material at my disposal. During the
last twelve years I have collected, arid many friends have generously
sent to me, large numbers of specimens of Arenicola, in various stages
of growth, selected examples of which have recently been added to
the British Museum Collection. The possession of this abundant
material has enabled me to revise and extend previous work upon
the characters used in diagnosis, and to ascertain their range of
variation. In addition to the acknowledgments made in the text, I
am glad to have this opportunity of tendering my sincere thanks to
the following friends, who have aided my work by the gift or loan of
specimens : Prof. W. B. Benham, F.E.S., Prof. H. C. Buinpus,
Geheimrat Prof. Dr. E. Ehlers, Prof. P. Fauvel, Prof. J. D. F.
Gilchrist, Prof. W. A. Haswell, F.K.S., Prof. Harold Heath, Prof.
A. D. Howard, Dr. E. S. Lillie, Prof. F. Mesnil, Mr. E. Southern,
and the Directors of the Marine Laboratories at Alexandrowsk (Gouv,
Archangelsk), Cette, Millport, Plymouth, Santander, Sevastopol and
Trieste.
To Prof. F. Jeffrey Bell and to Dr. James Eitchie, of the Eoyal
Scottish Museum, Edinburgh, who have kindly read the proofs, I am
greatly indebted for helpful suggestions.
J. H. ASHWOETK
ZOOLOGICAL DEPARTMENT,
UNIVERSITY OF EDINBURGH.
September 23, 1912.
CATALOGUE
OF THE
AKENICOLIDAE
HISTORICAL ACCOUNT OF THE CHAETOPODA, WITH
SPECIAL REFERENCE TO THE POLYCHAETA AND
THEIR CLASSIFICATION.
NATURALISTS as remote as Aristotle were acquainted with Chaeto-
poda and other worms, the records of which thus extend backwards
to the earliest works on natural history. The chief object of the
historical account given in the following pages is to trace the
principal stages in the growth of knowledge regarding the Chaeto-
poda, especially the Polychaeta and their classification, and to
indicate in the different schemes of classification proposed the
position of the worms which form the subject of the present
Catalogue.
Aristotle recorded in his " Historia Animalium " the occurrence
of marine scolopendrae-,1 similar to their terrestrial congeners but
somewhat smaller, redder in colour, and having a larger number of
more slender feet. He stated that these animals are to be found in
the neighbourhood of rocks, and that they do not occur in very deep
water. The animals referred to were probably nereidiform worms.
Aristotle also mentioned helniinthes or intestinal worms. Pedacius
Dioscorides 2 described the use in medicine of Scolopendra marina,
earthworms and leeches.
Allusions to marine scolopendrae occur in the writings of Pliny 3
and Aelianus,4 and the former also referred to Hirudo and Lumbricvs.
1 Lib. ii, cap. xiv, 2. o-KoX(nr«i>8pat daXarrtm.
2 De Materia Medica [written probably about 60 A.D.] . Beeens. C. Sprengel,
Lipsiae (1829), pp. 174, 195, 708, 709.
3 Nat. Hist., Lib. ix, cap. Ixvii, 3 [about 78 A.D.] .
4 De Natura Animal., Lib. vii, cap. xxvi [about 220 A.D.] .
B
2 Catalogue of Chaetopoda
To Pliny and his contemporaries, and to his successors during the
next sixteen centuries, the names Hirudo and Lumbricus1 had a
much wider significance than they have at the present day ; these
writers included leeches of all kinds under the name Hirudo, and
they applied the designation Lumbricus to intestinal worms or to
earthworms,2 or so used it as to include both.
From the time of Pliny onwards for more than a thousand years
little real advance was made in regard to the knowledge of worms.
During this period various authors repeated, wholly or in part, the
accounts of Aristotle and Pliny, sometimes with fanciful embellish-
ments, but, for the most part, they added little or nothing new.
Most of the references to worms in these old writings relate to
parasitic worms, leeches and earthworms, and especially to the
medicinal use of the two latter. The treatise " De Animalibus " in
he works of Isidorus, Bishop of Seville (560-636 A.D.), is noteworthy
for a chapter3 — " De Vermibus " — under which heading are included
Sancjuisuga [leeches], parasitic worms (" Vermes carnium "), namely,
Lumbricus, Ascaridae, etc., and also Multipes [centipedes],4 Scorpio,
Limax, Bombyx, Teredo, etc. Isidorus placed the Vermes next the
snakes, but took care to point out the fundamental distinction
between them, that is, that the former are without a backbone —
" non est illi spinae rigor."
Albcrtus Magnus' (1193-1280) "De Animalibus" contains brief
notes, based chiefly on the works of previous writers, especially
Pliny, on the marine scolopendra, Seta \i.e. Gordius\, Sanguisuga and
Lumbricus.
Edward Wotton 5 (1552) gave a clearly written digest of previous
works, but added little new information ; in his description of fishes
reference is made to leeches and, in the chapter on " Insects," to
Scolopendra marina, Intestina terrae [i.e. earthworms], Ascaridae and
other parasitic worms.
Shortly after the middle of the sixteenth century there appeared,
in close succession, two great memoirs, both of which contained new
observations on worms, evidently made on living specimens. Belon 6
1 Pliny, op. cit., Lib. xxxii, cap. xlii, 2; Lib. xi, cap. Hi, 1.
2 E.g., L. J. Mod. Columella, De Re Rustica, Lib. vi, cap. xxv ; Lib. vii,
cap. ix. [Probably written early in the first century.]
3 Orig. sive Etymolog, Lib. xii, cap. v, p. 106, in Opera Omnia, Emend. J.
du Breul, Coloniae Agrippinae (1617).
4 The words within square brackets are not in the original ; they are
explanatory comments of the present writer.
5 De Differentiis Animalium, Paris (1552).
" De Aquatilibus, Libri duo, Paris (1558).
Historical 3
(1553) recorded interesting and accurate observations on the earth-
worm and lugworm, and on their habits. This is the first definite
mention of the lugworm, which Beloii named Lumbricus marinus in
contradistinction to the earthworm (L. terrestris).
The work of Eondeletius (1554, 1555) surpasses that of any
previous writer. Evidently a keen observer, especially of marine
animals, Eondeletius described, and gave good woodcuts of, two kinds
of Scolopendrae marinae, Hirudo marina, Vermis microrynclioteros and
Vermis macrorynchoteros [two Sipimculids], Vermes in tiibulis delites-
centes [Serpulids] and Penicillus marinus [a Sabellid].1 In a further
paragraph on marine worms 2 — " I)e vennibus stagni marini " — he
gave a short account of " Lumbrici stagni," and in another place 3
referred to Lumbricus marinus as being similar to Lumbricus terrenus.
His figures are, in most cases, faithful representations and were
freely copied by Gesner, Aldrovandus and others. Eondeletius
added notes on the use in medicine of some of the worms. Gesner's
treatise (1558) 4 is, at any rate as regards the articles on worms, a
compilation from the works of previous writers, especially Belon and
Eondeletius.
Some of the later authors above mentioned, for example, Eonde-
letius, without proposing any systematic classification of animals, so
arranged those which they described as to indicate the possession
of some idea of their affinities. One of the earliest classifications
in which worms are included is the tabular statement of the
subdivisions of " Insects " given by Aldrovandus at the beginning
of his treatise "De Aniuialibus Insectis "(1602). In this Table
" Insects " are divided into " Terrestria " and " Aquatica," and
each of these is again divided, according to the presence or
absence of feet. Among the Terrestria without feet are Lumbricus
terrestris and worms found in man and animals ; among the
" Aquatica Pedata " are Scolopendra marina and " Vermes in tubulis
delitescentes " [Serpulids] ; in the subdivision " Aquatica apoda " are
Seta aquatica [Gordius], Hirudo paludosa and marina, Lumbricus
marinus, Vermis macrorinclwteros and Vermis microrinchoteros
[Sipimculids described by Eondeletius]. Liber VI — " De Vermibus "
— of the treatise of Aldrovandus deals with the Terrestria Apoda,
including Lumbricus terrestris and parasitic worms, but does not
1 Univ. Aquatil. Hist., pars altera, Lugduni (1555), Liber de Insect, et
Zooph., pp. 108-111.
2 Op. cit., p. 145.
3 Libri de Piscibus Marinis, Lugduni (1554), p. 399.
* Hist. Anim., Liber iiii, Tiguri (1558), pp. 503, 513, 597, 818, 1226, 1227.
B 2
4 Catalogue of Chaetopoda
refer to any of the marine worms above mentioned ; the description
of these is given in the following book, which is headed "De
Aquaticis." A similar practice was followed by a number of sub-
sequent writers, for instance, Eay and Linnaeus, who placed marine
worms among " Insects," and earthworms and parasitic worms in the
class " Vermes."
During the next century and a half there appeared several
memoirs which included studies and figures of worms. Among these,
works by Columna 1 and Bonannus 2 are noteworthy for good figures
of a Serpulid and of a Nereid and its jaws ; Molyneux 3 gave figures
of the external characters and " an account of a not yet described
Scolopendra marina," evidently an Aphrodite; Ellis4 described and
figured tubicolous worms, and Peysounel 6 published " Observations
upon the Sea Scolopeudra," in which he described the external
features and the action of the pharynx of a nereidiform worm.
During this period there were also four works of more outstanding
importance by Willis, Eedi, Eay and Bonnet. In Willis' classical
account 6 of the earthworm the external features, gut, circulatory and
reproductive systems are described, and minutiae, such as chaetae,
dorsal pores, etc., are discussed. Eedi 7 described and figured
portions of the anatomy of Hirudo and Lumbrieus terrestris, he noted
the occurrence of different species of earthworms, figured Scolopendra
marina [a nereid] and its alimentary canal, gave descriptions and
figures of Hystrix marina [Aphrodite] and its alimentary canal, and
two figures of a Serpulid. Eay in his " Historia Insectorum " (1710)
divided " Insects " into those which undergo metamorphosis and
those which do not. The latter were subdivided into " Apoda " and
" Pedata." Among the " Apoda Terrestria " were placed Lumbrici
terrestres (of which Eay distinguished four kinds), and some parasitic
worms — " Lumbrici intestinorum " ; among the "Apoda Aquatica"
were ranged the Hirudines. The " Pedata " were classified according
to the number of feet present — six, eight, fourteen or many. Those
1 Aquat. et Terr, aliquot Anim., pp. xxi, xxii, in Minus Cogn. Stirp., Roma
(1616).
2 Recreatio Mentis et Oculi, in Obs. Anim. Test., Romae (1684), pars i,
cap. v, p. 30, tab. ii.
3 Phil. Trans. R. Soc. Lend., xix (1695), p. 405.
4 Nat. Hist, of Corallines, London (1755), p. 90, pi. 36, " Tubularia
arenosa Anglica" [Sabellaria] ; p. 92, pi. 34, " Corallina tubularia melitensis"
[a Sabellid] .
8 Phil. Trans. R. Soc. Lond., li (1759), p. 35.
6 De Anima Brutorum, Londini (1672), p. 47.
7 De Animalculis vivis. Ex Etruscis Latinas fee. P. Costae, Amstelae-
darai (1708). [1st Edit. 1684.]
Historical
with many feet — the " Polypoda " — were divided into "-TeVrestria "
and " Aquatica " ; the section " Terrestria " comprised Julus and
Scolopendra, while the " Aquatica " included " Lugs " and Scolopendra
marina. This classification of the ametabolous " Insects " followed,
in part, that of Aldrovandus ; the extensions were due to Eay's friend
Francis Willughby. Bonnet 1 instituted an extensive series of
experiments and observations on Naids, with special reference to the
regeneration following removal of the anterior and posterior ends.
A preliminary account of these researches was given in letters to
Sir Hans Sloane,2 in which also remarks were made on similar
studies on regeneration in earthworms.
The first edition of Linnaeus' " Systema Naturae " (1735) marks
no advance on previous knowledge as regards worms ; the only
marine worm mentioned therein is Scolopendra marina, which is
placed in the class Insecta. Among the " Vermes Eeptilia " (the
class being divided into Eeptilia, Testacea and Zoophyta) are Gordius,
Taenia, Lumbricus (including Intestinum terrae, L. latus, Ascaris),
Hirudo and Limax. In the sixth edition of the " Systema " (1748)
the genera of " Vermes Eeptilia " are Gordius, Ascaris, Lumbricus,
Taenia, Fasciola, Hirudo, and, included among the "Vermes
Zoophyta," are the genera AmpJiitritc, Nereis 3 and Aphrodita.
Amphitrite is not mentioned in the tenth or twelfth editions ; the
reappearance of this name in the thirteenth (Gnielin's) edition is due
to the fact that Miiller had, in the interval between the twelfth and
thirteenth editions, founded a genus of worms with this designation.
In the tenth edition of the Systema (1758), which is now regarded
as the foundation of zoological nomenclature, Linnaeus included the
genera Lumbricus (including the species terrestris and marinus),
Hirudo, Aphrodita, Nereis and Serpula, the species of which together
number more than forty; in the twelfth edition (1767) Terebella
and Sabella (and Sipunculus) were added to the list. The names
Lumbricus and Hirudo had been in use since the time of Pliny,
though the former, as defined in the tenth edition, has a much
less extensive significance than it bore in pre-Linnaean writings
(see p. 2) ; the other generic names appear to have been used for
the first time by Linnaeus.
In the tenth and twelfth editions of the "Systema," Linnaeus
divided animals into six classes — Mammalia, Aves, Amphibia, Pisces,
1 Traite d'Insectologie, 2 Partie, Paris (1745).
2 Phil. Trans. R. Soc. Lond., xlii (1743), pp. 468-487.
3 Under which Scolopendra marina is given as a synonym.
6 Catalogue of Chaetopoda
Insecta and Vermes — distinguished by the number of chambers in
the heart and the nature of the blood, the first two classes with
"sanguine calido, rubro," the third and fourth " sanguine frigido,
rubro " and the last two " sanie frigida, albida." Insects were distin-
guished by the possession of antennae, Vermes by having " tentacula."
It follows from this mode of classification that any invertebrate not
having antennae, and therefore not referable to the class Insecta,1
would fall into the class Vermes, which therefore necessarily became
a very heterogeneous assembly. In the twelfth edition (1766-8),
which was the last revised by Linnaeus, the class Vermes was
subdivided into seven orders — Tardigrada, Irnperfecta, Intestina,
Mollusca, Testacea, Lithophyta and Zoophyta — only three of which
need be considered in this account. The genera were arranged under
these three orders in the following manner : —
VERMES INTESTINA, terrena quondam dicta, ob sumrnam simplicitatem
corporis, terebrant omnia. Animalia simplicia, absque artubus, nuda. Lum-
bricus, Sipunculus, Fasciola, Gordius, Ascaris, Hirudo, Myxine.
VERMES MOLLUSCA, nuda, brachiata, vagantur pleraque per maria, ....
Animalia simplicia, nuda (absque Testa inhabitata) artubus instructa. Actinia,
Ascidia, Limax, Aplysia, Doris, Tethis, Holothuria, Terebella, Triton, Sepia,
Clio, Lernaea, Scyllaea, Aphrodita, Nereis, Medusa, Asterias, Echinus.
VERMES TESTACEA, mollusca, domiporta, calcareaque domuncula nobilitata
.... Animalia Mollusca simplicia, domo, saepius calcarea, propria obtecta.
Chiton, Lepas, Pholas, Mya, Solen, Tellina, Cardium, Mactra, Donax, Venus,
Spondylus, Chama, Area, Ostrea, Anomia, Mytilus, Pinna, Argonauta,
Nautilus, Conus, Cypraea, Bulla, Voluta, Buccinum, Strombus, Murex,
Trochus, Turbo, Helix, Nerita, Haliotis, Patella, Dentalium, Serpula, Teredo,
Sabella.
It is evident from this commingling of worms and members of
other phyla that the work of previous naturalists and his own obser-
vations were not sufficient to indicate clearly to Linnaeus the
characteristic features of the worms which we now group together as
Annelids, the seven genera of which he placed in three different
classes, or even to enable him to separate worms from Mollusca and
Echinoderma. Linnaeus had, however, sonvj conception of the
affinities of both Serpula and Sabella, for, after ihe name of the
former genus he added "Animal Terebella" .and after the name of
the genus Sabella "Animal Nereis" (12th edition, pp. 1264, 1268),
and under the species Sabella alveolata he stated " Genus hoc multa
habet comnumia cum Nereidibus sed & os & tentacula oris diver-
1 In both the tenth and twelfth editions of the " Systema " (pp. 639, 1064,
respectively), Linnaeus placed Scolopendra marina in the class Insecta. In
the twelfth edition he stated that this animal was used as bait for herrings.
There can be no doubt that one or more species of Nereis were thus indicated.
Historical 7
sissmia ; " But the presence of the "test" evidently out-
weighed these many common characters, so that Scibella, was not
placed near Nereis but among the shelled Mollusca.
Gmelin, in his (the thirteenth) edition of the "Systema" (1788),
made no advance in regard to the separation of Worms from Mollusca.
The only changes from the twelfth edition which call for comment
here are — (1) the addition to the Venues Mollusca of the genera
Amphitrite Miiller, Spio Fabricius, and Nais Miiller ; and (2) the
removal of the species Scolopendra marina from the Insecta, and its
reduction to a synonym under Nereis versicolor and noctiluca. Gmelin
seems to have taken practically no notice of the suggestive work of
Pallas on Serpula (vide infra), for he still retained this worm among
the shelled Mollusca placed in the Venues Testacea, and did not
adopt the improved arrangement of some of the worms suggested by
Miiller (see p. 8).
The stimulus given to the systematic study of animals by the
appearance of the " Systema Naturae " soon produced a marked
effect on the growth of knowledge in regard to the class of Vermes.
Observations on worms, in some cases accompanied by fairly adequate
descriptions of their characters, appear* i .n treatises of natural
history, in records of travel and in fan in ic works, and there were
also accounts or memoirs published ou single genera or species.
Seba * figured Milleptda marina [two aereidiform worms], Eruca scu
Scolopendra marina [Aphrodite], Pem<-ai-i.//i marinum [a Sabellid]
and a cluster of slender worm tubes. Baster2 prepared a series
of plates with good figures of the external characters of Nereids,
" Scolopendrae plumosae " [Sabellids], Serpulae [including a frag-
ment of a Lanice and its tube], " Hirudo piscium" [Pontobdella],
Aphrodita aculeata, A. squamata [a Polynoid] and Nereis pelagica ;
in the case of the last three some details of the feet were given.
Pennant's " British Zoology " (vol. IV, 1777) contains figures of
Lumbricus marinus, t^restris and minor, leeches, a Sipunculid,
Aphroditidae and Polynoids, Nereids and the tubes of Serpula and
Spirorbis.
Pallas 3 published in 1776 an account of his admirable researches
on the anatomy, both external and internal, of Aphrodita [including
under this name Aphrodite, Polynoids and Amphinomids?], Nereis
1 Locupl. Eerum Nat. Thes. i, Amstelaedami (1734), tab. Ixxxi, 7, 8 :
tab. xc, 1-3 ; iii (1758), tab. iv, 7, 8: tab. xvi, ?A, 7u: tab. c. 8.
2 Op. Subseciva, i, Harlemi (1759-60), tab. iv, v, ix, x ; ii (1765), tab. vi.
3 Miscell. Zool., Hagae Comitium (1766), tab. vii-xi.
8 Catalogue of Chaetopoda
cylindraria [Pectinaria], Nereis conchilega \Lanicc\, Nereis lutaria
[a Sabellid], Serpula, and Lumbricus echiurus \Echiurus\, and in
1788 there appeared a further series of his studies x on various
" Nereis" including " Nereis lumbricoides " [Arenicola marina], and
some tubicolous worms [including Spirorbis].
Up to the time of Pallas, and, indeed, for a considerable period
subsequently, the tubes of Serpula were described and figured in
works on conchology 2 along with the more loosely coiled gastropod
shells ; but Pallas showed in his earlier paper 3 that the shell of
Serpula is different from that of the true Testacea, that Serpula
agrees fundamentally in structure with Nereis and Aphrodite, with
which it should be united to form an order, in which should also be
placed the genera Lumbricus, Hirudo, Ascaris, Gordius, and even
Taenia. Pallas was thus the first to recognise some of the essential
differences between worms and molluscs.
Otto Friedrich Miiller 4 and Otto Fabricius 5 successfully
elaborated the systematic details regarding worms of various kinds,
devoting much care to the distinction and definition of genera and
species. Miiller founded the genera Amphitrite and Nais, and did
much to clarify the diagnoses of previously established genera of
worms. His classification of the Vermes (1776) — the class having
the limits defined by Linnaeus — is well worthy of notice. He
divided the class as follows : —
1. Infusoria [animals living in infusions] .
2. Helminthica.
3. Mollusca [similar to the order Mollusca of Linnaeus, except that the
genera Aphrodita and Nereis were transferred to the division
Helminthica] .
4. Testacea [corresponding to the Testacea of Linnaeus] .
5. Cellularia [corresponding to the Lithophyta and Zoophyta of Linnaeus] .
The Helminthica found in Denmark and Norway were subdivided into two
groups : I. Mutica, containing Gordius, Ascaris, Echinorhynchus,
Hirudo, Taenia ; II. Setosa, containing Lumbricus, Nereis, Amphi-
trite, Nais, Aphrodita.
This classification marks a distinct advance on that of Linnaeus,
showing good progress in the direction of a separation of worms and
molluscs. Muller's order Helminthica contains worms only. There
1 Nova Acta Acad. Sci. Imper. ii, 1784, Petropoli (1788).
2 See, for instance, d'Argenville's Conchyliologie, Paris, 3 Edit., vi (1780),
tab. Ixviii.
3 Op. cit. (1766), p. 74.
4 Vermium Terr, et Fluv., Havniae, i (1773), pars i : pars altera (1774) ;
Zool. Dan. Prodr. (1776).
5 Fauna Groenlandise, Hafniae (1780).
Historical 9
are, however, three worms not included with the rest, namely,
Fasciola L., the newly denned genus Flanaria Miiller, and Serpula
L. ; but it must be admitted that, taking into account the state of
knowledge at that time, these three were difficult genera to place
correctly in the scheme of classification. Miiller referred Fasciola
and Planaria to the Mollusca, and Serpula to the Testacea. He does
not appear to have known the work of Pallas 011 Serpula ; at any
rate, he did not refer to it in his synonymy. Miiller was the first to
use the presence of chaetae as the distinguishing character of a group
of worms.
Blunaenbach1 pointed out that Vermes differ from Insecta not
only in the absence of antennae but also of jointed locomotor organs.
He was the first to state and emphasise this fundamental difference
between the jointed appendages of " Insecta " [i.e. Arthropoda] and
the feet of worms. His classification closely follows that of
Linnaeus.
Barbut,2 Bruguiere3 and others, produced systematic memoirs
based largely on the Linnaean system and reproducing many of
its errors. The majority of treatises on natural history published
during the last third of the eighteenth century held tenaciously
to the Linnaean classification of the Vermes, and in the hands
of most workers this class was still in the same unsatisfactory
condition as it had been left by Linnaeus. The work of Pallas on
Serpula and the outline classification given by Miiller were the first
indications of the dawn of order, which, in the closing years of the
eighteenth century, broke upon the chaotic assemblage of Vermes.
In 1795 Cuvier communicated - to the Societe d'Histoire naturelle of
Paris a memoir 4 on the circulation in " animaux a sang blanc," in
which he described the heart and blood-vessels of various molluscs,
and also gave a Table showing the nature of these organs in various
classes of animals. The work done in preparation for this memoir
brought clearly before him the characters which distinguish worms
from molluscs, and from this time forwards Cuvier separated these
two classes of animals. In his next memoir — " Tableau elementaire
de 1'histoire naturelle des animaux " (Paris, An 6, = 1*798) — the two
1 Handb. der Naturg., Gottingen (1799), 6 Aufl., p. 401. [1st Edit., 1779.]
2 Genera Vermium, London (1783).
3 Hist. nat. des Vers in Encyclop. method., Paris (1791). Bruguiere
established a new order in the class Vermes — Vers Echinodermes — to contain
the star-fishes, sea-urchins, etc. The other Vermes were left in the same
arrangement as in the Systema.
4 Bull, des Sci. par la Soc. Philom., Paris, i, An iii [1795] , p. 91.
10 Catalogue of Chaetopoda
classes, Mollusques (p. o72) and Vers (p. 624), are defined and
described in some detail, and the " Vers " arranged thus : —
A.. Vers pourvus d'epines ou de soies pour s'aider dans leur mouveinens : —
Les Aphrodites. Les Serpules. Les Nereides.
Les Amphinomes. L'Arrosoir.1 Les Naiades.
Les Amphitrites. Les Dentales. Les Lombrics.
La Furie.-
B. Vers depourvus d'epines et de soies : —
Les Sangsues. Les Planaires. Les Vers intestins.
A comparison of this Table with that of Linnaeus published
thirty years previously demonstrates the great advance made in the
classification of worms. "While much of the credit for this is
undoubtedly due to Cuvier, it is also clear that the observations of
Pallas and Miiller were important contributing factors; it will be
observed that Serpula is placed near Aphrodita, as recommended by
Pallas, and that Cuvier, following Miiller, used the presence of
chaetae as a distinguishing character for one of his subdivisions. The
Table presents two defects, namely, the inclusion of Les Dentales
[Dentaliuni] and of L'Arrosoir \Brechitcs or Aspergillurni\, but it
should be remembered that only the shell of the latter was then
known, and that both these are strikingly different in appearance
from most Mollusca, the former in particular presenting such a
combination of characters that it was not until Lacaze Duthiers
(1857) had carefully investigated its anatomy that its systematic
position could be safely defined, and then it was found necessary to
establish a separate class to receive it.
In his " Lecons d' Anatomic Comparee," published two years later,
Cuvier separated worms into two series, according as they possess or
lack external organs of respiration.3 This mode of classification was
adopted by Lamarck in his " Systeine des Animaux sans Vertebres "
1 This was first referred to the genus Serpula (8. penis) by Linnaeus ; it was
retained in this genus by Cuvier (Regne Animal, p. 522) and others.
• A genus established by Linnaeus for a creature named Furia infernalis L.,
said to be found in Eastern Sweden, and described as having a linear, filiform
body, provided on each side with a row of pointed hairs. This animal, on
coming in contact with mammals or the naked skin of man, was stated to enter
the flesh, causing death if treatment were not immediately available. As Bosc
remarked (Nouv. Diet. d'Hist. Nat., Paris, An xi [1803], ix, p. 144), it was
probably a creature of the imagination, and it is doubtful whether the dried
specimen of an animal shown to Linnaeus, by an inhabitant of the country, had
any connection with the attacks described. At any rate, Furia could not have
been a Chaetopod ; it may have been a dipterous larva, some of which produce
severe myiasis.
3 See Table at end of Tome i '(1805).
Historical 1 1
(1801). He removed Les Arrosoirs to the Mollusca, but was evidently
not certain (p. 98) that this was a correct procedure, and added the
new genera Arenicola and SpirorMs. His arrangement of the worms
is tabulated thus : —
1" Ordre. Vers exterieurs (ou externes).
I. — Corps muni d'organes exterieurs.
A. Ceux qui ont des branchies externes . . . . ,
Nereis, Aphrodita, Ampliinome, Arenicola, Terebella, Amphitrite,
Serpula, SpirorHs, Dentalium.
B. Ceux qui sont depourvus de branchies externes,
Furia, Nais, Lumbricus, Thalassema.
II. — Corps depourvu d'organes exterieurs —
Gordius, Hirudo, Planaria.
2me Ordre. Vers intestins —
Fasciola, etc.
Bosc, in his "Histoire Naturelle des Vers" (1802), arranged the
genera of worms with external organs (i.e. those in Section I. above)
in two subdivisions, according as they aro nude or live in tubes. In
the former division he placed Aphrodita, Amphinome, Arenicola,
Nais, Lumbricus and Thalassema. This was the first time that the
presence of a tube had been brought into use as the character of a
subdivision.
In 1802 Cuvier * stated that he thought it could be shown that
all Lombrics, Sangsues, Nayades, Nereides, Aphrodites, Arnphitrites
and Serpules have red blood, and, though he had not examined the
Amphiuomes and the rest of the articulate non-intestinal worms, he
believed that they would also prove to possess red blood.2 He gave
an account of the vascular system of Arenicola, and pointed out, in
conclusion, that the possession of red blood by the " Vers articules "
is a very striking character by which they can be distinguished from
the intestinal worms.
To this class of segmented worms with red blood, Lamarck, in his
course of zoology in 1802, gave the name Annelides,3 but it was not
until some years had passed that the name found general acceptance.
Cuvier, in his " Eegne Animal " (1817), divided the Annelides
1 Bull. Sci. Soc. Philom., Paris, An x [1802] , No. 64.
2 Others remarked that. not all Annelids have red blood, e.g. Blainville
pointed out that in Aphrodite the blood is yellow. Nevertheless, the state-
ment of Cuvier may be taken as generally holding good.
3 Disc, d'ouverture, 27 floreal, An x, Mus. d'Hist. Nat., Paris. " La
nouvelle classe des Annelides." See reprint of the discourse in Bull. Sci.
Franc. Belg. xl (1907), p. 56.
12
into three orders 1 — Tubicoles, Dorsibranches and Abranches — using
the respiratory organs as the principal distinguishing character. In
the Tubicoles the gills are anterior, while in the Dorsibranches they
are situated along the sides of the middle part of the body. Cuvier
further stated that the genera of the first two orders have bundles of
chaetae along their sides, serving as feet ; but some genera of the
third order do not possess these. He arranged the genera in their
orders thus : —
I. — Lea Tubicoles. II. — Les Dorsibranches III. — Les Abranches.
Les Serpules. Les Nereides. Les Lombrics.
Les Sabelles. Les Eunices. Les Thalassemes.
Les Terebelles. Les Spio. Les Naides.
Les Amphitrites. Les Aphrodites. Les Sangsues.
Les Arrosoirs. Les Amphinornes. Les Dragonneaux.2
Les Dentales. Les Arenicoles.
Les Siliquaires.
Lamarck 3 (1818) developed the basis of classification. Reused
additional morphological characters4 in subdividing the Annelids
into three orders, in which he arranged the genera into families,
disposed as shown below : —
Apodes.' Antenn6es.'; Se"dentaires.7
Les Hirudinees. Les Aphrodites. Les Dorsalees (Arenicole,
Les Echiur^es. Les Nereidees. Siliquaire).
Lombric. Les Eunices. Les Maldanies (Clyinene,
Thalasseme. Les Amphinomes. Dentale).
Cirratule. Les Amphitrites.
Les Serpulees.
Savigny 8 adopted practically the same morphological characters 9
as aids to classification, but attached primary importance to the
presence or absence of chaetae. He formed four orders by grouping
the Annelids around four central genera, which gave their names to
1 Retained in new edition, iii (1830), and in " Edit, de Disc."
2 Gordius.
3 Hist. Anim. sans Vert., v, 286.
4 Probably the introduction of these characters, especially the nature of the
chaetae, should be credited to Savigny, who in May 1817 had presented to the
Academic des Sciences an account of his researches on the classification of
Annelids, and in July of the same year the first part of his classical memoir,
which was not published until 1820.
5 No feet ; no feelers ; respiratory structures, if any, internal,
6 Definition as under Nereideae of Savigny (see p. 13).
7 Definition as under Serpuleae of Savigny (see p. 13).
8 Syst. des Annel. (1820), p. 5.
9 See footnote (*) above.
Historical 13
the orders. The orders were thus defined : (1) Nereideae — feet with
retractile subulate chaetae but without crotchets, a distinct head with
eyes and feelers, and a protrusible proboscis almost always armed
with jaws; (2) Serpuleae — feet with retractile subulate chaetae and
crotchets, head without eyes or feelers, proboscis not armed with
jaws ; (3) Lumbricinae — without projecting feet and with chaetae
rarely retractile, head without eyes or feelers, and without jaws ;
(4) Hirudineae — without locomotor chaetae, characterised by the
presence of a sucker at each extremity and by having eyes. The
families were arranged in the orders thus : —
I. With chaetae for locomotion.
1. Order Nereideae. Families — Aphroditae, Nereides, Eunicae, Am-
phinomae.
2. Order Serpuleae.
(1) Gills none or few ; if present situated on the anterior segments
of the body ; feet of several kinds.
Families — Amphitritae, Maldaniae.
(2) Gills numerous, not on the anterior segments of the body ; feet
of one kind.
Family — Telethusae.
3. Order Lumbricinae. Families— Echiuri, Lumbrici.
II. Without chaetae.
4. Order Hirvidineae. Family — Hirudines.
This is the first list of Annelids published from which all
Mollusca are excluded.1 It is also of interest from our special point
of view, as the family Telethusae was formed for the reception of the
single genus Arenicola.
Savigny's classification is more natural than any of its pre-
decessors, as it is based not on a single feature, but on a group
of characters. More than forty years afterwards Prof. Ehlers con-
sidered it to be so excellent that he adopted it, with only a slight
change, in his monograph on " Die Borstenwurmer," and the
classification in use at the present day is based on an extension of
the principles of Savigny's system. In addition to his fundamental
improvement of the classification of Annelids, Savigny also carefully
delimited the known genera and -founded more than a score of new
ones, most of which remain valid.
Latreille2 adopted Cuvier's classification in a modified form,
1 Savigny observed that Dentalium was not an Annelid, and he also
excluded L'Arrosoir and Siliquaria.
2 Families nat. Begne Anim., Paris (1825).
14 Catalogue of Chaetopoda
the principal change being the formation of an order for the family
Telethuses. His arrangement may be tabulated thus : —
I. Anterior extremity of body usually provided with feelers and tentacles ;
almost all have feet, and the gills are external.
1. Notobranches. 2. Cephalobranches. o. Me"sobranches.
Aphroditees. Serpulees. Telethuses.
Eunicees. Sabellees.
Nereidees. Amphitritees.
Solenicoles.1 Oecodontes.2
Amphinomees.
II. No head or antennae, the majority have no feet, organs of respiration
internal ; live in fresh water or earth, some are parasites.
4. Enterobranches.
Maldanies. Lombricines. Filiformes.3 Hirudinees.
This classification shows in a striking manner how a too exclusive
use of one character, namely the gills, brings together forms which
are really not related. For instance, Latreille placed under the
Mesobranches, in the family Telethuses, the genera Arenicola and
Brancliellion, although he remarked that the latter genus appeared
to belong to the Hirudinees, but he was so obsessed with the value
of the branchiae as a character, that the presence of gill-like out-
growths along the middle region of Branchcllion outweighed all its
other characters. The association of the Maldanies with the earth-
worms was another mistake of the same kind. The re-introduction
of some Mollusca and of Gordius among the Annelids was also a
retrograde step. Altogether, therefore, the classification of Latreille
marked no advance in knowledge, but tended to confusion.
In 1816 Blainville4 published a classification of the animal
kingdom, in which the seventh and eighth classes of articulate
animals were designated respectively Setipodes and Apodes, the former
comprising worms with, and the latter worms without chaetae. The
class "Apodes" included " Entozoaires " and leeches, which latter
were thus separated from the rest of the ringed worms ; this class
need not be further considered here. The Setipodes were divided
into three orders, according as the rings of the body were markedly
dissimilar, slightly dissimilar or similar. In 1828 Blainville 5 re-
1 For the genus Spio.
2 Contains the genera Dentalium and Siliquaria.
3 For the genus Gordius.
4 Bull. Sci. Soc. Philomath., Paris (1816), p. 105.
5 " Vers," in Diet. Sci. Nat., Ivii, Paris (1828). In this later classification
the subdivision " Apodes " includes also Sipunculids.
Historical 1 5
published this classification with a set of new designations for the
principal subdivisions, but of all the terms used in his two memoirs
only one has survived to the present day ; the rest had a very short
existence. In his later paper he modified the hybrid term Setipodes
into the more correct Chetopodes. The families were arranged in
the order thus : —
Chetopodes. Heterocriciens. Serpulides, Sabulaires.
Paromocriciens. Maldanies, Telethuses.
Homocriciens. Amphinornes, Aphrodites, Nereides, Nerei-
scoles, Lombricines, ilchiurides.
The chief point of interest in this classification is the clear
principle involved in the definite formation and designation of the
great division Chetopodes. This division had been foreshadowed by
Miiller ; and Cuvier, Lamarck and Savigny had recognised, to a
greater or less degree, the importance of the chaetae as a divisional
character, but it was left to Blainville to name the division. The
name Chaetopoda has persisted up to the present day, for, in spite of
certain disadvantages which it involves, such as the wide separation
of earthworms and leeches, it has been found convenient as a descrip-
tive term to designate all those Annelids in which the lateral series
of chaetae form a conspicuous feature, by means of which these worms
can, with few exceptions, be readily distinguished from all other
animals.
The grouping together of the Maldanies and Telethuses in the
order Paromocriciens is noteworthy. Blainville attached less value
than most of his contemporaries to the presence or absence of gills
as a systematic character, and did not hesitate to associate in one
order these two families, although one contains branchiate and the
other abranchiate Annelids, because he found them to agree in the
nature of their chaetae and in the similar segmentation of the body.
In 1829 Audouin and Edwards presented to the Academic des
Sciences their memoir on the classification of Annelids.1 They stated
that they were unable to adopt the classification of either Savigny or
Blaiuville, but the one they presented was, after all, fundamentally
that of Savigny and similar to that of Lamarck. The morphological
characters used by Savigny were again employed, but in addition
the cirri and other soft2 appendages of the body were taken into
account, and thus the limits of the four orders were set forth in
1 Ann. Sci., Nat., xxvii (1832), p. 337; also in Hist. Nat. Litt. France
(1834).
2 That is, soft in contrast to the chaetae.
16 Catalogue of Chaetopoda
greater detail. The Errantes, which are adapted for creeping or
swimming, have well developed soft appendages on almost all the
body segments. This order, the only one fully considered by the
authors, was defined in almost the same terms1 as the Nereideae
(Savigny). The other three orders, named Tubicoles or Sedentaires
(with soft appendages aggregated at the anterior end), Terricoles and
Suceuses, corresponded nearly 2 to the Serpuleae, Lumbricinae and
Hirudiues of Savigny. The authors established seven new genera and
more than a score of new species. The families of the order Errantes
only were given, namely, Aphrodisiens, Amphinomiens, Euniciens,
Nereidiens, Ariciens, Feripatiens, Chetopteriens, Arenicoliens.
The orders Errantes and Tubicoles (Sedentaires) of this classifica-
tion were accepted with little modification by Quatrefages in his
" Histoire naturelle des Anneles " and by Claparede in his " Annelides
chetopodes du golfe de Naples," and consequently were adopted by
nearly all subsequent authors, especially in France and Great Britain,
until almost the close of the last century.
The family Telethuses, founded by Savigny for the genus
Arenicola, was renamed Arenicoliens by Audouin and Milne Edwards,
and this designation, or some modification thereof, recalling that of
the genus, has been generally adopted.
The numerous advances in the study and classification of
Annelids, made from 1795 until 1834, had been almost entirely due
to the labours of the French School, that is, of Cuvier and his
disciples, who have left an enduring mark upon this branch of
zoology. The stimulus given by their work produced responses in
other countries, especially in Britain, Germany and Scandinavia.
Johnston, who drew up a classification of Annelids in 1846,3
interpreted the limits of the class in a wider sense than Cuvier,
Lamarck or Savigny. His classification is fundamentally that of
Savigny, with some modification of the limits of the subdivisions,
and with the addition of the Nemertina, a decidedly retrograde step.
E. Leuckart4 (1848) included the Neniatodes in the "Annelides"
and placed the leeches with the Turbellaria, Trematodes and
Nemertines ; and Quatrefages5 (1850) divided the worms into "Vers
1 Note, however, that Arenicola, was placed in this order, whereas Savigny
included it in the Serpuleae.
2 As is shown by the families referred to these orders by Edwards in his
Elem. de Zool., ii (1834), p. 1016.
3 Ann. Mag. Nat. Hist., xvi, p. 433.
4 Morph. u. Verwandtsch. d. wirbell. Thiere (1848), p. 44.
5 Ann. Sci. Nat. Zool., ser. 3, xiii (1850), p. 7.
Historical 1 7
dioiques," in which he placed " Annelides," and " Vers monoiques,"
which included Lombrines, Hirudinees,1 Turbellaries and Cestoides.
The separation of the earthworms from the rest of the Annelids was
unwarrantable and was not followed to any extent by subsequent
writers.
Grube's masterly paper 2 on the classification of Annelids appeared
in 1850. To him we owe the accurate delimitation of the order
Oligochaeta ; this he defined so as to exclude such worms as Cirra-
tulus, TropJionia, Travisia and some Gephyrea, which, by previous
systematists, had been placed in close association with Luminous.
As a result of his admirable studies on the external features and
internal structure of Annelids, and of the critical acumen which he
brought to bear on the problem, Grube was enabled to define the
limits of this order practically as they stand to-day. He introduced
the useful names Polychaeta and Oligochaeta, now universally used
and recognised, especially the latter, as designating natural assem-
blages of worms. Grube's work ranks, with that of Cuvier and
Savigny, as one of the great classics on this subject, and was
undoubtedly the most important work on the general classification
of Annelids published during the seventy years subsequent to the
appearance of Savigny's monograph. After giving a detailed account
of the structures which he proposed to use in the classification of
Annelids, Grube arranged these worms in five orders, which he
defined thus : —
I. Appendiculata Polychaeta — Annelids which, besides having
lateral bundles of bristles, bear on the dorsuni or on the head region
either lappets, filaments or compound structures; the bristles are
at least eight, and usually many more, in each segment ; these animals
live in the sea and, as far as is known, are of separate sexes. This
order corresponds to the orders Nereideae and Serpuleae of Savigny.
II. Gymnocopa, an order founded to contain the single genus
Tomopteris.
III. Onychophora for the genus Peripatus, which, since the time
of Audouin and Edwards, had been considered to be an Annelid.
1 A considerable number of authors associated the leeches with the flat-
worms; for instance, van Beneden (1850, 1852-54), Burmeister (1856), Haeckel
(1866), Schmarda (1871), O. Schmidt (1872), and Vogt and Yung (1888). But
the studies of the development of leeches, especially of their mesoblast
(Rathke, 1862), showed that they exhibit the fundamental characters of
Annelids, and they were so regarded in the text-books of Gegenbaur, Glaus
and Huxley.
Arch. f. Naturg., xvi Jahrg., i, p. 249.
0
18 Catalogue of Chaetopoda
IV. Oligochaeta — Annelids in which the lateral locomotor organs
consist of two to eight bristles projecting from scarcely recognisable
elevations and not accompanied by cirri, " Lippenblatter " or gills ;
the genital organs are hermaphrodite, paired, and limited to a few
segments ; the majority of these worms live in the earth or in fresh
water, only a few are found in the sea.
V. Discophora, corresponding to the Hirudineae of earlier-
systematists.
The Polychaeta were divided into two sub-orders — Eapacia and
Limivora — according to the mode of feeding ; but, as Grube carefully
pointed out, the members of the two sub-orders differ in many of
their structural characters. The families of Polychaeta were arranged
thus:—
A. Rapacia. B. Limivora.
Aphroditea. Phyllodocea. Opheliacea. Maldania.
Amphinomea. Glycerea. Pherusea. Terebellacea.
Eunicea. Syllidea. Chaetopterea. Hermellacea.
Lycoridea. Amytidea. Telethusa. Serpulacea.
Nephthydea. Ariciea.
In the years 1865, 1866 there appeared three works on Annelids.
In 1865 Johnston's " Catalogue of Non-parasitical worms in the
British Museum " was issued, in which these worms were arranged
in six orders, as follow : —
A. — Apodous : the body without bristles on the sides.
1. Body exannular.
I Order. Turbellaria.1
II Order. Bdellomorpha.2
V Order. Gymnocopa.
2. Body annular.
III Order. Bdellidea.
B. — Polypodous : the body with bristles along the sides.
IV Order. Scoloces. Without external soft appendages ; the segments
with simple spiniform or setaceous bristles, either
single or fasciculate.
VI Order. Annelides. With soft external appendages, and with
various bristles collected into fascicles on a more or
less protuberant basis.
The Annelides were divided into Eapacia and Limivora, in which
tribes the families were arranged as in Grube's classification. The
use of the term Annelides for a subdivision which did not include
1 Included animals now referred to the Turbellaria and Nemertea.
2 Included the genera Octobothrium, Entobdella, Malacobdella, etc.
Historical 1 9
such obviously segmented worms as leeches (Bdellidea) and earth-
worms (Scoloces) was indefensible. The wide separation of Tomopteris
(Gymnocopa) from its relatives is a further defect of the Table, and
there seems no sound reason for the adoption of the term Scoloces
for the Oligochaeta of Grube.
Quatrefages (Hist. nat. des Anneles, 1865) also restricted the
limits of the class Annelides, excluding from it all worms except the
Tubicoles and Dorsibranches (Cuvier) or Errantes (Audouin and
Edwards), so that the class, as he defined it, was equivalent to Grube's
order Polychaeta plus the Tornopterids. Quatrefages' classification of
Annelids depended primarily on the principle laid down by Blainville,
namely, the nature of the segments of the worms. Those Annelids
in which the segments of the body are similar to each other, and in
which, therefore, the body is not divided into distinct regions, were
placed in the order Errantes ; those in which the repetition of parts is
sharply interrupted in one or more places, and in which consequently,
the animal is divisible into distinct regions, were placed in the order
Sedentaires. These orders were equivalent respectively to the Eapacia
and to the Limivora plus Gymnocopa of Grube. The distribution of
the families under these two sub-orders is shown below.
Annelides Errantes Annelides Sedentaires
(A. Erraticae). (A. Sedentariae).
Aphroditiens. Chloremiens. Chetopteriens. Leucodoriens.
Palmyriens. Nereidiens. Tornopteridiens. Hermelliens.
Euniciens. Syllidiens. Clymeniens. Pectinairiens.
Lornbrineriens. Hesioniens. Arenicoliens. Terebelliens.
Amphinomiens. Phyllodociens. Opheliens. Serpuliens.
Nephtydiens. Glyceriens. Ariciens.
Neriniens. Polyophthalmiens.
Cirrhatuliens.
Prof. Ehlers x admitted that the order Oligochaeta, as defined by
Grube, formed a natural assemblage, but was doubtful whether the
order Polychaeta could be so regarded. He preferred the system of
Savigny, which he praised as embodying the soundest principles. He
regarded the three sub-orders Nereideae, Serpuleae and Lumbricinae
(the latter, of course, exclusive of the Echiuroidea) as representing
three essentially different types of Chaetopoda ; but finding that
certain genera could not be properly placed in these orders, Prof.
Ehlers founded a fourth sub-order, Ariciea, intended to contain
genera which had been placed by some authors in the Nereideae and
by others in the Serpuleae. Only the sub-order Nereidea was con-
1 Die Borstenwiirmer, Leipzig (1866), pp. 52-57.
c 2
20
Catalogue of Chaetopoda
sidered; no doubt the genus Arenicola would have been described
under the Ariciea had the work on these lines been continued.
The classification of the Polychaeta followed by most writers from
1865 onwards was that of Audouin and Edwards and of Quatrefages,
that is, the order was subdivided into Errantia and Sedentaria. A
considerable number of writers, no doubt finding difficulty in deciding
whether certain families or genera 1 should be referred to the Errantia
or to the Sedentaria, discarded these sub- orders, and, like Malmgren,
for instance, adopted the plan of placing the families in such
sequence as seemed to them to indicate best their relationships to
each other.
Dr. Levinsen 2 ranged the " Annulata " in three main divisions
— Chaetopoda, Gymnocopa (for Tomopteris) and Discophora (Leeches).
The Chaetopoda were divided into Polychaeta and Oligochaeta.
Dr. Levinsen grouped the families of Polychaeta so as to form
eleven sub-orders, which, however, he did not define. These sub-
orders and their families were arranged thus : —
Phyllodociformia.
(1) P. vera.
Phyllodocidae.
Alciopidae.
(2) Nephthydae.
Euniciformia.
(1) E. vera.
Eunicidae.
Onuphidae.
Lumbrinereidae .
Staurocephalidae .
(2) E. glycerina.
Goniadidae.
Glyceridae.
Maldaniformia.
Maldanidae.
Capitellidae.
Aphroditiformia.
(1) A. vera.
Aphroditidae.
Polynoidae.
Acoetidae.
Sigalionidae.
(2) Palmyridae.
Syllidiformia.
Sternaspiformia.
Sternaspidae.
Amphinomiformia.
(1) A. vera.
A mph inomidae .
Euphrosynidae.
(2) A. arenicolina.
Telethusae.
Scalibregmidae.
(1) 8. vera. (2) S. spionina.
Nereidae. Spionidae.
Hesionidae. Chaetopteridae.
Syllidae. Cirratulidae.
Nerillidae. Ariciidae.
Sphaerodoridae. Chloraemidae (?).
Ophelidae (?).
Ammochariformia. Hermelliformia.
Ammocharidae. Hermellidae.
Terebelliformia.
Terebellidae.
Ampharetidae.
Amphictenidae.
Sabelliformia.
Sabellidae.
Serpulidae.
1 Arenicola, for instance, was placed by some authors in the Errantia, by
others among the Sedentaria. The Ariciidae presented a similar difficulty.
* " Syst.-geog. Overs, nordiske Annulata," etc., in Vid. Medd. naturh. Foren.
Kj0benhavn 1882 (1883), p. 180.
Historical 21
This classification is an extension of Savigny's method — i.e. the
families are grouped around a central type ; they are classified not
by definition but by type, not by precept but by example. Although
this arrangement presents certain advantages over any previous
classification, it does not by any means solve the difficulties which
arise when the attempt is made to group the families of Polychaeta ;
see, for instance, the assemblage of divergent forms brought together
under the group Syllidiformia spionina. The close relationship of
the Arenicolidae and Scalibregmidae is well represented in this classi-
fication, but the association of these families with the Amphinomidae
does not appear to be justified by any community of structure.
During the ten years following the publication of Dr. Levinsen's
memoir no marked changes were introduced into the mode of
classification of Polychaeta ; most writers during this period adopted
the subdivisions Errantia and Sedentaria, others considered the
families separately in such order as each author thought best.
In 1893 Prof. Hatschek and in 1894 (and 1896) Prof. Benharn
suggested new classifications of the Polychaeta. Prof. Benham's
classification,1 which combines, to some extent, the systems of
Quatrefages and Levinsen, divides the Polychaeta into two grades
or branches — (a) the Eucephala, later2 named Phanerocephala, in
which the prostomium retains its original condition as a lobe over-
hanging the mouth and is not overgrown by the peristomium ; the
body-segments are similar so that the body is not divided into
regions; (b) the Cryptocephala, in which the peristomium grows
forwards and fuses with or entirely conceals the greatly reduced
prostomium ; the body-segments are differentiated into two regions
by a sudden change in -the character and arrangement of the chaetae,
and also by certain internal differences. The arrangement (1896) of
the families in the sub- orders is shown in the following Table : —
A. PHANEROCEPHALA.
Nereidiformia.
Syllidae. Amphinomidae.
Hesionidae. Eunicidae.
Aphroditidae. Glyceridae.
Phyllodocidae. Sphaerodoridae.
Tomopteridae. Ariciidae.
Nereidae. Typhloscolecidae.
Nephthydidae.
1 Kep. Brit. Assoc. (1894), p. 696.
* Cambr. Nat. Hist., vol. ii (1896), p. 258.
22 Catalogue of Chaetopoda
A. PHAJSTEROCEPHALA (continued).
Spioniformia. Capitelliformia.
Spionidae. Capitellidae.
Polydoridae.
Chaetopteridae. Scoleciformia.
Magelonidae. Opheliidae.
Ammochandae. Maldanidae.
Arenicolidae.
Terebelliformia. Scalibregmidae.
Cirratulidae. Chlorhaemidae.
Terebellidae. Sternaspidae.
Ampharetidae.
Amphictenidae.
B. CRYPTO CEPH ALA.
Sabelliformia. Hermelliformia.
Sabellidae. Hermellidae.
Eriographidae.
Amphicorinidae.
Serpulidae.
Although this classification has many good points it is not
without defects; for instance, the great sub-order Nereidiformia,
which contains about half the number of families and of genera
of Polychaeta, is rather unwieldly, and not entirely homogeneous.
The families Maldanidae, Arenicolidae and Scalibregmidae, and pos-
sibly the Opheliidae, contain series of more or less closely related
worms ; associated with these, in the sub-order Scoleciformia, are the
Chlorhaemidae and Sternaspidae, which stand considerably apart
from the preceding quartette ; but if the two latter families are not
included in the Scoleciformia they cannot be referred to any other
sub-order, and the formation of one or two new sub-orders would be
required for their reception.
In Prof. Hatschek's classification 1 the Polychaeta are separated
into two main subdivisions — namely, the Cirrifera — those in which
parapodial cirri are present, and in which the homonomy of the
segments is little disturbed — and Acirra — which are without clearly
marked parapodial cirri and in which heteronomy of the external
and internal structures indicates a division into regions. This
classification may be tabulated thus —
A.— CIRRIFERA.
1. Spiomorpha.
Spionidae. Appendices : Chaetopteridae.
Ariciidae. Pherusidae.
Opheliidae.
1 Lotos, xiii (1893), p. 123.
Historical 23
2. Amphinomorpha.
Amphinomidae.
3. Bapacia (Nereimorpha).
Glyceridae. Syllidae.
Nephthydidae. Phyllodocidae.
Eunicidae. Sub-fam. Phyllodocinae.
Aphroditidae. Alciopinae.
Stephanidae. Hydrophaninae.
Nereidae. Tomopterinae.
Hesionidae. Appendix: Myzostomidae.
B.— ACIRRA.
4. Drilomorpha.
Cirratulidae. Appendices : Sternaspidae.
Arenicolidae. Ctenodrilidae.
Capitellidae.
Maldanidae (incl. Ammocharidae).
5. Terebellomorpha.
Amphictenid ae .
Terebellidae.
6. Serpulimorpha.
Hermellidae.
Serpulidae.
The above arrangement, with a few slight alterations, was adopted
by Profs. Glaus and Grobben,1 who, however, did not employ the
division into Cirrifera and Acirra, a change for which there is full
justification. They divided the Polychaeta directly into six sub-
orders, similar in constitution to those defined by Prof. Hatschek,
except that the Opheliidae were removed from the Spiomorpha to
the Drilomorpha. This classification presents defects, similar to
those associated with Prof. Benham's arrangement, in regard to the
great size of the sub<-order Bapacia and the heterogeneous contents
of the sub-order Drilomorpha. Further, there seems to be little
warrant for the inclusion of the Pherusidae (Chlorhaeniidae) in the
sub-order Spiomorpha.
SUMMARY. — The systems of classification of the Polychaeta, which
have been, suggested and have met with acceptance during the last
hundred years, may now be summarised and the position of the
family Arenicolidae (or Telethusae) indicated in each.
I. Cuvier (1817) distinguished two orders of marine worms — Les
Tubicoles and Les Dorsibrancb.es — by the position of the gills, which
in the former are massed at the anterior end, while in the latter they
are distributed along the body, as, for instance, in Arenicola. This
1 Lehrb. d. Zool., Marburg (1905).
24 Catalogue of Chaetopoda
principle of classification was maintained, especially during the twenty
years subsequent to its enunciation, by a number of writers who
placed the family Telethusae in an order designated Dorsibranches,
Notobranchia or Mesobranches.
II. Savigny (1820) divided marine worms, according to the charac-
ters of the chaetae, head and proboscis, into two orders — Nereideae
and Serpuleae, to the latter of which the family Telethusae was
referred. The principles of classification laid down by Savigny were
adopted and extended by later workers, few of whom, however
retained the original ordinal names.
III. Orders of similar constitution to those of Savigny were pro-
posed by Lamarck (1818) and named Antenne'es and Sedentaires,
and by Audouin and Edwards (1832), who separated the Errantes
from the Sedentaires by their mode of life. This classification was
adopted by Quatrefages (1865), and the ordinal names Errantia and
Sedentaria were in general use during the next thirty years. Audouin
and Edwards placed Arenicola in the order Errantes, but Lamarck,
Quatrefages and most other writers have referred it to the Sedentaria.
IV. Grube (1850) used the mode of feeding, and certain mor-
phological characters, as a means of separating the Polychaeta into
two sub-orders — Eapacia and Limivora, to the latter of which
Arenicola was referred. This system of classification was adopted by
Johnston (1865) and others.
V. The systems of Profs. Benham and Hatschek are based on
anatomical characters, and divide the Polychaeta into six or seven
sub-orders. The family Arenicolidae is placed in the sub-order
Scoleciformia (Benham), which is similar to the sub-order Drilo-
morpha (Hatschek), the chief features of which may be stated thus —
the prostomium1 seldom bears sensory processes, the peristomium2 has
no cirri, the parapodia 3 are feebly developed and may be absent, cirri 4
are usually wanting, true uncini 5 are not present, the buccal region
and pharynx are eversible and there are no jaws, some or many of
the septa are wanting, and the nephridia are reduced to a compara-
tively few pairs, which are all alike.
1 The anterior portion of the head, namely, that part which is pre-oral ;
equivalent to the " head-lobe," or " Kopflappen " (Grube) of some earlier writers.
The posterior portion of the head, immediately following the prostomium,
and bearing the mouth.
3 Paired, unjointed, lateral outgrowths of the body wall in each body-
segment, bearing chaetae and serving as organs of locomotion.
4 Filamentous sensory processes.
5 Chaetae in the form of short and sharply curved hooks, characteristic
especially of Terebelliformia and Sabelliformia.
A renicolidae 2 5
It is evident from the preceding pages that the Polychaeta form
is art order difficult to classify, and it must be admitted that none of
the classifications hitherto proposed surmounts the many difficulties
involved. It will therefore be preferable, in the present state of the
subject, to adopt the method of most recent workers on Polychaeta,
that is, to consider the families separately, and in such order as
convenience directs. The families placed in the sub-order Scoleci-
formia seem especially to call for reconsideration ; but, until further
information is available with regard to some of them, particularly
the Chlorhaemidae and Opheliidae, nothing definite in the way of a
change of the constitution of the sub-order can be made. The
present Catalogue will place the knowledge of one of the families on
a broader basis and provide material which may be used in discussing
the affinities of this with other families of the sub-order.
AEENICOLIDAE Johnston, 1835.
Telethusae —
Savigny, Syst. Annel. (1820), p. 95.
Johnston, Catal. Worms Brit. Mus. (1865), p. 226.
Levinsen, Vid. Medd. Naturh. Foren. Kjobenhavn (1833), p. 133.
Telethusae, partim —
Latreille, Fam. nat. Begne Aniru. (1825), p. 244.
Telethusa, partim —
Danielssen, K. Norske Vid. Selsk. Skr., iv (1859), p. 121.
Grube, Arch. Naturg., xvi Jahrg., i (1850), p. 322.
Schmarda, Neue wirbell. Thiere, i, 2 Half. (1861), p. 51.
Thelethusidae —
Cunningham and Ramage, Trans. B. Soc. Edin., xxxiii (1888), p. 648.
Arenicolidae —
Johnston, Loudon's Mag. Nat. Hist, viii (1835), p. 566; Ann. Mag. Nat.
Hist., xvi (1845), p. 454.
Ashworth, Liverpool Mar. Biol. Comm., Mem. xi (1904), p. 71.
Fuchs, Jenaische Zeits., xlii (1907), p. 388.
Gamble and Ashworth, Q. J. Micr. Sci., xliii (1900), p. 538.
Lo Bianco, Atti B. Accad. Sci. Fis. Mat. Napoli, v, ser. 2, no. xi (1893), p. 9.
Arenicolidae, partim —
Johnston, Ann. Mag. Nat. Hist., iv (1840), p. 373.
Arenieoliens —
Audouin et Edwards, Ann. Sci. Nat., xxx (1833), p. 418; Hist. nat. Litt.
France, ii (1834), p. 282.
Fauvel, Mem. Soc. Nation. Sci. Nat. Math. Cherbourg, xxxi (1899), p. 161.
Mesnil, Bull. Sci. France Belg., xxx (1897), p. 145.
Quatrefages, Hist. nat. Annel., ii (1865), p. 259.
Arenieoliens, partim —
Edwards, in Lamarck's Hist. nat. Anim. s. Vert., 2e Edit., v (1838), p. 513.
26 Arenicolidae
Polychaeta of elongate, cylindrical form, which, when adult,
bear gills on a number of successive chaetiferous segments; pro-
stomium without tentacles or palps ; peristomium without cirri,
followed by an achaetous segment and by a number of chaetiferous
segments, each of which bears dorso-laterally a tuft of capillary chaetae,
and, more ventrally, a row of crotchets ; an achaetous " tail " is
present in some species. The pharynx has no jaws, but bears series
of papillae, the tips of which, in large specimens, may be capped
with chitin ; glandular caeca, one or more pairs, are present on the
posterior part of the oesophagus ; coelomic septa have disappeared
in the region of the body in which the " stomach " is situated, but
septa are constantly present at the anterior border of the first, third
and fourth chaetiferous segments, and also in a greater or less extent
of the intestinal region. Nerve-cord non-ganglionated.
TYPE GENUS. — Arenicola Lamarck.
HISTORICAL ACCOUNT. — The family Telethusae J was founded by
Savigny for the genus Arenicola, only one species of which,
A. marina (then usually designated A. piscatornm Lamarck) was
known.
Latreille included Branchellion — a genus of leeches — in this family,
for the sole reason that, like A. marina, it possesses gills on the middle
segments of the body.
In 1833 Audouin and Edwards designated the family, in which
they placed only the genus Arenicola, Arenicoliens, and two years
later the latinised form Arenicolidae was first used in an article by
Johnston. These names have been adopted by most subsequent
writers in preference to the original family name. It is a little
remarkable that Johnston, after using the name Arenicolidae in his
papers in 1835, 1840 and 1845, reverted in his British Museum
Catalogue 2 to the use of the designation Telethusae.
Several authors have attempted to add other genera to the
family, or to use the family name in an extended sense ; but,
with one exception, these changes have not been attended with
success. The term Arenicoliens was used by Edwards in 1838,
1 Telethusa, the wife of Lygdus and mother of Iphis. Ovid, Metam.,
ix, 682.
2 The name Arenicolidae is given (p. 214) as if it were a synonym of the
sub-order Limivora.
Historical 27
to designate a division in which he placed two tribes, namely,
Arenicolides, including the genera Arenicola and Chaetopterus, and
Ariciens, comprising the genera Cirratulus, Ophelia, Aricia and Aonis.
This usage of the name Arenicoliens was inconvenient, since the
six genera referred to the family formed an obviously heterogeneous
assemblage ; the conjunction of Arenicola and Chaetopterus was
especially indefensible, and was not accepted by subsequent authors.
In 1840 Johnston placed the new genus Travisia in the family
Arenicolidae, but he soon reached the conclusion that it was desirable
to remove it, for in his " Index to the British Annelides," published
in 1845, Travisia is found under the family Lumbricidae.
Grube was led by the general external resemblance between
Arenicola and his new genus Dasybranclius to add the latter to the
family Telethusa ; Danielssen referred three genera to this family,
namely, Arenicola, Scalibregma Eathke and Notomastus Sars.
Schinarda carried the inclusive process still further, placing in the
family the genera Arenicola, Dasybranchus, Eumenia Orsted and
Scalibregma. But Grube and Malmgren successively curtailed the
family by removing genera. Grube1 created a new family—
Capitellacea — for the reception of Dasybranchus, Notomastus and the
allied genus Capitella Blainville, and Malmgren founded the family
Scalibregmidae for the genera Eumenia and Scalibregma, and thus
reduced the family Thelethusae 2 to the single genus Arenicola.
A second genus was added to the family in 1881 when Langerhans
defined his newly discovered Branchiomaldane vincenti as a Telethusan
with simple filamentous gills.
Prof. Mesnil (1897) gave an account of B. vincenti, and of three
species of Clymenides^-sulfureus, ccaudatiLs and incertus3 — and pointed
out the resemblances of these small Polychaetes to Arenicola on the
one hand and to the Maldanidae on the other, liegarding them as
connecting links between the families Arenicolidae and Maldanidae,
he proposed to indicate the continuous series of forms presented by
these two families by combining them into one family, the " Arenicolo-
Maldaniens," which, however, he regarded as divisible into two
tribes, Arenicoliens and Maldaniens, differentiated by the nature of
their segments, " courts et assex nombreux " in Arenicoliens, " longs
et peu nombreux " in Maldaniens. Although the relationship
1 Arch. Naturg., xxviii Jahrg., i (1862), p. 366.
2 Ofvers. K. Vet. Akad. Forh., 1867 (1868), p. 188.
3 Since proved to be post-larval stages of Arenicola marina, ecaudata and
B. vincenti respectively.
28 A renicolidae
between the A renicolidae and Maldanidae is obvious and admitted,
it is not sufficiently close to justify the fusion suggested by Prof.
Mesnil. Moreover, the affinities of the Arenicolidae are not entirely
with the Maldanidae, but also with the Scalibregrnidae. The degree
of relationship in which these families stand to each other cannot be
determined fully until further investigations have been carried out,
but it seems to the present writer highly improbable that the results
of such investigations will lead to the fusion of any two of them.
These three families present characters which appear to indicate
their evolution along independent lines ; a discussion of their
affinities will be found on pp. 160, 161.
The account of Branchiomaldane (p. 147) shows that this genus
presents several resemblances to Arenicola, and that it must be
included in the family Arenicolidae, but the writer is not prepared
to follow Prof. Fauvel in merging the two genera, as they present
important differences, especially in regard to the gills, nephridia,
gonads and early stages of development.
The family Arenicolidae is therefore regarded as containing two
genera, adult examples of which may be distinguished by the
characters given in the following key : —
Branchial segments subdivided into five annuli ; gills
much branched, borne on the chaetiferous
annulus ; prostomium small and may be sunk in
the deep nuchal invagination ; dioecious, gonads
borne on the nephridia only ; an achaetous tail
in some species.... Arenicola, p. 29.
Branchial segments for the most part subdivided
into two rings, one chaetiferous, the other
branchiferous ; gills composed of one to four
finger-shaped filaments ; prostomium large, nu-
chal groove shallow ; monoecious, gonads borne
on the septa and oblique muscles ; ecaudate ;
small, not more than 2 cm. long Branchiomaldane, p. 147.
Young post-larval stages of the ecaudate species of Arenicola
exhibit a general external resemblance to BrancMomaldane, but the
presence in the latter of gonads, and of bi-annulate branchial
segments in which the chaetae and gills are borne on consecutive
annuli, and the absence of statocysts and pigment, are useful
differential characters.
Arenicola 29
ARENICOLA Lamarck, 1801, emend.
Arenicola —
Lamarck, Syst. Anim. s. Vert. (1801), p. 324 ; Hist. Anim. s. Vert., v (1818),
p. 335.
Asliworth, Liverpool Mar. Biol. Comm., Mem. xi (1904), p. 71 ; Proc. U.S.
Nat. Mus., xxxix (1910), p. 2.
Audouin, Diet, class, d'hist. nat., i (1822), p. 534.
Audouin et Edwards, Ann. Sci. Nat., xxx (1833), p. 419 ; Hist. nat. Litt.
France, ii (1834), p. 284.
Blainville, Diet. Sci. Nat., Ivii (1828), p. 446.
Bosc, Hist. nat. Vers, i (1802), p. 161.
Cams, Prodr. Faun. Medit., i (1885), p. 251.
Cunningham and Bamage, Trans. R. Soc. Edin., xxxiii (1888), p. 648.
Fleming, Encyc. Brit., 7 Edit., xi (1842), p. 219.
Gamble and Ashworth, Q. J. Micr. Sci., xliii (1900), p. 540.
Gervais, Diet. univ. d'hist. nat., ii (1842), p. 102.
Johnston, Catal. Worms Brit. Mus. (1865), p. 229.
Levinsen, Vid. Medd. Naturh. Foren. Kjobenhavn (1883), p. 134.
Lo Bianco, Atti E. Accad. Sci. Fis. Mat. Napoli, v, ser. 2, no. xi (1893), p. 9.
Quatrefages, Hist. nat. Annel., ii (1865), p. 262.
Savigny^ Syst. Annel. (1820), p. 95.
Arenicola, partim —
Fauvel, Mem. Soc. Nation. Sci. Nat. Math. Cherbourg, xxxi (1899), p. 161.
Chorizobranchus —
Quatrefages, op. cit., p. 267.
Clymenides —
Claparede, Beobacht. Anat. wirbell. Thiere Normand. (1863), p. 30.
Clymenides, partim —
Mesnil, Bull. Sci. France Belg., xxx (1897), p. 148.
Lumbricus, partim —
Linnaeus, Syst. Nat., x Edit., i (1758), p. 647 : xii Edit., i, 2 (1767), p. 1076.
ADULT. — Arenicolidae usually found burrowing in sand ; pairs of
branched gills are borne dorsally on the chaetiferous annuli of a
number of the segments, in the caudate species on all except the
first six, and in the ecaudate species from the twelfth or sixteenth
usually to the last. Prostomium small, bounded posteriorly by the
nuchal invagination. Each chaetiferous segment, except the first
three or four, is subdivided usually into five annuli, that which bears
the parapodia being larger than the others. Each parapodium consists
of a conical notopodium bearing capillary chaetae, and a neuropodium
in the form of a muscular ridge, traversed by a deep groove, in
which a row of crotchets is situated. In some species there is a
posterior " tail," composed of achaetous segments. There is a pair of
hearts a short distance behind the oesophageal glands. The first
nephridium opens on the fourth or fifth segment, the dorsal lip of
30 A renicolidae
the funnel is fringed with ciliated vascular processes, the margin of
the ventral lip, which is not fringed, is either entire, frilled, or
deeply notched in the middle. Dioecious, the reproductive organs
are borne on the nephridia only. There is a pair of statocysts in the
peristomium (except in A. pusilla).
POST-LAKVAL STAGES. — Arenicolidae found either pelagic, or semi-
tubicolous, living among algae or in sand. Gills absent, or present
on a few segments, but small. Prostomium large, conical and
overhanging the mouth ; nuchal groove present. Annulation either
absent or as in adult. Capillary chaetae and crotchets present in each
chaetiferous segment, a transient crotchet in some of the later formed
notopodia. An achaetous "tail" in some species. Hearts and
nephridia present, the latter have either larval funnels or simple
early phases of the adult funnel. Eeproductive organs absent or
minute. A pair of statocysts in the peristomium (except in
A, pusilla).
TYPE SPECIES. — A. marina (Linnaeus).
HISTORICAL ACCOUNT. — The first mention of a representative of
this genus is found in Belon's De Aquatilibus (1553), in which obser-
vations are given on the common lugworm, to which Belou gave the
name Lumbricus marinus. L. mannus is not mentioned in the first
edition of the Systema Naturae, but Linnaeus recorded and figured
it in the account (1747) of his journey through West Gothland,
and placed it in the sixth and subsequent editions of his Systema.
The descriptions of the lugworm given by Pallas, Fabricius and
others before the end of the eighteenth century served to bring into
notice differences between this worm and the earthworm, which led
Lamarck, in 1801, to place these two worms in separate genera.1
1 Gervais (GJJ. cit.) states that Boucher d'Abbeville first indicated, in 1798,
that the lugworm should be placed in a genus apart from Lumbricus. The
writer has searched carefully for publications by Boucher in the hope of finding
his remarks on this point, and is indebted for help to M. Ch. Gravier, who has
also spent considerable time in the same quest, among the literature of the
period, in the Library of the Museum d'Histoire Naturelle, Paris. Only one
paper by Boucher, dealing with Lumbricus marinus, can be found (Soc.
d'Emulation d'Abbeville, Cl. Sci. et Arts, Eapp. du Trimestre de Vendemiaire,
An 7), but this does not contain any indication of a division of the genus
Lumbricus. Fortunately, there is not even a suggestion that Boucher put
forward a name for the alleged new genus, so that there is no danger of the
generic name Arenicola losing priority and falling, as so many other well-known
names have done of late, into the limbo of synonymy.
Arenicola : Historical 31
The earthworm was left in the old genus Lumbricus, and the
lugworm removed to a new genus Arenicola,1 because, as Lamarck
observed in 1818, the presence of external gills rendered impossible
its retention in the genus Lumbricus. Lamarck then (1818) gave a
fuller diagnosis of the genus Arenicola, based on the single species
(A. piscatorum = marina) known to him, in the following terms :
"Corpus molle, longum, annulatum, cylindricum, postice nudum;
setarum fasciculi biseriales in parte media anticaque. Branchiarum
externarum arbusculae aut penicilli ad basim fasciculorum dorsalium.
Os terminale nudum. Oculi nulli."
Audouin and Edwards (1833) described, from specimens which
were doubtless ecaudate, a species, A. branchialis, which differs
from the lugworm in the number and arrangement of its gills, and in
1835 Johnston described the species A. ecaudata. The discovery of
this species, in which the feet and gills extend to the posterior end
of the worm, necessitated an emendation of Lamarck's diagnosis of
the genus, the statement " postice nudum " being no longer
applicable to the genus as a whole. But a considerable number of
writers, including Johnston (1865), continued to define the genus
Arenicola by stating the characters of the lugworm only, neglecting
completely the existence of the ecaudate species.
Suggestions for a subdivision of the genus have been put forward
by Lutken and Prof. Mesnil. Liitken 2 proposed that A. antillensis
(= cristata) should be placed in a sub-genus Pteroscolex, because of
the feathered or pinnate nature of the gills. He made this proposal
evidently with some diffidence, for he remarked that, in regard to its
other external features, this worm was a typical " Sandorm."
Claparede (1868) promptly rejected this sub-genus on the ground that
a similar form of gill to that occurring in " Pteroscolex " had been
found by Williams in examples of the common lugworm.3
Prof. Mesnil4 proposed to retain in the genus Arenicola those
species with a small number of segments — seventeen to nineteen—
and a long achaetous tail, namely, A. marina, claparedii ( = pusilla)
and cristata, but to erect a new genus Arenicolidcs for the two species
— branchialis and ecaudata — having a large number of chaetiferous
segments and no tail. The writer, while not prepared to go so far as
Prof. Mesnil suggests, admits that there is something to be said in
1 Arena, sand ; colere, to. inhabit.
2 Vid. Medd. Naturh. Foren. Kjobenhavn, 1864 (1865), p. 121.
3 The gills of some specimens of A. marina are almost as highly pinnate
as those of A. cristata.
4 Bull. Sci. France Belg., xxxii (1899), p. 326.
32 A ren icolidae
favour of the recognition of the differences between the caudate and
ecaudate species. The latter differ from the former in their brain
and prostomium, in the absence of tail, and in the mode of branching
of their gills, but the two ecaudate species diverge very sharply from
each other in the number of their nephridia and the nature of their
reproductive organs ; in regard to the last-named character especially
the differences between A. branchialis and A. ccaudata are as great
as between the latter and any caudate species. The opinion of
the writer is that the caudate and ecaudate species present such
a number of common characters as to warrant their inclusion in a
single genus, and that the differences presented by the ecaudate
species would be sufficiently recognised by regarding them as of
sub-generic importance. It is therefore proposed to maintain all the
species in the genus Arenicola.
Prof. Fauvel has merged Brancliiomaldane with Arenicola, but,
for reasons set forth in another part of this volume (p. 155), the writer
does not consider this advisable, and therefore maintains the two
genera.
Quatref ages' genus Ckorizobranchus was based on his interpreta-
tion of a badly executed figure of " Lumbricus marinus," given by
Delle Chiaje in 1825, in which the branchiferous segments are
shown separated by abranchiate ones. There can be no doubt that
this figure was intended by Delle Chiaje to represent a specimen of
Arenicola, for in 1841 he himself cited the figure among the synonyms
of A. piscatorum. This new genus, being established on an obviously
defective basis, as Claparede soon pointed out, was not recognised by
any subsequent writer.
The genus Clymenides (see p. 75), as defined in the single species
sulpliurea of its author, Claparede, is merged with Arenicola because
the worm described under this name was almost certainly a post-
larval stage of A. marina. The examples of C. sulfur cus described
by Prof. Mesuil were undoubtedly young stages of A. marina, and
his two new species C. ecaudatus and incertus have been proved to
be young phases of A. ecaudata and Branchiomaldane vincenti
respectively.
A GENERAL ACCOUNT OF THE GENUS ARENICOLA.
The following account of the genus Arenicola relates to the
external features, and to those internal organs which are used as
factors in diagnosis in the subsequent part of this Catalogue.
External Characters of Arenicola
33
EXTERNAL CHARACTERS. — All the species of Arenicola are elongate,
cylindrical worms, which live, when adult, in sand or mud, or in
coarse gravel. Some of the species, especially A. marina, loveni and
cristata, may attain a length of 400 mm. ; one specimen of A. cri&tata
was as much as 515 mm. long and 75 mm. in girth.
Examples of this genus have the morphological components
found in other Polychaeta, namely, prostomium, peristomium, a
number of body-segments, and a terminal segment or pygidiuin, but
the last named has- generally been lost in the adult. A certain
number, or all, of the body-segments (except the first) bear parapodia,
but the latter and the prostomium are considerably modified and
reduced, as compared with the corresponding structures of more
active, mobile Polychaeta, such as Nereis (PL XII, Figs. 36,
37, 38).
In the caudate species of Arenicola the prostomium (Figs. 1, 2) is
a small trilobate structure,1 which, even in large specimens, seldom
N.GR.
PR.
-PtR.
A.B.S.
CaSee!
Fig. 1. — Arenicola loveni. Anterior end, dorsal as-
pect. PR. Prostomium ; PER. Peristomium ; N.GR.
Kuchal groove ; A.B.S. Achaetous body-segment ;
CH.SEG.I First chaetiferous segment.
X 6
Fig. 2. — A. pusilla. Anterior end, dorsal
aspect ; showing the large and folded
lateral lobes of the'prostomium.
exceeds 2 mm. in diameter, and, since it is liable to be retracted
within the crescentic nuchal groove situated immediately behind it,
is often seen with difficulty, and then only in part. The prostomium
1 Fabricius (Fauna Groenl. (1780), p. 284), in describing Liimbricus papil-
losus ( = A. marina), mentioned the presence of a short, foliate, trifid " rostrum,"
and Savigny drew attention to this small, trilobed " caroncule," but its nature
was not understood thoroughly until Dr. Levinsen (1883) pointed out its
homology with the head-lobe (prostomium) of Scalibregma.
I)
34 Arenicolidae
does not bear any sensory processes — tentacles or palps— and though
eyes are present they are minute and sub-epidermal, and are not
visible on external examination, except in the case of specimens less
than 10 mm. in length.
The proportionate size of the median and lateral lobes of the
prostomium varies considerably in the different caudate species, and
forms a useful specific character — for instance, in A. loveni the
median lobe is large, while in A. pusilla the lateral lobes are very
highly developed (cf. Figs. 1, 2). In the two ecaudate species the
prostomium forms a transverse ridge, the mid-dorsal portion of which,
in some specimens, is slightly elevated above the rest (Fig. 3). In
these species the prostomium merges ante-
riorly with the dorsal oral papillae, which
form an " upper lip," while posteriorly
it is bounded by the nuchal groove. The
N.GR- --^^MD^R conical anterior end of each of these
species is therefore not entirely prostomial
in nature, it is constituted also, in fact
largely, of the " upper lip." A. pusilla
Fig. S.-A. branchMis. Anterior possesses the most complex and highly
echaigtot;TKe.cprosSumNu' developed prostomium, while the two ecau-
date species stand, in this respect, at the
opposite end of the series, the prostomium being feebly developed.
The prostomium is large in the larval and post-larval stages (see
PI. X), and in these its pre-oral nature is well seen. In the adults
of all species, however, the prostomium is much smaller, relatively
to the peristomium and following segments, than in larval and post-
larval stages, and is not pre-oral in position, for it is situated behind
the " upper lip."
In Arenicola the segmentation of the body is somewhat obscured
by the subdivision of each segment into rings or annuli. The
annuli are generally five in number, and one, larger than the rest,
bears the parapodia.
The parapodia are obviously much reduced, as compared with
those of Nereis (PI. XII, Fig. 38), no doubt in correlation with the very
different habits of the worms ; the " feet " of Nereis are well adapted
for use in rapid crawling or in swimming, while the parapodia of
Arenicola are more fitted to its burrowing habits. The two rami of the
acirrate parapodia of Arenicola (PI. XII, Fig. 39) are dissociated : they
arise, not from a common basal piece, but directly from the body wall.
The notopodium, which is situated dorso-laterally, is a cylindro-
External Characters of
conical elevation, and on or near its rounded end is the oval mouth
of the chaetal sac, from which the tips of a pencil of chaetae1
project. The chaetal sac traverses the axis of the notopodium and
extends into the coelomic cavity. Fixed into the bottom of the
sac are the numerous capillary chitinoid chaetae, moved collectively
by special protractor and retractor muscles, which govern the extent
to which the chaetae protrude. The notopodium is capable of con-
siderable extension and retraction ; in PI. XII, Fig. 39, it is shown
in a semi-contracted condition, its terminal part having been partially
withdrawn into the basal portion. The notopodia are of a similar
type throughout the genus and are present on all the chaetiferous
segments, except in some examples of A. branchialis, in which the
notopodia of the first segment are wanting.
The neuropodium is a muscular ridge traversed dorso-ventrally
by a narrow slit — the mouth of the setal sac — from which the tips of a
row of crotchets project. The section drawn (PL XII, Fig. 39) has
passed immediately anterior to the chaetal sac, within which the
inner ends of the crotchets are indicated. The muscular ridge and
its hooked crotchets are excellently adapted for aiding the worm in
its movements up and down its burrow ; by their means one or more
segments can fix themselves to the wall of the burrow, and the rest
of the body can then be drawn towards this fixed portion by con-
traction of the longitudinal muscles. There are two types of neuro-
podia. In A. pusilla and assimilis the neuropodia form more or less
oval, cushion-like pads on the lateral portions of the chaetiferous
annuli ; but, even in the posterior branchial region, where the
neuropodia are best developed, they do not approach the mid-ventral
line. In the other species of the genus the neuropodia are elongate
muscular ridges, which, in the middle and posterior branchial
segments, reach almost to the mid-ventral line. The neuropodia of
the anterior segments (the first six or seven) are smaller than the
rest, and in A. cristata neuropodia are not generally visible on the
first two (sometimes three) chaetiferous segments.
The posterior segments of some specimens of A. cristata and
loveni exhibit, between the notopodium and neuropodium, an oval
depression not more than *5 mm. in diameter (PL V, Fig. 13, and
Fig. 44, p. 104). The position of these pits corresponds to that of the
1 The chaetae are not simple hairs ; they possess " Sageblatter " (see p. 44),
that is, series of spine-like processes. When the chaetae are pressed into the
sand their processes offer resistance. These chaetae are thus more efficient
than simple hairs would be in aiding locomotion.
D 2
36 Arenicolidae
" Seitenorgane " of other Polychaeta, but it has not been found
possible to determine, on the material available, if the pits are
really sensory structures.
The number of segments characteristic of each of the caudate
species is, on the whole, constant, only very few variations having
been observed. A. cristata and glacialis have 17 segments, A. marina,
pusilla, loveni and assimilis var. affinis have 19 segments, while the
typical form of A. assimilis has 20 segments.
In the ecaudate species there are considerably more segments,
the full number of which — about 42 in A. branchialis and 64 in
A. ecaudata — is already present at the end of the post-larval stage.
The number of segments in these species does not increase with
age, on the contrary, segments are usually lost posteriorly and
are not regenerated, so that specimens are generally found to
have fewer segments than stated above ; average specimens of
A. foanckialis have about 30, and of A. ecaudata about 45 to 50
segments.
Each chaetiferous segment, except the first two or three, is sub-
divided into five rings,1 and a consideration of the internal anatomy
shows that the posterior limit of the segment is at the posterior edge
of the ring which follows the chaetiferous one. Thus each of the
segments, posterior to the third, consists of the chaetiferous annulus
together with the three annuli in front of and that behind it.
The third segment consists of three or four rings, the penultimate
being chaetiferous ; the second segment is generally subdivided into
three rings, of which the middle one bears the parapodia. The first
segment2 is usually composed of two rings, the anterior of which
is chaetiferous; in rare cases another small ring is present and
lies in front of the chaetiferous annulus. The limits of these
segments are ascertained chiefly by an examination of the internal
septa, which are a constant feature of this region in all species
of Arenicola.
Between the anterior margin of the first chaetiferous segment
and the prostomium there is a region which, in most adult specimens
of Arenicola, is subdivided by encircling grooves into three or four
(or more) rings. There are good reasons for stating that this region
is composed of the peristomium and a body-segment which is with-
1 Occasionally the last one or two segments in A. branchialis, and the last
one to four segments in A. ecaudata, are subdivided into fewer than five
annuli.
2 That is, the first chaetiferous segment. The word " segment " throughout
the following pages means " chaetiferous segment."
External Characters of Arenicola 37
out chaetae in the adult. In post-larval stages of A. marina (PL X,
Fig. 27) and ecaudata (PL XI, Fig. 34) the region between the
prostomium and the first ordinary chaetiferous segment is sub-
divided by a groove into two parts. The anterior and usually
rather smaller portion is undoubtedly the peristomium ; it never
bears chaetae, but the paired statocysts may be seen near its anterior
margin. The posterior of the two parts is, in the post-larval stages
which the writer has examined, achaetous, but a chaeta has been
observed in this segment, in either A. marina or A. ecaudata, by
Professors Ehlers, Benham, Mesnil and Fauvel, a fact which demon-
strates that this is a true segment.1 In later post-larval stages, in
which the annulation is making its appearance, the peristomium and
the segment in question become subdivided into secondary rings, so
that, henceforward, the segmentation of this region, like that of the
rest of the body, is obscured; but it frequently happens that the
original groove between the peristomium and the segment under
consideration remains more obvious than any of those subsequently
formed, and is recognisable even in the adult (Fig. 54, p. 118).
Dr. E. S. Lillie2 does not agree with the interpretation given
above, because he could not find, in young A. cristata, a septum
corresponding to the achaetous segment. But the considerable
length and subdivision of, and the presence of two apparently
segmental pigment-bands in, the region in question (PL X, Fig. 30)
suggest that it includes the peristomium and another segment.
The composition of this region is probably constant throughout
the family.
In A. ecaudata and branchialis the parapodia are continued to
the posterior end of the animal ; but in A. marina, pusilla, assimilis,
loveni, cristata and glacialis there is a " tail " in which parapodia and
gills are not present. The tail is marked with a number of slight
constrictions, which indicate the boundaries of the somites and
correspond to internal septa. The number of tail-segments varies
considerably in different individuals of the same species, because
several segments, or even the major portion of the tail, may be thrown
off on irritation.
During development, new chaetiferous segments are formed
immediately in front of the terminal segment or pygidium. In the
1 Evidence confirmatory of this interpretation is afforded by the arrangement
of the giant nerve-cells (Ashworth, Liverpool Mar. Biol. Conim. Mem. xi
(1904), p. 11).
2 Mitt. Zool. Stat. Neapel, xvii (1905), p. 358.
38 Arenicolidae
ecaudate species all the segments are produced in this growing zone,
the activity of which becomes exhausted about the end of the post-
larval stage. In the caudate species, after the full number of
chaetiferous segments has been formed, the succeeding or tail-segments
are evidently produced at the anterior end of the tail ; for in this
region each segment is short from before backwards, while in the
middle and posterior regions of the tail the segments are longer, and,
in adult or late post-larval specimens, are subdivided into annuli.
In A. cristata the full number of tail-segments — 38 to 40 — is acquired
before the end of the post-larval stage. Examination of adult
specimens of A. marina and loveni, however, indicates that new
segments are continually being added to the tail at its anterior end,
and, as a consequence, the number of tail- segments may become
very large, e.g., in the tail of an example of A. loveni there were
175 septa, indicating as many segments. In A. marina there may
be 60 to 70 tail-segments, though usually there are fewrer, owing
to losses posteriorly.
In many of the tail-segments of all the caudate species of
Arenicola there is one annulus slightly larger and more deeply
pigmented than the rest, upon which distinctly larger epidermal
papillae are borne. Each of these larger annuli occupies a position
in the tail-segment corresponding roughly to that of the chaetiferous
annulus in the pre-caudal segments of the worm.
Traversing the whole length of the mid-ventral line, in many
specimens of A. marina, pusilla, assimilis and loveni, there is a shallow
groove which marks the position of the ventral nerve-cord. A short
distance in front of the first chaetiferous annulus this groove unites
with the two metastomial grooves, which pass round the sides of
the peristomium (metastomium), in an antero-dorsal direction, to
the region of the prostomium (Fig. 53, p. 118). The metastomial
grooves indicate the course of the oesophageal connectives. In other
species the ventral and metastomial grooves are either faint or
absent.
EXTERNAL APERTURES. — The mouth, when the proboscis is with-
drawn, is a crescentic or semicircular transverse slit in the antero-
ventral region of the peristomium. It is overhung by a series of
papillae, which belong to the peristomium and form the upper lip,
dorsal and posterior to which the prostomium is situated. The anus
is posterior and terminal.
The nuchal organ is a pro-curved, crescentic or U-shaped, ciliated
Chaetae of Arenicola
39
ST.O.
invagination at the junction of the prostomium and peristomium,
and into it, in the caudate species, the prostomium may be with-
drawn so as to be almost or quite hidden from view.
In A. marina, assimilis and glacialis the statocysts open to
the exterior by pores situated on
the dorso-lateral wall of the peri-
stomium. In A. marina the pore 1 is
present, on each side, near the point
at which the metastomial groove
crosses the first inter-annular groove
(PL XII, Fig. 40). In A. assimilis
the pore 1 is situated at the origin of
the metastomial groove, that is, close
to the prostomium on each side
(Fig. 4). The position of the aper-
ture in A. glacialis has not been
definitely ascertained, but it is pro-
bably similar to that of A. marina.
The nephridial apertures are
situated immediately dorsal and
"
Slightly posterior tO the Upper ends
'
ot the neuropodia of the segments
on which they occur. In A. marina,
assimilis2 and glacialis the first
nephridiopore is on the fourth segment, in A. cristata, pusilla, loveni,
branchialis and ecaudata the first pore is on the fifth segment.
There are six pores on either side in A. marina, assimilis,'2' glacialis
and cristata, five in A. pusilla, loveni and branchialis, and thirteen in
A. ecaudata.
CHAETAE.
In adult specimens the notopodia never contain crotchets, but a
crotchet, either alone or accompanied by one or more capillary chaetae,
was observed by Prof. E. B. Wilson (1883) in the notopodia of
larval A. cristata, and by Prof. Mesnil (1897) in specimens of
" Clymenides ecaudatus" afterwards shown to be post-larval speci-
1 These apertures are minute, and can be seen only in those specimens in
which the peristomial region is well extended.
2 In examples of A. assimilis var. affinis from South Africa there are only
five pairs of nephridiopores, the first of which is on the fourth segment.
Fig. 4. — A. assimilis var. affinis.
end, dorsal aspect ; showing prostomium
very fully protruded, exposing to view the
median posterior part (P.), which is usually
hidden in the nuchal organ ; M. Median,
L. Lateral lobe of prostomium ; ST.O.
External opening of statocyst.
40
Arenicolidae
mens of A. ccaudata. I also found crotchets1 in the posterior
notopodia of a post-larval A. ecaudata, 8 mm. in length. This
Fig. 5.— A. ecaudata. Outline of the posterior end of a post-larval specimen, 8 mm. long, to
show the chaetae.
specimen has recently been subjected to further
clearing, and this has rendered it possible to get
a better view of the dorsal crotchets, which are
not as short as they are drawn in the figure cited.
Fig. 5 is a more accurate representation of this
specimen and of its two types of crotchets, which
are shown more highly magnified in Figs. 6, 28
(p. 56). Elongate crotchets, similar to that of
Fig. 6, are present in the last five notopodia of
post-larval examples of A. branchialis, 4*4 and
5 • 8 mm. long respectively.
I have examined a series of larval and post-
larval A. cristata for notopodial crotchets, which
are already present in larvae with four or five
chaetiferous segments. A larva, • 7 mm. long, with
ten chaetiferous segments (Fig. 7), bears in each
of the last six notopodia a crotchet of the long
Fig. K.-A. ecaudata. tvPe- ^n an older specimen, 2 • 6 mm. long, which
o6- has the ful1 number (seventeen) of chaetiferous
segments, only one notopodium, the penultimate,
contains a crotchet ; and in a specimen 3 mm.
long crotchets are not present in any of the notopodia.
It is clear from these observations that a crotchet, differing from
1 Figured in Q. J. Micr. Sci., xliii (1900), pi. xxiv, fig. 37.
Chaetae of Arenicola
41
those of the neuropodia in the greater length of its shaft, is present,
but for a, short time only, in a few of the last-formed notopodia of
very young specimens. A notopodium never contains more than one
crotchet, and after this has been cast out it is not replaced by a chaeta
Fi^. 7. — A. cristata. Outline of a larva, about -7 mm. long, to show the chaetae.
PR. Prostomium.
of a similar kind, but henceforward capillary chaetae only are formed
in the notopodium. The evidence afforded by the young stages of
A. cristata described above shows that, in this species, the crotchets
are lost from the notopodium within a very short time of the
attainment of the full number of chaetiferous segments. Probably
this is also the case in other species, for in none of the notopodia of
post-larval stages of A. marina (of which examples only 3 • 6 mm.
long have been examined) or of A. assimilis has the
writer been able to find a crotchet.
0
NOTOPODIAL CAPILLARY CHAETAE OF YOUNG SPECI-
MENS.— The capillary chaetae successively present in
any one notopodium exhibit a series of changes of
form, the principal phases of which, traced chiefly
in A. pusilla, cristata and marina, may be noticed
here. Within twenty-four hours after hatching, the
larva of A. pusilla or A. cristata acquires its first
chaetae — a pair situated some distance behind the
middle of its length. There are no elevations of
the body-wall, that is, no actual notopodia, but
the two chaetae indicate the position of the first T, First n'ot»ppdiai
notopodia. The free end of the chaeta (Fig. 8 A)
is almost spoon-shaped, the shaft being continued,
but tapered, along the axis of the flat " bowl " of
the " spoon." In older larvae, with three or four
segments, each notopodium contains a chaeta similar to that just
described, but in each of the anterior two or three segments there
chaeta of a larva
•25 mm. long ; B,
Notopodial chaeta
of an older larva
with four chaeti-
ferous segments.
42
Arenicolidae
\
Fig. 9.— A. marina. Notopodial
chaetae of a post-larval specimen,
4-3 nun. long.
Fig. 10. — A. ecaudata. Distal halves of notopodial chaetae from
post-larval specimens about 7 mm. long.
Chaetae of Arenicola 43
is also a chaeta, the free end of which is spear-like (Fig. 8 B).
Spoon- and spear-headed chaetae are also present in the notopodia
of young larvae of A. cristata, in which only two or three segments
are indicated ; but the spoon-shaped chaetae are soon cast out, and
successive spear-headed chaetae, in which both shaft and head are
of gradually increased length, are formed during the rest of the
larval period. The tip of each of the later formed spears is drawn out
into a long, fine point. In post-larval specimens there are all
transitional forms, from spear-headed to laminate chaetae similar to
those of the adult, as shown in Fig. 9, which represents chaetae from
a post-larval A. marina, 4*3 mm. long. Each notopodium of this
worm contains one chaeta of the type shown in Fig. 9 A, accompanied
by from one to five of the longer capillary chaetae shown in Fig. 9 c.
Fig. 9 B represents a form transitional between those represented in
Figs. 9 A, c. Similar growth-phases are exhibited by the notopodial
chaetae of post-larval A. assimilis var. o.ffmis. The spear-headed
chaetae probably do not persist long after the post-larval stage
has abandoned its free-swimming habit, for, in a young specimen
of A. marina, 17 mm. long, from the shore, spear-shaped chaetae
were not present ; the chaetae were all of the adult form, laminated
along one margin only.
In post-larval stages of A. ecaudata 1 there are two kinds of
capillary chaetae — (1) long tapering chaetae, similar to the majority
of those seen in late post-larval A. marina, and (2) shorter chaetae of
the kind shown in Fig. 10B, noteworthy for the presence of a slight
constriction about the junction of middle and distal thirds. A few
chaetae, like that shown in Fig. 10 A, are transitional forms suc-
ceeding spear-headed chaetae of earlier stages of development.
These observations indicate that, throughout the genus, there is
a sequence of growth-forms of the notopodial chaetae, from spoon-
and spear-headed early phases to tapering chaetae, which alone are
found in the adult.
THE XOTOPODIAL CHAETAE OF ADULT SPECIMENS. — Each noto-
podial chaeta of an adult specimen is a yellow or golden, slender,
chitinous, tapering structure. It is inserted at its thicker, proximal
end, along with a number of similar chaetae, in a chaetal sac, which
is moved by protractor and retractor muscles (p. 35). The differences
between the chaetae of the various species consist in the presence or
1 Also of A. branchialis, though these have not yet been as fully studied.
44
Arenicolidae
absence of a lamina along the distal portion, and in the
nature and comparative abundance of the processes present
in that region of the chaeta.
The most highly developed notopodial chaetae present in
the genus are found in A. loveni. In the notopodia of this
(and some other) species the chaetae seem to be in two more
or less distinct series, an anterior and a posterior; the
chaetae of the anterior are shorter than those of the posterior
row, but they have the same form and structural detail.
The longer chaetae are about 6 • 6 to 6 • 8 mm. long, and the
shorter ones 5-3 to 5-6 mm. Each has a moderately
uniform diameter for the greater part of its length, but in
its distal portion tapers to a fine point. For a distance of
1 to 1*3 mm. behind the tip, there is, along one edge of
the chaeta, a well-marked lamina (Fig. 11 A), which attains
a breadth of 15 /z, and, as seen under medium magnification,
is marked by closely set oblique lines and has a finely
dentate margin. The opposite edge of the chaeta bears
numerous regularly arranged processes, which, under low
or medium magnification, appear as fine teeth projecting
at an angle of about 30° to 40° from the shaft of the chaeta,
but which, examined with an immersion lens, are seen to
be crests passing round the shaft (Fig. 11 B). The undivided
base of each crest is fixed to
the shaft, and the distal por-
tion of the crest, that is, its
free margin, is subdivided
into a large number of fine
teeth. Each crest appears
to be a comb-like structure,
bent so as to envelop the
greater part of the shaft of
the chaeta, the curved por-
tion of the crest being seen
in profile where it projects
from the shaft. The regu-
larly arranged structures
visible, under low power, as
tine teeth along one margin
of the chaeta are, then, the
crests seen in profile, and
Fig. 11.— A. loveni. A, Distal third of a notopodial
chaeta, from a specimen 335 mm. long ; B, The region
marked + in A more highly magnified.
Chaetae of Arenicola
45
these remind one of the similar crests or " Sageblatter " of the
chaetae of some Aphroditidae and certain other Polychaeta. The
laminate portion of the chaeta bears on its surface numerous fine
processes, the pointed tips of which are directed at slightly different
angles ; those viewed in profile at the margin of the lamina form a
regular series of very fine teeth. In each interval between the
" Sageblatter " there is a denser transverse band, the presence of
which, at regular distances of about 10 to 12 /z, gives to the distal
portion of the shaft of the chaeta a transversely striated appearance,
which is seen clearly even under low magnification (about 50). This
well-marked striation and the great development of the crests on the
shaft are two characteristic features by which the chaetae of A. loveni
may be distinguished from those of any other species of Arenicola.
The notopodial chaetae of other species apparently all possess crests
of a similar type to those of A. loveni, but of
more feeble development. The crests break
up into their individual teeth and the latter
become spread, by use, in different directions,
so that the shaft of the chaeta is covered,
to a greater or less extent in different species,
with numerous hair-like or spine-like pro-
cesses, the association of which with one
another to form comb-like crests, is, in many
cases, no longer obvious.
The chaetae of young specimens (up to
about 48 mm. long) of A. cristata are
laminate along one side for a short distance,
but the lamina is markedly dentate and soon
breaks up into teeth. In older examples
the chaetae, even when newly formed, are
non-laminate. The tip of an unworn chaeta,
from a specimen 280 mm. long, is represented
in optical section in Fig. 12 A. The chaetae
of this species, when the tip has been worn Fig. IZ.—A. cristata. A, Tip of an
•, ., , unworn notopodial chaeta, seen
away by use, present the appearance shown in optical section, from a speci-
T,i- i o T i i i • -I «>en 280 mm. long ; B, End of a
in Jblg. 12 B. In large examples, m which worn chaeta, from a specimen
.-, i , . i .*.«_* A ,1 403 mm. long.
the chaetae attain a length of 9 mm., the
spinous processes (teeth of the Sageblatter) are very numerous.
The chaetae of A. glacialis resemble those of A. cristata, but are
rather less spinous.
46
Arenicolidae
The chaetae of A. marina, pusilla and assimilis possess, along one
side of their distal fourth or fifth, a thin lamina, which, in large
/
Fig. 13.— A. m<m'na(250 mm. long). A, Distal
fourth of a notopodial chaeta ; B, The re-
gion marked + in A more highly magnified.
Fig. 14.— A. assimilis var. affinis (250 mm.
long, from Otago Harbour, N.Z.). A, Distal
third of a notopodial chaeta ; B, The re-
gion marked + in A more highly magnified.
Chaetae of Arenicola
chaetae, may attain a width of 15 to 20 //..
The lamina may be entire at its margin, and
crossed by numerous fine oblique lines, or it
may be breaking up, from the edge inwards,
along the course of the oblique striae, so
that its margin becomes denticulate. On
the opposite side of the chaeta and pressed
closely to the shaft, are Sageblatter, the spines
of which are smaller than in A, cristata.
Figs. 13 A, B (the latter
an optical section) are
drawn from the chaetae
of A. marina, but the
figures would serve also
for some specimens of
A. assimilis. The chaetae
of the latter species are,
however, usually rather
less hairy and the spines
are smaller (Fig. 14) than
those of A. marina, but
examples from different
localities have been found
to exhibit variation in this
respect. Chaetae of A.
pusilla also present con-
siderable differences in the
degree of their "hairi-
ness," some closely resem-
ble those of A. marina,
than which, however, they
are usually rather less hairy. The fractured
end of a large chaeta, from a massive example
of A. pusilla, is represented in Fig. 15, and
shows the Sageblatter ; the figure would serve
almost equally well for a chaeta of A. marina.
The chaetae of A. ecaudata and branchi-
alis are identical in form and characters.
Although they are as stout basally as chaetae xiooo
of the same length from the caudate species,
they begin to taper nearer to the proximal Fig 16_A A
end, and their distal portion is consequently
more slender. The newly formed chaetae of B> A-,!>
47
x iooo
Fig. 15.— A. pusilla. The
end of a fractured
chaeta, from a large
specimen from Un-
alaska.
podial chaeta, surface view.
48 A renicolidae
the ecaudate species have, along one side, a narrow lamina (2 to 4 /A
wide), which, however, soon breaks up into fine teeth (see the left
proximal portion of Fig. 16 A). The opposite side of the chaeta
bears longer spines. Towards the tip the shaft of the chaeta appears
to be encircled by series of spines (Sageblatter), which can be resolved
only with difficulty (Fig. 16 B).
The only species of Arenicola in which the notopodial chaetae
present characters sufficiently striking and definite to be of real
service in systematic work is A. loveni, the chaetae of which are
distinguished by their well- developed Sageblatter, and the transverse
striation of their distal portion. The notopodial chaetae in the case
of a specimen of any other species would serve, at most, to indicate to
which of three groups — marina-pusilla-assimilis, eristata-glacialis,
ecaudata-branchialis — the specimen belonged.
NEUROPODIAL CKOTCHETS. — The successive generations of crotchets
exhibit progressive changes which, although small, result in the end
terms of the series being of markedly different form, that is, the
crotchets of the larval and post-larval stages differ widely from those
of the adult.
A. marina. — The crotchets of a post-larval specimen of A. marina,
5 mm. long, have the form shown in Fig. 17. The proximal end of
the shaft is fixed to the bottom of the setal sac and the greater part
of the length of the shaft, up to and including the well marked
dilatation present upon it, is enclosed in the sac.
The distal portion of the crotchet is bent almost at
a right angle to the shaft and forms a beak-like
structure — the rostrum. Immediately proximal to
the rostrum, on the convex (i.e. ventral) side of the .
curvature of the crotchet,1 there are three (or four)
teeth, of which that nearest the rostrum is the
largest. On the shaft, just under the rostrum, there
is generally visible a small pointed process — the
sub-rostral process — which is more highly developed
1 'crotchet ' fronT'a in some crotchets than in others. Careful focussing
S^n, 5amm! long™ shows that the series of teeth is continued round
the sides of the rostrum, and that the sub-rostral
process is the expression of the smallest of these ; thus the rostrum
projects from a series of teeth encircling its base. This is more
clearly seen in the crotchets of post-larval stages of A. assimilis
(Fig. 21, p. 50) and also in the adult crotchets of certain species,
e.g. A. branchialis (Fig. 30, p. 57).
1 The position of the crotchets in the neuropodiurn is shown in PI. XII, Fig. 39.
Crotchets of Arenicola
49
Fig. 18. — A. marina.
Crotchet from
A crotchet from a young A. marina, 17 nim. in length, which
had assumed the adult form and mode of life, is shown in Fig. 18.
The teeth are proportionately smaller, and the rostrum
is placed at a greater angle to the shaft — about
120°, instead of about 90° in the younger crotchet
of Fig. 17. Specimens about 100-130 mm. long have
crotchets of the form shown in Fig. 19 ; there are
four or five minute teeth behind the rostrum, which
latter is placed at an angle of about 135° to the
shaft.
Crotchets from very large specimens have a
markedly elongate rostrum, still more nearly in line
with the shaft, and are entirely without teeth. The
absence of teeth is not due to their having been
i i
worn away by use, as may be
shown by isolating the entire ZT!0ngdult> 17
series of crotchets and selecting
for examination those which have not yet
come into use at the ventral end of the
series. The ventral portion of such a pre-
paration is shown in Fig. 20. The tip of
the crotchet on the left is projecting from
the lip of the chaetal sac, the outline of
which is shown, and would soon have come
into use.1 Various stages in the formation
of crotchets are seen, and it will be noted
that teeth are not developed. New crotchets
are being constantly produced at the ventral
end of the series and the old, worn ones cast
out- at the dorsal end of the chaetal sac.
Occasionally small relict crotchets are found
in the bottom, and usually near the dorsal
end of the chaetal sac, from which they
should have been cast along with their con-
Fig. i9.— 4. marina. A, Crotchet temporaries, but for some reason — probably
from a specimen 125 mm. long ; , , • , i , •
B, Tip of another crotchet entanglement in the tissue or mucus — they
from the same specimen. , , . ,
have been retained.
The principal changes in the crotchets of A. marina, pari passu
with the increase in size of the worm, are (1) increase in size and
1 This chaetal sac contained 117 other crotchets, practically identical in
size and form with that shown on the left of the figure.
50
Arenicolidae
number, (2) gradual reduction and eventual loss of the teeth
behind the rostrum, (3) increase of the angle between the rostrum
and shaft, and (4) elongation of the rostral region, which is seen
only in crotchets from very large specimens. The crotchets of other
species of Arcnicola exhibit corre-
sponding changes.
A. assimilis.1— Crotchets from a
post-larval example of the var.
affinis, 7 ' 6 mm. long, are shown in
Fig. 21. The left one is drawn with
the rostrum almost in optical sec-
tion ; the right one, which is shown
Fig. 20. — A. marina (250 mm. long). The
ventral end of a neuropodial chaetal sac,
showing the formation of crotchets.
Fig. 21. — A. assiiinlis var. affinis. Crotchets
from a post-larval specimen, 7-6 mm. long.
with the surface of the rostrum focussed, demonstrates that the
series of teeth extends round the base of the rostrum, and that the
sub-rostral process is the lowest and smallest of the series. Fig. 22 A
represents a crotchet, from a specimen 136 mm. long. This is
similar in form to that of A. marina (Fig. 19), and does not present
any dilatation of the post-rostral region (contrast the crotchets of
1 The neuropodia of A. assimilis n,nd.pusilla, being much shorter than those
of A. marina, contain fewer crotchets ; an average number, in specimens about
five inches long, is 30 to 40 in each neuropodium of the branchial region.
Crotchets of Arenicola
51
A. pusilla, Fig. 24). A crotchet from a specimen of A. assimilis
var. affinis, 208 mm. long, is drawn in Fig. 22 B. It is 1 • 1 mm. in
length, and its characters — the elongate edentulous rostrum (a little
worn at the tip) making a wide angle with
the shaft — are such as would be expected
in a crotchet from so large a specimen.
A. ylacialis. — The crotchets of this
species are similar in general form to those
of A. marina, and have no post-rostral
dilatation (Fig. 23). A neuropodium of
one of the fragmentary type specimens
yielded large crotchets of the type shown
in Fig. 23 c, in which the rostrum is longer
and is curved almost like the blade of a
scythe. This represents probably the final
growth- phase.
A. pusilla. — The crotchets of this species
exhibit a full rounded curvature of the
region behind the rostrum, so that the free
end of the crotchet resembles the head and
beak of a swan. This character is shown
best in small or medium sized specimens
(Fig. 24 A, B), and is especially marked
in the crotchets of the type specimen
(Fig. 24 B). It is also obvious, but to a
less degree, in the large crotchets
(Fig. 24 c), which represent the latest
growth-phase seen by the writer, of a
massive specimen 160 mm. in length.
The head-like curvature is more strongly
marked in this species than in A. cristata.
As A. pusilla is one of the most difficult
species to identify, this character is of
considerable value, for in the two species
with which A. pusilla is most easily
confused, namely, A. marina and assimilis
var. affinis, the crotchets do not present any
dilatation of the post-rostral portion.
A. cristata. — The sequence of growth-phases (Figs. 25, 26) has
been found to be similar to that described for A. marina. In
crotchets (Fig. 26 D, E), which show the final phase of growth, from
E 2
Fig. 22. — A. assimilis var. affinig.
A, Crotchet from a specimen
136 mm. long, from Otago Har-
bour, N.Z. ; B, Crotchet from a
specimen 208 mm. long, from
Kerguelen.
52
A renicolidae
a massive Floridan example 330 mm. long, the shaft and rostrum
are practically in line, and merge into each other. The tip of
the rostrum, shown in Fig. 26 E, which represents the end of a newly-
Fig. 23.— A. glaciate. A, Young crotchet ; B, Later phase ; C, Latest phase of
growth found.
formed, unused crotchet, soon wears away, leaving a rounded end
(Fig. 26 D).
The crotchets of A. cristata are intermediate between those
Crotchets of Arenicola
53
of A. marina and pusilla in the form of their post- rostral
region.
A. loveni. — Crotchets of large examples only, exhibiting late
growth-characters, are available (Fig. 27, A from the type specimen
and B from a similar specimen
collected in Saldanha Bay). They
are intermediate in their characters
between those of A. marina and \"^
cristata, but are, on the whole, f \ 111
rather nearer those of the latter
species.
A. ecaudata and branchialis. —
The crotchets of these two species
are practically identical in size
and form. They do not attain so
great a size as the crotchets of the
caudate species ; for they appear
not to exceed *4 mm. in length,
whereas in large examples of
A. loveni the crotchets attain a
length of '8 mm., in A. marina
and cristata *9 mm., and in A.
assimilis and pusilla 1 • 1 mm.
A crotchet from a post-larval
A. ecaudata, 8 mm. long, is shown
in Fig. 28, and presents the usual
characters found in small crotchets.
Fig. 29 represents two crotchets
from the same
neuropodium of an
adult A. ecaudata
200 mm. long.
There were in this
neuropodium 120
crotchets, of which
the small one was
the most dorsal and
was about to be cast out, while the large one was just coming
into use at the ventral end of the series. There is not usually so much
difference in size between the extreme crotchets in the neuropodia of
A. branchialis. The rostrum of the crotchets of both these species
Fig. 25. — A. cristata.
First crotchet of a
larva '25 mm. long.
Fig. 24. — A. pusilla. A, Crotchet from a Nea-
politan specimen, 17 mm. long ; B, From the
type specimen ; C, From a large specimen,
160 mm. long, from Unalaska.
54
Arenicolidae
has, when unworn, a slender and slightly upturned tip (Fig. 29),
which, however, is soon worn away when the crotchet comes
into use. Fig. 30 represents the latest growth-phase found
in the crotchets of these species.
E
X 110
Fig. 26. — A. cristata. A, Crotchet from a young adult, 48 mm. long ; B, From a specimen 130 mm.
long ; C, From a specimen 250 mm. long ; D, A worn crotchet, and E, The' tip of an unused crotchet,
from a specimen 330 mm. long.
The crotchets of the larval and post-larval stages do not afford
any reliable help in diagnosis, their form and characters seem to
change so rapidly during the very early phases of growth that
larval or post-larval crotchets of the same species, but of different
GUIs of Arenicola 55
ages, may present differences as great as those between crotchets
from different species but of about the same age. But soon after
the worm has settled down to its littoral habit the crotchets assume
the form characteristic of the species, and, henceforward, change
only gradually and in a definite manner (see p. 49).
Among the caudate species the crotchets of A. pusilla are most
readily recognised by reason of the full rounded curve of their post-
rostral region, giving the free end of the crotchet the appearance of
a swan's head and beak. The crotchets of A. marina, assimilis and
glacialis, which present no dilatation of their post-rostral portion,
are so closely similar that their aid cannot be invoked in separating
these species from one another, but they may be of use in dis-
tinguishing this trio from the remaining species. The crotchets of
A. cristata are intermediate, in the form of their post-rostral region,
between those of A. marina and pusilla, and those of A. loveni are
intermediate between those of A. marina and cristata.
GILLS.
The gills are paired hollow outgrowths of the body- wall, situated
immediately posterior to the notopodia in certain segments. They
do not arise, in A. marina, until after the full number of chaetiferous
segments, and a considerable number — about thirty — of tail-segments
have been developed. The first indication of the formation of gills
is seen in the penultimate and two or three preceding chaetiferous
segments, in which, behind each notopodium, the segmental blood-
vessels form a well-marked loop, over which there arises a slight
elevation of the body-wall— the incipient gill (cf. PI. X, Fig. 30).
The gills of these segments become successively conical, digitiform
and branched, and, meanwhile, gills make their appearance on the
last and on the more anterior segments until the full number
(thirteen pairs) has been attained. The gills are, from their earliest
stage of formation, respiratory structures ; there is no evidence that
they are modified cirri.
The gills of A. cristata arise in a similar manner and sequence ;
they first make their appearance in young examples, about 5 mm.
in length, which have the full number (seventeen) of chaetiferous
and about twenty tail-segments.
In A. ecaudata also, the gills do not arise until the worm has
almost attained its full number of segments. When the worn.
possesses about sixty fully formed segments, the formation of gill,Q
56
Arenicolidae
may be looked for, in the first instance on the sixteenth to nineteenth
segments inclusive. Subsequently gills are formed on the succeeding
segments, but a considerable period elapses
before the posterior segments acquire their
branchiae ; for instance, in a specimen 15 mm.
long, with sixty-four segments, the last twenty
segments are still abranchiate.
The gills are well supplied with blood-
vessels and are, therefore, generally red in
colour, but in old specimens they become
pigmeuted, assuming a dark "brown colour.
They are sensitive and, on stimulation,
usually contract, their red colour disappear-
ing almost entirely. Specimens intended for
the study of gills should be narcotised before
being killed— successive small quantities of
absolute alcohol being placed on the surface
of the water in which they are living — so
that the gills may remain in an extended
condition. In specimens which have been
suddenly plunged into the killing fluid, especi-
ally strong alcohol, the gills are so much
contracted that their mode of
Fig. 27.— A. looeni. A, Crotchet branching is difficult to deter-
from the type specimen ; B, , '
From a similar specimen from mine. In OCCaSlOlial SpeCl-
Saldahha Bay. ,, .,, , ,
mens the gills have lost some
of their branches either by friction against the
sand or owing to the attacks of enemies, e.g. certain
Crustacea.1
Each gill exhibits a number of main stems which
radiate, in the ecaudate species, from a common basal
trunk, or, in the caudate species, from a crescentic
fold, immediately behind the notopodium. In some
cases the cresceutic fold is of considerable extent
and forms, for instance in A. marina, a web-
like membrane between the bases of the gill-axes.
In the other species in which it occurs, this " web " is not by any
means a constant character, for instance, it is present in examples
1 See D'Orbigny, in Journ. Physique, xciii (1821), p. 198, for an account of
the attacks of the Amphipod Coropliium longicorne (now called C. volutator)
on Arenicola and other worms.
Fig. 28.— A. ecaudata.
Crotchet from a
post - larval speci-
men, 8 mm. long
(see Fig. 5).
Gills of Arenicola
57
of A. assimilis from New Zealand, but has not been found in those
from other localities.
The dorsal axes of each gill are almost invariably the largest and
evidently the oldest, judging by the number of their branches ; new
axes are added to the gill ventrally (see PI. XIII, Fig. 43).
Gills are not present in the genus Arenicola on the first six
segments ; out of some thousands of specimens the writer has seen
Fig. 29.— A. er.audata. The dorsal (small)
and ventral (large) crotchets of the same
neuropodium of a specimen 200 mm. long.
Fig. 30. — A. branchialls.
Crotchet from a specimen
230 mm. long.
only one in which a gill — a very small one — was present on the sixth
segment.1 In A. marina, pusilla, assimilis var. affinis, loveni, cristata
and glacialis the first gill is normally on the seventh segment, in
A. assimilis (typical form) on the eighth segment, in A. branchialis
on the twelfth, and in A. ecaudata on the sixteenth. In A. marina,
pusilla, loveni and assimilis (including the variety) there are thirteen
pairs of gills ; in A. cristata and glacialis eleven pairs ;inA. branchialis
1 One of Ranzani's specimens of A. clavatus (= marina) possessed a small
gill on the sixth segment.
58 Arenicolidae
and ccaudata the number varies in different specimens, the maximum
number seen in the former species is thirty pairs, and in the latter
forty-seven pairs.
In all the species the first gill is almost invariably small, and, in
a considerable percentage of examples, is reduced to minute pro-
portions or is absent. The gills extend generally to the posterior
end in adult ecaudate examples : but from one to nine segments in
A. ecaiidata, and from one to four in A. branchialis, may be gill-less.
In the caudate species of Arcnicola there are two different types
of gills, the pinnate and the fruticose (or bushy). In most specimens
the gills are readily referred to one or other of these types, but,
occasionally, it is difficult to state to which of the two forms the
gill belongs, that is, the two types merge into each other. In the
pinnate type the gill-axes are elongate, and along the sides of each
axis there are numerous — ten to twenty — opposite or alternating
branches placed at regular intervals, producing a pinnate appearance.
The subsequent division of the lateral branches is either dichotomous,
or, especially in the case of the larger ones, pinnate ; the ultimate
branches form the finger-like gill-filaments. The fruticose gill has
shorter axes, each of which bears few (three to six) lateral branches
on each side ; these branches are closely set or irregularly placed,
and they do not subdivide in a pinnate manner, but dichotomously,
or in such a manner that the ultimate branches, that is, the gill-
filaments, form a cluster. The collective effect of the massing
together of, say, eight or ten axes, similar to that described, is to
give the gill the appearance of a dense bush.
The gills of A. cristata are invariably of the pinnate type. Those
of a specimen 175 mm. long are selected (PL XIII, Figs. 41, 42) as
an average example of their size and condition in this species. The
first and smallest gill consists of eight axes, of which that shown in
Fig. 41 is the most dorsal and largest. It is 2 • 8 mm. long and bears
nine branches on each side. Owing to the shortness of these branches
their mode of subdivision seems to be somewhat irregular ; some of
them dichotomise, while others subdivide almost at once into a
cluster of gill -filaments. The largest gills of the same specimen are
composed of about fourteen or fifteen axes. The dorsal axis, 7 ' 5 mm.
long, of such a gill is shown in Fig. 42. The lower and middle
branches are subdivided freely, often in a pinnate, sometimes in a
dichotomous manner, and their terminal filaments lie, for the most
part, in one plane. In the figure these branches are represented as
seen in full view, but they actually lie in a plane almost at right
Gills of Arenicola
59
angles to that in which they are drawn. This gill-axis and the three
hundred gill-filaments it bears, affording a very large aerating surface,
would be a most efficient respiratory structure.
All the known examples of A. loveni possess typically pinnate
gills, practically identical in their form and details with those of
A. cristata.
Both types of gill are found in A. marina. The large Laminarian
form has pinnate gills similar to those of A. cristata ; the smaller
littoral form has fruticose gills.
The second gill of a littoral example of A. marina, 120 mm. long, is
shown in PI. XIII, Fig. 43. The gill consists of nine axes, " webbed "
at their base, and a tenth is just making its appearance. The longest —
dorsal — axis is about 2 mm. in length, and its lateral branches are
Fig. 31. — A. marina (from Wood's Holl), dorsal
axis of fifth gill.
Fig. 32.— A. vwilla (from Unalaska). Dorsal
axis of fifth gill.
typical of those found in this form of gill. The ventral axis is a
little unusual in that one of its branches is disproportionately
large.
A gill-axis from a specimen of A. marina (200 mm. long) from
Wood's Holl, exhibiting a rather extreme form of the bushy type, is
shown in Fig. 31. The lateral branches are few and are subdivided
into a comparatively small number of very long filaments. The
presence of eleven or twelve such axes, of which the gill is composed,
in an area about 9x6 mm., produces the effect of a dense bush.
The gills of nearly all the specimens of A. pusilla examined con-
form to the pinnate type (cf. PI. XI IF, Fig. 41). Those of massive
examples (160 mm. long) of this species from Unalaska are, however,
of different form (Fig. 32) : the axes are proportionately very short
(2 • 5 mm.) and bear on each side only three, or at most four, branches,
60 Arenicolidae
and these are subdivided into only two to four gill-filaments. These
gills have therefore a bushy appearance.
The gills of A. assimilis and of the examples of the var. affinis
from Auckland Island are similar to those of the littoral form of
A. marina, from which they differ only in the absence of " webbing "
at the base of the gill-axes. The gill-filaments of most of the
specimens examined are elongate, almost as long relatively as those
shown in Fig. 31. Examples of A. assimilis var. affinis from New
Zealand, the Falkland Islands and South Africa have pinnate gills.
A. glacialis has small gills, which present an extreme form of the
bushy type. The axes even of the largest gills are not more than 2 mm.
long. The most fully expanded gill found on any of the specimens
is shown in Fig. 33. It consists of nine or ten axes, which arise from
a short, curved, common basal structure situated immediately behind
A.
Fig. 33. Fig. 31.
Figs. 33, 34.— A. glacialix. Two gills from different specimens. A few gill-axes have been cut
away to afford a better view of the rest.
the notopodium. The longest axis (c) bears five forked branches ;
of the resultant gill-filaments the longest are thumb or finger-shaped
and not more than •? mm. in length, and the shortest are .mere
tubercles. The smaller axes of this gill bear only two or three
branches, which may be simple, that is, undivided distally (A, B).
A well expanded gill from another specimen is represented in Fig. 34.
It is smaller than that just described, the largest of the seven axes of
which it is composed being scarcely 1 mm. in length from its base to
the tip of its filaments. This axis (A) consists :of three main stems,
each of which bifurcates, and one of the two so formed again divides,
but the other does not. In this manner, three groups, each of three
gill-filaments, are clustered at the end of the axis. In all the gills
examined the branches borne by an axis are clustered at the end,
the result of the great abbreviation of the axis. A. glacialis and
Gills of Arenicola
61
cristata, both of which have eleven pairs of gills, are the extreme
terms in the gill-series : in the former the axes are reduced and the
branches clustered, in the latter the axes are elongate, and have
numerous pinnately arranged branches.
The gills of the two ecaudate species, A. ecaudata and branchialis,
which are identical in form, differ markedly from those of the
caudate species. One of the smaller gills of a Neapolitan example
of A. branchialis (76 mm. long) is shown in Fig. 35. Arising from a
short common trunk are three stems about 1 mm. long, each bearing
three branches, which are given off on one side only. The sub-
divisions of these branches are similarly restricted to one side, and
the division is invariably dichotomous. The larger gills of the same
Fig. 35.—^!. branchialis, entire gill.
Fig. 36. — A. ecaudata.
Dorsal gill - stem.
The gill had four
other stems similar
to this, all united
at their bases.
specimen have four or five main stems with more numerous
branches. A careful examination of many gills gives one the
impression that the stem is not a true axis but a sympodium. A
dorsal gill-stem of a British example of A. ecaudata (190 mm. long),
represented in Fig. 36, exhibits the same mode of branching.
COELOM AND COELOMIC SEPTA.
The coelom is spacious and continuous from one end of the
animal to the other. In front it is traversed by three transverse
septa placed at the anterior boundary of the first, third and fourth
chaetiferous segments respectively. These septa are present in all
species of the genus.
The first septum is the strongest, for a portion of the pharyngeal
62 Arenicolidae
musculature has become associated with it. In all the species,
except A. pusilla and assimilis, this septum bears two backwardly
directed muscular pouches which lie to the sides of, and ventral to,
the oesophagus (PI. XIII, Pig. 46), and open into the coelomic space
in front of the septum. The function of the pouches is unknown, but
it has been suggested that they may be of use in aiding the eversion of
the proboscis. The relative size of these pouches is practically constant
in the members of the same species, but varies considerably in the
different species ; the grade of development of these structures,
therefore, forms a useful systematic character. Septal pouches are
not represented, even as vestiges, in A. pusilla and assimilis; in
A. marina and ylacialis they are small, conical or thumb-shaped
structures, only about 2 to 3 mm. long in full grown specimens.
The pouches of A. ecaudata and branchialis are finger-like, extend
backwards almost as far as the second septum, and, in large speci-
mens, are 5 to 8 mm. long. Those of A. cristata are usually of similar
shape and length, bub in very large American specimens they attain
a length of 13 mm. The septal pouches reach the highest grade of
development in A. loveni, in large examples of which they are
25 to 26 mm. long and about 3 to 4 mm. in diameter at their widest
part (PI. IV, Fig. 11). They extend backwards through apertures in
the second septum, so that their blind ends lie against, or almost
touching, the third septum. The enormous size of the septal pouches
is the most striking feature in a dissection of this species.
The second and third septa are more extensive than the first but
much thinner; they are fenestrated and permit the passage of the
coelomic fluid and corpuscles.
From the third septum, that is, the anterior end of the fourth
segment, backwards to about the fifteenth segment the body-cavity
is uninterrupted by septa, but about the latter region vestigial
septa may be recognised as strands of connective tissue of greater or
less width accompanying some of the afferent and efferent branchial
vessels. In the succeeding segments the septa are more perfect,
and in the nineteenth segment, if not earlier, form easily recognisable,
and, at first sight, complete partitions. These septa, which are not
usually fenestrated, are, however, incomplete ventrally, that is, above
the nerve-cord, and possibly also mid-dorsally. They are well seen
in A. ecaudata and A, branchialis, and are present, though demon-
strable with some difficulty, in the tail region of the caudate species,
where they correspond in position with the inter-segmental grooves
present on the external surface.
Alimentary Canal of Arenicola 63
ALIMENTARY CANAL: BURROWING.
The alimentary canal presents an almost uniform structure
throughout the genus, but the associated glands — the oesophageal
caeca — exhibit certain differences which are of value in diagnosis.
The canal consists of (1) an eversible buccal mass and pharynx ;
(2) a cylindrical oesophagus, often transversely wrinkled, which
pierces the three septa, and, a short distance behind the level of the
last of these, bears two or more oesophageal glands; (3) the
"stomach," which is covered with yellow cells, gradually merges,
about the level of the eleventh or twelve segment, into (4) the
intestine, which extends to the posterior end of the worm and
opens at the anus to the exterior.
During life the first part of the alimentary canal, the " proboscis,"
is being constantly everted and withdrawn carrying sand or mud, with
the contained vegetable and animal organisms, into the oesophagus.
During eversion the buccal mass is first extruded, armed with
numerous rounded, conical or triangular (Fig. 45, p. 106) vascular
papillae ; afterwards is everted the pharynx, covered with small
rounded processes, which give it a mammillated appearance. In
large examples of A. marina the pointed tips of the buccal papillae are
provided with shining, black or brown, chitinoid caps. There is no
other armature associated with the alimentary canal of Arenicola;
jaws are entirely absent.
The oesophageal glands, which form a valuable diagnostic feature,
open into the posterior part of the oesophagus. In A. pusilla and
assimilis there are several of these glandular caeca on each side of
the oesophagus (PJ. XIII, Figs. 44, 45); in all the other species only
a single pair is present (Pis. IV, IX, VIII, Fig. 17). In A. marina,
cristata, glacialis and loveni the glands are generally conical in shape,
but in some cases, owing to dilatation of their anterior portion, they are
clavate. They are usually relatively smaller in A. cristata than in
other species. In A. ecaudata and branchialis the oesophageal glands
are clavate or flask-shaped, being almost always dilated anteriorly.
In the two species, A. pusilla and assimilis, in which several glands
are present, the most anterior caecum on each side is considerably
longer than the rest and has usually thinner walls. This anterior
gland is generally finger-shaped and may be nearly an inch in length ;
the others are more or less pear-shaped or ovoid and are much
shorter, some of them being only about a millimetre in length.
All the species of Arenicola burrow in sand or gravel. Burrowing
64 Arenicolidae
is accomplished by repetition of the following operations : the
" proboscis " is extended, pressed into the sand, and withdrawn full
of sand, which is passed backward into the oesophagus. The body
is thrust forwards, partly by the action of the longitudinal muscles
and partly by the peristaltic waves produced by the successive con-
tractions of the circular muscles of the body. By the latter means,
which causes surging forwards of the coelomic fluid, the anterior end is
rendered tense, and, in the caudate species, especially in A. marina,
becomes dilated, and is thus able to enlarge the depression which has
been made in the sand. The passage, which is made partly by the
sand being swallowed, partly by its being forced aside, is smoothed
by contact with the tense anterior segments, and may be lined with
mucus secreted by the epidermis of the anterior region.1 The first
few segments are thus of chief importance in burrowing operations ;
the branchial region, being in most examples of the caudate species
narrower than that which precedes it, is therefore less subject to
friction, and in all species the notopodial chaetae are capable, when
extended fan-wise, of affording the gills some protection against
undue friction. The branchial region of the animal is more or less
passively drawn forwards, after each onward thrust of the anterior
region, as the animal progresses in its burrow ; meantime, the waves
of contraction pass regularly forwards from segment to segment, and
serve the double purpose of rendering the anterior region turgid and
of assisting respiration by agitating the water in the burrow, thus
causing a change of water around the gills. These waves are, of
course^ best seen in the aseptate region of the body. After
burrowing more or less vertically downwards, to a depth of from one
to twro feet, the littoral form of A. marina may make a horizontal or
oblique passage, and then a second vertical one which opens at the
surface of the sand in a small funnel-shaped aperture. This funnel-
like aperture is said by M. Bohn to be due to the subsidence of the
sand at the surface brought about through the removal of the subjacent
sand, during feeding, by the proboscis. M. Bohn believes that from
the vertical shaft of the burrow one or more horizontal galleries are
formed, but that they have no communication with the exterior.
This is undoubtedly sometimes the case, as the writer can corro-
borate, for, while digging for small specimens about mid-way between
tide-marks, he has exposed them in L-shaped burrows. The blind
1 The sand in contact with the burrow often exhibits a reddish or brownish
discolouration, due to some chemical change induced in the iron -containing
constituents.
Food of Arenicola 65
end of the horizontal limb of each of these burrows, where the head
of the worm was found, was somewhat dilated. But in most cases,
the burrows, when complete, are U-shaped, one end terminating in
the funnel and the other being indicated by the casting. The
burrows of the Laminarian form of A. marina are vertical or
L-shaped, and the worms in them are invariably found head down-
wards.1 The depth of the burrow of both forms is often such that
the anterior region of the worm is situated below the superficial
firmer layer of sand, and extends into the subjacent, more or less
semi-fluid, mixture of sand and water.
The food and digestion of Arenicola have been investigated only
in A. marina, but no doubt closely similar conditions hold in the
other species. The material swallowed consists of sand together
with small vegetable organisms, e.g. diatoms, small animals and
animal remains ; occasionally a larger animal is swallowed, e.g. Saint-
Joseph found in one specimen a partially digested Nereid. This
material is passed into the oesophagus, where it is mixed with
mucous secretions from the oesophageal cells and, further back, the
trypsin-like secretion of the caeca is poured upon it. In the stomach
the secretion from mucus-forming and digestive cells is added to
the mass. The swinging backwards and forwards of the stomach,
brought about by the muscles of the body-wall and by the protrusion
and retraction of the proboscis, tends to produce a thorough mixing
of the sand and digestive secretions, and thus the latter are brought
into contact with the organic substances of various kinds contained
in the sand. The soluble products of digestion are absorbed in the
sinuses on the stomach by the blood, which passes almost immediately
to the hearts, whence.it is pumped into the ventral vessel and thus
to all parts of the system. The sand or mud, as passed from the
intestine by the anus, forms a rounded or trochoid heap of vermicular
coils, along each turn of which a thin cord of mucus may often be
seen. These coiled castings of A. marina are familiar objects on
innumerable sandy beaches of northern and western Europe, and
similar castings are formed by the other caudate species when
feeding in not too coarse a medium.
The burrows of the ecaudate species are oblique or sinuous
cavities in the gravel or between the stones and rocks among
which these worms live, and the castings, being composed of coarse
1 Many of the specimens seen in their burrows were found with the anterior
and middle parts of the body lying in the horizontal limb, a position doubtless
correlated with the greater abundance of water in this region of the burrow.
F
66 A ren icolidae
material, having little coherence, generally soon fall to pieces. In
any case the castings are inconspicuous among their surroundings,
and therefore do not betray the presence of the worms, as in the case
of A. marina.
NERVOUS SYSTEM AND SENSE-ORGANS.
The brain is situated in the prostomiuni. In the caudate species
it may be compared in form to the letter H, or, more accurately, to
two slightly flattened pears, lying side by side, with their narrower
faces adjacent and fused along the middle third of their length. The
more massive anterior portions of the pears represent the anterior,
and the tapering portions the posterior brain-lobes, the latter of
which lie below the nuchal organ. In the ecaudate species the brain
is of simple form — practically non-lobate, almost band-like — and
merges at each end into the oesophageal connectives. The brain
gives off anteriorly and posteriorly bundles of nerves to the pro-
stornial epithelium and the nuchal organ respectively.
The oesophageal connectives arise, in the caudate species, from
the anterior and middle regions of the brain. In all species the con-
nectives run obliquely backwards and ventrally (PI. XIII, Fig. 46), and
unite with the ventral nerve-cord some distance in front of the first
chaetiferous annulus — that is, in the achaetous body-segment which
precedes the first chaetiferous segment. The course of the con-
nectives and the ventral nerve-cord is indicated externally, in some
species, by the metastomial and ventral grooves (Fig. 53, p. 118).
The oesophageal connectives give off nerves to those annuli through
wrhich they pass, and to the statocysts.
The ventral nerve-cord does not exhibit, in dissections, any
obvious signs of segmentation, its nerve-cells are not aggregated into
definite ganglia, but are distributed along the lateral and ventral
portions of the whole length of the cord. In all species, except
A. pusilla, there are, at segmental intervals, among the ordinary
nerve-cells, much larger "giant cells," which are connected with
remarkable "giant fibres." The ventral nerve-cord gives off a pair
of nerves to each inter-annular groove, and one or more pairs to each
chaetiferous annulus and its parapodia.
The organs of special sense are the statocysts, the nuchal organ
(see p. 38), and the eyes. Other sensory structures are the pro-
stomium, the papillae of the "proboscis," scattered sense-cells in
the epidermis, the notopodial chaetae (around the bases of which
Statocysts of Arenicola 67
Prof. Eetzius found nerve-endings), and, possibly, the pits present on
certain of the chaetiferous annuli of A. loveni and cristata (p. 35).
The statocysts are the most highly developed sense-organs of
Arenicola. They are present in all the known species, except
A . pusilla, and afford valuable help in specific work.
The statocysts of the lug worm were the first statocysts observed
in Annelids : they were discovered, in 1838, by Grube, who, how-
ever, mistook them for ganglia, but Stannius (1840) and von Siebold
(1841) at once recognised the analogy between these organs and the
statocysts of Molluscs. Meissner (1857), in a note1 long overlooked,
first showed that the statocysts of the lugworin open to the exterior
by means of a canal. During the last twenty years the statocysts of
Arenicola have been the subject of researches by Profs. Elders and
Fauvel and Drs. Gamble and Ash worth.
The statocysts are situated a short distance from the brain, external
to the dorsal or dorso-lateral portions of the oesophageal connectives
(PL XIII, Fig. 46). Each statocyst is primarily an imagination of
the epidermis, and in A. marina, assimilis and glacialis the connection
with the epidermis and the exterior is maintained by means of a
narrow bent tube, the minute aperture of which may be found near
the origin of the metastomial groove (see p. 39). The walls of the
statocyst and tube are composed of sensory and epithelial cells ;
some of the latter are glandular and secrete the thin cuticle which
lines the vesicle and the tube. Each statocyst contains one or more
statoliths, and a fluid composed of a mixture of sea water and the
secretions of the gland cells in the wall of the organ.
It is important to note that, in those species in which there is a
tube leading from the statocyst to the exterior, the shape and nature
of the statoliths vary considerably in different specimens of the same
species, according as the tube is functionally open or closed. This
has been shown, by the present writer, to be the case in both
A. marina and A. assimilis var. affinis. Numerous specimens of the
former species, from different localities, have been examined. In
those in which the statoliths consist of many foreign bodies, such
as quartz-grains, portions of sponge-spicules, frustules of diatoms, etc.,
practically without any secreted covering (PI. XIV, Fig. 47), the tube of
the statocyst was found to be open ; in others in which the original
statoliths had become covered with layer upon layer of pale-yellow
secreted substance (Fig. 37 A) the tube was found invariably to have
1 Zeits. ration. Med., 3 Reihe, i. (1857), p. 635 f.n.
F 2
Arenicolidae
ST.T ;
Fig. 37.—^.. marina. Statoliths, and cuticular lining: of statocysts, of specimens from Jersey (A),
and Trieste (B). ST.T. Tube leading to exterior.
ST.T.
A
B
Sr.T
Fig. 38. — A. assimilis var. affinis. Statoliths, and cuticular lining of statocysts ;
A, Of a specimen, 136 mm. long, from Otago Harbour, N.Z. ; B, Of a specimen,
128 mm. long, from the Falkland Islands. ST.T. Tube leading to exterior,
Statocysts of Arenicola 69
become closed, either by apposition of its walls or by blocking of its
lumen by granular substance secreted by the gland cells in the wall
of the tube. A striking instance of this latter condition was exhibited
by a specimen from Trieste, in which each statocyst (Fig. 37 B) con-
tained about forty statoliths, approximately spherical, nearly uniform
in diameter, and composed almost entirely of secreted chitinoid
substance, there being in each only a small central " nucleus." The
statocysts were completely shut off from the exterior, the tube of each
being closed by a plug of granular secretion.
Similar conditions are met with in A. assimilis var. affinis. The
statoliths of examples from Otago Harboiir, New Zealand, are
irregular bodies (Fig. 38 A) ; but those of specimens from near
Wellington, New Zealand, from Tasmania and from the Falkland
Islands (Fig. 38 B), are rounded, each being composed of a central
granule with a thick envelope of yellow secreted material.1 The
canal of the statocyst is moderately widely open throughout its
length in the Otago examples, but in all the others is closed at one
or more points, generally by small masses of secretion of the same
refringent nature as that composing the statoliths. In each statocyst
of the two Falkland specimens examined there are two statoliths larger
than the rest. They were the first statoliths of the post-larval stage.
These observations on A. marina and A. assimilis var. affinis
indicate clearly that the nature of the statoliths depends on whether
actual open communication with the exterior is or is not maintained.
The form of the statoliths in those species in which a canal leads
from the statocyst is variable, and is therefore a character of little
value in systematic work.
Only one statocyst of A. glacialis is available for examination.
The lumen of the tube which connects the statocyst to the exterior
is open throughout its length, and the
statoliths are numerous naked sand-
grains (Fig. 39).
In A. cristata, loveni, branckialis
and ecaudata the connection of the
statocyst with the epidermis and ex- Fig 39—4. giaciai^~si^mhs, and
terior has been lost, and the organ has ^KMftSSk^1*1 '
become a closed, oval or spherical sac,
in which the statolith or statoliths are spherical, oval or lenticular
chitinoid bodies. In A. cristata (Fig. 40) and loveni there is a
1 The statoliths are of this latter type also in two specimens of A. assimilis
from Uschuaia.
70
Arenicolidae
single statolith throughout life. In A. ecaudata and Iranchialis
(Fig. 41) there is at first only one statolith. Later many others are
formed, but the original one remains conspicuous by reason of its
larger size.
The statocysts of A. assimilis attain a much larger size than those
of any other species : indeed, they are the largest known in the
Polychaeta. There is some difference in the size of these organs in
similar specimens of the same species from different localities.
Fig. 38 A, B, which represent the statocysts of similar specimens of
A. assimilis var. affinis, from Otago and the Falkland Islands
respectively, illustrate an extreme instance of local variation in the
size of these organs.
The eyes are of simple structure. Each is formed of a lens
Fig. 40.— A. cristata. Statolith, and
cuticular lining of statocyst.
Fig. 41.— A. branchialis. Stato-
liths, and cuticular lining of
statocyst.
and a cup-shaped mass, about 8 to 20.//, in diameter, composed of
reddish-brown pigment-spherules (PI. X, Fig. 25). In the early
stage of larval life the eyes are actively functional, and during the
first two days after hatching the larvae are phototropic ; but by the
third day this preference for light is lost. The eyes soon sink below
the epidermis, and become imbedded in the masses of ganglion-cells
which form the dorsal and anterior portion of the brain. With the
increase in the amount of pigment in the prostomial epithelium the
eyes become difficult to find, and are finally indistinguishable. It
seems unlikely that in adult specimens the eyes' can have any
functional importance.1
1 Arenicola is sensitive to light, resembling earthworms in its reaction to
this stimulus, and, as in them, the response may be due to the stimulation of
the sense-cells in the epidermis, especially of the anterior end ; it is unlikely
that it is due to specific action through the eyes, for the reasons given above.
Nephridia of Arenicola 71
KEPHEIDIA.
There are five pairs of nephridia in Arenicola pusilla, lovenTand
branchialis, six pairs in A. marina, assimilis,1 cristata and glacialis,
and thirteen pairs in A. ecandata.
Each nephridium may be divided into three regions — an anterior
funnel, a middle excretory portion, and a posterior vesicle or bladder.
The funnel, which is usually bright red in colour, owing to its rich
vascular supply, opens into the coelom by a slit -like aperture. The
larger dorsal lip of the funnel is fringed with ciliated vascular pro-
cesses, which increase in number and size as the worm grows: In
the caudate species these processes are flattened and spatulate or
triangular in shape, and their distal margin is usually subdivided into
several rounded lobes (PL XIV, Figs. 48, 49, 50). In the ecaudate
species the processes are more cylindrical, and are more deeply divided
distally into two or three, or in large specimens two to six, finger- or
thumb-shaped branches (PI. XV, Fig. 51). The ventral lip is not
fringed, and its margin is either entire and almost semicircular in shape,
as in A. marina, or it is deeply notched in the middle, as in the
ecaudate species. In A. assimilis the edge of the ventral lip of the
funnel is thrown into folds or frills (Fig. 50) ; a similar condition is
very occasionally met with in one or two other species, but in these the
" frilling" is much less marked than in A. assimilis. In A. cristata
the middle portion of the ventral lip is often thicker than the rest.
Owing to the reduction in the number of septa in Arenicola the
typical relationship of nephridium to septum, as exhibited in many
Polychaeta and Oligochaeta, is seen in the adult of only three species,
and then only in regard to the first pair of nephridia. In A. marina,
assimilis 2 and glacialis the funnels of the first pair of nephridia are
situated on the anterior face of the third septum ; in the other
species the first nephridium is in the following somite.
The excretory part of the nephridium is a thin-walled spacious
sac, usually dark brown, sometimes black, in colour, owing to the
presence of large numbers of brown excretory granules in the cells
lining the sac. This part of the organ tapers posteriorly and leads
into the contractile bladder, which opens to the exterior by a small
oval aperture situated near, and slightly behind, the dorsal end of the
corresponding neuropodium.
1 South African examples of A. assimilis var. affinis have only five pairs, •
the nephridia of the fourth segment being wanting.
2 Except in South African examples of the var. affinis (see footnote ').
72 A renicolidae
BEPRODUCTIVE ORGANS.
The reproductive organs are closely associated with the nephridia.
In the caudate species and in A. branchiali? the gonad is present
f--\ immediately behind the funnel of each
nephridium, except the first, and is a small,
ovoid or cylindrical mass of cells (PL XIV,
Figs. 48-50; PL XV, Fig. 51) around the
anterior portion or the whole length of the
gonadial vessel,1 which is a continuation of
the blood-vessel traversing the dorsal lip of
the funnel. The genital products are shed at
an early stage from the gonads into the
coelomic fluid, and by an examination of this
the sex of a given specimen is determinable.
There the small groups of sperniatogonia
undergo repeated division and become succes-
sively spermatocytes, spermatids and sperma-
tozoa, large discoidal masses of which are
present in the coelom of mature worms. The
oocytes are shed from the ovary when they
are about 12 to 20 /i in diameter; while in
the coelomic fluid their yolk is elaborated
and they grow to the definitive size. The
c ripe ova of A. marina, pusilla, assimilis
and cristata 2 are not spherical but biconvex
(Fig. 42 B) ; the face of the ovum is either
circular or oval and its two diameters are
from • 14 to • 20 mm., while the third axis
of the egg is about • 08 mm. The vitelline
membrane is comparatively thin, being 1 to
2 /i in thickness. The ova of A. Iranchialis
ina. Ripe sper- an(^ ecaudata, which have a very stout
matozoon ; B, A. marina. Ripe vifpllinp mpmhranp ri to fi // in tliinViiPca
ovum, face view by transmitted ^el Diane, ^ O /i in UllCKlieSS,
light, profile view by reflected QT>P nval in elianp nnrl arp papVi ol>r>n1
light: C, A. bmnchialis. Ripe are OVal L sllaPe an^
• 17 mm. long and • 15 mm. broad (Fig. 42 c).
The reproductive organs of A. ecaudata are much larger and more
complex than those of the other species, and form the most striking
1 There is a gonadial vessel on the first nephridium, but a gonad appears
never to be associated with it.
2 Probably also those of A. glacialis and loveni, but eggs of these species
have not been available in a sufficiently good state of preservation to enable
the writer to determine their true shape.
Gonads of Arenicola 73
feature in a dissection of this species. In the female the gonad is
produced into processes, which at first are few, small, and more or
less conical in- shape, but later on increase in number and size, and
in maturing examples assume very large proportions (PL XV, Fig. 52).
Such processes are packed with numerous oval oocytes, about • 12 mm.
in diameter, each with a thick vitelline membrane. In male specimens
the gonad bears one, two, or occasionally three or four, thin reniforin
outgrowths, pink, grey or milk-white in colour, according to the
condition of their contents (Fig. 53). Within each of these out-
growths, which may attain a length and breadth of 6'0 and 4'5 mm.
respectively, are present male cells in all phases of development up
to almost ripe spermatozoa. In this species, therefore, the repro-
ductive products are retained in association with the gonad to a
much later stage of growth than in the other species of the genus.
Just before the breeding period, the envelope of the gonad is
ruptured, and the sexual products fall into the coelom and there
undergo their final stages of growth.
The genital products, in all the species of Arenicola, escape from
the coelom to the exterior by way of the nephridia,1 the vesicles of
which are often found, during the breeding season, strongly distended
with ova or sperms which have accumulated therein preparatory to
discharge.
DEVELOPMENT.
Max Schultze 2 found on the island of Neuwerk, off Cuxhaven,
large numbers of castings of Arenicola marina, and near to many of
them a pyriform, greenish-yellow, gelatinous mass, about half an inch
in length, fastened into the sand by a gelatinous stem about two
inches long. He traced the development of the eggs within these
masses, which he regarded as the egg-masses of the lugworm, an
opinion shared by a few subsequent writers. Messrs. Cunningham
and Ramage and Profs. Ehlers and Fauvel ascribed these egg-masses
to Scoloplos armiger, and Dr. Groot 3 has definitely proved their
parentage by finding them in an aquarium in which specimens of
S. armiger, but no examples of Arenicola, were living.
1 M. Bohn states that the ova escape by perforations, due to histolysis
of the body-wall at the breeding season (C. B. Acad. Sci. Panis, cxxxiii (1901),
p. 647). The present writer has not observed this phenomenon in any of the
numerous ripe examples which have passed through his hands.
2 Abh. naturf. Ges. Halle, iii (1856) p. 216.
3 Proefschr. Univ. Leiden (1907), p. 23.
74
Arenicolidae
In spite of the abundance in innumerable places of the adult
worm, and of much searching by many workers, the egg-masses of
Arenicola have never been found on the coast of Europe. The egg-
masses of only one species — A. cristata — are known, and they have
been recorded only from the eastern shore of the United States,
from Wood's Holl to South Carolina. They are huge gelatinous
masses, often irregularly cylindrical, three to four feet long and two
to four inches in diameter, each of which contains several hundred
thousand eggs. The vitellus of the egg has a cinnamon colour, so
that in bulk the egg-mass has a reddish-brown tint.
The early stages of development of two species of Arenicola have
been investigated, namely, A. cristata by Profs. E. B. Wilson * and
C. M. Child 2 and Dr. E. S. Lillie,3 and A. pusilla by the writer.4
These two species seem to develop along practically identical
lines. Within about twenty-four hours after fertilisation, the egg
gives rise by spiral cleavage to a blastula, from which a gastrula
is formed by growth of the ectoderm cells over the yolk-laden
endoderm cells. Shortly afterwards the stomodaeal invagination and
the prototroch appear (PL X, Fig. 21), and within three days after
fertilisation the paratroch is formed, and one or two eyes are present
on the anterior portion of the larva (Fig. 22). About the end of the
third day the larva pushes its way out of the vitelline membrane
through a thin area which had previously made its appearance.
During the following day the first pair of notopodial chaetae is formed
(Fig. 23), and in the next two or three days the first crotchets are
produced. For the first day or two after hatching the larvae are
phototropic and swim near the surface of the water ; but
then they begin to settle down, and may be found crawling about
the bottom, surrounded by a more or less tubular film of mucus,
with which foreign bodies may be entangled. The belts of cilia
decrease in size and soon disappear. The alimentary canal is about
this time complete from mouth to anus, and is divisible into three
regions — the anterior and moderately active oesophageal part, the
stomach, which still contains a considerable amount of yolk, and the
intestine (Fig. 24). The coelom, brain and nerve-cord, and muscle-
fibres in the body- wall are clearly recognisable. Shortly after the
larvae settle down on the bottom, the pharynx becomes active as
Stud. Biol. Lab. Johns Hopkins Univ., ii (1882), p. 278.
Arch. f. Entwick., ix (1900), p. 587.
Mitt. Zool. Stat. Neapel, xvii (1905), p. 341.
Liverpool Mar. Biol. Comm., Mem. xi (1904), p. 55.
Development of Arenicola 75
a feeding organ, and food particles are passed into the oesophagus.
The subsequent stages of larval development have been followed
only in A. cristata, to which species, therefore, the succeeding part
of this account relates. New segments are formed in the growing
zone immediately in front of the anal segment (pygidium) until the
full number of chaetiferous segments is attained. Henceforward the
segments formed (thirty-eight to forty in number) are of a different
nature and are without chaetae (PI. X, Fig. 30). By the time that
about twenty tail-segments have been formed, gills begin to make
their appearance on the posterior chaetiferous segments in the
manner described on p. 55. The changes which take place in
the internal organs have been traced only in relation to the septa,
nephridia and alimentary canal. Septa are formed and are for
some time present between all the chaetiferous segments, and pro-
nephridia are developed in association with the third to the tenth.
The first two of these pro-nephridia become degenerate ; the others
are transformed into the nephridia of the post-larva. In the
meantime the regions of the alimentary canal have become more
clearly marked; blood, blood-vessels and hearts have been formed,
and the nervous system and sense-organs have become more fully
differentiated.
POST-LARVAL STAGES, WITH A DISCUSSION OF THE GENUS
CLYMENIDES.
Prof. Benham applied the term " post-larval " to that stage of
development of Arenicola marina in which the worm has attained
the 'full adult number of chaetiferous segments, and is divisible into
an anterior chaetiferous region and a posterior achaetous region or
tail, but in which the gills are not yet completely formed or have
not even made their appearance.
Post-larval stages of five species of Arenicola are known, namely,
A. marina, ccaudata, branchialis, assimilis and cristata. Those of
the two first-named species have been the subject of considerable
discussion, because by some writers they were regarded, not as
stages in the growth of Arenicola, but as belonging to a separate
genus, Clymenides.
There can be little doubt that the worm described by Claparede
in 1863,1 and referred by him to a new genus and species —
1 Beobacht. Anat. wirbell. Thiere Normandie (1863), p. 30, taf. xv,
tigs. 24-27.
76 Arenicolidae
Clymenides sulpkurea — of the family Maldanidae,1 was a post-larval
example of Arcnicola marina. The specimen, which was 3-4 mm.
long, was found in mud, surrounded by a mucous tube. There are
only two points in which Claparede's account does not fully apply to
a post-larval Arenicola marina, namely, his specimen is said to have
had twenty-two chaetiferous segments, whereas only nineteen are
present in A. marina, and oesophageal glands are neither mentioned
in the description nor shown in the figure (op. cit., Fig. 24) in which
the rest of the alimentary canal is represented. Nevertheless the
account is so fully in agreement with the characters presented by a
young Arenicola marina that we may conclude, with Prof. Mesnil,
that Claparede was dealing with a post-larval specimen of this species.
Prof. Ehlers2 described in 1892 the chief features of a young
Arenicola marina, 3*5 inm. long, enveloped in a gelatinous sheath,
taken in the plankton off Heligoland, and of a similar example,
taken at the mouth of the Ems, which was examined in sections,
and in which the presence of statocysts was ascertained.
A more detailed account of " post-larval " examples of A. marina
was given by Prof. Benham3 in 1893. This was based on two
specimens, collected near Plymouth, each about 6 • 8 mm. long, and
enveloped in a colourless, transparent sheath.
Prof. Mesnil4 states that Clymenides sulfur eus Clap, was taken
commonly in the townets at Wimereux in June and July, 1892 and
1893, and that the specimens were evidently similar to those studied
by Prof. Benham, and could be described, systematically and
anatomically, as young Arenicola marina, without gills and with
the crotchets of a Clymenid. Although these young worms so
closely resembled A. marina, Prof. Mesnil preferred to regard them
as Clymenides sulfureus, and as belonging to the family Clymenidae,
a conclusion to which he was impelled largely by the characters of
the crotchets.
In his later paper (1897) Prof. Mesnil described two new species
of Clymenides, namely, ccaudatus and incertus. Though at first
inclined to regard the latter as the young phase of BrancMomaldanc
1 Quatrefagcs (Hist. nat. Annel., ii (1865), p. 249) placed Clymenides
sulfureus in the family Clymeniens (= Maldanidae); it was included in the
Maldanidae also by Prof. Baoovitza (Arch. Zool. Exper., ser. 3, iv (1896), p. 229
and f.n.).
2 Nachr. K. Ges. Wiss. Gottingen (1892), pp. 415, 416.
3 J. Mar. Biol. Assoc., iii (1893), p. 48, pi. i.
4 C. B. Soc. Biol. Paris, ser. 10, iii (1896), p. 388; Bull. Sci. France Belg.,
xxx (1897), p. 144.
Post-Larval Stages of Arenicola 77
vincenti, he concluded, chiefly because of differences in the structure
of the chaetae, that the two forms did not stand in this relationship.
He believed the genus Clymenides (with three species) to be homo-
geneous, defined it, and regarded it as intermediate between the
Clymenidae (Maldanidae) and Arenicolidae. While admitting that
he had not seen gonads in any specimen, he expressed the opinion
that, if these examples of Clymenides had an ulterior development,
it would not be towards Arenicola but parallel to it. His studies
on these worms led him to put forward the view that there is a
continuous series connecting the Maldanidae and Arenicolidae, and
to suggest the union of these two families (see p. 27).
Prof. Fauvel's1 investigations led him to the conclusion that
C. sulphureus was the young of Arenicola marina, that C. ecaudatus
and C. incertus were stages in the growth of A. ecaudata, and that,
therefore, the genus Clymenides was invalid. By keeping an example
of C. ecaudatus in an aquarium until it grew into an A. ecaudata
50 mm. long, he produced conclusive proof of the identity of these
two forms.
In a paper published in the same year Prof. Mesnil2 admitted
that C. sulfureus and C. ecaudatus were early phases of A. marina
and A. ecaudata respectively, and expressed the opinion, based on
renewed observations, that C. incertus was probably the young
form of Brancliiomaldane vincenti. The writer is able to confirm this
opinion after having examined, through the courtesy of Prof. Mesnil,
the three original specimens of C. incertus.
Thus the species of Clymenides have been merged either with
Arenicola or with BrancMomaldane, and Clymenides therefore dis-
appears as a generic name.
Post-Larval Stages of ARENICOLA MARINA.
The earliest known stages of Arenicola marina have the full
number of chaetiferous segments and about twenty tail-segments.
They are found in the surface waters of the sea, not far from shore,
each enclosed in a mucous or gelatinous tube, which usually extends
beyond the worm at either end (PI. X, Fig. 26). The worm is capable of
wriggling movements, which are but little impeded by the enveloping
tube. Nothing is known concerning the duration of the pelagic life
of the post-larval stage, but it is apparently at least several days.
1 C. R. Acad. Sci. Paris, cxxvii (1898), p. 733; Proc. 4th .Int. Congr. Zool.
(1899), p. 229.
2 Zool. Anz., xxi (1898), p. 637.
78 Arenicolidae
Post-larval stages have been taken off the British, French and
German coasts, from March to August, but the majority were found
either in March, April, or in the early part of May. Most post-larval
specimens of A. marina seem to take to a littoral habit before the
gills have been formed, or, at any rate, when only a few pairs of gills
are indicated : but the writer has two specimens, found free-swimming,
which bear the full complement of gills. In one of these the annula-
tion of the body is well marked, and the prostomium is proportion-
ately small ; this worm had reached the end of the post-larval stage
and would doubtless soon have settled down to its littoral habit.
The following account, based on the examination of about thirty
post-larval specimens, some of which were examined alive, applies
more particularly to specimens about 4*5 to 6 mm. in length. The
prostomium (PI. X, Fig. 27) is large, conical or spatulate in form,
and overhangs the mouth. It bears dorsally, on each side of the
middle line, two to four eyes, one of which — that first formed in
the larva — is larger than the others. The peristomium is always
achaetous. Within it are the statocysts, the internal diameter of
which is '04 to *06 rum., from each of which the tube leading to
the exterior may be traced. The succeeding segment is achaetous
in all the specimens examined by the writer, but Profs. Ehlers and
Benham found in some of their specimens a minute chaeta in this
segment ; evidently this is a transitory condition, for the chaeta
soon disappears, leaving the segment achaetous, as it is invari-
ably in the adult. Both the peristomium and this segment are
generally rather smaller than the succeeding chaetiferous segments,
and both are subdivided, usually into two, by a shallow groove, so
that, as in the adult, the region between the prostomium and first
chaetiferous segment is formed of four rings. The nineteen segments
which follow are all chaetiferous, each bearing notopodial and neuro-
podial chaetae, which are described on pp. 43, 48.
The tail has thirty to fifty segments, of which the anterior are
usually the smallest (see p. 38).
The skin is glandular ; it contains numerous scattered cells, filled
with yellow granules, and mucus-forming cells, which secrete the
enveloping tube. The secondary annulation of the skin, which
corresponds with that of the adult, is seen in many of these post-
larval stages. For an account of the formation of the gills, see p. 55.
The gut, which has already attained the adult form, usually
contains only a small amount of food-matter, in fine debris. The
blood-vessels and paired contractile hearts are well developed, and
Post- Larval Stages of Arenicola 79
arranged as in the adult, and six pairs of tubular nephridia l are
present.
Post-larval examples of A. marina are from 3 -5 to 8 -5 mm.
long, and may be identified by reference to their general form, their
nineteen chaetiferous segments, the presence of six pairs of nephridia
(the pores on the fourth to the ninth segments are generally visible),
a single pair of oesophageal glands, and open statocysts.
Post-Larval Stages of ARENICOLA CRISTATA.
Near Beaufort, North Carolina, Prof. E. A. Andrews2 found,
enveloped in a gelatinous tube, a young Arenicola, evidentlv
belonging to the species A. cristata, in which statocysts were
present, each containing a single large statolith. There is no other
record of the capture of a post-larva of this species, but Dr. E. S.
Lillie has reared specimens in aquaria.
The full number of body-segments, that is, seventeen chaetiferous
segments, is acquired by the time the young worm is about 2 mm. in
length. When it has attained a length of 5 mm. about twenty tail-
segments have also been formed, and gills are beginning to make
their appearance on the posterior chaetiferous segments. The worm
continues to grow in length, by elongation of the body- segments and
by the formation of new tail-segments, until the latter have reached
a definite number, namely, thirty-eight to forty (PI. X, Fig. 30).
Meanwhile, the formation of gills proceeds from behind forwards
until these organs appear on the seventh segment. The end of the
post-larval stage has then been reached, and the worms have become
young adults in structure and in form, and are about 6 to 7 mm. long.
Most later phases present a tail region comprising considerably fewer
than forty segments, due to the readiness with which segments are
lost from the posterior end.
The principal diagnostic features of post-larval stages of this
species are — seventeen chaetiferous segments, six pairs of nephridia
(their pores on the fifth to the tenth segments), one pair of
oesophageal glands, a pair of moderately large septal pouches, and a
pair of closed statocysts, each containing a single statolith. These
characters can be seen in most preserved examples, which have been
stained lightly, and cleared carefully in cedar-wood oil.
1 For an account of their structure, see the writer's Liverpool Mar. Biol.
Comni. Memoir (1904), p. 67.
2 Proc. U.S. Nat. Museum 1891, xiv (1892), p. 300.
80 A ren icolidae
Post-Larval Stages of ARENICOLA ASSIMILIS var. AFFINIS.
Mr. E. Vallentin found three worms on the surface of the sea,
near the Falkland Islands, which the writer1 has shown to be
post-larval stages of A. assimilis var. affinis. The specimens were
7 • 6, 8 ' 7 and 11 • 1 mm long respectively, and were abranchiate. The
largest was provided with a transparent gelatinous envelope about
1 mm. in diameter, which covered the worm except for a distance of
nearly 1 mm. at each end. These specimens resembled post-larval
stages of A. marina, except that there were six to eight oesophageal
glands on each side (PI. X, Fig. 29). Six pairs of nephridia were
present, and on the last three the gonad was already recognisable.
The statocysts were found as two in v aginations of the peristomial
epidermis, the lips of each being approximated so as to form a short
tube. In each statocyst there were four to six statoliths — sand-
grains or fragments of spicules. A gill-less post-larval stage of this
species and variety, 6 * 5 mm. long, was found among the " roots " of
seaweeds near Uschuaia.2 These four are the only known post-larval
specimens of this species.
Post-larvae of A. assimilis may be differentiated from those of all
other species of Arenicola, except A. pusilla,s by the presence of
several pairs of oesophageal glands. The presence of statocysts,
which was established only after careful examination, showed that
the specimens described above could not belong to the species
A. pusilla, but must be examples of A. assimilis, and, having
nineteen chaetiferous segments, they were referable to the variety
affinis.
Post-Larval Stages of AEENICOLA ECAUDATA.
The writer has examined about thirty specimens, a dozen of
which were abranchiate. The latter range in length from 3 to
9 '4 mm., and, in addition to the peristomium and the achaetous
body-segment, have fifty-three to fifty-eight fully formed and
chaetiferous segments, and two or three recently differentiated and
as yet achaetous segments, followed by the pygidium (PI. XI,
Fig. 34). The prostomium is large and bluntly conical, and bears
groups of eyes latero-dorsally. The achaetous peristomium contains
1 Q. J. Micr. Sci., xlvi (1903), p. 764.
2 Ehlers, E., " Polychaeten," in Hamb. Magalh. Sammelreise, ii, 1 (1897),
p. 104.
3 Post -larval stages of this species have not yet been discovered.
Post- Larval Stages of Arenicola 81
the closed statocysts, each with a single, spherical, secreted statolith.
The following segment is achaetous in all the examples seen by the
writer, but Profs. Mesnil and Fauvel have recorded the presence, in
some^of their specimens, of a single capillary chaeta in this segment.
The succeeding segments, except in some cases the two or three last
formed, are chaetiferous. In several of the posterior notopodia there
is for a short time a crotchet, accompanied usually by one or more
capillary chaetae (p. 40). The characters of the chaetae are described
on pp. 40, 43, 53.
Gills are present only in well-grown examples, not less than about
8 mm. long, with approximately sixty fully formed chaetiferous
segments. The gills first appear on the sixteenth to eighteenth
segments, and then on the succeeding segments (PI. XI, Fig. 35) ; but
for a considerable time the posterior segments are abranchiate. For
instance, specimens with sixty-two and sixty-three segments are gill-
less behind the thirty-second and forty-fourth respectively. By the
time the gills have become bifid or trifid the worm begins to change
its habitat. It leaves the bases of the algae among which it has
hitherto lived, and moves to sand or gravel, in which it commences
to burrow.
The body- wall is reddish or pale -greenish yellow, or it is dark
green, owing to the presence of a considerable amount of pigment,
which is especially abundant in the first few segments.
The alimentary canal has assumed the adult form, and the
iiephridia, of which there are thirteen pairs, are already (in specimens
10 mm. long) becoming saccular, and a definite funnel is present ;
but the dorsal lip has not yet developed the processes present
thereon in the adult.
Post-Larval Stages of AKENICOLA BRANCHIALIS.
Among a collection of post-larval and young stages of Arenicola,
taken in September, 1910, among the "roots" of Laminaria in
Blacksod Bay (Mayo), by Mr. E. Southern, the writer has found four
post-larval examples of A. hranchialis, the first known specimens.
They are 4 '4, 5*5, 5 '8 and 6'5 mm. long, and have thirty-eight,
forty-two, forty and forty-one chaetiferous segments respectively. In
the first, third and fourth specimens there are two newly-formed
achaetous segments immediately in front of the pygidium. The
specimens are abranchiate, and exhibit yellow pigmentation anteriorly
and posteriorly.
G
82 A renicolidae
The general appearance of these worms is similar to that of post-
larval A. ecaudala, but they have about twenty segments fewer.
The chaetae are practically identical with those of A. ecaudata , and,
as in post-larvae of that species, a crotchet is present in four or five
of the last formed notopodia.
Each statocyst contains one large and about eight minute
statoliths.
The nephridia, which have simple funnels, are short wide tubes,
opening posteriorly on the fifth to the ninth segments. Of great
interest is the presence, in one specimen, of paired vestigial funnels
in the tenth, eleventh and twelfth segments, suggesting that the
series of nephridia probably at one time extended further back
than it does now. It is possible that these funnels might have
disappeared during the subsequent phases of growth, but they are
so well marked, that it seems more probable that the three segments
which contain them would have been provided with small funnels,
similar to that figured by the writer1 in the tenth segment of an
adult specimen of this species.
Post-larval stages of A. branchialis differ from those of A. ecaudata
in having fewer segments and nephridia.
Examples of Branchiomaldanc vincenti present a general external
similarity to post-larval stages of A. ecaudata and branchialis; but
the former may be recognised by the bi-annulate gill segments, in
which the chaetae and gills are on consecutive rings (cf. Figs. 33, 35,
PI. XI), by the presence of gonads and only two pairs of nephridia,
and by the absence of statocysts and pigment.
Separation of the Genus ARENICOLA into Sections and Species.
The genus Arenicola is divisible into two sections, one — the
caudate section — contains those species, six in number, which
possess a posterior region or " tail " upon which neither parapodia
nor gills are borne : the other — the ecaudate section — comprises two
species in which the parapodia, and generally also the gills, extend
to the posterior end of the worm. In addition to this obvious dis-
tinction, the two sections of the genus exhibit several other
differential characters, both external and internal,
1 Q. J. Micr. Sci., xliii (1900), pi. xxvi, fig. 54,
Caudate Species of Arenicola 83
The Caudate Section of the Genus AEENICOLA.
The characters of the caudate section may be given thus : — The
parapodia and gills do not extend to the posterior end of the worm,
an achaetous and abranchiate " tail " is present. There are eleven
or thirteen pairs of gills, the first borne usually on the seventh x or
eighth 2 segment ; the gills, the axes 3 of which bear branches
bilaterally, are either pinnate or fruticose (bushy). The pro-
stomium is trilobate. Each statocyst4 is either provided with
a tube leading to the exterior, in which case numerous statoliths,
generally of foreign origin, are present, or it is a closed vesicle
containing only a single secreted statolith. The dorsal lip of each
nephridiuin bears a fringe of flattened vascular processes; the
margin of the ventral lip is not deeply notched, it may be thrown
into folds or frills, but it is more often simple. The gonad is small,
the ova are biconvex,5 and their vitelline membrane thin (1-3 //,).
KEY TO THE CAUDATE SPECIES OF AEENICOLA.
1. Nineteen or twenty chaetiferous segments; thirteen (or
twelve) pairs of gills, the first on the seventh or eighth
segment 2.
Seventeen chaetiferous segments ; eleven pairs of gills,
the first on the seventh segment 6.
2. Neuropodia of the posterior branchial segments long, their
grooves extending almost to the mid-ventral line ; one
pair of oesophageal glands ; one pair of septal pouches 3.
Neuropodia of the posterior branchial segments short,
forming oval pads on the sides of the segments, their
grooves not neatly reaching to the mid-ventral line ;
several pairs of oesophageal glands ; no septal pouches 4.
8. Lobes of the prostomium almost equal in size ; nephridia
opening on the fourth to the ninth segments ; septal
pouches small ; statocyst s each with a tube leading to
the exterior, and with numerous statoliths (sand-grains) marina, p. 86.
Median lobe of the prostomium large ; nephridia opening
on the fifth to the ninth segments ; septal pouches very
large; statocysts closed, each containing a single large
secreted statol th loveni,6 p. 103.
1 The gill of this segment may be reduced or absent.
2 In typical examples of A. assimilis.
3 In A. glacialis the gill-axes are much reduced and the branches clustered.
4 Statocysts are not present in A. pusilla.
5 In those species in which ova have been examined in the fresh condition.
The ova of two species have not been available in the fresh state.
6 The notopodial chaetae of this species, with their well developed " Sage-
blatter" and transverse striation, are very characteristic (see p. 44).
G 2
84 A renicolidae
4. Twenty chaetiferous segments ; nephridia opening on the
fourth to the ninth segments ; statocysts large, each
with a tube leading to the exterior and with numerous
statoliths assimilis, p. 123.
Nineteen chaetiferous segments 5.
5. Lateral lobes of prostomium of moderate size, not dilated
or folded anteriorly ; nephridia opening on the fourth (or
fifth1) to the ninth segments ; statocysts present, each
with a tube leading to the exterior and with numerous
statoliths assimilis var.
Lateral lobes of prostomium large or very large, generally o-ffims, p. 124.
folded at their anterior end ; nephridia opening on
the fifth2 to the ninth segments; statocysts absent;
the post-rostral region of the neuropodial crotchets
is more dilated and convex than in the preceding
species pusilla, p. 114.
(=; claparedii).
6. Gills large, pinnate ; nephridia opening on the fifth to the
tenth segments ; septal pouches large ; statocyfcts
closed, each containing one large secreted statolith cristata, p. 105.
Gills small, bushy ; nephridia opening on the fourth to the
ninth segments ; septal pouches small ; statocysts each
with tube to the exterior and with numerous statoliths
(sand-grains) glacialis, p. 1 1 1 .
It is advisable not to depend on external characters alone when the
species marina, assimilis and pusilla are concerned. An incision
should be made along the mid-dorsal line of the specimen, extending
from the eleventh segment nearly to the prostomium, so as to
permit examination of all the important organs. Especial care is
necessary in discriminating A. pusilla and A. assimilis var. affinis.
If the prostomial lobes are well preserved they offer most valuable
help in diagnosis, but if their preservation is defective reference
should be made in turn to the statocysts, crotchets and nephridia.
As the statocysts are more or less imbedded in the muscle and
connective tissue, careful search is necessary, or they may escape
observation.
The Ecaudate Section of the Genus AEENICOLA.
The characters of the ecaudate section {Arenicolides Mesnil3)
may be stated thus : — The parapodia, and generally also the gills,
extend practically to the posterior end of the worm ; there is not an
elongate " tail," but behind the last chaetiferous annulus there is a
terminal conical portion, consisting of not more than about six.
1 In South African specimens of A. assimilis var. affinis^
2 Rarely on the fourth to the ninth (see p. 118).
3 See p. 31.
Ecaudate Species of Arenicola 85
annuli. Gills are not present on the first eleven or fifteen segments ;
the main gill-stems, which seem to be of the nature of sympodia, bear
branches unilaterally. The prostomium x is simple and non-lobate, it
is a transverse band or ridge, generally exhibiting a slight median
elevation ; the prostomium merges into the " upper lip " of the
peristomium, and forms with this a conical structure overhanging
the mouth. Each statocyst is a closed sac, which contains, in the
adult,2 numerous spherical secreted statoliths. The dorsal lip of
each nephridium bears on its margin several digitiform, often bifid
or trifid, vascular processes; the ventral lip is deeply notched in
the middle. The eggs are oval and have a thick vitelline mem-
brane (5-6 /*).
KEY TO THE ECAUDATE SPECIES.
First gill on the sixteenth segment ; thirteen pairs of
nephridia opening on the fifth to the seventeenth
segments; gonads large ecaudata, p. 132.
First gill on the twelfth segment ; five pairs of nephridia
opening on the fifth to the ninth segments ; gonads
small branchialis, p. 138
(= grubii).
About sixteen other species of Arenicola have been founded, but,
as will be shown subsequently, they must all be merged with one or
other of the eight species mentioned in the keys. Attempts have
been made previously, but on insufficient data, to merge some of the
species; for instance, Ives (1891) believed that all specimens of
Arenicola then known could be properly referred to three species,
namely, marina, cristata, ecaudata. That suggestion was based on
imperfect acquaintance with the external, but especially with the
internal, characters of several of the species in question. At that
time, and for a few years afterwards, the internal anatomy of all
the species, except A. marina, was practically unknown, and that
of two of the species has become known only during the last
two years, owing to the investigations carried out by the writer in
preparation for this Catalogue.
1 Prof. Fauvel describes the prostomium of A. ecaudata as an obtuse cone,
and that of A. branchialis as reduced to a simple transverse ridge. The writer
has examined a large number of specimens of both species, but cannot find any
constant difference between them in regard to their prostomia ; the variations
of form exhibited by the anterior end are due apparently to differences in the
amount of contraction taking place on fixation.
2 In young post-larval stages only a single statolith is present, others are
formed subsequently ; but the original one is distinguished from the rest by its
greater size.
86 Arenicolidae
ARENICOLA MAEINA (Linnaeus).
Plate I ; Plate IV, Fig. 10 ; Plate X, Figs. 26, 27, 28 ; Plate XII, Figs. 39, 40 ;
Plate XIII, Figs. 43, 46 ; Plate XIV, Figs. 47, 48.1
Lumbricus marinus —
Belon, De Aquatil., ii (1553), p. 444.
Aldrovandus, Aniin. Insect. (1638), p. 734.
Barbut, Genera Verm. (1783), p. 13, tab. i, fig. 9 (Bognor).2
Bruguiere, Tabl. encycl. Vers, etc., i (1791), p. 102, pi. xxxiv, fig. 16.
Daly ell, Pow. Creator, ii (1853), p. 135, pi. xxix, figs. 1-3.
Dumeril, Bull. Soc. Philom., Paris, i (1797), p. 114 (Treport).
Fabricius, J. C., Reise Norwegen (1779), p. 257.
Fabricius, 0., Fauna Groenl. (1780), no. 262.
Home, Phil. Trans. E. Soo. Lond. (1817), p. 1, pi. iii, figs. 1-3.
Linnaeus, Wastgota Resa (1747), p. 189, tab. iii, fig. 6 ; Syst. Nat., x Edit.,
i (1758), p. 648 : xii Edit., i, 2 (1767), p. 1077 : xiii Edit. (Gmelin), i, 6
(1788), p. 3084; Fauna Suec., Edit, altera (1761), no. 2074; Amoen.
Acad., Rar. Norweg. (1769), p. 483.
Mutter, Zool. Dan. Prodr. (1776), no. 2609 ; Zool. Dan., iv (1806), p. 39,
tab. civ, figs. B 1-5 (Heligoland).
Oken, Isis., i (1817), 469, taf. iii.
Olafsen et Povelsen, Voy. Islande, i (1802), p. 139.
Pennant, Brit. Zool., iv (1777), p. 34, pi. xix, fig. 7.
Eoyet, Bridgew. Treat., v. i, 2 Edit. (1834), p. 276.
Lumbricus littoralis —
Olafsen u. Povelsen, Reise Island, ii (1772), p. 478, taf. x, fig. 8.
Lumbricus maximus —
Linnaeus, Syst. Nat., vi Edit. (1748), p. 71.
Lumbricus papillosus —
Miiller, Zool. Dan. Prodr., no. 2615.
Fabricius, Fauna Groenl., no. 267.
Lumbricus punctis prominulis —
Linnaeus, Fauna Suec. (1746), no. 1270.
Arenicola piscatorum —
Lamarck, Syst. Anim. s. Vert. (1801), p. 324 ; Hist. Anim. s. Vert., v
(1818), p. 336; 2 Edit. (Edwards), v (1838), p. 580.
Audouin et Edwards, Ann. Sci. Nat., xxx (1833), p. 420, pi. xxii, figs.
8-12 ; Hist. Nat. Litt. France, ii (1834), p. 285, pi. viii, figs. 8-12.
Bos, Tijdschr. Ned. Dierk. Ver., i (1874), p. 58 (Groningen).
Caillaud, Ann. Soc. Acad. Nantes, xxxvi (1865), p. 27 (Loire-Infer.).
Carrington, Proc. Lit. Phil. Soc. Manchester, iv (1865), p. 186 (Southport).
Chenu, 111. conchyliol., i (1842), pp. 1, 11, pi. i, figs. 1-4.
Cori, Naturfr. am Strande Adria . . . (1910), p. 9.
Cosmovici, Arch. Zool. Exp., viii (1880), p. 241.
Danielssen, K. Norske Vid. Selsk. Skr., iv (1859), p. 121; Nyt Mag., xi
(1861), p. 54 (along coast of Norway to Vadso).
1 For other figures of this species, see Figs. 9, 17, pp. 42, 48, chaetae of
post-larval stages ; Figs. 13, 18, 19, 20, pp. 46, 49, 50, chaetae of adults ;
Fig. 31, p. 59, gill ; Fig. 37, p. 68, statocysts.
2 Hill's L. scaber, from Bognor (Hist. Anim., iii (1752), p. 15), was probably
the lug worm.
Arenicola marina 87
Arenicola piscatorum (continued) —
Edwards, Ann. Sci. Nat. Zool., ser. 2, x (1838), p. 221, pi. xiii, figs. 1, la.
Giard, Bull. Sci. Dep. Nord., x (1878), p. 34 (Wimereux).
Gibson, Proc. Lit. Phil. Soc. Liverpool, xl (1886), App.,p. 156 (L'pool Bay).
Grube, Anat. u. Phys. Kiemenwiirm. (1838), pp. 2-18, taf. i; Aus-
flug n. Triest (1861), p. 167 ; Abh. Schles. Ges., Abt. Nat. (1869),
pp. 99, 127 (St. Vaast) : (1872), pp. 93, 115, 142 (St. Malo ; Roscoff) ;
?"Annulaten" in MiddendorfFs Eeise nord. u. ost. Sibir., ii (1851),
Zool. I, pp. 1, 17.
Guerin-Meneville, Iconogr. Regne Anini., ii, pi. iv, fig. 1.
Heape, J. Mar. Biol. Ass., ii (1888), p. 169 (Plymouth).
Johnston, Loudon's Mag. Nat. Hist., viii (1835), p. 567 (Berwick Bay) ;
Catal. Worms Brit. Mus. (1865), pp. 229, 344.
Kicer, Nyt Mag., xlii (1904), pp. 64, 73, 76 (Drobak Sd.) ; Tromso Mus.
Aarsh., xxviii (1906), p. 17 (Bals Fj.).
Koehler, Ann. Sci. Nat. Zool., ser. 6, xx (1885), no. 4, pp. 8, 16, 37, 45
(Jersey, Guernsey, Herm).
Lafont, Acta Soc. Linn. Bordeaux, xxviii (1873), p. 264 (Arcachon).
Landsborough, Exc. Arran, with Ref. to Nat. Hist., 2 ser. (1852), p. 49.
Lankester, Ann. Mag. Nat. Hist., ser. 3, xvii (1866), p. 390 (Guernsey).
Maitland, Descr. Syst. Anim. Belg. Sept. (1851), p. 209.
Marcialis, Boll. Soc. Roman. Zool., i (1892), p. 250 (Sardinia).
Marshall, Brehm's Thierleben, x (1893), p. 120 (Nice); D. Meere u. ihre
Bewohner (1896), pp. 12, 194.
Mettenheimer, Abh. Senck. Naturf. Ges., iii (1859-61), p. 292 (Norderney).
Meyer u. Mobius, Fauna Kieler B., i (1865), p. xi.
Orsted, Naturh. Tidsskr., R. I., iv (1843), p. 126 (Greenland) : R. II, i (1845),
p. 414 (Christiania Fj.) ; Annul. Dan. Consp., i (1843), p. 47, tab. i,
figs. 1, 13; K. Dansk. Vid. Selsk. Nat. Afh., x (1843), p. 207.
Packard, Mem. Boston Soc. Nat. Hist., i (1867), p. 293 (Belles Amours,
Labrador).
Payraudeau, Catal. Ann. et Moll. Corse (1826), p. 18.
Pollard, in Morey's Nat. Hist. I. of Wight (1909), p. 234.
Quatrefages, Hist. Nat. Annel., ii (1865), p. 262, pi. x, fig. 18.
Sars, M., Beskr. Bergen. Kyst levende Dyr (1835), p. 47 ; Nyt Mag., vi
(1851), p. 206 (Tromso and Ox Fj.).
Savigny, Syst. Annel. (1820), p. 96.
Scott, 15 Ann. Rep.' Fish. Board Scotl. (1897), p. 159 (L. Fyne).
Stannius, Arch. Anat. Phys., Jahrg. 1840, p. 352 (Fohr; Copenhagen).
Stimpson, Sinithson. Contr. Knowl., vi (1854), Art. V, p. 31 (Grand
Manan) ; Proc. Boston Soc. Nat. Hist., v (1856), p. 114 (Massach. Bay).
Thompson, Rep. 13 Meet. Brit. Ass. (1844), p. 273; Nat. Hist. Ireland,
iv (1856), p. 432.
Verany, Catal. Anim. invert. Genova (1846), p. 10.
Verrill, Bull. Essex Inst., iii (1872), p. 6 (Eastport, Maine).
Wagner, Wirbell. d. weiss. Meer., i (1885), pp. 42, 46 (Solwetzky).
Williams, Rep. 21 Meet. Brit. Ass. (1852), p. 160, etc.
Arenicola piscatorum, partim —
Grube, Anat. u. Phys. Kiemenwiirm. (1838), p. 1 ; Act., Ech., u. Wiirmer
d. Adriat. u. Mittelm. (1840), p. 66.
Schmarda, Neue wirbell. Thiere, i (1861), 2 Half., p. 52.
Vogt et Hung, Traite Anat. Comp. (1888), p. 481.
Arenicola marina —
Allen and Todd, J. Mar. Biol. Ass., n.s., vi (1901), p. 195 (Salcombe Esty.) ;
(1902), p. 321 (Exe Esty.).
88 Arenicolidae
Arenicola marina (continued) —
Ashivorth, Liverpool Mar. Biol. Cornm. Mem. xi (1904) ; Fisheries Ireland
Sci. Invest. 1908, vii (1909), p. 1 (Dublin Bay ; Galway) ; Ann. Sci.
Nat. Zool., ser. 9, x (1910), p. 112; Mitt. K. Zool. Mus. Berlin, iv
(1910), p. 348 (Labrador; Marquesas and Kingsniill Is.); Proc. U.S.
Nation. Mua. xxxix (1910), p. 5 (Nova Scotia; Chile).
Beaumont, Proc. R. Irish Acad., ser. 3, v (1900), p. 784 (Valencia).
Benham, J. Mar. Biol. Ass., iii (1893), p. 48, pi. i (post-larva) ; Camb. Nat.
Hist., ii (1896), p. 333.
Bohn, Bull. Mus. Nat. Hist. Paris, ix (1903), p. 62.
Browne and Vallentin, J. B. Inst. Cornwall (1904), p. 130 (Scilly Is.).
Collin, Lim Fj. Fauna (1884), pp. 8, 20.
Cunningham and Bamage, Trans. B. Soc. Edin., xxxiii (1888), p. 648.
Dahl, 6 Ber. Kornm. Wiss. Unters. Kiel (1893), p. 171 (Elbe).
Desmarest, Encycl. Hist. Nat. (Chenu) (1859), p. 304, pi. xxxvii, fig. 3.
Ehlers, S.-B. phys.-rned. Soc. Erlangen, v (1873), p. 9 (W. Finmark) ;
Nachr. K. Ges. Wiss. Gottingen (1892), p. 413 ; Zeits. Wiss. Zool., liii,
Suppl. (1892), p. 217, etc., taf. xi, xii (statocyst).
Elwes, J. Mar. Biol. Ass., n.s., ix (1910), p. 64 (Torquay).
Fauvel, C. B. Acad. Sci. Paris, cxxvii (1898), p. 733 (post-larva) ; Mem. Soc.
Nation. Sci. Nat. Math. Cherbourg, xxxi (1899), p. 171 ; Bull. Sci. Fr.
Belg., xxxiii (1899), p. 313; Ann. Sci. Nat. Zool., ser. 9, vi (1907),
p. 27 (statocyst).
Ferronniere, Bull. Soc. Sci. Nat. Quest France, ser. 2, i (1901), p. 18, etc.
(Loire-Infer.).
Gamble and Ashworth, Q. J. Micr. Sci., xli (1898), p. 1, pi. i-v ; xliii (1900),
pp. 422, 541.
Graeffe, Arb. Zool. Inst. Wien, xv (1905), p. 10 (Trieste).
Grieg, Bergens Mus. Aarb. 1888, no. 2 (1889), p. 8 (Moster).
Hornell, Proc. Trans. Liverpool Biol. Soc., v (1891), p. 248 (L'pool to Beau-
maris ; I. of Man).
Horst, Tijdschr. Ned. Dierk. Ver., Suppl. i (1884), p. 556 (E. Schelde) :
2nd ser., v (1896), p. 24 (N. Sea Is.) : 2nd ser., xi (1909), pp. 138, 149
(Wieringen, Zuider Z.) ; Notes Leyden Mus., xi (1889), p. 37, pi. iii, figs.
2-5 (gills, chaetae).
Lenz, Anh. J.-B. 1874-5 Komm. Wiss. Unters. Kiel (1878), p. 11 (Trave-
miinder B.).
Leslie and Herdman, Invert. Fauna Forth (1881), p. 66.
Levinsen, Vid. Med. Naturh. Foren. Kjobenh. (1883), p. 134.
M'Intosh, Invert, and Fish. St. Andrews (1875), pp. 101, 125.
Malm, K. Vet. Handl. Goteborg, xiv (1874), p. 88 (Bohuslan).
Malmgren, Ofvers. K. Vet. Akad. Forh., 24 Arg (1868), p. 188 (Spitsbergen ;
Proven and Godhavn, Greenland).
Metzger, Hannover J.-B., xx (1871), p. 23: xxi (1871), p. 32 (Friesland) ;
J.-B. Comm. Wiss. Unters. Kiel, 1 Jahrg (1873), p. 175 (Norderney).
Michaelsen, J.-B. Komm. Wiss. Unters. Kiel, N.F., ii (1896), p. 67.
Mobius, J.-B. Comm. Wiss. Kiel, i (1873), p. 107 (Sassnitz) ; S.-B. K. Preuss.
Akad. Wiss. Berlin (1893), 1 Halbbd., p. 77 (W. coast Schleswig).
Nobre, Ann. Sci. Nat. Porto, viii (1903), p. 91 (Foz de Douro).
Nordgaard, Hydrogr. Biol. Invest. Norw. Fjords (1905), pp. 163, 235
(Sandhorno).
Norman, Ann. Mag. Nat. Hist., ser. 7, xii (1903), p. 283 (Sydvaranger Fj.).
Petersen, Beretn. Danske Biol. Stat., i (1892), p. 171 (Hollbsek Fj.) ; iii
(1893), p. 33 (Fam0).
Saint-Joseph, Ann. Sci. Nat. Zool., se"r. 7, xvii (1894), p. 121 (Dinard) :
ser. 8, v (1898), pp. 217, 219 (Concarneau; Le Croisic).
Sars, G. 0., Nyt Mag., xix (1873), p. 247 (Christiania Fj.).
Aremcola
Arenicola marina (continued) —
Tauber, Annul. Danica (1879), p. 110.
Templeton, London's Mag. Nat. Hist., ix (1836), p. 234.
Verrill, Amer. J. Sci., 3 ser., x (1875), p. 39 (Noank, Conn.).
Webster and Benedict, U.S. Comm. Fish., ix (1884), p. 725 (Race Run.
Mass.).
Willem, Trav. Stat. Zool. Wimereux, vii (1899), p. 574.
Wiren, Vega-Exped. Vet. Arb., ii (1883), p. 406 (C. Ragosin, Kara Sea).
Arenicola marina, partim —
Ives, Proc. Acad. Nat. Sci. Philad. 1890 (1891), p. 74.
Marenzeller, Zool. Jahrb. Abt. Syst., iii (1888), p. 12.
Arenicola carbonaria —
Leach, Encycl. Brit., 4th Edit., Suppl. i (1816), p. 452, pi. xxvi.
Caillaud, Ann. Soc. Acad. Nantes, xxxvi (1865), p. 28.
Chenu, 111. conchyliol., i (1842), pp. 1., 12, pi. i, fig. 7.
Arenicola clavatus —
Eanzani, Opusc. Sci., ii (1817), p. 110, tab. iv ; Isis (1817), 1449-1452,
taf. xi.
Arenicola natalis —
Girard, Proc. Boston Soc. Nat. Hist., v (1856), p. 88.
Arenicola papillosa —
Quatrefages, Hist. Nat. Annel., ii (1865), p. 266.
Arenicola tinctoria —
Leach, Encycl. Brit., 4th Edit., Suppl. i (1816), p. 452.
Arenicole des pecheurs —
Cuvier, Bull. Sci. Soc. Philom. Paris (1802), no. 64, pi. vii, figs. 1-5; Regne
Anim., ii (1817), p. 527 : op. cit., 2 tidit., iii (1830), p. 197 : op. cit.,
Edit. Disc., Aanel. (Edwards), pi. i, pi. viii, fig. 1.
Clymenid.es sulphurea —
Claparede, Beobacht. Anat. wirbell. Thiere Normand. (1863), p. 30.
Fauvel, Hist. nat. Cotentin, iii (1905), p. 75 (St. Vaast).
Clymenides sulfurea —
Claparede, op. cit., p. 118, Descr., taf. xv, figs. 24-27.
Clymenides sulfureus —
Mesnil, C. R. Soc. Biol. Paris, ser. 10, iii (1896), p. 388 (Wimereux) ; Bull.
Sci. Fr. Belg., xxx (1897), pp. 148, 163.
Eruca marina,1 — the fishers call it Lug —
Sibbald, Hist. Fife and Kinross (1710), p. 56.
Lugg—
Carew, Survey Cornwall (1602), p. 34 b.
1 The "Eruca marina — ad littus maris in Cornubia" of Merrett (Pinax
Rerum Nat. Brit., Lond. (1667), p. 36), was possibly the lugworm, previously
recorded from Cornwall by Carew. Merrett also mentions (p. 196), " Lumbricus
mar."
90 A renicolidae
Nereis lumbricoid.es —
Pallas, Nova Acta Acad. Sci. Imp. Petrop., ii (1788), p. 233, tab. v, figs.
19, 19*.
Orm —
Linnaeus, Sk&nska Eesa (1751), p. 315 (Helsingborg).
Vermis ex arena effossus Lug dictus —
Sibbald, Scotia 111., ii (1684), pars 3, p. 34.
Vermes marini scolopendroides, Corrmbiensibus Lugs dicti —
Ray, Hist. Insect. (1710), p. 46.
Ver du Havre —
Dicquemare, Obs. sur la Phys., Eozier, xiii (1779), p. 19, pi. ii.
Caudate Arenicola with nineteen * chaetiferous segments ; thirteen
pairs of gills, the first, which is on the seventh segment, may be
small or absent ; gills either bushy or pinnate ; the three lobes of
the prostomium are nearly equal in size — at any rate, the lateral
lobes are seldom much larger than the median one ; neuropodia
clearly visible in each segment, in the posterior branchial segments
forming long muscular ridges reaching nearly to the mid-ventral
line ; six pairs of nephridia, which open on the fourth 2 to the ninth
segments ; one pair of oesophageal glands, conical or club-shaped ;
one pair of small globular, conical or flask-shaped septal pouches ;
a pair of statocysts, each with tube to the exterior, statoliths
numerous, composed of sand-grains, which may be enveloped to a
greater or less extent with material secreted by the walls of the
statocyst.
HISTORICAL ACCOUNT. — This worm was first described by Belon
(1553), who observed the use of the "proboscis" in burrowing, the
power of contraction of the worm, the tufts of hair in the "joints"
in front of the plumes [i.e. the gills], the yellow colour exuded
from it, and the castings.
The first reference to this worm in British literature seems to be
that by Carew (1602), which is further noteworthy as being the first
record of the name " Lug," 3 by which this species is still commonly
known among fishermen.
1 Prof. Benham (Cambr. Nat. Hist, ii, p. 333) attributes to A. marina twenty
chaetiferous segments, but this number has been found only in a small percentage
of post-larval stages examined ; the normal number in young and adult specimens
is nineteen.
2 The first nephridium is not uncommonly reduced or even absent.
3 Low German — slow, heavy. The word "lob," which is sometimes used
instead of lug, is of similar origin, and expresses " the general notion of some-
thing heavy, clumsy."
Arenicola marina 91
Willughby (in Eay's Hist. Insect.) was the first to enter into
detail regarding its external characters, such as the inequality of
the rings, the number of "cirri" [notopodia], the presence of a
tail and anus. The only internal organs which had been mentioned
by previous writers were the "proboscis" and the intestine.
Willughby saw the hearts and probably the two series of nephridia,
which he called black testes, and the stomach, with its peculiar
marking into oval areas, which, however, he mistook for a uterus.
Linnaeus recorded and figured Lumbricus marinus in the account
of his journey through West Gothland (1747), and introduced the
name of this worm into the next (sixth) edition of the " Systema "
(1748) ; but, probably owing to a misprint, the specific name was
given as maximus. In the tenth and twelfth editions of the
" Systema " the worm was named Lumbricus marinus ; thus Belon's
name for the lugworm, which had been in use for two centuries,
received the imprimatur of Linnaeus. The generic name has
necessarily been changed, and the specific name was, for a time,
eclipsed by piscatorum, but, being subsequently restored, it remains
as a nexus with the earliest mention of this worm in zoological
literature.
Dicquemare (1779) published a general description of the
external features and colours of the " Ver du Havre," which also
included a short account of the gut. He mentioned the extensive
use of this worm for bait, and that it was even an object of
commerce, being gathered in Basse Normandie and taken to Havre
for sale.
Otto Fabricius (1780) gave a clear description of Lumbricus
papillosus, evidently the common lugworm (see p. 93), in which he
referred to the short, foliate, retractile, trifid rostrum [the prostomium],
the proboscis, the groove [ventral groove] along the abdomen, the
nineteen bundles of setae, protrusible and movable in various
directions, and the occurrence behind each bundle, except the first
six, of a- soft brownish branched cirrus [gill]. The subdivision of
the segments into annuli, the presence of a cuticle, the sandy
contents of the intestine, the burrows and the spiral castings were
also noted.
In 1801 Lamarck founded the genus Arenicola for the lugworm
(p. 31), but, instead of retaining the specific name which had been
so long in use, he re-named it Arenicola piscatorum, a designation
which was adopted for the lugworm by all subsequent writers, with
two exceptions, until 1868. The two exceptions were Templeton
92 Arenicolidae
(1836) and Desmarest (1859), Loth of whom used the name Arenicola
marina. Malmgren (1868) placed this name at the head of the
section dealing with this worm in his well-known " Annulata
Polychaeta." Claparede, in immediately following his example,
pointed out the incontestable priority of the Linnaean specific name ;
but the designation A. piscatorum had attained such a firm hold
that its use was continued for many years after Claparede had
shown its invalidity ; indeed, it is only during the last ten or
fifteen years that the correct name, A. marina, has been generally
employed.
In 1802 Cuvier, in his paper on worms with red blood, gave an
account of the gills and vascular system of Arenicola. His figures
contain good representations of tbe hearts and blood-vessels, the gills,
setal sacs and muscles, and the alimentary canal. They also show
five pairs of "bourses noiratres" [i.e. nephridia], the function of
which was unknown to Cuvier, but appeared to him to be connected
with reproduction. The function of two other " bourses charnues "
[oesophageal glands], attached to the oesophagus, was also then
unknown.
Oken (1817) made an unaccountable mistake in the number of
gills. He emphasised the statement that there are sixteen pairs, and
not fourteen.1 He gave a good description of the form of the gills
and the gut, and pointed out the true nature of the " proboscis."
Savigny (1820) made a more careful examination of the external
features of A. piscatorum than any of his predecessors. He was the
first to notice the presence of crotchets. He also observed, above the
first segment, the small trilobed " caroncule " [prostomium], retractile
into a transverse groove [nuchal groove].
Milne Edwards gave a short account, illustrated with classical
figures, of Arenicola piscatorum in Cuvier's Eegne Animal. Grube's
thesis (1838) contains an excellent description of each system of
organs of the worm. Cosmovici (1880) dealt particularly with the
circulatory system and excretory organs, aud Prof. Ehlers (1892)
with the external features of the anterior end, the nervous system,
and sense-organs. Vogt and Yung (1888) and Saint-Joseph (1894)
have published general accounts of this worm, and Drs. Gamble
and Ash worth (1898) a more detailed study of its anatomy and
morphology. The memoir of the last-named author (1904) contains
the latest description of the lug worm.
1 0. F. M filler (1806) had stated that the worm had fourteen pairs of gills.
Arenicola marina 93
OBSERVATIONS ox THE RECORDS. — The worms recorded and figured
by Olafsen and Povelsen as Lunibricus littoralis were specimens of
Arenicola, and may be safely referred to A. marina, which is the
only species known from Iceland. L. papillosus, first described briefly
by Miiller, and afterwards in greater detail by Fabricius, was regarded
by Quatrefages as a distinct species — Arenicola papillosa — because
Fabricius had referred to the presence of small appendages at the
base of the " rostrum " [prostomium]. The remainder of the
description given by Fabricius (see p. 91) accords so accurately with
A. marina, which is the only species known from Greenland, that
there need be no hesitation in referring the record to this species.
The appendages, on the presence of which emphasis was laid by
Quatrefages, were either the papillae of the upper lip or the everted
nuchal epithelium.
Lumbricus punctis prominulis, of the first edition of Linnaeus'
Fauna Suecica, was given in the later edition as a synonym of
L. marinus.
Of the records cited under Arenicola piscatorum only a few
require comment. Grube (1851) recorded under this name a single
specimen collected by Middeudorff during his journey "in den
aussersten norden und osten Sibiriens." The record is placed here
provisionally, for if the specimen was found on the east coast of
Siberia it was taken close to the area of distribution of A. pusilla,
and may have belonged to this species. Grube stated that the
specimen was about two inches long, and possessed only eighteen
chaetiferous segments and twelve pairs of gills, which numbers are
not normal for either A. marina or pusilla, or indeed for any other
known species. The specimen probably belonged to one of these
species, but exhibited reduction in the number of segments and gills.
The records by Marcialis from Sardinia, by Marshall from Nice,
by Payraudeau from Corsica, and by Verany from Genoa, should be
accepted with caution until other specimens from these localities
have been examined and shown to belong to the species A. marina
and not to A. pusilla.
Several of the records of Arenicola piscatorum from the Mediter-
ranean and Adriatic almost certainly include A. pusilla, which occurs
in both seas, and are therefore placed under "A. piscatorum, partim."
Grube referred specimens from Italy and Sicily (1838), and from the
Mediterranean generally (1840), to the species A. piscatorum. In the
" Collection Grube " in the Kgl. Zoologisches Museum, Berlin, there
is a bottle containing specimens labelled " Arenicola piscatorum.
94 A renicolidae
Mittelmeer," possibly some of those mentioned in the two memoirs
cited. These specimens belong to the species A. pusilla (see the
writer's paper on this collection, 1910). Schmarda (1861) stated
that he found in the Mediterranean, the Channel and on the coast of
the Pacific the same species, A. piscatorum; but from a subsequent
statement in his description it is clear that the Pacific examples were
not of this species.1 Vogt and Yung mention that the examples of
A. 'piscatorum from Naples are smaller than those from the Channel
and North Sea. The former are examples of A. pusilla. It should
be borne in mind, when considering these records, that it was not
until 1883 that Dr. Levinsen pointed out the characters which
distinguish A. daparedii ( = pusilla) from A. marina, and that about
fifteen years elapsed before the former species was generally accepted.
Up to the time of Dr. Levinsen's memoir all specimens of Arenicola
with nineteen segments and thirteen pairs of gills had been referred
to the species A. marina, and this practice prevailed, with only one
or two exceptions, until almost the end of last century.
Passing to the records under Arenicola marina, the writer has
identified, as belonging to this species, specimens in the Kgl.
Zoologisches Museum, Berlin, with labels indicating that they were
collected in the Marquesas and Kingsmill (Gilbert) Islands ; but as
the information is regarded as being a little uncertain, the records
are stated under reserve. The writer's record from Chile rests upon
a specimen, in the collection of the Zoological Institute of Vienna,
which Prof. K. Grobben kindly sent for examination. The label
reads " Arenicola piscatorum, Chile." Although the specimen is not
in a good state of preservation, it can be identified with certainty as
A. marina. There is, unfortunately, no other information as to the
history or exact place of capture of the worm. If it be from Chile
it is, so far as the writer is aware, the only specimen of A. marina
from the west coast of America, and before this species is regarded as
a constituent of the fauna of that coast it is desirable that other
examples be procured therefrom.
Ives referred all specimens of Arenicola with six pre-branchial
and thirteen branchial segments to "A. marina," which was thus
made to comprise several species. The localities cited show that,
besides A. marina, there were included A. glacialis, pusilla, assimilis
var. affinis, and possibly A. loveni. The examples placed by Prof, von
Marenzeller under "A. marina" have been shown by the writer to
1 For remarks on these specimens, see p. 120.
Arenicola marina 95
include representatives of two other species, namely, A. pus-ilia (from
Vancouver) and A. assimilis var. affinis (from Angra Pequena).
Leach defined A. carbonaria as having "body, coal black." The
specimen, which was found near Leith, is doubtless that in the
British Museum Collection labelled "Arenicola carlonaria. Black
Eock, Frith of Forth. Mus. Leach." This is a very dark example
of A. marina (cf. PI. I, Fig. 3).
Eanzani based his species Arenicola clavatus on three specimens
in the Museum, of the University of Bologna.1 The place of origin of
the specimens 2 was unknown. Eanzani distinguished his new species
from A. piscatorum, as described by Pallas and Cuvier, because the
anterior region was inflated and thicker than the middle region, the
tail was long and " articulated," and the gills black. The dilatation
of the anterior portion, due to the forward rush of the coelomic
fluid, and the articulation of the tail, caused by strong contraction of
some of the circular muscles, are features of no specific value ; they
are seen in many specimens of A. marina which have been killed
quickly in alcohol. The specimen figured by Eanzani was about
217 mm. long, so that, if from the Adriatic or any other European
source, it is certain to have been an example of A. marina, as the
other externally similar European species — A. pusilla — attains only
about half this length. A. clavatus may therefore be safely merged
with A. marina.
The specimens 3 on which Girard founded the species A. natalis
were shortly and insufficiently described. Nevertheless, it is certain
that they were ordinary examples of A. marina. It is evident that
Girard mistook the ventral for the dorsal surface, as he stated that
the dorsal region was marked by a conspicuous smooth line, dividing
on the cephalic region into right and left branches, which united
anteriorly. This smooth line, the dorsal position of which was given
as one of the specific characters, is, however, mid-ventral : it marks
the position of the nerve-cord, and is seen in all specimens of
A. marina. The other distinguishing features of A. natalis — the
1 During a visit to that Museum the writer made inquiry for Banzani's
specimens, and careful, but unsuccessful, search was made for them ; they are
no longer preserved.
2 Oken (Isis (1817), 1452), but without stating his grounds, said that they
came from the Adriatic. The writer has examples of A. marina from Trieste,
which agree closely in size and appearance with those described by Banzani.
3 The specimens have apparently not been preserved. The Curator of the
Boston Society of Natural History stated, in answer to the writer's inquiries,
that he had not been able to locate the type of A. natalis, and that there was
no record of its having been given to the Society.
96 Arenicolidae
cephalic region not club-shaped but tapering, and the reticulation of
the anterior end — are worthless as systematic characters, for they
depend largely on the degree of extension, and therefore on the
mode of preservation adopted. Girard's specimens, which were from
Chelsea, Mass., were examples of A. marina, which species has been
recorded from other stations in the same State.
A. papillosa has been considered already (p. 93). A. tindoria
was a light-coloured example of A. marina. It was denned by
Leach as having ': body yellow, inclining to cinereous, beautifully
banded with blue ; organs of respiration blood-red, tail greenish."
There is in the British Museum Collection a specimen labelled
" Arenicola tindoria, Musselborough, Frith of Forth. Mus. Leach,"
probably the type specimen of this species. It is light brown in
colour, and in life was probably similar to that represented in PI. I,
Fig. 1, which was also obtained at Musselburgh.
The small worm described and figured by Claparede as Clymenides
sidplmrca or sill/urea was almost certainly a post-larval example
of A. marina, as were also undoubtedly the specimens designated
C. sulfiLreus by Prof. Mesnil (pp. 75-77).
Pallas's account and figures of Nereis lumbricoides, and his remark
on its use as bait for Gadus and Pleuronectes, show clearly that this
worm was A. marina. The description given by Linnaeus of the
common " Orin " shows that the lugworm was before him, although
he attributed to it twenty pairs of bristles.
BIONOMICS, VARIETIES, SIZE. — Arenicola marina is abundant in
northern and western Europe J on numerous beaches, where the sand
is not shifting and contains a considerable proportion of the decom-
posing organic matter on which these worms feed. They are often
very numerous near sewage outfalls, and in other places where a
rich diet of decomposing matter is available ; their absence or com-
parative fewness in other stretches of sand depends on at least two
factors — (1) the purity of the sand, that is, the almost total absence
of food ; (2) the force of the sea and the constantly shifting character
of the sand. A. marina is usually present only in small numbers
on sandbanks well out to sea, and on certain beaches where
decaying matter is scarce ; its absence from other beaches is accounted
for by the second factors named above. Some idea of the abundance
of the worms in favourable situations may be obtained by reference
to the enumerations of their castings given on p. 99, and by the
1 For an account of the distribution, see p. 101.
Arenicola marina 97
observation of Dr. Groot, who, working at Helder, dug out in the
sand a rectangle, two metres by one metre, to a depth of three
decimetres, and found in this quantity of .sand ninety-three specimens
of A. marine.
Specimens of A. marina may be separated into two kinds or
forms — the littoral and the Laminarian — according to their habitat
and the nature of their gills. Specimens taken in the littoral zone
(pp. 64, 65) are generally found in U-shaped burrows,1 have bushy
gills (p. 58), and average 180 to 230 mm. in length;2 but
occasionally larger specimens, up to 360 mm. in length, are obtained.
Specimens from the upper part of the Laminarian zone, which can
be readily obtained only at very low tides, are found in vertical or
L-shaped burrows (p. 65), and generally possess pinnate gills (p. 58).
Laminarian examples are more massive than those from the littoral
zone, and attain a length of 400 mm., and a girth, at the widest part,
of about 70 mm. Besides the difference in the character of the gills,
noted above, the Laminarian differs usually from the littoral form in
the subdivision of the interval between the second and third
chaetiferous annuli: in littoral examples this region is almost
invariably divided into three rings, while in Laminarian specimens
only two rings are indicated. The Laminarian form has been found
on the Lancashire coast, in the Firth of Forth, in Salcombe Estuary
(S. Devon), in Jersey, on the north-west coast of France, the North
Sea coast of Germany,3 and is represented by two specimens in the
British Museum, from Deal.
Beyond the statement by M. Bohn, that A. marina leaves its
burrow at night to swim in the sea, nothing is known of the habits
of this worm when covered by the sea. Prof. Ehlers (1892) has
recorded the swimming of adult A. marina 4 and the capture, before
1 Burrows of similar form, occasionally with a heap of sand or mud near
one of the apertures, are abundant in Cambrian, and not uncommon in Silurian
and Devonian rocks. It is believed they were made by Polychaeta, and some
authors attributed them to Arenicola (A. carbonarius Binney, Mem. Lit. Phil.
Soc. Manchester, 2 ser., x (1852), p. 192; A. didyma Salter, Q. J. Geol. Soc.,
Lond., xii (1856), p. 248) ; but, as the evidence for this was insufficient, the
generic name associated with these burrows was changed to Arenicolites.
- Specimens from near low- water mark are usually larger than those found
near high-water mark ; those from sand rich in organic. matter are larger than
those found in purer sand.
3 This locality is included because the gills of the specimens collected there
by Oken are described as being like a mimosa leaf ; they must therefore have
been markedly pinnate, as is evident also from Oken's figures.
4 Mr. H. G. Chadwick (19th Ann. Rep. Liverpool >Mar. Biol. Comm. (1905),
p. 13) observed a specimen make its way slowly upwards, in a large aquarium
tank, by strong and frequent flexions of the body.
98 A renicolidae
sunrise, of specimens (80-120 mm. long) in the surface tow-net, in
shallow water at Heligoland.
Arenicola marina is present in certain estuaries in which, especially
in times of flood, the water is of much less density than sea water.
The few records available indicate that Arenicola adapts itself less
readily than Nereis to estuarine conditions — e.g. Ferronniere found,
while collecting in the estuary of the Loire, that A. marina ceased at
St. Nazaire — i.e. at the mouth of the river, while N. diversicolor
extended about sixteen kilometres further up the river, to a point
well above Paimboeuf. Similarly only one specimen of A. marina
was found at Greenlands, three miles up the estuary of the Exe,
although N. diversicolor was very common there.1 The water in this
estuary is, at certain times, of low density.2 Eecent observations in
the Forth show that A. marina extends a considerable distance into
estuarine water, and, indeed, occurs in situations — e.y. a quarter of a
mile above Kincardine 3 — which are subject from time to time to
submersion in almost fresh water. Above Kincardine the river
channel is comparatively narrow ; below that town it opens out into
the broad estuary. Specimens living above Kincardine will therefore
be submerged in water of low density, and, in times of flood, in
practically fresh water. Possibly at those times the worms retire
deep into the mud, and thus, perhaps, minimise the effects produced
by fluctuation in the density of the water.
FOOD. — Arenicola marina feeds on small living organisms, sucli
as diatoms, algae, foraminifera, etc., but probably to a greater extent
on the small dead animals — Crustacea, worms, etc. — or their frag-
ments, which are to be found in the littoral zone where Arenicola
marina occurs in greatest abundance. Occasionally a larger object is
found in the alimentary tract of the lugworm — for instance, a piece
of seaweed, or a partially digested Nereis.
1 J. Mar. Biol. Ass., n.s., vi, pp. 299, 321.
2 Dr. Miohaelsen (op. cit. (1896). p. 195) thinks that the decrease in the
Polychaete fauna, observed on passing from the Sound and the Belt into the
Baltic, is probably correlated with the decrease in the salinity of the water.
In the Belt there are ninety-six species of Polychaeta, in the western part of the
Baltic only forty-three, and in the eastern part, from and including Eiigen, only
nine, including A. marina. Sassnitz, on Riigen, is the most easterly locality
in the Baltic from which A. marina has been recorded (Mobius). The occur-
rence of this worm much further eastwards seems unlikely, for had it been
present it would doubtless have been noted in the faunistic lists given for East
Prussia. Dr. Alex. Luther, of the University of Helsingfors, has informed the
writer that Arenicola does not occur in the vicinity of Helsingfors.
3 The author is indebted to Mr. William Evans for this unpublished record.
Arenicola marina 99
THE CLEANSING OF THE SAND BY THE AGENCY OF ARENICOLA. — The
lug worm burrows to a depth of two feet or more,1 swallowing sand
as it goes (p. 64). Some, probably the greater part, of the organic
matter in the sand ingested is removed during its passage through
the alimentary canal of the worm, and the sand is eventually dis-
charged, in the form of a "casting," on the surface, where it is
subjected to further purification by the action of the air and water.
This worm performs great service in regard to " the cleansing of
the littoral," 2 taking a prominent share in bringing about the
removal of substances which, if left to accumulate, would become
objectionable. When it is borne in mind how great are the numbers
of castings visible on many of our beaches, that they are renewed
twice each day as the tide falls, and that probably the worms carry
on similar operations during the intervals in which they are covered
by the sea, the magnitude of the collective work done by lugworms
becomes evident.
Dr. Davison 3 estimated the amount of sand brought to the
surface by lugworms on the Holy Island sands. After finding the
average number of castings on nineteen measured areas to be 82,423
per acre, he weighed about fifty castings, and from the results calcu-
lated that the average amount of sand brought up to the surface
each year on these areas was about 1,911 tons per acre, which, if
spread evenly, would form a layer about thirteen inches in depth.
Taking two feet as the average depth to which the worms descend,
the sand in which they live would be passed through their alimentary
canal once in every twenty-two months.
The writer (1904) made similar observations near Musselburgh
and Portobello, Firth of. Forth, on the beaches of both of which lug-
worms are abundant. In the former locality the castings varied in
number from twelve to fifteen per square yard, and were evidently
formed by large worms ; near Portobello the castings were more
numerous — 34 to 38 per square yard, but much smaller, so that the
amount of sand brought up was about the same in both cases, and
was estimated to be about 3,700 tons per acre annually, equivalent
to a layer about two feet in thickness.
THE USE OF ARENICOLA MARINA FOR BAIT. — A. marina is the best
known worm of our shores by reason of its extensive employment
1 In cold or stormy weather the worms seem to burrow more deeply.
2 J. Hornell, Journ. Mar. Zool., i (1894), p. 27.
3 Geol. Mag., n.s., Dec. Ill, viii (1891), p. 489.
II 2
100 A ren icolidae
for bait.1 It forms an excellent bait for flat fish, is also good for
Gadidae in general — haddock, cod, whiting, — and is used as a general
bait for lines on both sides of the North Atlantic.
Although certain beaches have been regularly despoiled of
Arenicola marina for use as bait, this worm is still present there in
practically undiminished numbers. Prof. M'Intosh suggested that
the worms have "resisted the attacks of man because a sufficient
stock of ripe examples and the very young are covered at all times
by the tide." There are certainly plenty of old examples in the area
covered by the tide, judging from the large specimens obtainable at
low tide. How far seawards the worms extend it is impossible to
say, but no doubt there are very substantial reserves always covered
by the sea. Even in the area exposed at an ordinary tide, the
number of worms is so great thai the removal of those collected at
any one gathering of bait makes no appreciable diminution. For
instance, the area from which the Musselburgh fishermen dig their
bait probably contains at least three millions of the worms, and
therefore the removal of a few thousands per day produces little
effect on the numbers accessible at ordinary low tides.
PERIODS OF MATURITY. — In north-western Europe A. marina has
two periods of maturity annually, namely, about February to April,
and about July to September.
At the conclusion of the larval development, which is unknown,
the post-larval stage (described on pp. 77-79), enclosed in a mucous
tubular envelope (PI. X, Fig. 26), becomes for a time pelagic. As a
rule the worm settles down to its littoral habitat before gills are
formed, but these organs develop almost immediately.
Young specimens, 17 mm. long, from the sand, taken near the
end of June, possessed the full number of gills, already well branched ;
and in every respect, other than the gonads, the worms had
assumed the adult form. Probably these worms were produced from
eggs laid in the preceding February or March, and were thus about
three to four months old at the time of capture. Nothing is known
definitely regarding the correlation between the size and age of the
subsequent stages of development ; specimens five or six inches
long are probably about a year old, but no estimate can be given of
the age of the large examples obtainable at low spring tides.
1 The only other Polychaeta at all commonly used as bait in this country
are certain Nereids, e.g. Nereis (Alitta) virens. Large quantities of Hermellids
are used for bait in the neighbourhood of Marseilles.
Arenicola marina 101
COLOUR. — Young specimens of Arenicola marina are almost pink
in colour, as the numerous blood-vessels are seen through the
translucent body-wall. The gills of such specimens are usually
bright red.
Older specimens are darker, but their colour is very variable.
The amount of pigment is increased, especially at the anterior end of
the worm, which becomes brown or greenish, and in the tail, which
becomes yellowish green, while the middle region remains of a pink
or light red colour. Some specimens finally become very dark — a
velvety greenish black — with beautiful metallic green and iridescent
sheen. The gills of these dark examples are generally also pigmented,
and thus have a reddish brown or black appearance. The colours
of typical light and dark examples are shown in Plate I,
Figs. 1 and 3.
The amount of dark pigment present depends to some extent on
the age of the specimen, but the nature of the sand in which the
worm has been living seems to be a more important factor. It is
generally agreed that light coloured examples are found in almost
pure sand, while dark ones live in sand or mud containing much
organic matter. Light and dark specimens may be taken within a
comparatively short distance of each other, in the same beach ; but
it will generally be found that the dark ones show a predilection for
certain places where there^ is muddy, black sand, or, to state the
matter more correctly, the conditions in these areas produce dark
worms, while in a neighbouring clean patch of sand the worms are
light in colour. The two specimens figured in Plate I were taken
at the same time from the beach opposite Fisherrow, Musselburgh.
DISTRIBUTION. — Arenicola marina occurs in suitable situations on
the shores of western Europe as far south as Foz de Douro, Portugal.
It extends northwards to the extreme north of Norway, and it has
been found in the White Sea, off Cape Eagosin in the Kara Sea, and
on the west side of Spitzbergen, the last being the most northerly
definite locality for the species and genus. A. marina is present in
the western part only of the Baltic, Riigen being the most easterly
locality in which it has been found in that sea. It occurs at Trieste,
and possibly at other stations in the western Mediterranean (see
p. 93) ; but its range of distribution in that area has not yet been
ascertained. This species is present in the Faeroes, and on the shores
of Iceland and Greenland, and extends down the east coast of
America as far as Noank, Conn., which is apparently the most
102
Arenicolidae
southern limit to the distribution of the species on that coast.
There are single records, given, however, under some reserve, from
Chile and the Marquesas and Kingsmill Islands (see p. 94).
The distribution, as far as it is known, indicates that A. marina
is practically restricted to the shores of the North Atlantic Ocean,
north of 41° N". lat., the neighbouring parts of the Arctic Ocean and
the northern part of the western Mediterranean.
Deal, Kent
Sandgate ....
Littlehampton .
Plymouth
,, (post-larval stage)
Teignmouth, Devon .
Polperro, Cornwall .
Penzance, Cornwall .
Coast of Cornwall . • .
Jersey ....
» • •
Aberystwyth
E. T. Pritchett, Esq.
Rev. Geo. Smith.
Mus. Leach.
Norman Coll.
Ashworth Coll.
Mr. Degen.
Dr. Baird.
Norman Coll.
Mus. Leach.
95. 4. 30. 1 & 2.
Old Coll.
Old Coll.
1912. 4. 8. 1 & 2.
1912. 4. 9. 1.
86. 9. 23. 1.
62. 5. 5. 47.
65. 11. 16. 6.
68. 1. 17. 8.
85. 2. 26. 15.
98. 5. 6. 20.
Old Coll.
Port Erin, Isle of Man
Millport, Cumbrae
)» )5 • • •
Shetland .....
(" Arenicola tinctoria ") Mussel-
borough, Frith of Forth.
Musselburgh ....
(" Arenicola carbonaria ") Black
Bock, Frith of Forth.
Berwick Bay
Holy Is. . .
Holy Is. .
Arcachon, Gironde . . .
Santander ....
Trieste . . ...
Klosterelv Fjord, Finmark.
Kola Fjord, Euss. Lapland
Eeykjavik, Iceland . .
Godthaab, Greenland
Greenland
Ashworth Coll.
D. Eobertson, Esq.
Ashworth Coll.
Mus. Leach.
Ashworth Coll.
Mus. Leach.
Dr. Johnston.
Dr. Johnston.
Ashworth Coll.
Norman Coll.
Ashworth Coll.
Holboll Coll.
Copenhagen Mus.
1912. 4. 9. 18.
60. 10. 2. 12.
1912. 4. 9. 15-17.
1912. 4. 9. 6.
Old Coll.
1912. 4. 9. 2-5.
Old Coll.
47. 10. 11. 33.
Old Coll.
Old Coll.
1912. 4. 9. 7. & 8.
1912. 4. 9. 9.
1912. 4. 9. 12.
1902. 7. 8. 68.
1912.4.9. 10 & 11.
1912. 4. 9. 13 & 14.
53. 10. 17. 40.
82. 5. 12. 12.
65. 9. 23. 4.
Arenicola loveni
103
N.GR
PR.
AKENICOLA LOVENI Kinberg, emend.
Plate III; Plate IV, Fig. 11.
Kinberg, Ofvers. Kongl. Vet.-Akad. Forhandl., 1866 (1867), p. 355 (Port Natal,
Durban) ; Eug. Eesa, Zool., vii, Annul. (1910), p. 73, t. xxix, 1.
Ashworth, Arkiv for Zool., vii (1910), no. 5, 1 pi. (Saldanha Bay) ; Ann.
S. Afr. Mus., xi (1911), p. 1, pi. i (False Bay).
Fauvel, Mem. Soc. Nation. Sci. Nat. Math., Cherbourg, xxxi (1899), p. 179.
Caudate 1 Arenicola with nineteen chaetiferous segments ; thirteen
pairs of gills, the first gill on the seventh segment, gills large and
pinnate; the median lobe of the prostomiuin is large, the smaller
lateral lobes are of almost uni-
form width, that is, they are not
dilated or lobate at their anterior
ends ; neuropodia are clearly
visible in each segment, those
of the branchial and of the two
prebranchial segments are long
dorso-ventrally and almost reach
the mid- ventral line ; each noto-
podial seta bears numerous
finely-toothed crests or " Sage-
blatter" at regular intervals
along the distal third of its
Fig. 43.— Arenicola loceni, from Saldanha Bay.
Shaft, and this part Of the Seta Anterior end, dorsal aspect. PR. Prostomium ;
PER. Peristomium ; N.GR. Nuchal groove ; A.B.h.
presents a well-marked trans- Achaetous body-segment; CH.SEG.I First chaeti-
lerous segment.
verse striation ; 2 five pairs of
nephridia, which open on the fifth to the ninth segments ; one
pair of oesophageal glands ; two enormous septal pouches which
pass through apertures in the second septum and terminate imme-
diately in front of the third septum; a pair of closed statocysts,
each containing a single large secreted statolith.
HISTORICAL ACCOUNT. — The species Arenicola loveni, which was
founded on a specimen collected at Port Natal, near Durban, was
defined by Kinberg in the following terms : " Scgmentum buccale
1 Worthy of note is the very large number of tail segments in this species ;
in three specimens there were respectively 175, 186 and 205 septa in the tail,
indicating as many segments.
2 See Fig. 11, p. 44. Crotchets are shown in Fig. 27, p. 56,
A.B.S.
CH.SEG!
104
Arenicolidae
triannulum ; segmenta setigera 20 quorum sex anteriora siugulunique
postremum ebranchiata ; longitude 395-400 mm. ; latitude 20 mm."
Following this diagnosis is the reference, " Eug. Eesa, Ann , t. xxviii. 1."
The plate cited, which forms one of a series containing figures of
the Annulata collected on the voyage round the world of the frigate
' Eugenie,' was prepared for issue in 1857, that is, ten years prior to
the publication of the diagnosis of the species ; but it was not
actually published till 1910, though copies were to be found previous
to this date in some libraries. In 1910 the original diagnosis was
reprinted, and issued with the plate, which was re-numbered xxix.
Fig. 44. — A. loveni. Type specimen ; a portion of the nineteenth chaeti-
ferous segment, the extra (twentieth) segment and notopodium (N -»),
and a portion of the tail, seen from the right side. The most ventral
axis of the last gill (BR '3) is represented, but only the origins of the
other axes are shown ; P. Pit (possibly sensory, see p. 35) ; NR >9, Nine-
teenth neuropodium.
Prof. Fauvel pointed out that, as far as could be ascertained from
the figures on this plate, A. loveni differed from a large example of
A. marina only in the presence of a ring, with a little tuft of chaetae,
between the last branchial segment and the tail, and suggested this
might be due to error of observation. He concluded that, on the
information available, it was impossible to decide whether A. loveni
should be regarded as a distinct species or merged with A. marina.
The writer's examination of the type specimen, placed at his
disposal by Prof. Theel, showed that A. loveni is a valid species.
From the type, and four specimens received from Prof. Gilchrist, and
Arenicola cristata 105
taken by him in Saldanha Bay, a full description and diagnosis of
the species were prepared (1910).
HABITAT, SIZE, COLOUR. — The habitat of A. loveniis similar to that
of A. marina, the specimens found in Saldanha Bay were a foot or
so beneath the surface.
The type specimen is 405 mm. long, the tail being 155 mm.
The specimen figured on PI. lit closely approaches the type in length
(385 mm.), and in the proportion of body to tail, but is rather stouter.
There are no observations available regarding the colour of this
species in life. The appearance of the preserved specimens suggests
that, when living, their colour would be similar to that of examples
of A. manna of light or medium tone.
KEMARKS ON THE TYPE SPECIMEN. — -The type specimen possesses
an additional chaetiferous, but abranchiate segment, in which, however,
only notopodia — smaller than those of the preceding segments — are
present (Fig. 44, p. 104). Kinberg's figure x and description are correct
in regard to this twentieth segment, but, as the type specimen is
abnormal in this respect, the diagnosis of the species has been emended
so as to state that nineteen chaetiferous segments are present.
DISTRIBUTION. — Arenicola loveni has been found only in three
places, namely, Port Natal, near Durban, Saldanha Bay and False
Bay, Cape Colony.
Type specimen in Kiksruuseum, Stockholm.
Saldanha Bay .... Ash worth Coll. 1912. 4. 9. 21.
ARENICOLA CRISTATA Stimpson.
Plate V, Figs. 12, 13 ; Plate VIII, Fig. 17 ; Plate X, Fig. 30 ; Plate XIII,
Figs. 41, 42.2
Arenicola cristata —
Stimpson, Proc. Boston Soc. Nat. Hist., v (1856), p. 114 (Maurice I.,
Charlestown Harb.).
Andrews, Proc. U.S. Nat. Mus. 1891, xiv (1892), pp. 289, 300 (Beaufort, N.C.).
Ashworth, Proc. U.S. Nat. Mus., xxxix (1910), p. 21 (Curacao; San Pedro
and Monterey Bay, Cal. ; Suez ; Barrow I. ; Japan).
1 The difference in the sculpturing of the skin of the pre-branchial and
branchial regions is not marked and abrupt as shown in Kinberg's figure.
PI. Ill, Fig. 9, accurately represents the sculpturing of the epidermis.
2 For other figures of this species, see Figs. 7, 25, pp. 41, 53, chaetae of
larva ; Figs. 12, 26, pp. 45, 54, chaetae of adult, Fig. 40, p. 70, statocyst.
106 A renicolidae
Arenicola cristata (continued) —
Child, Arch. Entw.-mech., ix (1900), p. 587 (Wood's Holl and North
Falmouth, Mass.).
Gamble and Ashworth, Q. J. Micr. Sci., xliii (1900), pp. 423, 541, pi. xxii,
fig. 1, pi. xxiv, fig. 30 (Jamaica).
Horst, Notes Leyden Mus., xi (1889), p. 40, pi. iii, figs. 6-11 (gills, chaetae).
Ives, Proc. Acad. Nat. Sci. Philad. 1890 (1891), p. 73.
Lillie, Mitt. Zool. Stat. Neapel, xvii (1905), p. 344 (nephr., devel.).
Lo Bianco, Atti B. Accad. Sci. Fis. Mat. Napoli, v, ser. 2, no. 11 (1893),
p. 11, tav. i, fig. 1, tav. ii, fig. 1, tav. iii, figs. 5, 6; Mitt. Zool. Stat.
Neapel, xiii (1899), p. 484 : xix (1909), p. 577.
Verrill, Trans. Conn. Acad. Arts Sci., xi (1901), p. 39 : xii (1907), p. 147.
Webster, Bull. U.S. Nat. Mus., no. xxv (1884), p. 323 (Bermuda).
Wilson, Studies Biol. Lab. Johns Hopkins Univ., ii (1882), p. 278 (devel.).
Arenicola ? cristata —
Webster, 32 Ann. Eep. N.Y. State Mus. (1879), p. 117 (New Jersey).
Arenicola antillensis —
Liitken, Vid. Med. Naturh. Foren. Kjobenhavn 1864 (1865), p. 120
(St. Croix).
Ehlers, Mem. Mus. Comp. Zool. Harvard, xv (1887), p. 173 (Florida;
Captiva Key) ; Zeit. Wiss. Zool., liii, Suppl. (1892), pp. 218, 255,
tafl xiii, figs. 30-32.
Arenicola cristata, partim —
Fauvel, Mem. Soc. Nation. Sci. Nat. Math. Cherbourg, xxxi (1899), p. 169.
Mesnil, Bull. Sci. France Belg., xxx (1897), p. 163.
Caudate Arenicola, with seventeen chaetiferous segments ; eleven
pairs of gills, the first situated on the seventh segment ; gills large
N.GR.
CH. Ses!
Fig. 45.— A. cristata, from Wood's Holl. Anterior end,
dorsal aspect ; buccal mass protruded : PR. Prostomium ;
PER. Peristomium ; N.GR. Nuchal groove; A.B.S. Achae-
tous body-segment ; CH.SKG'. First chaetiferous segment.
and pinnate, their axes generally joined basally by a web-like mem-
brane ; median lobe of the prostomium larger than the lateral lobes :
A r en j co la cr is tat a 107
neuropodia are absent on the first and usually also on the second
and third segments ; the neuropodia of the posterior branchial region
are long dorso-ventrally and almost reach the mid- ventral line ; six
pairs of nephridia, which open on the fifth to the tenth segments ;
one pair of oesophageal glands, conical, cylindrical or clavate, and
comparatively short ; a pair of large finger-shaped septal pouches ; a
pair of closed statocysts, each containing a single, large, secreted
statolith.
HISTORICAL ACCOUNT.— This species was founded by Stimpson to
contain some large examples of Arenicola collected by him on the
shore of Maurice Island, at the entrance to Charlestown Harbour.
He noted that in these specimens there were only seventeen chaeti-
ferous segments and eleven pairs of highly contractile gills, each
composed of twenty main axes bearing regularly arranged branches,
and that, on the tail region there were thick cutaneous processes.
He also recorded observations on the colours of the living animals,
and on the nature of their burrows and egg-masses. Stimpson's
description was apparently not known .to Liitken, who re-described in
accurate detail the external features of this species, under the name
of A. antillensis. Liitken drew special attention to the strikingly
pinnate character of the gills, which he believed to be so important
as to require the formation of a new sub-genus — Pteroscolex — for the
reception of this species. As is shown on p. 31 this sub-genus could
not be upheld, and has not been accepted by subsequent workers.
The first record of, and observations on, examples of A. cristata
from the Old World, were those of Dr. Horst, who gave an account
of the gills and chaetae of Neapolitan specimens. Prof. Ehlers studied
the anterior end and statocyst, and Lo Bianco described the external
features and habitat of Neapolitan examples ; his Tav. I, Fig. 1, gives
a good idea of the colouration of the body, but the gills, which
are represented as being brownish, are usually a rich dark red colour.
Prof. -Fauvel and Drs. Gamble and Ashworth gave accounts of the
anatomy ; and the admirable researches, first of Prof. E. B. Wilson,
and subsequently of Prof. Child and Dr. R. S. Lillie, have made
known the course of development of this species from the egg-
cleavage to the adult.
OBSERVATIONS ON THE RECORDS.- — There is no doubt that Stimp-
son's A. cnstata and Liitken's A. antillensis are the same species.
108 A renicolidae
Stimpsou's type is apparently no longer in existence,1 but Liitken's
specimens are preserved in the Universitetets Zoologiske Museum,
Copenhagen, and were recently examined by the writer, who found
them to agree in every respect with examples from Florida, Carolina
and Massachusetts.
Profs. Mesnil and Fauvel included in this species A. ylacialis,
which, at the time of publication of their memoirs, was insufficiently
described, but the writer has shown that A. cristata and glacialis are
distinct species.
BIONOMICS. — Like other species of Arenicola, A. cristata seems to
be more abundant in sand containing a considerable proportion of
decomposing organic matter (Lo Bianco, 1899 ; Lillie, 1905).
Mr. Cyril Crossland found specimens near Suez in clean sand, but
this was rich in Foraminifera, which no doubt served as food for the
worms.
A. cristata descends in the sand or inud to a depth of twelve to
eighteen inches, or, in some cases, two feet. The burrow, in which
the worm is found head downwards, is, according to Stimpson, at
first vertical and then almost horizontal, and thus resembles that
usually made by a Laminarian example of A. marina. The entrances
to the burrows of the massive American specimens of A. cristata are
large and conspicuous.
Mr. Crossland has informed the writer that the burrows of
A. cristata, which he saw at Suez, were very deep and (J -shaped,
and, like those of littoral examples of A. marina, their two ends
were marked respectively by a heap of castings and a funnel-shaped
depression.
SIZE. — This is the largest species of the genus. Stimpson saw
one or more specimens sixteen inches (400 mm.) long and an inch
in diameter. The writer has had six specimens from Wood's Holl,
each exceeding 400 mm. in length ; one of them was a veritable giant
among Polychaeta, as it had attained a length of 515 mm. (the
tail was 190 mm. long) and a girth of 75 mm. Specimens almost
as large have been received from Florida and North Carolina. Most
American examples, though large, are, however, considerably shorter
1 The Curator of the Boston Society of Natural History, to whom I wrote
for information regarding the type specimen, kindly informs me that it is not
in the Society's Museum, but that it was probably in Stimpson's own col-
lection, and, if so, was in all likelihood destroyed with the Chicago Academy
of Sciences in the great Chicago fire.
Arenicola cristata 109
than those mentioned above ; they usually range in length from
about 200 mm. to 300 mm. (tail about 60 to 100 mm.).
The Neapolitan are more slender than the American specimens,
especially in the tail region (cf. Figs. 12, 13, PI. V). The former are
stated by Lo Bianco (1893) to attain a length of 400 mm. ; ten
specimens seen by the writer were from 200 to 300 mm. long. The
examples from Suez were smaller, namely, 120 to 185 mm. in length.
COLOUR. — In life A. cristata displays beautiful colouration. In
Neapolitan specimens the greater part of the body generally exhibits
a fine dark green colour, with play of iridescence; sometimes the
middle region is brown. The gills are almost invariably of a rich
dark red or deep crimson colour, and the notopodial chaetae golden
yellow. American and West Indian examples seem to exhibit similar
colouration, according to the accounts of Stimpson, Verriil and others.
Mr. Crossland found, among the examples collected at Suez, two of a
deep greenish- black colour, and others were yellowish or pinkish.
VARIATIONS IN THE ORGANS. — The first gill is subject to consider-
able variation in size, but it is rarely wanting. In one specimen a
very small additional gill is present, namely, on the left side of the
sixth segment ; this is the only specimen of Arenicola, out of some
thousands seen by the writer, in which a gill occurs in front of the
seventh segment.
In American examples of this species the tail usually consists of
few segments, about seven to ten ; 1 each specimen, when adult, has
therefore about thirty caudal segments fewer than it had in the post-
larval stage, due to loss of segments from the posterior end. Each
tail-segment consists- of a large annulus and a number of smaller
ones ; the former bears a series of hollow thumb-shaped processes,
which are generally largest in the first caudal segment, where they
attain a length of about 2 mm. Occasionally the most dorsal one is
branched distally and resembles a small gill (PL V, Fig. 13). The
morphology of these processes is obscure ; it has been suggested that
they are rudimentary gills, and the position and branching of the
dorsal member of the series lends some support to this view, but
there is no evidence that the more ventrally placed outgrowths are
more than exaggerated epidermal papillae. There is some variation
in the degree of development of the processes, even in specimens
from neighbouring localities ; but, as a rule, they are well developed
1 One specimen has seventeen tail segments.
110 A renicolidae
in examples from the east coast of the southern United States and
from the West Indies and Bermudas ; they are smaller in Californian
specimens.
Neapolitan specimens generally exhibit a considerable number of
tail segments: as many as forty may be present (PI. V, Fig. 12).
The epidermis of the tail is raised into numerous papillae, but they
are all of the same type; slightly larger ones are present on the
larger segmental rings, but there are no thumb-shaped outgrowths
such as occur in the American examples described above. The
specimens from Suez, Barrow Island and Japan agree with those
from Naples in lacking special caudal processes.
The number of nephridia is practically constant in this species.
Two interesting departures from the normal number have, however,
been found : one specimen possessed an additional nephridium on
one side, and another had an additional pair, in both cases in the
segment following that normally bearing the last nephridia.
PERIOD OF MATURITY, DEVELOPMENT. —Stirnpson and Andrews
found the egg-masses of A. cristata about the burrows, on the shores
of Carolina, during the latter part of March. The breeding season
of this species at Wood's Holl extends from May to August, and
is at its height in the middle of June. Lo Bianco states that
Neapolitan examples are mature from June to August.
This is the only species of Arenicola of which the egg-masses are
known, and they have been found only on the eastern coast of the
United States, at and south of Wood's Holl. They occur in the form
of gelatinous ropes, three to four feet long and two to four inches in
diameter, each containing several hundred thousand eggs.1 The
masses are at first associated with the burrows of the worms, but, as
they are swayed about by the tide, they are liable to be washed loose.
Accounts of the development and of post-larval stages are given on
pp. 74, 75 and 79.
DISTRIBUTION. — Arenicola cristata has been found on the east
coast of the United States, from Wood's Holl, Mass, southwards, at
a number of stations, and seems to be quite common in some places.
Prof. Andrews states that he found it to be "abundant" and
" excessively numerous " in two localities near Beaufort, N.C. It
extends along the western coast of Florida to Pensacola, which is
the most westerly point in the Gulf of Mexico from which the
species has been obtained. A. cristata occurs also on several of the
1 300,000. according to an estimate by Prof. Andrews.
Arenicola glacialis
111
Floridan Keys, in the West Indian Islands, e.g. Jamaica and Santa
Cruz, and in the Bermudas. It was reported by the writer from
Curacao, this being the first record from South America.
A. cristata has been known for more than twenty years from
Naples, but has not been recorded from any other station in the
Mediterranean. It was never common at Naples, and latterly seems
to have become more rare.
This species is evidently widely distributed in the Indo-Pacific
Ocean, but it has, as yet, been found only at a few stations. Mr.
Crossland obtained it in the mud flats near Suez, and the writer has
recorded specimens from Barrow Island (north-west Australia), from
Misaki and Tomo Harbour, Japan, and from San Pedro and Monterey
Bay, California.
The range of distribution may be stated thus : — A. cristata
is known from Naples, Suez, the warmer parts of the Indo-
Pacific Ocean (records from north-west Australia, south Japan and
California), the Atlantic sea-board of the United States from Wood's
Holl southwards, the Bermudas, and the eastern parts of the Gulf
of Mexico and the Caribbean Sea (including the West Indies).
All the stations at which specimens have been obtained are in
latitudes less than 40°, except Naples and Wood's Holl, which,
however, are very little north of this parallel. A. cristata appears
therefore to occur only in the tropics or on the shores of the warmer
temperate regions ; its distribution thus presents a sharp contrast to
that of the northern A. marina and the austral A. assimilis.
Naples
Suez
Wood's Holl
Florida
(larvae) .
(post-larval stages)
Norman Coll.
Ashworth Coll.
98. 5. 6. 1 & 2.
1912. 4. 9. 22.
1912. 4. 9. 23.
1912. 4. 9. 24.
1912. 4. 9. 25.
1912. 4. 9. 26.
ARENICOLA. GLACIALIS Murdoch.
Plate VI.1
Arenieola glacialis —
Murdoch, Rep. Internat. Polar Exped. to Point Barrow, Alaska (1885),
p. 155 ; Proc. U.S. Nat. Mus. 1884, vii (1885), p. 522.
Ashworth, Proc. U.S. Nat. Mus., xxxix (1910), p. 24.
Caudate Arenicola with seventeen chaetiferous segments ; eleven
pairs of small gills, the first situated on the seventh segment ; the
gill-axes are very short and bear at their distal ends few branches, each
1 For other figures of this species, see Fig. 23, p. 52, crotchets ; Figs. 33, 34,
p. 60, gills ; Fig. 39, p. 69, statocyst.
112
Arenicolidae
of which is either simple or divides dichotomously once or twice, the
finger- or thumb-shaped gill-filaments forming clusters at the end of
each axis ; the median lobe of the prostomium is small, the lateral
ones are well developed but not markedly dilated and not folded at
their anterior ends ; neuropodia are clearly visible in each chaetiferous
segment, those of the posterior branchial segments are long dorso-
ventrally and almost reach the mid-ventral line; six pairs of
nephridia, which open on the fourth to the ninth segments; one
pair of conical oesophageal glands ; a pair of small septal pouches ;
a pair of statocysts, opening to the exterior, and each containing
numerous statolilhs composed of sand
^flHKkw .--PR.
grains.
HISTORICAL ACCOUNT. — A few speci-
mens of Arcnicola — five picked up on the
beach (12th Sept., 1882) at Cape Smyth,
Alaska, after a fresh westerly gale, and
two mutilated ones taken from the gullet
of an eider duck — provided the material
on which this species was based. Murdoch
gave little information concerning his new
species ; he remarked that the worms under
Fig. 46.— A. giaciaii*. Anterior end, observation were closely allied to A.
dorsal aspect ; PR. Prostomium ; -1^11111 i i
N.GK. Nuchal groove, the posterior manna, but they had only eleven branch-
lip of which is slightly everted. ./> TT i -r, j -11
Both the iirst notopodia (NOT.I) iferous segments. He described a gill as
are retracted, leaving slits on the • , • p i i> i nr>,
surface of the segment. consisting ot a cluster of about fifteen
simple cirri, and noted that the tail, which
formed about one-third of the total length of each worm, was
without tubercles or other appendages. Murdoch gave no figures
and no other information regarding his species, which was therefore
defined insufficiently. Prof, von Marenzeller (1888) * held that, accord-
ing to the characters mentioned by the author, this species was
not separable from A. marina, a view shared by Saint Joseph
(1894) 2 and Prof. Elilers (1901) 3; but Profs. Mesnil (1897) and
Fauvel (1899) considered A. glacicdis as a synonym of A. cristata.*
1 Zool. Jahrb. Abt. Syst., iii (1888), p. 15.
2 Ann. Sci. Nat. Zool., ser. 7, xvii (1894), p. 123.
3 Fests. K. Ges. Wiss. Gottingen (1901), p. 176.
4 References to these two papers are given in the synonymy of A. cristata
(p. 106).
[lor.1
Arenicola glacialis
113
The original specimens were sent recently to the writer,
who has shown that A. glacialis is a distinct species, and has
given the first description of its more important features.
NOT'.---
CE.GL.
'---BR'.
D.V.
Fig. 47. — A. glacialis. Diagram of a dissection of the
anterior portion. BRi. First gill ; D.V. Dorsal blood-
vessel ; H. Heart ; NOTI. First notopodium ; NPHI.
First nephridium ; (E.Gt. (Esophageal gland ; PR.
Prostomium ; S'. First septum ; S.P. Septal pouch.
EEMARKS ON THE TYPE SPECIMENS. — Of the five original examples
only one is complete, another is in two parts held together by a
strand of muscle, the other three are in pieces. All are dark
brown or nearly black in colour. The complete specimen, shown
i
114 A renicolidae
in PI. VI, Fig. 14, is 90 mm. long ; the tail is strongly contracted,
being only 11 mm. in length. In the figure the tail has been
represented in a rather more normal condition of extension. This
specimen possesses on each side a neuropodium additional to the
number normal for the species. The second specimen is 105 mm.
long, the tail being 45 mm. in length.
The striking feature of the specimens is the small size of the
gills, the longest axes of which are not more than 2 mm. from their
origins to the tip of their terminal filaments (p. 60). The clusters of
filaments at the ends of the very short axes, together with the number
of the gills, are characteristic of the species. In the only other
species in which there are eleven pairs of gills, namely, A. cristata,
these organs are highly developed and pinnate, and are in complete
contrast to those of A. glacialis.
Murdoch states that the branchial segments have six rings, but
the writer found in every case only five.
The papillae on the tail are very feebly developed ; there are no
processes present such as occur on the tail of American examples of
A. cristata.
The crotchets are similar to those of A. marina (p. 51).
The diagram on p. 113 embodies all that could be ascertained
about the internal anatomy of the only fragment it was permissible
to use for inspection of the organs. The small septal pouches,
the single pair of oesophageal glands, and the nephridia, are similar
to those of A. marina. The statocyst is small ; its interior is shown
in the section figured (Fig. 39, p. 69), which indicates the origin
of the tube leading to the exterior.
Types, the only specimens known, in the Smithsonian Institution,
Washington.
ARENICOLA PUSILLA Quatrefages.
(-4. claparedii Levinsen.)
Plate VII, Fig. 15 ; Plate VIII, Fig. 18 ; Plate X, Figs. 21-25 ;
Plate XIII, Fig. 44 ; Plate XIV, Fig. 49.1
Arenicola pusilla —
Quatrefages, Hist. nat. Atmel., ii, p. 266 (Coquimbo).
Ashworth, Ann. Sci. Nat. Zool., ser. 9, x (1910), p. 115.
Fauvel, Mern. Soc. Nation. Sci. Nat. Math. Cherbourg, xxxi (1899), p. 176.
1 For other figures of this species, see Fig. 8, p. 41, chaetae of larva;
Figs. 15, 24, pp, 47, 53, chaetae of adult ; Fig. 32, p. 59, gill.
Arenicola pusilla 1 1 5
Arenicola claparedi [sic] —
Levinsen, Vid. Med. Naturh. Foren. Kjobenhavn (1883), p. 134 (Naples).
Horst, Notes Leyden Mus., xi (1889), p. 38, pi. iii, fig. 1 (gills, chaetae).
Arenicola claparedii —
Ashworth, Q. J. Micr. Sci., xlvi (1903), p. 773; Mitt. Zool. Mus. Berlin, iv
(1910), p. 349 (Ossero ; No. Japan) ; Proc. U.S. Nat. Mus., xxxix (1910),
p. 11 (Aleutian Is. ; Vancouver; Huinboldt Bay, Gal.).
Ehlers, Zeits. Wiss. Zool., liii, Suppl. (1892), p. 246, taf. xiii, figs. 21-29.
Fauvel, torn. cit. (1899), p. 175.
Gamble and Ashworth, Q. J. Micr. Sci., xliii (1900), p. 423, etc., pi. xxiv,
figs. 26-29 (Crescent City, Cal.).
Lo Bianco, Atti R. Accad. Sci. Fis. Mat. Napoli, v, ser. 2, no. 11 (1893),
p. 9, tav. ii, fig. 3; Mitt. Zool. Stat. Neapel, xiii (1899), p. 484: xix
(1909), p. 576.
Arenicola claparedei [sic] —
Johnson, Proc. Boston Soc. Nat. Hist., xxix (1901), p. 421.
Arenicola marina —
Child, Trans. N.Y. Acad. Sci., xvi (1898), p. 387 (Puget Sd.).
Claparede, Annel. de Naples (1868), p. 300.
? Ehlers, Fests. K. Ges.Wiss. Gottingen (1901), p. 176 (Puerto Montt, Chile).
Jaquet, Mitt. Zool. Stat. Neapel, vi (1886), p, 347, taf. xxi, figs. 50, 51,
57, 58.
Lo Bianco, Mitt. Zool. Stat. Neapel, viii (1888), p. 401.
Arenicola marina, partim —
Ives, Proc. Acad. Nat. Sci. Philad. 1890 (1891), p. 74.
Marenzeller, Zool. Jahrb. Abt. Syst., iii (1888), p. 12.
Arenicola piscatorum —
Grube, Insel Lussin u. Meeresfauna (1864), p. 87, (Ossero); ? Vid. Med.
Naturh. Foren. Kjobenhavn 1858, (1859), p. 120 (Callao).
Arenicola piscatorum, partim —
? Delle Chiaje,1 Descr. Anim. invert., iii (1841), p. 92; v, p. 100.
Grube, Anat. Phys. Kiemenw. (1838), p. 1 ; Act. Ech. u. Wuvnier d.
Adriat. (1840), p. 66.
? Schmarda, Neue wirbell. Th., i (1861), lte Half., p. xvii : 2te Half., p. 52.
Arenicola assimilis, partim —
Ehlers, Polych., in Hamb. Mag. Sarnmelreise, ii, 1 (1897), p. 104
(California).
? Lumbricus marinus, partim —
Delle Chiaje, Mem. Anim. s. Vert., ii (1825), p. 423.
? Chorizobranchus marinus —
Quatrefages, Hist. nat. Annel., ii, p. 267.
Caudate Arenicola with nineteen chaetiferous segments ; thirteen
pairs of gills, the first, which is on the seventh segment, may be
small or absent ; gills usually of the pinnate type, but occasionally
bushy ; lateral lobes of the prostomium much larger than the median
lobe, and generally folded in their anterior portion ; neuropodia
1 For comments on this record, see p. 144.
I 2
116
Arenicolidae
clearly visible in each segment, those of the posterior branchial
region are short and do not approach the mid-ventral line ; the distal
part of each crotchet has a form resembling that of a swan's head,
that is, the region just proximal to the rostrum of the crotchet has
Fig. 48.— A . pusilla, from California.
Anterior end, dorsal aspect ; show-
ing the large and folded lateral
lobes of the prostomiuin.
PR,
Mo.--
Fig. 49.— A. pusilla, from Atka Island. Anterior aspect,
showing the prostomiiun (PR.), with its large lateral
lobes, the nuchal groove (N.Gn.), and the mouth (Mo.).
a full, convex curvature,1 and is proportionally larger than in any
other species ; five pairs of nephridia, which open on the fifth 2 to the
ninth segments ; several (four to sixteen) pairs of oesophageal glands,
the anterior fairly long and slender, the others shorter and more or
less pear-shaped ; septal pouches absent ; statocysts absent.
HISTORICAL ACCOUNT AND E EM ARKS ON THE TYPE SPECIMEN.—
The species Arenicola pusiila was founded by Quatrefages on a single
incomplete specimen from Coquimbo, Chile. The diagnosis — " Annuli
ebranchiati 9. Branchiae magnae ramosissirnae " — the only infor-
mation given, was inadequate, and the position of this with regard
to other species of the genus was indeterminable until the writer
(1910) examined the type specimen.
Claparede (p. 301) seems to have suspected that Neapolitan
examples of "A. marina" might be specifically distinct from North
Sea specimens. He noted that the former were much smaller and
that their gills were not bushy; but it is remarkable that, while
studying the blood-vessels and nephridia, he did not observe and
1 This character is especially clear in specimens not more than about
100 mm. in length.
2 Rarely is a nephridium present opening on the fourth segment.
Arenicola pusilla 117
comment upon the presence of several oesophageal glands. Dr.
Levinsen placed the Neapolitan specimens in a new species, " A.
Claparedi," distinguished from A. marina by the presence of pinnate
gills and by certain chaetal characters,1 which, however, are valueless
for specific discrimination. As pinnate gills occur in some specimens
of A. marina this character does not serve to differentiate Dr.
Levinsen's species. Under these circumstances it is not surprising
that many years elapsed before this species was accepted generally.
It was, in fact, not until examination had shown that the internal
organs depart very markedly from those of A. marina that Dr.
Levinsen's species could be regarded as definitely established.
Dr. Horst made a careful study of the gills and chaetae ; Prof.
Ehlers described the external features of the anterior end, and
demonstrated the absence of statocysts 2 — the most remarkable
character of this species ; Prof. Fauvel gave a general description
of the internal organs, and Drs. Gamble and Ashworth a more
detailed account of the species, recording the first extra-Neapolitan
specimen.
The writer (1910) has made an exhaustive examination of the
type specimen of A. pusilla, which is about 35 mm. long and 3 mm.
in diameter, and is incomplete, only
the anterior region, as far back as
the eleventh chaetiferous segment,
being preserved. The first gill is
borne on the eighth segment, not
on the tenth as stated by Quatre-
fages, but is small. The neuropodia
of the branchial region are of the
short type, and the crotchets
, . _ . Fig. 50. — A. pusilla. Type specimen, right
(Fig. 24 B, p. 53) present dlStally aspect of the tenth chaetiferous segment.
N ° ' *- u Note the short, wide neuropodium (XEUR.).
the form of a swan s head, previously
found to be characteristic of A. daparedii. The prostoniium
(Figs. 51, 52, p. 118) is very fully extended, bringing into view the
posterior median portion, which in most specimens is hidden in the
1 The footnote, which gives Dr. Levinsen's diagnosis of the species, is as
follows : " Den middelhavske Art, for hvilken jeg foreslaar Navnet A. Claparedi,
stemmer overens med vor Art [i.e. A. marina] i, at Gjaellerne begynde paa
syvende b0rstebaerende Ring og straekke sig over 13 Binge, men afviger fra den
ved f01gende Karakterer : Gj seller, som kun i et meget kort Stykke ere forbundne
ved Grunden, langstrakte, med 10 Par Grene ; Bygb0rster med meget svagt
udviklede Haar, Bugb0rster med staerkere tilspidset, lidt afsat, Endedeel."
2 Which, however, he believed were represented by a pair of crypts near the
origins of the metastomial grooves.
118
A renicolidae
nuchal organ. There are six pairs of nephridia, opening on the fourth to
ninth segments, twelve oesophageal glands, six on each side, and no
septal pouches. Careful search failed to reveal the presence of stato-
L.
M.GR
N.GR.
NOT.
Fig. 51. Fig. 52.
Figs. 51, 52. — A. pusilla. Type specimen, antero-vcntral (Fig. 51) and dorsal (Fig. 52) views of the
anterior end. In Fig. 51 all the parts, except the prostomium, are seen somewhat fore-shortened.
L, Lateral lobe of prostomium ; M, Median lobe ; M.GR, Metastomial groove ; Mo, Mouth ;
N.GR, Nuchal groove ; NOT1, First notopodium ; P, Median posterior portion of prostomium.
cysts, and the writer believes them to be absent.1 The type was
compared directly, point by point, with a long series of examples of
N.GR.
M. GR.
PER.
A.B.S.
P"7n;-
Fig. 53. Fig. 54.
Figs. 53, 54. — A. pusilla. Specimen from California, antero-ventral (Fig. 53) and dorsal (Fig. 54)
views of the anterior end, for comparison with Figs. 51, 52. PKR, Peristomium ; A.B.S,
Achaetous body-segment (note the strongly developed groove between these segments, see p. 37).
A. duparedii. The anterior end of one of these, from Crescent City,
California, is represented in Figs. 53, 54, which show that, making due
1 To establish, beyond doubt, the absence of statocysts, it would be necessary
to make serial sections of the anterior end, a course which is obviously precluded
in this case.
Arenicola ptisilla 119
allowance for some contraction of the oral region and compression
of the median prostomial lobe, this specimen and A. pusifla have
prostomia of an identical type. They agree also in their internal
organs, except that in A. claparedii there are typically only five
pairs of nephridia ; but this difference is not sufficient to justify
the separation of two otherwise identical forms, as it may be an
individual or a local variation.1 The writer two years ago reached
the conclusion, which subsequent examination of further material
has amply confirmed, that A. pusilla and claparedii are identical,
and the two species are therefore merged under the older name.
OBSERVATIONS ON THE EECORDS. — Prof. Child's specimens of "A.
marina" were those afterwards examined and recorded by Dr. H. P.
Johnson as A. claparedei. The Neapolitan specimens examined by
Claparede and Jaquet, and those recorded by Lo Bianco, were
examples of A. pusilla ; Jaquet's figures show that several oesophageal
glands and five pairs of nephridia were present, and that statocysts
were absent — characters which apply only to A. pusilla. A. marina
does not occur at Naples.
The two specimens on which Prof. Ehlers' record from Puerto
Montt was based, which are in a bad state of preservation, have been
carefully examined by the writer. In the number of their segments,
the number and position of their gills, in the presence of short
neuropodia — the only external characters2 preserved — and in the
number of oesophageal glands and absence of septal pouches, these
specimens agree with A. pusilla and assimilis var. affinis. Statocysts
could not be found, although the anterior end of one of the worms
was cut into serial sections ; the preservation was, however, so
defective that it is possible the statocysts had disappeared owing to
maceration. The writer has recorded these specimens as A. claparedii
( = pusilla), and it seems advisable to retain this record with a query,
and with the proviso that there is some possibility that the specimens
may be A. assimilis var. affinis.
Prof, von Marenzeller's material of " A. marina " from several
localities included specimens from Naples and Vancouver Island.
The writer has recently examined one of the Vancouver examples,
1 Such a variation is seen in the number of nephridia in A. assimilis var.
affinis ; examples from South Africa have only five pairs, while those from
South America, New Zealand and Tasmania possess six pairs.
2 The crotchets were worn, and did not serve to decide the identity of the
species; in their characters they were not typical of A. pusilla, but tended
towards those of A. assimilis.
120 A renicolidae
which proved to be A. pusilla. Among the localities given by Ives
for "A. marina" are Coquimbo and Vancouver, but the records
from both these places relate to A. pusilla.
The specimen from Ossero, referred by Grube to " A. piscatorum"
which is preserved in the Kgl. Zoologisches Museum, Berlin
(Ash worth, 1910)x is an example of A. pusilla.
Grube's record from Callao is a mere mention of the specific
name A. piscatorum. The writer has endeavoured, without success,
to trace the material on which the record was founded ; it is not in
the museums of either Copenhagen or Berlin. The record is cited
under A. pusilla on the ground that Callao lies within the known
range of this and of no other species.
In the " Collection Grube " in the Berlin Museum are specimens —
probably those collected by Grube and mentioned in his two memoirs
(1838, 1840) — labelled " Mittelmeer," which belong to the species
A. pusilla. Among the localities cited by Grube are Naples, Italy,
Sicily, and on the ground of the inclusion of the first named, as well
as on the result of the examination of his specimens, his record is
included pro parte under this species.
Schmarda recorded examples from the Mediterranean, the English
Channel and the Pacific Coast (the Bay of Paita, or Payta, Peru),
and remarked that they all belonged to the same species, A. pisca-
torum. The subsequent statement that the specimens from Paita
possessed twenty oesophageal glands shows that they were either
A. pusilla or assimilis. Although the author has endeavoured to
trace Schmarda's specimens he has failed to find them, so their
identity cannot be established with certainty. Prof. Ehlers has
included Schmarda's record under A. assimilis, .but the respective
distributions of A. pusilla and assimilis suggest that Schmarda's
specimens more probably belonged to the former species, and his
record is therefore cited here with a query.
Prof. Ehlers' record of A . assimilis from California is based on a
specimen — a duplicate from Agassiz's collection — in the Gottingen
Museum. Agassiz's collection is at present in the writer's hands,
and from it was selected the example shown in Figs. 53, 54, p. 118.
The Gottingen specimen has been compared directly with this and
found to agree in every respect ; it is undoubtedly A. pusilla.
The information given by Delle Chiaje regarding his specimens
of Lumbricus marinus is very imperfect and unsatisfactory. The
specimens were collected near Naples, and among them was apparently
one or more with the first gill on the seventh segment, and therefore
Arenicola pusilla 121
belonging probably to the species A. pusilla. The description and
figures are, however, in agreement with A. branchialis in several
striking points, namely, the absence of tail and of dilatation of the
anterior region of the body, the repeated dichotomous branching of
the gills, the single pair of oesophageal glands and the size and
shape of the septal pouches. It is clear from Delle Chiaje's later
memoir (1841) that he did not, even then, recognise the difference
between a caudate and an ecaudate Arenicola, for he referred speci-
mens, some of which were undoubtedly A. branchialis, to the species
A. piscatorum. It is probable that the earlier record also referred in
part to A. branchialis. The carelessly drawn figure in Delle Chiaje's
memoir formed the basis for the genus Chorizobranchus (see p. 32).
BIONOMICS. — A. pusilla is moderately common in shallow water,
down to about six metres, in parts of the Bay of Naples, where the
bottom is muddy ; it is abundant where organic matter is plentiful,
e.g. near the outfall of drains. Lo Bianco states that in summer the
worm either disappears or is found only rarely.
The general habits of this species, which the writer had an
opportunity of observing in Naples for some weeks, are similar to
those of A. marina.
Examples taken by Prof. A. D. Howard in Puget Sound were
found generally in ordinary sandy beaches, but two larger specimens
were burrowing in a coarse gravelly and rocky beach.
SIZE. — Neapolitan specimens are usually small — not more than
60 to 70 mm. in length. Lo Bianco states that they may attain a
length of 150 mm., but that is an exceptional size ; the writer has
not seen, among the numerous Neapolitan specimens he has examined,
any exceeding 100 mm. in length.
Examples from the Pacific attain a greater size — 130-175 mm. in
length.1 Those from Dutch Harbour, Unalaska, are the largest known
examples of the species ; their length, 160 mm., is not remarkable,
but they are of very massive build, being 50 to 60 mm. in girth at
the widest point.
COLOUK. — Small Neapolitan specimens are pink and semi-trans-
parent, so that the blood-vessels and internal organs can be well
seen. In most cases there is a darkening, a " smoky " appearance,
1 One reaches the length of 207 mm., but its tail is of extraordinary length
(117 mm.), probably due to extreme relaxation post-mortem.
122 A renicolidae
at the anterior end ; the tail is generally yellow — chrome to gamboge —
and the gills light red.
Large specimens are reddish brown in the middle region, their
anterior end is often yellowish or darkened, the tail is yellow or
greenish yellow, and the gills reddish brown.
The American specimens had apparently been, in life, darker in
colour ; some are brown (in alcohol or formalin), but others, especially
those from California, are very dark — almost black, and similar in
colour to preserved specimens of the dark variety of A. marina
(cf. PI. I. Fig. 3).
VARIATIONS IN THE ORGANS. — The varied forms assumed by the
prostomium may be seen on reference to Figs. 51-54, 48, 49).
In examples from the coast of California there is a strong
tendency to the reduction and loss of the first gill. Out of seven
specimens from that coast only two have the full number of gills, and
in one of these the right and left first gills are very small ; specimens
from other localities possess practically constantly the full number
of gills.
There is a clear, and sometimes a striking, difference in the
number of oesophageal glands exhibited by Mediterranean and
Pacific specimens. The former seldom have more than four pairs,
or at the most five pairs of caeca (PI. VIII, Fig. 18), whereas the
writer has seen only one American example with as few as five
pairs, others had six to ten pairs (PL XIII, Fig. 44), and Dr. Johnson
records specimens with fifteen and sixteen pairs.
PERIOD OF MATURITY, DEVELOPMENT. — Lo Bianco (1909) stated that
A. pusilla is sexually mature, in the Bay of Naples, from November
to May. The writer found that artificial fertilisation was successful
from April 19th to May 16th, 1900, and that worms collected after
the latter date had shed their genital products.
Nothing is known of the form in which the ova are deposited.
The egg-cleavage and young larvae (p. 74) have been described by
the writer, but later larval stages and post-larvae are unknown. It
is remarkable that, in spite of the daily tow-nettings taken in the
Bay of Naples, and the careful examination to which the plankton is
subjected in the Zoological Station, the post-larval stages of A. pusilla
have not been met with. Possibly the habitat of these stages is
different from that of the corresponding phases of A. marina and
A. assimilis, and they do not come into the surface waters.
Arenicola assimilis 123
The writer found, in mud dredged near Naples (May 15, 1900), a
very small example, 7 to 8 mm. long, which already possessed the
full number of branched gills and four pairs of oesophageal caeca.
The nephridia had also assumed practically the adult form, but the
prostomium was in a transitional condition.
DISTEIBUTION. — A. pusilla is known to occur in Europe only at
Naples and at Ossero (on the Island of Cherso) in the Adriatic.1 It
is possible that some of the records credited to A. marina from the
Mediterranean (see p. 93) relate to the present species.
A. pusilla has been obtained at several stations on the western
seaboard of America, namely, the Aleutian Islands (Amchitka, Atka,
Unalaska), Vancouver Island, Puget Sound, Crescent City and
Humboldt Bay, Cal., and Coquimbo (Chile). Examples recorded
(under the name A. piscatorum) from the Bay of Paita, Peru, were
probably A. pusilla, and two specimens from Puerto Montt, Chile,
are placed provisionally in this species. The writer has seen two
examples of A. pusilla from North Japan.
The records suggest that this species is present generally on the
shores of the North Pacific, and that it extends well down the west
coast of South America. How far the species extends into the
Behring Sea and along the Coast of Siberia 2 is unknown.
Type specimen in the Museum d'Histoire Naturelle, Paris.
Naples Ashworth Coll. 1912. 4. 9. 27.
Dutch Harbour, Uualaska . „ „ 1912. 4. 9. 28.
San Juan Island, Puget Sound . „ „ 1912. 4. 9. 29.
ARENICOLA ASSIMILIS Ehlers, and var. affinis Ashworth.
Plate VII, Fig. 16 ; Plate X, Fig. 29 ; PL XIII, Fig. 45 ;
PL XIV, Fig. 50.3
Arenicola assimilis Ehlers.
Arenicola assimilis, partim —
Ehlers, Polych., in Hamb. Mag. Sammelr., ii, 1 (1897), p. 103 ; Fests. K.
Ges. 'NViss. Gottingen (1901), pp. 176, 177.
1 Careful search for this species has been made at Palermo and near Messina,
but without success. Prof. C. Viguier, Director of the Zoological Station,
Algiers, has informed the writer that he has not seen Arenicola in that neigh-
bourhood.
2 See remarks on a specimen from Siberia on p. 93.
3 For other figures of this species, see Figs. 14, 22, pp. 46, 51, chaetae of
adult ; Fig. 21, p. 50, crotchets of post-larva ; Fig. 38, p. 68, statocysts.
124 A ren icolidae
Arenicola assimilis —
Ashworth, Q. J. Micr. Sci., xlvi (1903), p. 740; Mitt. Zool. Mus. Berlin, iv
(1910), p. 351 ; Proc. U.S. Nat. Mus., xxxix (1910), p. 17.
Arenicola marina oder ein sehr naher Verwandter —
Michaelsen, Eeiseber., in Hamb. Mag. Sammelr., i (1896), p. 9 (Punta
Arenas).
Caudate Arenicola with twenty chaetiferous segments ; thirteen
pairs of gills,1 the first, which is on the eighth segment, may be
small or absent ; median lobe of prostomium moderately large, the
lateral lobes in the form of a V, the limbs of which are of uniform
thickness, that is, not dilated anteriorly though they may be bent ;
neuropodia clearly visible in each segment, those of the branchial
region are short and do not approach the mid- ventral line ; post-
rostral region of the crotchets not dilated (contrast A. pusilla) ; six
pairs of nephridia, which open on the fourth 2 to the ninth segments ;
several (six to sixteen) pairs of oesophageal glands, the anterior pair
long and slender, the others smaller and more or less pear-shaped ;
septal pouches absent ; a pair of large statocysts, each with tube to
the exterior ; statoliths numerous.
Arenicola assimilis var. affinis Ashworth.
Arenicola assimilis var. affinis —
Ashworth, Q. J. Micr. Sci., xlvi (1903), p. 764 (Otago Harb. ; Macquarie I. ;
Falkland Is.); Mitt. Zool. Mus. Berlin, iv (1910), p. 351 (Susanna
Cove ; Kerguelen) ; Proc. U.S. Nat. Mus., xxxix (1910), p. 18
(Stewart I., N.Z.) ; Ann. S. Afr. Mus., xi (1911), p. 18 (Table Bay ;
Liideritzbucht ; Plimmerton, N.Z. ; Tasmania).
Benham, Subant. Is., New Zeal., Art. xi (1909), p. 246 (Campbell I.).
Ehlers, Discovery Rep., vi (1912), Polych., p. 25 (Auckland I.).
Arenicola assimilis —
Ehlers, Zool. Jahrb., Suppl. v (1901), p. 265 (Susanna Cove).
Arenicola assimilis, partim —
Ehlers, op. cit. (1897), p. 104; Fests. K. Ges. Wiss. Gottingen (1901),
p. 178.
Arenicola claparedii —
Pratt, Mem. Proc. Manchester Lit. Phil. Soc., xlv (1901), 13, p. 12 (post-
larva).
Arenicola claparedi Lev. ? —
Ehlers, Abh. K. Ges. Wiss. Gottingen, Math. Phys. Kl., N. F., v, 4 (1907),
p. 21 (Warrington,3 N.Z.).
1 All the specimens of A. assiinilis (typical form), and those of the variety
affinis from Auckland Island, have bushy gills ; all other examples of the
variety have been found to have pinnate gills.
2 In South African specimens of the var. affinis, fifth to ninth.
3 ? Wellington.
Arenicola assimilis
125
; ST.O.
Fig. 55. — A. asuimttis, co-type, from
Uschuaia. Anterior end, dorsal aspect;
the prostomium is in a state of normal
extension.
Fig. 56. — A. assimilig var. a finis, from Otago
Harbour, N.Z. Anterior end, dorsal aspect ;
the buccal mass and pharynx are fully pro-
truded, and the prostomium is well extended
Si.O. External aperture of statocyst.
Fig. 57.— A. assimilig var. ajffinis, from the
Falkland Islands. Anterior end, dorsal
aspect ; showing prostomium very fully ex-
tended, exposing to view the median pos-
terior part (P.), which is usually hidden in
the nuchal organ ; M. Median ; L. Lateral
lobe of prostomium ; ST.O. External aper-
ture of statocyst.
Fig. 58. — A. assimilis var. affinis, from Susanna
Cove. Anterior end, dorsal aspect ; the
lateral lobes of the prostomium are larger
than usual, but are still considerably smaller
than those of A. pusilla (of. Fig. 48).
^ «"*?. ;
/
126 A renicolidae
Arenicola marina, partim —
Marenzeller, Zool. Jahrb. Abt. Syst., iii (1888), p. 12
Ives, Proc. Acad. Nat. Sci. Philad. 1890 (1891), p. 74.
Arenicola piscatorum Cuv. [sic] var. —
Grube, Monatsb. K. Preuss. Akad. Wiss. Berlin 1877 (1878), p, 511
(Kerguelen).
The variety affinis has nineteen segments ; thirteen pairs of gills,
the first, which is on the seventh segment, may be small or absent.
Other characters as given above (p. 124).
HISTORICAL ACCOUNT. — The species A. assimilis was founded by
Prof. Ehlers on examples collected by Dr. Michael sen in the Strait
of Magellan. Prof. Ehlers stated that these worms appeared to be
so closely similar to A. marina that, at first sight, he took them for
examples of this species, but the presence of the first gill on the
eighth segment, together with the provenance of the specimens,
seemed to him to justify their separation from A. marina, as a
closely allied species. He also remarked that the middle prostomial
lobe seemed to be proportionately smaller in these specimens than in
A. marina, and the dorsal chaetae more feebly "feathered." In 1901
Prof. Ehlers stated that the gut, vascular system and nephridia of
A. assimilis agreed, as far as he had been able to ascertain, with
those of A. marina, but there were differences in regard to the
statocysts, and the position of the external apertures of these organs,
which were apparently nearer the brain in A. assimilis.
.The writer (1903) gave a full account, with figures, of the
anatomy of A. assimilis, based on the study of co-types from
Uschuaia and Punta Arenas, and showed that this species has
twenty * chaetiferous segments, that the prostomium differs in form
from that of A. marina, that the oesophageal glands are multiple,
septal pouches are absent, the ventral lips of the nephridia are
peculiarly frilled, and that the statocysts are remarkable for their
large size. He also described examples from Otago Harbour, New
Zealand, and Macquarie Island, belonging to the species assimilis,
but differing from the type in having nineteen chaetiferous segments,
and statoliths of purely external origin 2 — quartz grains, etc. The
1 This unusual number of segments was not the subject of comment by
Prof. Ehlers ; he seems to have been more impressed with the unwonted
position of the first gill.
7 Those of the Fuegian specimens were spherical, and composed almost
entirely of secreted substance.
Arenicola assimilis 127
latter difference, which was discussed in its taxonomic bearings,
was regarded as unimportant (see p. 69). The difference in number
of segments between the Fuegian and New Zealand examples,
though striking, was not thought to be sufficient to justify the
erection of a new species, in view of the fact that in all other points
the two series of examples presented complete agreement. The
presence in A. assimilis of two forms, one with twenty, the other
with nineteen chaetiferous segments, seemed, however, to call for
some recognition, seeing that in other caudate species the number
of chaetiferous segments is constant. The New Zealand specimens
were therefore referred to a new variety, to which the name affinis
was given, indicating its close connection with, and resemblance to,
the type. In the same memoir were described, from the Falkland
Islands, post-larval and adult specimens, the latter agreeing with
those from New Zealand except in the form of the statoliths. From
the series of examples studied a full diagnosis of the species
was given.
OBSERVATIONS ON THE EECORDS. — Prof. Ehlers, in his original
account, recorded examples of A. assimilis from Punta Arenas,
Uschuaia, Lapataia Nueva, South Georgia and California. The adult
specimens from Punta Arenas,1 Uschuaia 1 and South Georgia1 have
twenty chaetiferous segments, and are typical examples of the species.
Those from Lapataia Nueva * and a young abranchiate specimen,
6*5 mm. long, found among the "roots" of seaweeds at Uschuaia,2
have nineteen segments, and are thus referable to the variety affinis.
The inclusion of California in the range of distribution of this
species is erroneous, for it rests on a specimen in the Gottingen
Museum which Prof. Ehlers referred to A. assimilis solely because
he found it to agree with this species in the arrangement of
its gills (of which there were only twelve pairs). The writer
has shown (p. 120) that this specimen belongs to the species
A. pusilla.
Prof. Ehlers' second memoir gives an additional station for the
species, namely, Susanna Cove. The writer has examined the original
1 The writer has examined the original specimens from these stations,
preserved in the Naturhistorisches Museum, Hamburg.
2 This is the only station from which both the typical form and the variety
(represented by a single post-larval specimen) have been recorded. Adults of
the typical and varietal form occur, however, not far from one another in
the Beagle Channel — at Uschuaia and Lapataia Nueva respectively, and in
the Strait of Magellan, at Punta Arenas and Susanna Cove respectively.
128 A ren icolidae
specimens, which have nineteen segments, and thus belong to the
variety affinis. In this memoir Prof. Ehlers makes the following
statement : " Arenicola assimilis Ehl. kommt im antarctischen Kreise
und im magellanischen Gebiete vor ; ebenso an der chilenischen
Kiiste, denn die von Schmarda erwahnte Arenicola piscatorum von
' den Kiisten der Sudsee ' ist nach Ausweis eines der Schmarda'schen
Stucke der Sammlung des Zoologischen Instituts in Wien Arenicola
assimilis; und die Fundortsangabe des Thieres heisst hier Chile".
Die Art tritt an der kalifornischen Kiiste wieder auf ; ob eine litorale
Verbindung zwischen dem nordlichen und sudlichen Verbreitungs-
gebiete besteht, bleibt noch zu erweisen ; sollte Arenicola pusilla
Qtrfgs. von Coquiinbo mit Arenicola assimilis Ehl. zusammenfallen,
so ware damit, wie niit dem Schmarda'schen Funde, eine Anbahnung
gegeben." The specimen from the Californian coast, erroneously
referred to the species A. assimilis, has been discussed above.
The writer addressed to Prof. Grobbeu enquiries for the specimen
of Schmarda mentioned by Prof. Ehlers, and he replied that in the
catalogue of the collection in the Zoological Institute of Vienna
there is no mention of an Arenicola collected in the Bay of Paita.1
There is in the Vienna collection a specimen of "A. piscatorum aus
Chile," but this was not obtained by Schmarda. His record states
definitely that his specimens were taken in the Bay of Paita, which
is on the most northerly portion of the coast of Peru, about a
thousand miles north of the nearest point of the Chilian coast. It
seems clear, therefore, that the Vienna specimen "aus Chile" has
nothing to do with Schmarda's record. This specimen is recorded
under A. marina (p. 94), to which species it undoubtedly belongs.
It is more probable, judging from the distribution, that the specimen
or specimens found by Schmarda in the Bay of Paita belonged to
the species A. pusilla, for this bay is within the known range of
A. pusilla, but is more than three thousand miles north of the
nearest station from which A. assimilis has been recorded with
certainty.
The example recorded by the writer from Kerguelen is that
formerly recorded by Grube (loc. cit.) as " Arenicola piscatoi'um Cuv.
var." Grube described this specimen as a variety of the common
species because in most of the branchial segments he could dis-
tinguish only four, instead of the usual five, rings. The specimen is
in very bad condition, but as it is the only one recorded hitherto
1 Prof. Grobben was unable to state whether Schmarda's material was
preserved or where it might be sought.
Arenicola assimilis 129
from that remote island1 it is worthy of careful re-examination.
The specimen is in three pieces, which, when joined together, are
208 mm. in length, of which the tail forms 74 mm. Assuming that
all the parts are present, which is apparently the case, there are
nineteen chaetiferous segments, the last thirteen of which bear gills.
The writer is unable to confirm Grube's statement regarding the
composition of the branchial segments, for, in each of the segments
of this region in which the annuli are distinguishable, there are five,
although one of them may be rather smaller than the others. The
neuropodia are of the short type found in A. assimilis and pusilla.
The outline of the prostomial lobes is sufficiently retained to show
that the prostomium agrees with that of A. assimilis. Oesophageal
glands are wanting, owing to damage, probably at the time of
capture. Septal pouches were found to be absent. The number of
nephridia cannot be ascertained on account of the damaged condition
of the anterior nephridial region, and the search for statocysts was
precluded by the leathery condition of the anterior end. The
diagnosis rests, therefore, almost entirely on the form of the
prostomium and the crotchets (Fig. 22 B, p. 51), but the writer has
no hesitation in referring the specimen to the species A. assimilis
var. affinis.
Prof, von Marenzeller recorded Arenicola marina from Angra
Pequeria (Liideritzbucht), but examination (Ashworth, 1911) of
extensive well-preserved material from that bay, and of one of Prof,
von Marenzeller's original specimens,2 showed that the species which
occurs there is A. assimilis var. a finis. Ives' statement that A. marina
occurs in South Africa is based upon Prof, von Marenzeller's work.
1 Since this account was finished M. Ch. Gravier has published notes on an
example of Arenicola from Kerguelen (Bull. Mus. Hist. Nat. Paris, xvi (1910),
p. 198; Ann. Inst. Oceanogr., iii, fasc. 3 (1911), p. 35). The specimen was
incomplete and in a very bad state of preservation. M. Gravier has referred it,
but under great reserve, to A. assimilis. Prof. Ehlers has kindly informed me
that among the collection made at Kerguelen by the German South Polar
Expedition there is a specimen of A. assimilis var. affinis. Had M. Gravier 's
specimen been complete it would probably also have been found to belong to
the variety affinis.
2 This specimen was not in good condition at the anterior end, the outlines
of the prostomial lobes were defectively preserved, statocysts could not be demon-
strated, and only five pairs of nephridia were present, so it was recorded
(Mitt. Zool. Mus. Berlin, iv (1910), p. 351) as A. claparedii. Subsequent
microscopic examination of the stained and cleared anterior end showed that
there were remains of a statocyst on one side (the rest of this organ and that of
the other side had disappeared owing to maceration), and therefore the former
determination was incorrect. The specimen is A. assimilis var. affinis, and
agrees with all other South African examples of this species in having only five
pairs of nephridia.
130 A renicolidae
The examples from the Falkland Islands recorded by Miss Pratt
were abranchiate post-larval stages, and were referred to A. claparedii
because they possessed several oesophageal glands, a character which
was at that time known only in, and believed to be diagnostic
of, that species. The writer (1903) examined these specimens
subsequently and showed that they were A. assimilis var. affi.nis.
The specimen from New Zealand, recorded by Prof. Ehlers as
A. claparedi Lev.,? is in the British Museum. Though it is not in
good condition its statocysts are demonstrable, and in its prostoniium,
nephridia and crotchets it agrees with other examples of A. assimilis
var. ajfinis from New Zealand.
HABITS, SIZE, COLOUK. — The habits of this species seem to be
similar to those of A. marina. Dr. Michaelsen describes the
occurrence in the sand flats near Punta Arenas of the " Sand- oder
Fischer-wurm (Arenicola marina oder ein sehr naher Verwandter
dieses Nordsee-Thieres)," with its worm-like castings, of almost pure
sand, forming innumerable hillocks over wide stretches of the flats
uncovered at low tide. These observations relate to the typical
form of A. assimilis.
The seven specimens of A. assimilis (typical form) examined by
the writer range in length from 110 to 160 mm. (the tail being
45 to 48 mm.). The examples of the variety ajfinis from the Falkland
Islands and the southern extremity of New Zealand are about the
same size as the foregoing. The largest examples are those from
Macquarie Island and Kerguelen, which are 217 and 208 mm. long
respectively (tail 85 and 38 mm. respectively), and the smallest are
those from Tasmania, which are 46 to 58 mm. long.
Specimens, in alcohol or formalin, are brown, generally light
brown, and have a similar appearance to preserved light -coloured
examples of A. marina. A few have a rather darker tone, and some
are yellower, especially those obtained in Table Bay, which Prof.
Gilchrist states were of a striking yellow colour when alive.
VARIATIONS IN THE ORGANS. — Examples of A. assimilis from
Fuegia, and of the variety from the Falkland Islands and from
Auckland Island, exhibit a tendency to the reduction or absence of
the first gill. None of the examples of the variety from Tasmania
has gills on the seventh segment, and only two (out of seven) have
gills on the eighth segment. The full number of gills is usually
present in specimens from other localities.
Arenicola assimilis 131
The South African examples of the variety affinis afford a striking
instance of variation, for nephridia are, without exception, absent in
the fourth segment. In examples from other localities, nephridia
are invariably present in this segment, and seldom (two out of
twenty-four cases) show any marked reduction.
The oesophageal glands (PI. XIII, Fig. 45) vary in number from
six to sixteen pairs, and the number does not appear to be correlated
with the size of the worm, for a specimen from Macquarie Island
has seven pairs, while another, about half its length, from Susanna
Cove, has fifteen pairs.
PERIOD OF MATURITY, POST-LARVAL STAGES. — The writer found
that in specimens of A. assimilis var. affinis, taken in Otago Harbour
about the end of August, 1902, the nephridial vesicles had been
subjected to great distension, doubtless by the accumulation therein
of genital products, shortly before capture of the worms. The post-
larval example, recorded from Uschuaia by Prof. Ehlers, was found
in October, 1892, so that there is a breeding season in that region
also about the month of August.
The mode of deposition of the eggs and the early development
are unknown. Only four post-larval specimens (see p. 80), all
referable to the variety, have been recorded. Three of these were
taken by Mr. E. Vallentin on the surface of the sea near the
Falkland Islands, the fourth was found among " roots " of seaweeds
at Uschuaia. All were abranchiate.
DISTRIBUTION. — Arenicola assimilis has been recorded from Punta
Arenas (Strait of Magellan), Uschuaia (Beagle Channel) and South
Georgia. Specimens referable to the variety affinis have been found
at the following stations 1 : Uschuaia (an abranchiate post-larva),
Lapataia Nueva (Beagle Channel), Susanna Cove (Strait of Magellan) ;
the Falkland Islands ; Kerguelen ; Otago Harbour, New Zealand,
and islands to the south, namely, Stewart, Campbell, Auckland and
Macquarie Islands ; Plimmerton (near Wellington, N.Z.) ; Burnie, on
the north coast of Tasmania ; Table Bay and Luderitzbucht, South
Africa.
These records, which show that A. assimilis is a characteristically
1 It is possible that two examples from Puerto Montt, Chile, recorded on
pp. 115, 119 as A. pusilla, may be A. assimilis var. affinis, but, as no evidence
of the presence of statocysts could be obtained in these badly preserved speci-
mens, they have been placed provisionally in the former species.
K 2
132 Aren icolidae
southern species, are noteworthy in connection with the discussion
on the former greater extent of the Antarctic continent.
Type specimen in Naturhistorisches Museum, Hamburg.
A. assimiUs.
(co-types) . Uschuaia . . Naturh. Mus. Hamb. 1912. 5. 25. 1/2.
Yar. affinis
New Zealand . . Prof. Benham, F.R.S. 1907. 5. 1. 31.
Auckland I. . . " Discovery " Exped. 1907.5.9.48-50.
Stewart I. . . Ashworth Coll. 1912. 4. 9. 30. .
Burnie, Tasmania . ,, ., 1912. 4. 9. 31.
Liideritzbucht . „ „ 1912. 4. 9. 32, 33.
Falkland Islands 1912. 4. 9. 34.
ARENICOLA ECAUDATA Johnston.
Plate II, Figs. 7, 8 ; Plate IX, Fig. 19 ; Plate XI, Figs. 34, 35 ;
Plate XV, Figs. 52, 53.1
Arenicola ecaudata —
Johnston, London's Mag. Nat. Hist., viii (1835), p. 566 (Berwick Bay) ;
Catal. Worms Brit. Mus. (1865), pp. 231, 345.
Ashworth, Trans. Liverpool Biol. Soc., xi (1897), p. 30 (Port Erin) ; Fisheries
Irel. Sci. Invest. 1908, vii (1909), p. 2 (Galway) ; Ann. Sci. Nat. Zool.,
ser. 9, x (1910), p. 114 (Kerity).
Beaumont, Proc. R. Irish Acad., ser. 3, v (1900), p. 784 (Valencia).
Bidenkap, Vid. Selsk.Forh. Christiania (1894), no. 10, pp. 39, 112 (Bergen ;
Hvidingso).
Chenu, Illustr. conchyliol., i (1842), pp. 1, 12, pi. i, fig. 5.
Elwes, J. Mar. Biol. Assoc., N.S., ix (1910), p. 64 (Torquay).
Fauvel,C. R. Acad. Sci. Paris, cxxxv (1898), p. 733; Bull. Sci. France
Belg., xxxii (1899), p. 289, etc. ; Bull. Soc. Linn. Norm., ser. 5, ii (1899),
p. 64 (Cherbourg) ; Mem. Soc. Nation. Sci. Nat. Math. Cherbourg,
xxxi (1899), p. 163: (1900), p. 315.
Ferronniere, Bull. Soc. Sci. Nat. Quest France, ser. 2, i (1901), p. 19 (Loire-
Infer.).
Gamble and Ashworth, Q. J. Micr. Sci., xliii (1900), p. 432, pi. xxii, fig. 4.
Gemmill, Marine Worms, in, Fauna Clyde Area (1901), p. 361 (Cumbrae).
Koehler, Ann. Sci. Nat. Zool., ser. 6, xx (1885), Art. 4 (Jersey, Guernsey,
Herm).
Lafont, Acta Soc. Linn. Bordeaux, xxviii (1873), p. 264 (Arcachon).
Larikester, Ann. Mag. Nat. Hist., ser. 3, xvii (1866), p. 390 (Herm).
M'Intosh, Rep. 39 Meet. Brit. Assoc. (1870), p. 90 (Plymouth) ; Ann. Mag.
Nat. Hist., ser. 8, i (1908), p. 382 (Loch Maddy ; Co. Dublin).
Malm, K. Vet. Handl. Goteborg, xiv (1874), p. 88 (Gullmarn; Loken ; The
Skaw).
Malmgren, Ofvers. K. Vet. Akad. Forh. 1867 (1868), p. 189 (Bahusia).
Mesnil, Zool, Anz., xxi (1898), p. 631 ; Bull. Sci. France Belg., xxxii (1899),
p. 318 (C. la Hague).
Quatrefages, Hist. Nat. Annel., ii (1865), p. 265 (St. Vaast).
Storm, K. Norske Vid. Selsk. Skr. 1880 (1881), p. 95 (Trondhjemsfjord).
1 For other figures of this species, see Figs. 5, 6, 10, 28, pp. 40, 42, 56,
chaetae of post-larval stages; Figs. 16A, 29, pp. 47, 57, chaetae of adult;
Fig. 36, p. 61, gill.
Arenicola ecaudata 133
Arenicola ecaudata, partim —
Ives, Proc. Acad. Nat. Sci. Philad. 1890 (1891), p. 74.
Arenicola boeckii —
Eathke, Nova Acfca Acad. K. Leop.-Car., xx (1840), p. 181, tab. viii, figs.
19-22 (Trondhjeni).
Arenicola bucci —
Hanna, Proc. Belfast Natur. Field Club, ser. 2, iv (1898), p. 425 (Antrim).
Arenicola branchialis, partim —
Fauvel, Proc. 4th Intern. Congr. Zool. (1899), p. 229.
Johnston, Catal. Worms Brit. Mus., p. 231.
Marenzeller, Zool. Jahrb. Abt. Syst., iii (1888), p. 13.
Mesnil, Bull. Sci. France Belg., xxx (1897), p. 163.
Michaelsen, J.-B. Komm. Wiss. Unters. Kiel, N.F., ii (1896), p. 136.
Saint- Joseph, Ann. Sci. Nat. Zool., ser. 8, v (1898), p. 391.
Ijumbricus marinus, another species —
Dalyell, Powers Creator, ii (1853), p. 137, pi. xix, figs. 4-7 (Shetland).
Clymenides ecaudatus —
Mesnil, Bull. Sci. France Belg., xxx. p. 152 (St. Martin).
Ecaudate Arenicola, with first gill on the sixteenth l chaetiferous
segment ; thirteen pairs of nephridia, which open on the fifth to the
seventeenth segments ; gonads large, each gonad is produced, in the
mature male, into one or more thin reniform outgrowths, and, in
the mature female, into numerous digitiform or flattened processes.
HISTOKICAL ACCOUNT. — Johnston defined his new species in the
following terms: — "A. ecaudata. Branchial tufts more than twenty
pairs ; the first fourteen or fifteen pairs of feet abranchial, tail none."
There was, in the minds of some authors, considerable doubt as to
the validity of this species, which was confused with A. cjrubii
(— branchialis). Until 1898 there was no published reference to
the internal organs of A. ecaudata; then appeared, in close succession,
the observations of Drs. Gamble and Ash worth, and Profs. Mesnil
and Fauvel, which finally dispelled all doubts regarding the autonomy
of this species.
To Prof. Mesnil (1897) we owe the first description of the post-
larval stages, which, however, believing them to belong to the
genus Clymenides, he designated C. ecaudatus. Prof. Fauvel reared
an example of" C. ecaudatus" into a young Arenicola ecaudata, and
thus demonstrated their identity.
1 The first gill is often small, and in about twenty per cent, of the specimens
examined was wanting.
134 A renicolidae
OBSERVATIONS ON THE EECOKDS. — Most of the records under
A. ecaudata, being subsequent to 1898, were made in the light of the
newer work on this species, and are thoroughly trustworthy. The
earlier records to which definite localities are appended seem also to
be reliable. Lafont's is the most southerly record for this species,
and it is desirable that it should be ascertained definitely that
the species occurring at Arcachon is really A. ecaudata and not
A. branchialis.
Ives regarded all specimens of Arcnicola with eleven to fifteen
pre-branchial segments as A. ecaudata, the distribution of which he
gave as "Europe, Mediterranean, Black Sea." It is abundantly
evident that this " species " included A. branchialis.
Eathke's A. boeckii and Dalyell's ".Lumbricus marinus, another
species," were undoubtedly examples of A. ecaudata, with which they
agree in their form and ecaudate character, and in the position of the
first gill. Eathke's two examples were small and slender, the larger
one was only 42 mm. long, but Dalyell's specimen was well grown,
being about 215 mm. in length.
An examination of Mr. Hanna's original specimens of " A. bucci,"
which are small, proves their identity with A. ecaudata.
The statements of the authors cited under A. branchialis show
that they have included therein A. ecaudata. Prof. Fauvel spoke, at
the Zoological Congress of 1898, of A. boeckii as a synomym, and of
Clymenides ecaudatus and Branchiomaldane vinccnti as post-larval
stages of Arenicola branchialis, but in the same year (op. cit., 1898)
realised that he had confused the two species ecaudata and grubii
( =• branchialis) under the name branehialis, and that Branchiomaldane
was not a stage of either.
Johnston's idea of the characters of A. branchialis was evidently
very hazy ; in fact, he did not know the differences between it and
A. ecaudata. Of the specimens he ranged under A. branchialis,
three are mentioned, by the names A. nodosa, montagui and
dorvilliana, as if they were synonyms. But these names ought
not to have been included in the synonymy, as they were used by
Leach in labelling specimens in his own collection ; no description
of these three " species," nor any further reference to them was pub-
lished. These designations are nomina nuda and are therefore not
included in the synonymy in the present work. The specimens
labelled A. nodosa and montagui are still preserved, but " A. dorvil-
liana " is no longer in existence. " A. nodosa " is a complete and
typical dark example, with bluish-green sheen, of A. branchialis ;
Arenicola ecaudata 135
" A. montayui " is u specimen of A, ecaudata, it is in bad condition
and incomplete, but there is no doubt as to its species.
In the memoirs cited of Profs. Marenzeller, Mesnil, Michaelseii
and Saint Joseph, " A. branchialis " included all the ecaudate forms
then described — e.g. ecaudata, bocckii, yrubii, etc.
BIONOMICS. — Arenicola ecaudata is not found burrowing in the
ordinary sand of the beach like A. marina; it occurs in the littoral
zone but chiefly in sandy, gravelly or muddy material among
stones, or in clefts at the base of rocks in the debris formed by the
breaking down of the latter. A considerable amount of organic
matter is generally present in the material in which the worm lives.
The burrows of A. ecaudata and branchialis are oblique or sinuous
cavities, lined with a fair amount of mucus, and situated a few
inches below the surface in gravel or between rocks and stones.
The castings of the worm, being composed of coarse material having
little coherence, soon fall apart. The well-known signs — the sand-
rope-like heap of castings and the funnel-like depression in the sand
— which indicate the presence of A. marina on countless sandy
beaches, have no good counterparts in the case of the ecaudate
species, in which both the castings and the mouth of the burrow are
inconspicuous among their surroundings. Whether these species are
present in any given area is therefore not obvious from a super-
ficial examination, as is often the case where A. marina is con-
cerned ; their presence can only be ascertained after careful, and
sometimes prolonged, search in likely places, such as those above
described.
Little is known of the habits of A. ecaudata when it is covered
with water, but observations of Prof. Fauvel 1 are of interest in this
connection. He saw examples of A. ecaudata, which were kept in
an aquarium, leave the sand during the night to wander about at
the surface of the water, or to swim freely.2 Each was surrounded
by a thick envelope of mucus. On a light being brought near
the aquarium, the worms at once began to burrow into the sand,
leaving behind their mucous envelopes.
SIZE. — Average specimens of A. ecaudata, when normally extended
are about 130 to 180 mm. long. The longest seen by the writer was
255 mm. in length. When at first withdrawn from their burrows
1 Me'm. Soc. Nation. Sci. Nat. Math. Cherbourg, xxxi (1899), p. 141.
• Cf. the remarks on the swimming of A. marina, p. 97.
136 A ren icolidae
the worms contract, but soon extend in well aerated water to nearly
twice their reduced length.
COLOUR. — The colour of this species varies from dark brown or
black, with greenish metallic sheen, to light reddish brown. Most
of the British examples seen by the writer are of a yellowish red or
brownish red tone, and with a purple anterior region, as shown in
PI. II, Fig. 7, but about one-third of the specimens collected are
much darker, being coloured almost exactly like the example of
A. branchialis figured on the same plate (Fig. 5).
VARIATIONS IN THE ORGANS. — The most striking variation is in
regard to the number of segments. Adult specimens of this species
seldom exhibit as many segments as they possessed at the end of the
post-larval stage, but occasionally an unabbreviated example is met
with, in which case the number of segments is about sixty to
sixty-four. There are about forty-five to fifty segments in average
specimens.
The number of gills depends, of course, chiefly on the number of
chaetiferous segments, but even in unabbreviated specimens there
may be some reduction in the gill-series anteriorly, or posteriorly, or
at both ends. In about twenty per cent, of the specimens examined
the normal first gill (that is, that on the sixteenth segment) was
found wanting on both sides, and in a further twenty per cent, on
one side. The last- segment is not uncommonly abranchiate, and
the writer has seen specimens with two, three, four, six and nine
posterior abranchiate segments respectively.
Prof. Fauvel states that in his examples of A. ccaudata the
number of nephridia is "12 paires, parfois 13," the last nephridium
usually opening on the sixteenth segment, but all the British
specimens examined by the writer possess thirteen pairs, and there
was no sign of reduction of the last pair.
PERIOD OF MATURITY, DEVELOPMENT. — A. ccaudata was found to
be mature, in the neighbourhood of Port Erin, during April, 1897,
for the nephridial vesicles of specimens then dissected were greatly
dilated with ova ready to escape. Eipe examples were obtained from
Plymouth at the end of August, 1910, and from these Figs. 52
and 53, PI. XV, were drawn. Whether there is for this species
in Britain one continuous period of maturity, extending from the
beginning of April to September, or there are two periods, separated
by a non-breeding interval, the writer has not had the opportunity of
Arenicola ecaudata 137
determining with certainty. Prof. Fauvel states that, in the neigh-
bourliood of Cherbourg, the period of maturity of A. ecaudata extends
through a considerable part of the year, for from the end of March
to the beginning of October he has found individuals dilated with
reproductive products.
Nothing is known regarding the form in which the eggs of this
species are deposited. The early development is also unknown, the
earliest stages observed being post-larval examples, about 4' 5 mm.
long, with about fifty chaetiferous segments. These are abranchiate
and remain in that condition until about sixty fully formed
segments are present, then gills begin to appear, generally on the
sixteenth to nineteenth segments inclusive, and are subsequently
formed on the following segments.
Post-larval stages range in colour from reddish or pale greenish
yellow to dark green ; the first two or three segments and the
pygidium are generally darker than the rest of the worm. These
stages are found near low-tide mark, among algae, for instance,
among the " roots " of Laminaria, or in the crevices of Lithotlianmion.
When their gills have become well developed, and for the most
part ramified, the worms leave the crevices in and among algae and
begin to burrow in sand or gravel.
Most of the post-larval specimens recorded have been collected
in July, August or September, but Prof. Fauvel has found them also
in April, and M. Ferronniere in March. Mr. Southern took them in
numbers in October, 1910, and obtained a single specimen in
March, 1911. For an account of post-larval specimens see p. 80.
DISTRIBUTION. — Arenicola ecaudala has been obtained from several
widely separated British localities; it has been recorded from
Shetland, Berwick, Devon and Cornwall, the Isle of Man, Cumbrae,
Loch Maddy, and the writer has seen examples x from Loch Sween ;
in Ireland the species is known to occur in the north (Antrim), east
(Co. Dublin), west (Gal way and Mayo2) and south-west (Valencia
and Crookhaven 2).
This species has been found in the Channel Islands, and at several
stations on the north coast of France, namely, in the neighbourhood
of Cherbourg and at Kerity ; on the west coast, it has been recorded
from Finistere, the Loire estuary and Arcachon, this last being the
1 In the collection of Prof. J. Graham Kerr, F.E.S.
2 The specimens from Blacksod Bay, Mayo, and from Crookhaven were
collected by Mr. E. Southern.
138 A renicolidae
most southerly known locality for the species. A. ccaudata occurs
on the Swedish coast near and to the north of Goteborg, and on
the Norwegian coast at Hvidingso (near Stavanger), Bergen and
Trondhjem, this last being the most northerly station from which
the species has been obtained.
A. ecaudata is therefore known from the coasts of north-western
and western Europe as far south as about 45° N. lat.
Polperro, Cornwall ... 62. 7. 12. 61.
Cornwall 72. 8. 30. 28.
Falmouth . . . . W. C. Cocks. 50. 8. 20. 17.
(" A. montagui ") South Devon . Mus. Leach. Old Coll.
Plymouth ' Norman Coll. 1912. 4. 8. 3.
Plymouth .... „ 1902. 7. 8. 69-71.
Plymouth .... 96. 7. 15. 17 & 18.
Bordeaux Harb., Guernsey . . Prof. Jeffrey Bell. 89. 9. 16. 17.
Herm „ * „ 89. 9. 16. 9.
Millport Ashworth Coll. 1912. 4. 9. 20.
Cherbourg (post-larval stage) . ,, ,, 1912. 4. 9. 19.
ARENICOLA BRANCHIALIS Audouin and Edwards.
(A. cjrubii Claparede.)
Plate II, Figs. 5, 6 ; Plate IX, Fig. 20 ; Plate XV, Fig. 51.1
Arenicola branchialis —
Audouin et Edwards, Ann. Sci. Nat., xxx (1833), p. 422, pi. xxii, fig. 13;
Hist. Nat. Litt. France ii (1834), p. 287, pi. viii, fig. 13 (St. Malo).
Bobretzky, Mem. Soc. Nat. Kiev, i (1870), pp. 6, 248 (Black Sea).
Caillaud, Ann. Soc. Acad. Nantes, xxxvi (1865), p. 28 (Loire-Infer.).
? Chenu, Illustr. conohyliol., i (1842), pp. 1, 12, pi. i, fig. 6.
Fauvel, Bull. Soc. Linn. Norm., ser. 4, ix (1896), p. 141 (St. Vaast).
Johnston, Catal. Worms Brit. Mus. (1865), p. 345 (Cornwall).
Mesnil, Zool. Anz., xxi (1898), p. 631 ; Bull. Sci. France Belg., xxxii
(1899), p. 318 (La Hague).
Quatrefages, Hist. nat. Annel., ii (1865), p. 265.
Arenicola branchialis, near to —
Gosse, Rambles Devon. Coast (1853), p. 174 (Watermouth).
Arenicola branchialis, partim —
Johnston, op. cit., p. 231.
Marenzeller, Zool. Jahrb. Abt. Syst., iii (1888), p. 13.
Mesnil, Bull. Sci. France Belg., xxx (1897), p. 163.
Michaelsen, J.-B. Komm. Wiss. Unters. Kiel, N.F., ii (1896), p. 136.
Saint-Joseph, Ann. Sci. Nat. Zool., ser. 8, v (1898), p. 391.
Arenicola grubii—
Clapare&e, Annel. Naples (1868), p. 296, pi. xix, fig. 2; Mem. Soc. Phys.
Geneve, xx (1870), p. 36.
Allen and Todd, J. Mar. Biol. Assoc., N.S., vi (1901), p. 195 (Salcombe
Esty.).
1 For other figures of this species, see Fig. 3, p. 34, anterior end ; Figs. 16s,
30, pp. 47, 57, chaetae ; Fig. 35, p. 61, gill ; Fig. 41, p. 70, statocyst ; Fig. 42 c,
p. 72, ovum.
Arenicola branchialis 139
Arenicola grubii — continued.
Ashworth, Fisheries Irel. Sci. Invest. 1908, vii (1909), p. 2 (Gal way) ;
Mitt. Zool. Mus. Berlin, iv (1910), p. 353 (St. Malo; Koscoff; Nice;
Lesina (Adriatic)); Ann. Sci. Nat. Zool., ser. 9, x (1910), p. 113
(I. Chausey ; Tangier, Morocco).
Beaumont, Proc. R. Irish Acad., ser. 3, v (1900), p. 784 (Valencia).
Ehlers, Zeits. Wiss. Zool., liii, Suppl. (1892), p. 249, taf. xiii, figs. 33-37.
Fauvel, Bull. Sci. France Belg.. xxxii (1899), p. 292 (Cherbourg) ; Mem.
Soc. Nation. Sci. Nat. Math. Cherbourg, xxxi (1899), p. 166; Bull.
Inst. Ocean. Monaco (1909), no. 142, p. 8 (Berlinga Is.).
Gamble and Ashworth, Q. J. Micr. Sci., xliii (1900), pp. 429, 541, pi. xxii,
fig. 3 (I. of Man; Jersey; Port Appin).
Horst, Notes Leyden Mus., xi (1889), p. 43, pi. iii, figs. 12-15 (gills, chaetae).
Jourdan, C. B. Acad. Sci. Paris, xcviii (1884), p. 757 (Marseilles).
Lo Bianco, Atti B. Accad. Sci. Fis. Mat. Napoli, v, ser. 2, no. 11 (1893),
p. 10, tav. ii, fig. 2; Mitt. Zool. Stat. Neapel, xiii (1899), p. 484: xix
(1909), p. 577.
Arenicola grubei —
Ferronniere, Bull. Soc. Sci. Nat. Quest France, ser. 2, i (1901), pp. 39, 53
(Loire-Infer.).
Arenicola bobretzkii —
Czerniavshy, Bull. Soc. Imp. Nat. Mosc., Ivi (1881), p. 355 (Sevastopol).
Arenicola cyaneus —
Czerniavsky, Trudi Soc. Nat. St. Petersb. (1868), p. 27 (Black Sea).
Arenicola cyanea —
Czerniavsky, op. cit. (1881), p. 354 (Alupka, Black Sea).
Arenicola dioscurica —
Czerniavsky, op. cit. (1881), p. 355 (Suchum, Black Sea).
Arenicola ecaudata —
Grube, Schles. Ges. Vaterl. Cultur, Abt. Nat. (1872), pp. 91, 106, 142
(St. Malo ; Roscoff).
Arenicola ecaudata, partim —
Ives, Proc. Acad. Nat. Sci. Philad. 1890 (1891), p. 74.
Arenicola, eine andere Art -
Crrube, Anat. Physiol. Kiemenwiirmer (1838), p. 3 (Catania).
Arenicola piscatorum, partim —
Delle Chiaje, Descr. Anim. invert., v (1841), p. 100.
? Lumbricus marinus, partim —
Delle Chiaje, Mem. Anim. s. Vert., ii (1825), p. 423.
Ecaudate Arenicola, with first gill on the twelfth 1 chaetiferous
segment ; five pairs of nephridia, which open on the fifth to the ninth
segments ; gonads small, as in the caudate species.
HISTORICAL ACCOUNT. — In 1833 Audouin and Milne Edwards
recorded observations on Arenicola piscatorum and then proceeded to
1 The first gill is often small, and is not uncommonly missing on one or
both sides.
140 A renicolidae
describe a new species — A. branchialis— regarding which they gave
the following particulars : " Cette espece, que nous avons rencontre
pres de Saint-Malo, est beaucoup plus petite que la precedente, et
s'eii distingue principaleinent par le nombre des pieds et des branchies.
Ces derniers organes, au lieu de comuiencer au-dessus des pieds de
la septieme paire, ne se montre que sur 1'anneau qui porte les pieds
de la treizierne ou quatorzierne paire, et au lieu d'etre au nonibre de
treize paires, on en compte de dix-neuf a vingt paires. Du reste,
cette espece ne nous a presente rien de particulier." In the general
description of the genus Arcnicola the authors pointed out that this
worm is divisible into three regions — (a) an anterior, abranchiate,
and generally dilated, (b) a middle branchiferous, and (c) a posterior
apodous. The reference letters, a, b, c, are placed alongside the
corresponding regions in the figures of A. piscatwum and branchialis.
The latter figure represents a specimen about 117 mm. long, in which
are indicated thirty-one pairs of notopodia, beyond the last of which
is a region (lettered c), about 9 mm. in length, without chaetae and
gills. This region, consisting of six rings, of which the terminal one
is the largest, is almost as long as the three preceding chaetiferous
segments. The first right gill is shown on the fourteenth segment,
the first left one on the thirteenth ; there are eighteen gills on the
right side of the worm and nineteen on the left.
It is not surprising that most subsequent authors inferred, from
Audouin and Edwards' account, that in A. branchialis the occurrence
of a " tail" of some extent was to be expected. Some writers greatly
exaggerated the length of this region, for instance, Chenu figured a
specimen, labelled A. branchialis, in which are shown thirty-one
chaetiferous segments, the last nineteen of which are branchiferous,
followed by a tail as long as the branchial region. Quatrefages
added to the diagnosis of A. branchialis the statement " Cauda
quartam partem corporis circiter aequans," and wrote (p. 266) that
" 1'A. branchiale, dont la region caudale est presque aussi developpee
que dans 1'A. des pecheurs," was distinguished by this character from
A. ccaudata. Johnston stated that A. brajichialis and piscatoruru
" agree in having an abranchial tail," and remarked that there was no
complete specimen of the former in the British Museum collection.
Probably the fact that none of the specimens exhibited such a tail
as he expected to find induced him to regard them as incomplete.
His ideas of the characters of A. branchialis were not clear, for the
specimens which he labelled with this name include examples of
both the ecaudate species (see pp. 134, 135).
Arenicola branchialis 141
In 1868 Claparede defined Arenicola grubii in the following
terms — "Corpus longitudine 6-7 cent., latitudine 3-4 mm., nigrum
obscure viridescens, segmentis anticis branchiis destitutis decem,
posterioribus branchiatis viginti, cauda fere nulla." There is an
error in this diagnosis, there being eleven, not ten, anterior abranchiate
chaetiferous segments ; Claparede overlooked the first, a mistake
easily made because the first notopodiuni is often absent or minute.
Claparede remarked on the similarity of his species to A. branchialis,
but noted that in the latter the first pair of gills was said to be on
the thirteenth or fourteenth segment.1 He described the segniental
organs, of which he found five pairs, the nervous system and statocysts,
and noted the unilateral branching of the gills. The position of the
first gill, the absence of tail, and the presence of five pairs of
nephridia and of closed statocysts, serve to fix definitely the species
with which he was dealing.
The brief and imperfect description of A. branchialis given by its
founders has led to much confusion. Some writers have held that
this species was so insufficiently described that its identity could not
be established definitely; others considered it to be identical with
A. grubii, and a few, believing ecaudata and grubii to be synonymous,
have united them under the earlier name branchialis. This last view,
based on a consideration of the gross external features only, became
untenable immediately the internal organs of A. ecaudata were
inspected. The differences between the two ecaudate species in the
number of their nephridia and the nature of their gonads were first
commented upon by Drs. Gamble and Ashworth (1898), and Prof.
Mesnil shortly afterwards drew attention to differences in the number
of segments and gills, and in the position of the first pair of gills.
Accounts of the internal and external anatomy and of the differential
characters of this species were given by Prof. Fauvel and by Drs.
Gamble and Ashworth.
NOMENCLATURE OF THE SPECIES. — The possibility that A. branchi-
alis and A. grubii were identical has not been overlooked, but most
writers since the publication of Claparede's memoir (1868) have
preferred to use for this species the name grubii, because it was asso-
ciated with a description enabling the species to be at once identified.
The identity of A. branchialis cannot be determined by an appeal
1 And that " Johnston, qui parait decrire la meme espece sous le nom de
A. ecauda [sic], 1'indique meme au quinzieme ou seizieme." Claparede evidently
considered branchialis and ecaudata to be synonymous.
142 A renicolidae
to the type specimen, as it is no longer in existence. The only
authoritative information regarding the species is that given in the
original account and figure. The embellishments added to the
diagnosis by some subsequent writers, without reference to the type,
are not admissible as evidence.
The figure of A. branchialis given by Audouin and Edwards
represents an Arenicola with a short " tail, ' but with the characteristic
form of the ecaudate species, that is, the worm is only a little dilated
anteriorly. The writer has a number of specimens of A. grubii in
which, behind the last chaetiferous annulus, there is a region,
composed of three or four rings, about 6 mm. in length. The
corresponding region in Audouin and Edwards' specimen is drawn
about 9 mm. long. Their figure is almost certainly wrong in
representing this terminal portion as cylindrical. It should have
been conical. Making due allowance for this mistake, the figure
shows a specimen of such a character that, were it now in existence,
the writer has no doubt that it would be described as ecaudate, that
is, in contrast to species like A. marina, in which a well-developed
tail is present.
Having reached the conclusion that the specimen of A. branchialis
was ecaudate, it may be stated at once that there is no reason to
associate A. branchialis with A. ecaudata, for there is no known
specimen of the latter with gills so far forward as the thirteenth, or
even the fourteenth, segment. The first pair of gills in A. ecaudata
is on the sixteenth segment, and, after examination of more
than two hundred specimens, the author is convinced that a forward
extension of the gills in this species,1 so that they would correspond
in position to those of A. branchialis, never occurs. The first pair
of gills in A. grubii is normally on the twelfth segment, but not
infrequently the gills of this segment are wanting, and the thirteenth
is thus the first branchiate segment. The writer has seen more than
a dozen specimens of A. grubii exhibiting this condition, and has one
specimen in which the thirteenth segment bears a gill on the left
side only. The fourteenth and succeeding segments are provided
with paired gills. This specimen agrees exactly, in the position of
its anterior gills, with that of A. branchialis figured by Audouin and
Edwards. It has been shown already that the " tail " of A. branchialis
is of the same nature as, and only slightly longer than, that present
1 Only one specimen of A. ecaudata is known in which a forward extension
of the gills has occurred ; in this a small gill is present on the left side only of
the fifteenth segment.
Arenicola bmnchiahs 143
not uncommonly in examples of A. grubii. There is therefore no
character by which A. branchialis, as described by Audouin and
Edwards, can be distinguished from the examples of A. grubii above
mentioned.1 These two species are therefore merged under the earlier
name branchialis.
Prof. Mesnil considered A. branchialis and A. grubii to be
identical, and advocated a return to the former name for this species.
He suggested that Audouin and Edwards had counted and figured an
anterior abranchiate segment too many, and thus assigned the gills
to a position one segment too far back. The writer cannot see any
evidence of this in the figure, which represents the segmentation of
the anterior end approximately accurately, and considers it much
more probable that in Audouin and Edwards' specimen the anterior
gills were wanting, as in that described above.
OBSERVATIONS ON THE RECORDS. — Chenu's modification of the
original figure by the addition of a tail as long as the branchial
region was unwarrantable, and shows that his figure, instead of being
from nature, was a composition. Gosse placed his specimen near
A. branchialis, probably because the number of branchiate segments
was not the same as in Audouin and Edwards', but it was evidently
of this species. The five following citations refer to descriptions
which include both caudate species under the name A. branchialis
(see also p. 135).
The three species described by Czerniavsky from the Black Sea
all possessed the eleven anterior abranchiate segments characteristic
of A. Irancliialis, and differed from one another only in colour and in
the number of branchiate segments, of which they had twenty,
thirteen and fifteen respectively. The type specimen of A. bobretzkii
is no longer in existence, but the writer has had a dozen examples
from the same locality — the Bay of Sevastopol — all of which are
A. branchialis. By the courtesy of Prof. Nassonow the author has
been enabled to examine the types of A. cyanea 2 ( = cyaneus) and
dioscurica, which are preserved in the Zoological Museum of the
1 The writer has reached this conclusion only recently, and after examining
a long series of specimens, in which he found the examples cited above with
reduced gills and those with the terminal region more elongate than usual.
When PL II was printed, early in 1909, he was of opinion that the
identity of A. branchialis and grubii could not be established with certainty,
and that therefore the correct name of the species was A. grubii.
2 The much inflated anterior ring, mentioned in Czerniavsky's description
of this species, is the protruded pharynx.
144 Arenicolidae
Imperial Academy of Sciences, St. Petersburg. They are both
undoubted A. branchialis.
The three specimens recorded by Grube, from Saint-Halo and
Roscoff, as A. ecaudata, are preserved in the K. Zoologisch.es
Museum, Berlin, and have been shown by the writer to be examples
of A. branchialis.
Ives' definition of the " species " ecaudata — with eleven to fifteen
pre-branchial segments — and the localities cited — Europe, Medi-
terranean, Black Sea — show that A. branchialis was included.
The Catanian Arenicola described by Grube had thirty-eight
segments, the first eleven of which were abranchiate, and it therefore
belonged to this species.
In Delle Chiaje's account of his examples of " A. piscatorum"
the chief characters mentioned are that the worms were reddish
yellow, and had thirty-one chaetiferous segments, thirteen to twenty
of which bore bi- or tri-partite gills. A specimen with thirty-one
segments and twenty pairs of gills would have the first pair on the
twelfth segment, as in A. branchialis, and no doubt some of the
specimens belonged to this species. Those with thirteen pairs of
gills may have been examples of A. pusiila.
The unsatisfactory nature of the information given by Delle
Chiaje regarding " Lumbricus marinus " has already been noticed
(pp. 120, 121), and the reasons stated for believing that his series
of specimens included one or more A. branchialis.
BIONOMICS. — The habits of Arenicola branchialis are similar to
those of A. ecaudata (see p. 135), and the two species have been
frequently taken together. A. branchialis is usually found in
oblique or sinuous cavities1 in coarse, sandy or gravelly material,
among stones about the mid-littoral zone. Like other species,
A. branchialis is more plentiful in situations in which organic matter
is abundant ; for instance, in the Bay of Naples this species lives by
preference near the mouths of drains, where it is very common (Lo
Bianco). Prof. Fauvel found A. branchialis, near Cherbourg, in
black muddy sand which gave off an offensive odour; the worms
were so abundant there that they were collected for use as bait.2
This species is, however, seldom found in such large numbers, or
obtained so easily, as to make its collection for bait worth the labour
required.
1 Saint-Joseph (loc. cit.) found a specimen of A. branchialis, at St. Jean de
Luz, in the sand, in a U-shaped burrow similar to that of A. marina.
2 Bull. Soc. Linn. Norrnandie, ser. 5, ii (1899), p. 67.
Arenicola branchialis 145
SIZE. — Average British or French specimens of A. branchialis are
about 150 mm. long, when extended normally; the longest seen by
the writer reached a length of 250 mm. Specimens from Naples and
the Black Sea have a thinner body wall and are less robust than the
preceding, and seldom exceed 100 mm. in length.
COLOUR. — Examples of Arenicola branchialis from the Atlantic
shores of Great Britain, France, Spain and Northern Africa, range in
colour from bluish black to dark green, brown, and light reddish
brown, but the majority are very dark. The specimen represented
in PI. II, Fig. 5, exhibits the typical colouration of British specimens,
and indicates the greenish iridescence so frequently associated
with the anterior region. A few examples from the localities above
named exhibit lighter colours, similar to those shown in the figure
of A. ecandata on PI. II, Fig. 7.
Neapolitan specimens are generally dark iridescent green in
their anterior and posterior regions, and dark reddish brown in the
middle region of the body, but occasionally a lighter specimen —
yellowish red in colour— is met with.
VARIATIONS IN THE ORGANS. — The number of segments is subject
to much variation ; most specimens have lost some of their posterior
segments and thus exhibit fewer than they possessed at the end of
the post-larval stage, when forty to forty-three were present. The
number of segments in this species is therefore about twenty fewer
than in A. ecaudaf.a, in which there may be sixty to sixty-four.
Average specimens of A. branchialis have about thirty segments.
The gills are liable to reduction anteriorly (see p. 142) and posteriorly,
the last one to four segments being not uncommonly abranchiate.
The first notopodium' is either minute or wanting in about 30 per
cent, of the specimens examined, but the corresponding neuropodia
are well developed (PI. II, Fig. 6).
PERIOD OF MATURITY, DEVELOPMENT. — In the Irish Sea and the
English Channel the breeding season is about September to October.
Lo Bianco states that this species is mature at Naples in winter;
specimens examined there by the writer at the end of March,
1900 and 1906, were found to have finished spawning.
The form in which the eggs are laid, and the larval development
are unknown. The only known post-larval examples (described
on pp. 81, 82) were collected by Mr. 11. Southern, among the " roots "
of Laminaria, in Blacksod Bay, Mayo, in September, 1910.
L
146 Arenicolidae
DISTRIBUTION. — It is remarkable that Arenicola branchialis has
not been recorded from any point on the shores of the North Sea.1
The species is known from the following British localities — North and
South Devon, Cornwall, the south-west of the Isle of Man, Millport,
Port Appiu (Loch Linuhe), Loch Maddy2 (North Uist), Galway,
Mayo,3 Valencia, Port Stewart3 (Londonderry), as well as from
Jersey and Guernsey. It has been recorded from several points on
the north coast of France, from Luc-sur-Mer to lloscoff, and also
from the Loire estuary and St. Jean de Luz. This species also occurs
at Santander,4 and on the coast of Portugal at La Granja and the
Berlinga Islands, and the writer has recently recorded examples
from Tangier, Morocco. There is a specimen in the K. Zoologisches
Museum, Berlin, said to be from the South Atlantic, but no nearer
indication of the locality is given.
In the Mediterranean, A. branchialis occurs in the Gulf of Lyons,
at Nice, Naples and Catania,5 and at Triest and Lesina in the
Adriatic. It has been recorded from three stations — Sevastopol,
Alupka and the Bay of Suchum — on the northern shore of the Black
Sea, but it apparently does not occur on the western shore of this
sea in the vicinity of Varna.6
The distribution of A. branchialis may be summarised thus—
this species is known from the Atlantic coasts of western and
north-western Europe and Morocco, from several stations in the
Mediterranean (south coast of France, Naples, Sicily), from the
Austrian coast of the Adriatic and the northern shore of the
Black Sea.
On a portion of the Atlantic seaboard of western and north-
western Europe the two species A. branchialis and ecaudata are
found together, but the former does not occur so far north 7 as the
latter, and has not been found on the shores of the North Sea. But
A. branchialis has been found about 10° further south than
A, ecaudata, and extends into the Mediterranean, Adriatic and
1 The station nearest to the North Sea from which this species has been
recorded is Luc-sur-Mer (Calvados).
• Specimens in the collection of Prof. W. C. M'Intosh, F.R.S.
3 Specimens collected by Mr. R. Southern.
4 Specimens sent to the writer by Prof. Bioja y Martin.
5 Careful search has been made for this species in the neighbourhood of
Messina and Palermo, but without success. Prof. Viguier has informed me that
he has not seen any specimen of Arenicola on the coast of Algiers.
6 From information kindly given by Prof. B. Kurzius, of Sofia.
7 The most northern station from which A. branchialis has been obtained
is Loch Maddy, in North Hist, whereas A. ecaudata has been found as far
north as Trondhjem,
Branchiomaldane vincenti 147
Black Seas, from which A. ecaudata has not been recorded and in
which it probably does not occur.
Polperro, Cornwall ... 62. 5. 5. 48-52.
Cornwall 68. 1. 17. 9.
(" A. nodosa ") * South Devon . Mus. Leach. Old Coll.
Plymouth .... Norman Coll. 1912. 4. 8. 4.
Port Erin, I. of Man . . . Ashworth Coll. 1912. 4. 9. 43-5.
Blacksod Bay, Mayo (end of
post-larval phase) . ,, „ 1912. 4. 9. 40.
Naples . . . . . Nornian Coll. 98. 5. 6. 17-19.
Mediterranean 85. 8. 10. 49.
Cette, Herault .... Ashworth Coll. 1912. 4. 9. 39.
Eudoume, Marseilles. . . ,, ,, 1912. 4. 9. 41/2.
Sevastopol .... „ .„ 1912.4.9.38.
Santander .... „ „ 1912. 4. 9. 35-37.
BBANCHIOMALDANE Langerhans (1881).
BRANCHIOMALDANE VINCENTI Langerhans.
Plate XI, Figs. 31, 32, 33.
Branchiomaldane vincenti —
Langerhans, Nova Acta K. Leop.-Car. Akad., xlii (1881), p. 116, tab. v,
fig. 21 (Teneriffe).
Branchiomaldane vincenti —
Ashworth, Proc. B. Soc. Edin., xxxii (1912), p. 62.
Gamble and Ashworth, Q. J. Micr. Sci., xliii (1900), pp. 536, 553.
Mesnil, Bull. Sci. France Belg., xxx (1897), p. 156 (St. Martin) ; xxxii (1899),
p. 323; Zool. Anz., xxi (1898), p. 635.
Arenicola vincenti —
Fauvel, C. R. Acad. Sci. Paris, cxxvii (1898), p. 735; Bull. Sci. France
Belg., xxxii (1899), p. 313; Mem. Soc. Nation. Sci. Nat. Math. Cher-
bourg, xxxi (1899), p. 165.
Clymenides incertus —
Mesnil, Bull. Sci. France Belg., xxx (1897), p. 154.
Adult. — Small, ecaudate, feebly-pigmeuted Arenicolidae, found
living in mucous tubes among algae or on stones. Gills, consisting
of one, two or three, rarely four, finger-shaped filaments, borne
dorsally on the middle and posterior segments. The branchial
segments are, for the most part, bi-annulate, being composed of a
larger anterior chaetiferous and a smaller posterior branchiferous
annulus. Prostomium large, nuchal groove shallow. Two pairs of
nephridia, opening on the fifth and sixth segments, the second
nephridium elongate and extending backwards into the seventh and
eighth segments (or even further). Hermaphrodite, reproductive
organs situated on the septa and oblique muscles. Statocysts absent.
1 See pp. 134, 135, for remarks on this specimen.
L 2
148 A renicolidae
YOUNG STAGES. — Similar in form to adults, but abranchiate. The
anutilation may not have made its appearance, and gonads are
absent.
HISTORICAL ACCOUNT. — This genus and species were based by
Langerhans on some small worms which he found living in sand-
covered tubes on the north shore of Teneriffe. He stated that,
while these specimens exhibited unmistakable relationship with the
Maldanidae, the presence of gills on a number of the posterior
segments indicated that the worms should be placed in the family
Thelethusae. Langerhans briefly described the anterior end, the
chaetae and gills, and defined the genus thus : " Thelethusen mit
einfachfadenfonnigen Kiemen."
Prof. Mesnil gave some details regarding the segmentation of
the body, the chaetae, gills and alimentary canal of a specimen of
B. vincenti, which he had found at St. Martin, near Cape la Hague,
and in 1898 published observations on other specimens, which he
showed to be adult and hermaphrodite, and added a few notes on
the early stages of development.
Prof. Fauvel at first 1 regarded B. vincenti as a post-larval stage
of Arenicola ecaudata, but, on examining other specimens, he saw that
they were adult. He considered B. vincenti to be anatomically an
Arenicola — a dwarf Arenicola arrested at the " Branchionaaldane
stage" — and therefore referred it to that genus as A. vincenti.
Drs. Gamble and Ashworth, after stating the results of their
examination of two specimens of B. vincenti, concluded that the genus
Branchiomaldane should be retained, and the writer, who has recently
investigated the anatomy of the worm in detail, maintains this
view.
Prof. Mesnil at first considered Clymenides incertus to be
autonomous, but in 1898 expressed the belief that his specimens
were young stages of B. vincenti. The writer has examined the
original specimens, which are undoubtedly young B. vincenti.
EXTERNAL FEATURES. — B. vincenti is an elongate, cylindrical
worm, tapering slightly in its posterior half or third (PI. XI, Fig. 31).
It appears not to exceed a length of 20 mm., and most specimens
are considerably shorter — about 7 to 11 mm. The prostorniuni is
bluntly conical and overhangs the mouth. It bears dorsally and
1 Proc. 4th Internal. Congr. Zool. (1899), p. 229 ; Bull. Soc. Linn. Normandie,
s&. 5, ii (1899), p. liii,
Branchioinalda ne vinccnd
149
Fig. 59.— B. vincenti. Anterior end,
dorsal aspect ; PR. Prostomium,
bearing groups of eyes ; PER. Peri-
stomium ; A. B.S. Achaetous body-
segment, CH.SKG.I. First chaeti-
ferous segment. X 50.
laterally groups of eyes (Fig. 59), the number and disposition of
which vary a little in different specimens. The peristomiuin, which
is achaetous, is separated from the prosto-
miuni by a shallow groove. There is no
definite nuchal organ, that is, no pocket-
like invagiuation of the dorsal epithelium,
such as is present in late post-larval and in
adult examples of Arenicola. The next
segment, which is also without chaetae, is
homologous with the achaetous body seg-
ment of Arenicola (p. 37). Following this
are the chaetiferous segments and the
/ bluntly conical pygidium.
The number of chaeti-
ferous segments depends
on the stage of growth
attained. The largest number observed is fifty-one.
Each chaetiferous segment bears notopodial
chaetae and neuropodial crotchets. The notopodia
and neuropodia of all the preserved specimens are
only slightly elevated above the rest of the body
wall. The neuropodia are short, being much shorter
than those of post-larval ecaudate Arenicola (cf.
PL XI, Figs. 33, 35).
The annulation of the anterior and middle seg-
ments is much less definite, and the number of annul!
per segment less constant than in Arenicola. In the
larger specimens the segments from the third or
fourth to nearly the thirtieth are divided into four to
seven 1 rings. The last twelve to twenty segments
are generally bi-annulate, the larger anterior ring
bearing the chaetae and the smaller posterior one
the gills (PL XI, Fig. 33). This condition was evi-
-B. vincenti. dently presented also by Langerhans' specimens (see
Fig
Interior 'noto* his Fig. 21 g), and it seems to be sufficiently constant
& to be cited as one of the diagnostic features of this
worm.
to each other.
CHAETAE. — Langerhans observed the presence of two kinds of
notopodial chaetae, which he figured, but not very accurately.
1 Some of these may not be true annuli, but may be due to folding of the
body-wall brought about by contraction of its muscles.
150
Arenicolidae
They are not so markedly different as his figures imply. In each
notopodium (Fig. 60) there are from two to four, occasionally five,
straight or slightly curved chaetae of the type shown in Fig. 62 B,
and a similar number of chaetae, each of which is bent so that the
Fig. 61. — B. vincentijnv.
(" Clt/menides incer-
tiis "). Notopodial
chaeta.
Fig. 62. — B. vincenti. The distal portions —
in each case about three-fifths— of three
notopodial chaetae. B, C. Typical adult
chaetae ; B is drawn in optical section ;
A, transitional form, intermediate between
those shown in Fig. 61 and Fig. 62 B.
distal third or fourth makes with the proximal part an angle of about
150° (Fig. 62 c). Both these kinds of chaetae are cylindrical proxi-
mally, but beyond the middle of their length they become limbate
(cf. Fig. 62 A). The limbate region merges into the tapering terminal
BrancJiioinaldane vincenti
151
portion, which bears fine spinulations. The laminae of the chaeta are
not entire at their margin, but are broken up, from the edge inwards,
into fine, closely set teeth. The figures represent this part of the
chaeta as seen in optical section. In some cases this region of the
chaeta appears to be almost enveloped with the fine teeth, and the
terminal part is invariably covered with them. In some specimens
the two kinds of chaetae tend to merge into one another, and should
probably be regarded as different facies of the same type. A noto-
podial chaeta of " Clymenides incertus," having a broader distal region
and a well-marked constriction near the origin of the lamina on one
side, is shown in Fig. 61.
Fig. 62 A represents a
transitional form, interme-
diate between the young
chaeta of Fig. 61 and the
adult chaeta of Fig. 62 B.
The neuropodial
crotchets have the same
general form as those
Fig. 63.— B. vincenti
juv. ("Clymenides
incertus "). Neuro-
podial crotchet.
Fig. 64.— B. vincenti,
adult. Neuropodial
crotchet.
Fi<;. 65. — B. vincenti jnv.
(" Clymenides incer-
tus "). Crotchet from
one of the posterior
uotopodia.
of Arenicola, but the tip of the rostrum is very sharp (Fig. 64). The
crotchets in each neuropodium are always few in number, they
appear never to exceed nine or ten, and there are only two or three
in the first two and last segments.
Prof. Mesnil stated that in his specimens of " Clymenides incertus,"
which had twenty, twenty-two and twenty-three chaetiferous seg-
ments respectively, each of the last six segments bore dorsally a
crotchet, either alone or accompanied by a capillary chaeta. One of these
crotchets, drawn from one of the original examples of " 0. incertus"
A rcn icolidae
lent to the writer by Prof. Mesnil, is shown in Fig. 1)5. As in
Arenicola (pp. 39-41) crotchets occur in the notopodia for a short
period only ; they are no longer present in t wo specimens of B. vincenti,
4 and 5 mm. long respectively, with twenty-seven segments. .
GILLS. — The gills of B. vincenti are of a much simpler type than
those of Arenicola. Each consists of one, two or three, rarely four,
finger-like filaments, not more than -15 mm. long, each containing-
an extension of the coelom and a vascular loop. The position of the
first gill is subject to variation : for instance, in the specimens
examined by the writer, the first branchiate segment is the 18th,
19th, 19th, 20th, 21st and 21st respectively.1 The succeeding
segments, except perhaps the last or last two, are all branchiate.
Gills begin to arise about the time the worm has attained thirty
segments, and then develop rapidly, for in a specimen with thirty-
six segments, gills are present on the 19th to 34th inclusive.
HABITAT. — Langerhans found B. vincenti living in small sand-
covered tubes, among algae, on the rocks of the beach of Teneriffe.
Prof. Mesnil collected his specimens in rock pools near Cape la
Hague ; the worms were inhabiting transparent mucous tubes,
which were generally situated on the lower side of the encrusting
calcareous alga Litliothamnion.
COLOUR. — Langerhans states that his specimens were brownish.
Prof. Mesnil's first specimen was a clear grayish colour, but his later
ones pale rose. Specimens preserved by him in formalin, and given
to the writer, have a pale pink colour. The pigmentation is much
less in amount than in specimens of Arenicola ecaudata of about the
same size.
INTERNAL ANATOMY. — The coelom resembles, in its relations and
proportions, that of an ecaudate Arenicola. The coelomic fluid
contains numerous oval and spindle-shaped cells and the genital
products. Septa are present at the anterior end of the first, third
and fourth segments, and throughout the gill region. There are no
septal pouches (PL XI, Fig. 32).
The alimentary canal is similar to that of Arenicola, except that
the two oesophageal glands have a common duct.
1 Langerhans records examples in which the first gill was borne on the 23rd
and 24th segments respectively.
Branchiomaldane vincenti 153
The lobate brain, oesophageal connectives, non-gauglioiiated nerve-
cord (without giant fibres), and eyes are similar to those of a young
Arcnicola. Statocysts are absent.
The earlier statements regarding the nephridia of B. vincenti
give the impression that there is considerable variation in the number
of these organs. Prof. Mesnil (1897) referred to the presence of
pigmented segmented organs in the 5th, 6th, 7th and 8th chae-
tiferous segments, and, in 1898, stated that four or five pairs were
present ; Prof. Fauvel attributed three to five pairs of nephridia to
this worm, but Drs. Gamble and Ashworth found only two pairs,
opening on the fifth and sixth segments. The writer has examined
five specimens in regard to their nephridia, and in all of them
only two nephridiopores could be seen, situated immediately ventral
and posterior to the fifth and sixth neuropodia. By means of
serial sections of two specimens and by dissection of another it has
Fig. 66. — B. vincenti. Diagram of the nephridia of the left side, seen from the inner (median) aspect.
The crotchets of the fifth, sixth, seventh, and eighth neuropodia (v, vi, VII, vm), and the
external openings (N.o', N.O2) of the first and second nephridia 1 are indicated.
been proved definitely that only two pairs of nephridia are present
but the second is continued backwards, beyond its pore, as far as
the eighth or ninth neuropodium, where it ends blindly (Fig. 66).
The gonads are situated on the coelomic epithelium, especially
of the oblique muscles and septa. All the specimens examined by
the writer were hermaphrodite. The oocytes fall into the coelomic
fluid at an early phase of growth ; their later growth-phases are found
chiefly in the posterior segments, the coelomic cavities of which, in
mature specimens, are practically filled with large oocytes (Fig. 67).
When fully mature the eggs are, according to Prof. Mesnil, milk-
white and about '3 mm. long and -2 mm. broad. They are thus
considerably larger than those of any species of Arenicola, and taking
into account the sizes of the parent worms, the eggs of Brancliio-
1 The funnels of the nephridia, which are small and difficult to investigate
in preserved material, are apparently simple, but their structure can be
determined satisfactorily only in living specimens.
154
Arenicolidae
maldanc are relatively very large. A mature specimen of Arcnicola
may contain several or many thousands of full-grown oocytes, but a
mature specimen of B. vincenti contains comparatively few — about
120 were found in one specimen. The eggs of B. vincenti escape
by rupture of the body-wall in one or more of the posterior segments.
SR
Ov.
NOT;
NEUR.
V.V.
N.C.
Fig. 67.— B. vincenti. Transverse section through the fortieth segment.
D.V. Dorsal blood-vessel ; EP. Epidermis ; INT. Intestine ; M.CiRC. Circular
muscles ; M.LONO. Longitudinal muscles ; M.OB. Oblique muscle ; N.C.
Nerve-cord ; NEDR. Neuropodium ; NOT. Notopodium ; Ov Egg (oocyte) ;
SP. Mass of spermatocytes ; V.V. Ventral blood-vessel. X lift.
N.GR.
Fig. 68. — B. vincenti. Young stages of development (after
Mesnil, 1898) ; N.GR. Nuchal groove.
PERIOD OF MATURITY, DEVELOPMENT. — Mature examples of
B. vincenti have been recorded only by Prof. Mesnil, who collected
them at St. Martin in August and September, 1898. The whitish
eggs were found around the tubes which the worms inhabited.
To Prof. Mesnil we owe also the only observations on the develop-
Branchiomaldane vinceuti 155
ment of this worm (Fig. 68). He states that the " embryo " remains
in the egg-membrane up to an advanced stage of development,
finally becoming strongly flexed. When it becomes free, the young
worm has two pairs of eyes and several segments, of which the third,
fourth, fifth and sixth bear dorsal capillary chaetae, but not crotchets.
Cilia were uot visible except at the posterior dorsal margin of the
prostomium, that is, in the nuchal groove.
Through the courtesy of Prof. Mesnil the writer has been enabled
to examine the three original specimens of " Clymcnides inccrtus,"
which are about 2 • 5 mm. long, and he has no hesitation in stating
that they are young phases of B. vincenti. A comparison of the
capillary chaetae (Figs. 61, 62) of " 0. incertus" with those of
B. vincenti shows that they are all growth forms of the same type of
chaeta, and the neuropodial crotchets (Figs. 63, 64) present identical
characters. Other important points of agreement are afforded by
the prostomium, the segmentation of the body and the absence of
statocysts.
SYSTEMATIC POSITION. — Brancliiomaldane is more nearly related to
Arenicola than to any other Polychaete and must be included in
the family Arenicolidae, but the writer is of opinion that the union
of the two genera Branchiomaldane and Arenicola, recommended by
Prof. Fauvel, is not advisable. Prof. Fauvel has pointed out that
Brancliiomaldane presents several points of resemblance to a young
A. ecaudata, but it may be noted in this connection that, as these
worms live under practically identical conditions, some of the
similarities may be due to convergence. Further, some of the resem-
blances cited by Prof. Fauvel are not so close as they were believed
to be ; compare, for instance, the nephridia and the position of the
gills in Branchiomaldane and Arenicola. It is also worthy of note that
in the most nearly related species of Arenicola, namely, A. ecaudata
and A. branchialis, there are well developed statocysts and septal
pouches, which are wanting in Branchiomaldane. Other important
characters presented by Branchiomaldane — the occurrence of herma-
phroditism,'the extensive distribution of the reproductive organs on
the oblique muscles and septa, the production of comparatively
few, large and plentifully-yolked eggs, which do not give rise to
free swimming ciliated larvae — are not paralleled in Arenicola.
The striking differences, in the branchiferous segments — which are
bi-annulate in Branchiomaldane, the setae and gills being borne on
successive annuli, while in Arenicola they are subdivided into five,
156 A ren icolidae
the largest of which is chaetiferous and branchiferous — are, however,
alone sufficient, in the writer's opinion, to render necessary the
maintenance of the two genera.
While Brancliiomaldanc presents some primitive characters, for
instance, a simple conical prostomium, and homonomy of its segments,
there is considerable evidence of its having undergone secondary
modification and retrogression. Its small size, the simple form of
its gills, the absence or great reduction of certain sense organs
(statocysts and nuchal organ), the reduction in the number of
nephridia, its hermaphroditism, the large size of the eggs and the
absence of a free-swimming larval stage — features in which Branchio-
maldane departs from Arcnicola — are probably to a large extent
correlated with the much more sedentary life of the former.
The systematic position of Branch iomaldane mncenti may be
summarised thus— it is an Arenicolid worm, most nearly related to
the ecaudate species of Arcnicola, to the young stages of which it
presents some points of similarity, both in form and habits, but from
which it differs in several important structural characters. Although
their habits are at first similar, the species of Arenicola soon assume
a more wandering mode of life, which they maintain henceforward,
whereas Brancliiomaldanc remains sedentary, is, in fact, tubicolous,
and exhibits certain retrogressive changes which are often associated
with that mode of life.
Near Cherbourg . . . Ashworth Coll. 1912. 4. 9. 46.
THE INTER-BELATIONSHIPS OF THE MEMBERS
OF THE FAMILY AEENICOLIDAE.
The presence of homonomous segments, as in the ecaudate species
of Arenicola., is undoubtedly the primitive condition, while the
differentiation of the worm into two regions, an anterior in which
the segments bear parapodia and a posterior which has become
achaetous, and in which the segments are feebly marked, as in the
caudate species, is clearly secondary and is probably correlated
with a more sedentary mode of life. Of the ecaudate species
A. ecaudata possesses the greater number of segments, namely, about
sixty, compared with about forty in A. branchial?' s, and the former
may be regarded on this ground, as well as on account of its much
larger number of nephridia, as more nearly retaining the original
condition. The fact that A. ecaudata has, when complete, about
Inter-relationships of the Species of Arenicola 157
sixty segments, and that the definitive number of segments in
A. cristata is also about sixty (seventeen chaetiferous and forty
caudal), suggests that this may have been approximately the
number present in the common ancestor of the genus.
A. ecaudata possesses the largest number of nephridia, namely,
thirteen pairs, and probably, therefore, exhibits the nearest approach
to the primitive condition ; the other species do not possess normally
more than five or six pairs, but that the series of nephridia in these
species formerly extended further back is indicated by the occasional
occurrence of nephridia in one to three segments behind that
containing the last normal nephridium (see p. 82).
Well-developed statocysts are so characteristic a possession of
the genus Arenicola, there being only one species — pusilla — in which
these organs are absent, that it may be assumed they were present in
the ancestral form. The statocysts have retained their primitive
condition, as epidermal invaginations opening to the exterior, in
A. marina, assimilis and ylacialis ; in the other species they have
become transformed into closed vesicles, either with numerous stato-
liths as in the ecaudate species, or with a single endogenous statolith
as in A. loveni and cristata, which exhibit the most specialised con-
dition of the organ. The absence of statocysts in A. pusilla appears
to be a secondary, and not a primary condition.
The prostoniiurn, which in all species of Arenicola is reduced to
small dimensions (a condition no doubt associated with the semi-
sedentary mode of life), has the simplest form in the ecaudate species,
in which it has retained its primitive relations, being situated
anterior to the peristomium and partially overhanging the mouth.
In the caudate species the prostomium is retractile into the nuchal
groove and then no longer exhibits the typical relations.
The primitive characters are not all concentrated in one species
of Arenicola, but it seems clear that a greater number of them have
been preserved in the ecaudate species, and especially in A. ecaudata,
the statocysts of which have, however, advanced some distance on the
way of specialisation. In A. Irancliialis the segments and nephridia
have both been diminished in number, probably correlatively, and
the gonads are much smaller, but otherwise this species is similar to
A. ecaudata.
The caudate species are divisible into two divergent series, one—
including A. marina, glacialis, loveni and cristata — possessing
elongate neuropodia, septal pouches and a single pair of oesophageal
glands, the other — comprising A. assimilis and. pusilla — in which the
158 A renicolidae
neuropodia are short, septal pouches are absent, and there are several
pairs of oesophageal caeca. Of the caudate species, A. marina and
A. assimilis present fewest modifications and stand near the bases of
origin of the two series. Nearly related to A. marina is A. (jlacialis,
their close affinity being indicated by the similarity of their
neuropodia, chaetae, oesophageal glands, septal pouches, nephridia and
statoliths; the gills and prostomium of A. glacialis also more nearly
resemble those of A. marina than of any other species. The chief-
difference between these two species is that in A. glacialis the
chaetiferous segments and gills are reduced in number.
The two species A. loveni and A. cristata have apparently sprung
from the same stem, for in both the neuropodia are long, the gills
highly pinnate, the septal pouches large, and the statocysts closed and
cristata pusilla
branchialis
marina assimilis
BrancMomaldane
each containing only a single large statolith. Further indication of
their affinity is afforded by the similar form of their prostomia ;
while, in the character of its chaetae, A. loveni presents a closer
approach to A. cristata than to any other species. A. loveni exhibits
considerable specialisation in its extraordinary septal pouches and its
notopodial chaetae, while A. cristata has undergone modification in
another direction, namely, reduction in the number of its chaetiferous
segments and gills. The two species A. loveni and A. cristata are
clearly more nearly related to each other than either is to A. marina.
A. assimilis and A.pusilla diverge from the rest of the species in
several striking features (p. 157) and have developed along an
independent line. A. assimilis has primitive statocysts, and its
prostomium is little modified, being not much dissimilar to that of
Affinities 159
A. marina. The close resemblance of the chaetae of A. assimilis
and A. marina is also noteworthy. A assimilis is probably an old
species, perhaps as old, or nearly so, as A. marina. A. pusilla has
undergone considerable specialisation, for instance, in its crotchets, in
the high degree of development of its prostomium, and in the absence
of statocysts. In other respects A. pusilla presents characters similar
to A. assimilis and is clearly derived from the same stem.
Brancliiomaldane, which is most nearly related to the ecaudate
species of Arenicola (see pp. 155, 156), appears to have branched
off near the base of the primitive stem of the family, and, while
retaining some primitive characters, has undergone certain retro-
gressive changes associated with its tubicolous mode of life.
The relationships discussed above are indicated in the diagram
given on p. 158.
THE AFFINITIES OF THE ARENICOLIDAE.
The first satisfactory suggestion respecting the relationship of
Arenicola l was that of Blainville (1828), who, noticing that the
Telethuses and the Maldanies agree in possessing both subulate
chaetae and crotchets, placed these two families in one order,
although one contains branchiate and the other non-branchiate
worms (see p. 15). It is difficult to understand on what grounds
Milne Edwards (1838) united Arenicola and Chaetopterus in the
tribe Arenicolides, nor is it evident why he and, later, Oersted
(1843), suggested the affinity of Arenicola with the Ariciae. The
schema given by Grube in his classical paper (1850) shows that
he regarded the Telethusa2 as related on the one hand to the
Maldania and on the other to Scalibregma and Eumenia, a view
which subsequent work has confirmed. Dr. Levinsen (1883)
ranged the Telethusae with the Scalibregmidae, but united these
with the Amphinomidae to form a sub-order Amphinomiformia.
The Amphinomidae differ from Arenicola in so many important
features that there is no basis in support of the association
suggested. -
Prof. Benham placed the Arenicolidae in the sub-order Scoleci-
formia along with the families Opheliidae, Maldanidae, Scalibregmidae,
Chlorhaemidae and Sternaspidae, and Prof. Hatschek included the
1 Arenicola marina was the only species then known.
2 In which family Grube at first included Arenicola and Dasybranchus, but
later (1862) he removed the latter genus to a new family Capitellacea.
160 A renicolidae
Arenicolidae, Cirratulidae, Capitellidae and Maldanidae in the sub-
order Drilomorpha. On passing in review the characters of these
families it is at once seen that the Sternaspidae are far removed from
the Arenicolidae by the peciiliar arrangement of their gills, chaetae
and gonad, by the presence of ventral shields, genital ducts, a coiled
alimentary canal without oesophageal glands, and only a single pair
of nephridia, and by the absence of septa. The anatomy of the
Chlorhaeniidae, which is, however, only imperfectly known, affords
no evidence of relationship between this family and the Arenicolidae ;
there are so many pronounced structural differences — for instance, in
the nature of the prostomium, gills, chaetae, nerve-cord, the arrange-
ment of the septa and the nephridia — that it may be concluded these
are not allied families. The Cirratulidae are also separated from the
Arenicolidae by a series of striking differences, for instance, in their
chaetae, gills, nephridia and prostomium. The Capitellidae, though
having some points of external resemblance to the Arenicolidae.
exhibit such differences that it seems clear these families are not
nearly related ; consider, for example, the nephridia and genital
funnels of Capitellids, the different arrangement of their parapodia,
the presence of genital chaetae and hooded crotchets, the form
of the gills (when present), the regularly septate coelom, the
ganglionated nerve-cord, and the absence of blood-vessels and
oesophageal glands.
There are several characters common to the families Arenicolidae,
Scalibregmidae and Opheliidae, which are probably due to their
similar mode of life, the members of these families being limivorous.
They have a spacious coelom, subdivided anteriorly by septa but
non-septate in the middle portion of the animal, the alimentary canal
consists of an eversible pharynx, followed by an oesophagus (bearing
one or more pairs of glandular caeca), a dilated "stomach" and a
straight intestine. In addition to these features the Scalibregmidae *
agree with the Arenicolidae also in the subdivision of their segments
into annuli, in the sculpturing of the skin, and in the presence in
Scalibregma and Eumenia of branched gills of a type similar to those
of Arenicola. The brain and the non-ganglionated cord of Scalibregma
are similar to those of the caudate species of Arenicola. But there
are several characters in which the Scalibregmidae differ sharply
from the Arenicolidae ; for instance, the two rami of the parapodia
of the former are practically identical in form, there are no crotchets,
1 See J. H. Ashworth, " The Anatomy of Scalibregma inftatum Eathke," in
Q. J. Micr. Sci., xlv (1901), p. 237.
Affinities 161
but characteristic furcate chaetae are present, along with capillary
chaetae, in both rami of the parapodium ; in some of the Scalibregmidae
the parapodia form laminate appendages bearing dorsal and ventral
cirri; the gills do not extend, in the fScalibregmidae, backwards
beyond the fifth or sixth segment, the heart is a median dilatation
on the dorsal vessel, the nephridia are numerous and minute, and
complex lateral sense organs are generally present, but statocysts
and eyes are absent. .
Besides the features mentioned above (p. 160) as common to the
three limivorous families, the Opheliidae 1 agree with the Arenicolidae
in possessing uephridia of a~ similar type, but differ in several
important respects, for instance, in the form of the prostomium, in
having a ganglionated nerve-cord, in the nature of their gills which,
when present, are cirriform, in the presence of anal cirri and a dorsal
heart, in the absence of septa in the posterior region, and in the
absence of crotchets and statocysts.
The Arenicolidae present clear affinities with the Maldanidae.2
The head of some of the Maldanids, e.y. Praxillura, is similar in
form to that of the ecaudate species of Arenicola, but the cephalic
plate present in many Maldanids has no counterpart in Arenicola,
while, conversely, a trilobate prostomium like that of the caudate
species of Arenicola does not occur in the Maldanids. The two
families agree in the form of their parapodia and chaetae, capillary
chaetae and crotchets being present in both. The notopodial chaetae
of Maldanids closely resemble those of Arenicolidae, especially those
of young examples, and the crotchets of some Maldanids, e.g. Petalo-
proctus, might easily be mistaken for those of Arenicola. The brain
and non-ganglionated nerve-cord, the nephridia and gonads of
Maldanids are of a type similar to those of the Arenicolidae. The
Maldanids differ from the Arenicolidae in having paired nuchal
organs, and elongate and non-annulate segments, in lacking gills,3
oesophageal caeca, hearts and statocysts,4 and in the specialisation
of the anal segment. Branchiomaldane has been regarded, on
1 See W. Kiikenthal, Jenaische Zeits., xx (1887), p. 511 ; andM. Philippson,
Zool. Anz., xxii (1899), p. 417.
- See I. Arwidsson, Zool. Jahrb. Abt. Syst., Suppl. ix (1907), p. 1.
3 The Maldanid Jchnstonia, has, on the six pre-anal segments, numerous,
short, simple elevations, which serve as respiratory organs.
4 The Arenicolidae are regarded as having been derived from an ancestor
having statocysts. These organs are absent in Arenicola pusilla and Brancliio-
maldane vincenti, which, however, exhibit marked specialisation in several
other respects.
M
162 A renicolidae
account of its tubicolous habits, and of the feeble development of
its gills and the absence of statocysts, as forming a link between the
two families ; but, as already shown (p. 155), there is no doubt that
this genus is a member of the family Arenicolidae, though its habits
are similar to those of Maldanids.
A consideration of the characters of the Arenicolidae shows that
this family has clear affinities with the Maldanidae, and also, but in
less degree, with the Scalibregmidae, and in still less degree with-
the Opheliidae.
SYSTEMATIC INDEX TO THE
AEENICOLIDAE
Synonyms are printed in italics.
(Abbreviations— A. = Arenicola, B. = Branchiomaldane.)
affinis, var. of A. assimilis, 84, 124-132.
antillensis (A.), = cristata, 106, 107.
Arenicola, 28, 29 ; caudate section of
genus, 83 ; ecaudate section, 84.
Arenicola, cine andere Art, = bran-
chialis, 139, 144.
Arenicole des pecheurs, = A. marina,
89.
Arenicolidae, 25 ; affinites, 159 ; inter-
relationships of members of
family, 156.
Arcnicolides, = ecaudate species of
Arenicola, 31.
Arenicoliens, = Arenicolidae, 25, 26.
assimilis (A.), 84, 123-132.
assimilis, (A.), partim, = pusilla, 115,
120.
bobrctz'kii(A..), = branchialis, 139, 143.
boeckii (A.), = ecaudata, 133, 134.
branchialis (A.), 85, 138-147.
branchialis, partim, = ecaudata, 133,
134, 135.
Branchiomaldane, 28, 147 ; affinities,
155, 156, 159.
bucci (A.), = ecaudata, 133, 134.
carbonaria (A.), ;
Caudate species
key, 83.
Chorizobranchus
claparedei (A.), =
claparedi (A.), =
= marina, 89, 95.
of Arenicola, with
= Arenicola, 29, 32.
: pusilla, 115, 119.
pusilla, 115, 117 ;
assimilis var. affinis,
124, 130.
claparedii (A.), = pusilla, 115, 117-
119;
= assimilis var. affinis,
124, 129 f.n.2, 130.
clavatus (A.), = marina, 89, 95.
Clymenides, 29, 32, 75-77.
cristata (A.), 84, 105-111.
cyanea, cyaneus (A.), = branchialis,
139, 143.
dioscurica (A.), = branchialis, 139, 143.
ecaudata (A.), 85, 132-138.
ecaudata (A.) = branchialis, 139, 144.
Ecaudate species of Arenicola, 84,
key to, 85.
ccaudatus (Clymenides), = ecaudata
(A.), 76, 77, 133.
Eruca marina, = A. marina, 89 and
f.n.
glacialis, 84, 111-114.
grubei (A.), = branchialis. 139.
grubii (A.), = branchialis, 138, 139,
141-143.
incertits (Clymenides), = vincenti (B.),
76, 77, 147, 148, 155.
littoralis (Lunibricus), — marina (A.),
86, 93.
loveni (A.), 83, 103-105.
Lug. lugg, lugs, = A. marina, 89, 90.
lumbricoides (Nereis), = marina (A.),
90, 96.
Lumbricus, partim, = Arenicola, 29,
30.
marina (A.), 83, 86-102.
marina (A.), = assimilis var. affinis,
126, 129.
= pusilla, 115, 116, 119,
120.
M 2
164
Systematic Index to the Arenicolidae
marina (Eriica), = marina (A.), 89
and f.n.
marina (A.), oiler eine selir naJicr
Verwandter, = assimilis, 124,
130.
marinus (Chorizobranchus), = pusilla
(A.), 115.
marinus (Lumbricus), = marina (A.),
86, 91.
marinus (Lumbricus), another species,
= ecaudata (A.), 133, 134.
marinus (Lumbricus), partim,
= branchialis (A.), 139,
144.
= pusilla (A.), 115, 120.
maximus (Lumbricus), = marina (A.),
86, 91.
natalis (A.), = marina, 89, 95.
Nereis lumbricoides, = A. marina, 90,
96.
Orm, = A. marina, 90, 96.
papillosa (A.), = marina, 89, 93.
papillosus (Lumbricus}, = marina (A.),
86, 91, 93.
piscatorum (A.), = marina, 86, 87, 91-
94;
piscatorum (A.), = assimilis var.
affinis, 126, 128.
= branchialis, 139,
144.
= pusilla, 115, 120.
Pteroscolex, = Arenicola, 31, 107.
punctis prominulis (Lumbricus) =
marina (A.), 86, 93.
pusilla (A.), 84, 114-123,
scabcr (Lumbricus), = marina (A.),
86, f.n.2.
sul f urea, sulfureus, sulphurea (Clyme
nides), = marina (A.), 76, 77, 89.
Telethusa, Telethusae, Telethuses, =
Arenicolidae, 25, 26, 27.
Thelethusidae, = Arenicolidae, 25.
tinctoria (A.), = marina, 89, i)6.
Ver du Havre, = A. marina, 90, 91 .
Verrnis ex arena cffossus Lug dictus, =
A. marina, 90.
Vcrmcs marini scolopcndroides, Cornu-
bii'nsibus Lugs dicti, — ^.. marina,
90.
vinccnti (A.), = vincenti (B.), 147,
148.
vincenti (B.), 147-159.
GKENEBAL INDEX
Figures in thick type indicate the chief systematic reference.
For synonyms, see tlie Systematic Index on pp. 163, 164.
(Abbreviations—^. = Arenicola, B. = Branchiomaldane.)
Abranches (Cuvier), 12.
Abundance of A. marina, 97, 100
Achaetous body-segment of Arenicola,
36, 37; of post-lnrval A. marina,
78, ecaudata, 81 ; of B, vincenti,
149.
Aelianus, 1.
affinis, var. of A. assimilis, 84, 124-
132 ; external apertures of stato-
cysts and nephridia, 39 ; chaetae,
46 ; crotchets, 50, 51 ; gills, 60 ;
statocysts, 67-70 ; post - larval
stages, 80.
Affinities of Arenicolidae, 159-162 ; of
B. vincenti with Arenicola, 155,
156.
Albertus Magnus, 2.
Aldrovandus, on classification of " In-
sects," 3.
Alimentary canal of Arenicola, adult,
63-65, larva, 74, 75; of B. vin-
centi, 152.
Annelides, 11 ; classification of Anne-
lids, 11-19,
Annuli, segments subdivided into, in
Arenicola, 34, 36, 38, in B. vin-
centi, 149.
Antsnnees (Lamarck), 12, 24.
Apertures, external of Arenicola, 38,
39.
Apodes (Lamarck), 12.
Arenicola, 11, 13, 14, 20, 23, 24,
26, 27 ; distinguished from B.,
28, 155, 156; defined, 29, 30;
historical account, 30-32 ; exter-
nal characters, 33-38, prosl.o-
mium, 33, 34, parapodia, 34-36,
peristomium, 36, achaetous body-
segment, 36, tail, 37, 38, external
apertures, 38, 39 ; chaetae of noto-
podia, 39-48, of neuropodia (crot-
chets), 48-55; gills, 55-61 ; coelom
and septa, 61, 62; alimentary
canal, burrowing, 63-66 ; nervous
system and sense-organs (incl.
statocysts), 66-70 ; nephridia, 71 ;
reproductive organs, 72, 73 ; de-
velopment, 73-75 ; post - larval
stages, 75-82 ; the genus divided
into sections, 82, the caudate
species, 83, 84, the ecaudate
species, 84, 85 ; relationships of
the species, 156-159.
Arenicolidae, 24, 25-28 ; inter-
relationships of members of, 156-
159 ; affinities of, 159-162.
Arenicolites (burrows, fossil), 97 f.n. *.
Arenicolo-Maldaniens (Mesnil), 27.
Ariciea (Ehlers), 19, 20.
Aristotle, 1.
assimilis (A.), 84, 123-132 ; external
apertures of statocysts and ne-
phridia, 39 ; notopodial chaetae,
46-48 ; crotchets, 50, 51 ; gills, 60 ;
septal pouches wanting, 62 ; oeso-
phageal glands, 63 ; statocysts,
67-70; nephridia, 71; ova, 72;
post-larval stages, 80 ; relationship
to other species, 157-159.
Audouin and Edwards, on classification
of Annelids, 15, 16, 24 ; on A. bran-
chialis, 139, 140.
Bait, use as, of A. marina, 91, 99, 100 ;
of A. brancTiialis , 144.
Easter, 7.
166
General Index
Belon, on Lumbricus marinus, 2, 3,
30, 90.
Benham, on classification of Poly-
chaeta, 21, 24.
Bionomics of A. marina, 96, cristata,
108, jwsilla, 121, ccaudata, 135,
branchialis, 144.
Blainville, on Setipodes, 14 ; on Cheto-
podes, 1,5 ; on relations of Tele-
thuses, 15, 159.
Blumenbach, on difference between
Vermes and " Insecta," 9.
Bonannus, 4.
Bonnet, on Naids and earthworms, 5.
Bosc, 11.
Brain of Arenicola, 66.
branchialis (A.), 31, 32, 85, 138-147;
prostomium, 34 ; iiotopodial
chaetae, 47, 48 ; crotchets, 53, 57 ;
gills, 61 ; septal pouches, 62 ;
oesophageal glands, 63 ; stato-
cysts, 69, 70 ; gonads, ova, 72 ;
post-larval stages, 81, 82 ; distin-
guished from ecaudata, 85 ; re-
lationship to other species, 156-
158.
Branchiomaldane, 147 ; distinguished
from Arenicola, 28, 155, 156 ;
systematic position, 155, 156, 158,
159.
Breeding seasons of A. marina, 100,
cristata, 110, pusilla, 122, assimi-
lis, 131, ecaudata, 136, 137, bran-
chialis, 145, B. vincenti, 154.
Bruguiere, 9.
Buccal mass of Arenicola, 63.
Burrows and burrowing, A. marina,
63-65, 97, cristata, 108, ecaudata,
135, branchialis, 135, 144.
Bushy (fruticose) type of gill of Areni-
cola, 58-60.
Capitellidae, contrasted with Areni-
colidae, 160.
carbonarius (Arenicolites), 97 f.n. l.
Castings of A. marina, 65, 99, cristata,
108, assimilis, 130, ecaudata and
branchialis, 135.
Caudal processes of A. cristata, 109,
110.
Caudate species of Arenicola, 83, 84,
prostomium, 33, 34 ; gills, 58 ;
brain, 66 ; nephridia, 71 ; gonads
and ova, 72.
Chaetae, presence of, as character of
group of worms, 9, 10, 13, 14, 15 ;
of Arenicola. 35, notopodial, 39-
48, neuropodial, 48-55 ; of B. vin-
centi, 149-152.
Chaetopoda, 15, historical account of,
1-25.
Chetopodes (Blainville), 15.
Chlorhaemidae, contrasted with Arcni-
colidae, 160.
Cirratulidae, contrasted with Areni-
colidae, 160.
Classification of worms, 3-11 ; of Anr
nelids, 11-20; of Polychaeta, 20-
25.
Cleansing of the littoral by A. marina,
99.
Clymenidcs, 27, 29, 32, 75-77.
Coelom and coelomic septa of Areni-
cola, 61, 62 ; of B. vincenti, 152.
Colours of A. marina, 101, loveni, 105,
cristata, 109, glacialis, 113, pu-
silla, 121, 122, assimilis, 130,
ecaudata, 136, 137, branchialis,
145, B. vincenti, 152.
Colmnna, 4.
cristata (A.), 84, 105-111, crotchets
in notopodia of larva and post-
larva, 39-41 ; notopodial chaetae,
41-43, 45, 48 ; neuropodial crot-
chets, 51-54 ; gills, 55, 58, 61 ;
septal pouches, 62 ; oesophageal
glands, 63 ; statocysts, 69, 70 ;
nephridia, 71 ; ova, 72 ; egg-
masses, 74, 110 ; development, 74,
75 ; post-larval stages, 79 ; rela-
tionship to other species, 157, 158.
Crotchets, neuropodial, of Arenicola,
35, 48-55, of B. vincenti, 151,
152; notopodial of young Areni-
cola, 39-41, of young B. vincenti,
151-152.
CryptocephaJa (Benham), 21, 22.
Cuvier, on classification, of worms, 9
10, 11, of Annelids, 12, 15, 23
on Arenicola,. 92.
Development of Arenicola, 73-75 ; of
B. vincenti, 154, 155.
didyma (Arenicolites) 97, f.n. '.
Dioscorides (Pedacius), 1.
Distribution of A. marina, 101, 1C2,
loveni, 105, cristata, 110, 111,
pusilla, 123, assimilis and var.
affinis, 131, ccaudata, 137, 138,
branchialis, 146.
Dorsibranches (Cuvier), 12, 23, 24.
" dorvilliana " (A.), 134.
Drilomorpha (Hatschek), 23, 24.
General Index
167
Earthworms, 1, 2, 3, 4, 5.
ecaudate (A.), 31, 32, 85, 132-138;
crotchets in notopodia of post-
larva, 40 ; notopodial chaetae, 42,
43, 47, 48 ; neuropodial crotchets,
53, 56, 57 ; gills, 55, 56, 61 ; septal
pouches, 62 ; oesophageal glands,
63 ; statocysts, 69 ; ova, 72 ; go-
nads, 72, 73 ; post-larval stages,
80, 81 ; relationship to other
species, 156, 157, 158.
Ecaudate species of Arenicola, 31, 32,
84, 85 ; prostomium, 34, 85 f.n.1 ;
gills, 61 ; burrows, 65, 66 ; brain,
66 ; nephridia, 71.
Egg-rnasses, of A. cristata, 74, 110.
Eggs, vide ova.
Ehlers, on classification of Chaeto-
poda, 13, 19.
Ellis, 4.
Errantes (Audouin and Edwards),
Errantia, 16, 19, 20, 21, 24.
Estuarine conditions, A. marina under,
98.
Eyes, of Arenicola, 70, 74, 78; of
B. vincenti, 149, 153.
Fabricius, 8, 91.
Fauvel,on union of Branchiomaldane
with Arenicola, 148, 155.
Food of A. marina, 65, 98.
Forms (two) of A. marina, 97.
Fruticose (bushy) type of gill of Areni-
cola, 58-60.
Funnels of nephridia, of Arenicola, 71 ;
vestigial in post-larval A. bran-
chialis, 82.
Gesner, 3.
Gills, presence of, as character of
group of worms, 10-14, 23 ; of
Arenicola, 55-61, pinnate and
fruticose, 58 ; of post-larval A.
marina, 55, 78; cristata, 55, 79,
ecaudata, 55, 81 ; of B. vin-
centi, 152.
glacialis (A.), 84, 111-114; noto-
podial chaetae, 45, 48 ; crotchets,
51, 52 ; gills, 60 ; septal pouches,
62 ; oesophageal glands, 63 ; stato-
cysts, 67, 69 ; nephridia, 71 ; rela-
tionship to other species, 157, 158.
Gmelin, Systema Naturae, 7.
Gonads, of Arenicola, 72, 73; of B.
vincenti, 153.
Grooves, ventral and metastomial, 38.
Grube, on classification of Annelids,
17, 24 ; on Telethusa, 159.
Habitat of A. marina, adult, 96-98,
post-larval, 77, 78 ; loveni, 105 ;
cristata, 108 ; pusilla, 121 ; as-
similis, 130 ; ecaudata, adult, 135,
post-larval, 81 ; branchialis, adult,
144, post-larval, 81 ; JB. vincenti,
152.
Hatschek, on classification of Poly-
chaeta, 22, 24.
Historical account of, Chaetopoda,
especially Polychaeta, 1-24 ;
Arenicolidae, 26-28 ; Arenicola,
30-32 ; marina, 90-92 ; loveni,
103-105 ; cristata, 107 ; glacialis,
112, 113 ; piisilla, 116-119 ; as-
similis, 126, 127 ; ecaudata, 133-
135 ; branchialis, 139-141 ; B.
vincenti, 148.
Inter-relationships of members of
family Arenicolidae, 156-159.
Isidorus, 2.
Johnston, on classification of worms,
16, 18.
Key, to genera of Arenicolidae, 28 ; to
caudate species of Arenicola, 83,
84 ; to ecaudate species, 85.
Lamarck, on Annelides, 11 ; on classi-
fication of worms, 10, 11, of Anne-
lides, 12, 24 ; on Arenicola, 31, 91.
Laminariaii form of A. marina, 97.
Larvae of A. pusilla and cristata, 74,
75 ; their chaetae, 40, 41, 43.
Latreille, 13, 14.
Leuckart, R., 16.
Levinsen, 20, 159.
Limivora (Grube), 18, 24.
Linnaeus, Systema Naturae, 4, 5, 6.
Littoral, form of A. marina, 97 ;
cleansing of, by Arenicola, 99.
loveni (A.), 83, 103-105; notopodial
chaetae, 44, 45, 48 ; crotchets, 53,
56 ; gills, 59 ; septal pouches, 62 ;
oesophageal glands, 63 ; stato-
cysts, 69 ; relationship to other
species, 157, 158.
Liitken, on Pteroscolex, 31, 107.
Maldanidae, related to Arenicolidae,
27, 28, 159, 161, 162.
Malmgren, 20,
Hi8
General Index
marina (A.), 83, 86-102; external
apertures of nephridia and stato-
cysts, 39 ; notopodial chaetae, 42,
43,46-48; crotchets, 48-50 ; gills,
55, 59 ; septal pouches, 62 ; oeso-
phageal glands, 63 ; burrows, 64,
65 ; food, 65, 98 ; castings, 65, 99 ;
statocysts, 67-69 ; nephridia, 71 ;
ova and sperms, 72 ; post-larval
stages, 76-79 ; relationship to
other species, 157-159.
Mesnil, on Clymenides, 27, 76, 77 ; on
Arenicolo-Maldaniens, 27.
Mesobranches (Latreille), 14, 24.
Metastomial grooves of Arenicola, 38.
Molyneux, 4.
" montagui " (A.), = ecaudata, 134,
135.
Mouth of Arenicola, 38.
Miiller, on classification of worms, 8,
9, 10, 15.
Nephridia, of Arenicola, 71 ; vestigial
in post-larval A. branchialis, 82 ;
of B. vincenti, 153.
Nereideae, 13, 19.
Nervous system, of Arenicola, 66 ; of
B. vincenti, 153.
Neuropodia, two types of, in Arenicola,
35 ; of B. vincenti, 149.
"nodosa" (A.), = ecaudata, 134.
Notopodia, of Arenicola, 35; of B.
vincenti, 149.
Nuchal organ of Arenicola, 38, 39 ; of
B. vincenti, 149.
Oesophageal connectives of Arenicola,
66.
Oesophageal glands, of Arenicola, 63,
of B. vincenti, 152 ; variation in
number of, in A. pusilla, 122, in
A. assimilis, 131.
Oligochaeta, 17, 18, 19.
Opheliidae, affinities with Arenicolidae,
160, 161, 162.
Ova, of Arenicola, 72; of A. cristata,
74, 110; of B. vincenti, 153, 154.
Pallas, 7, 8, 9, 10.
Parapodia, 24 f.n. 3 ; of Arenicola, 34,
35, 37 ; of B. vincenti, 149.
Pennant, 7.
Peristomium, defined, 24 f.n. 2 ; of
Arenicola, 37, 78, 80; of B. vin-
centi, 149.
Peysonne), 4.
Phansrocephala (Benham), 21.
Pinnate type of gill of Arenicola, 58-61.
Pit on parapodia of A. cristata and
loveni, 35, 36.
Pliny, 1, 2,
Polychaeta (Grube),17; classification,
18-25.
Post -larval stages of Arenicola, 30,
75-77 ; of A. marina, 77-79, 100 ;
cristata, 79 ; assimilis var. affinis,
80; ecaudata, 80, 81, 137 ; 'bran-
chialis, 81, 82.
Prostomium, defined, 24 f.n. ' ; of
Arenicola, 33, 34, 78, 80; of B.
vincenti, 148.
pusilla (A.), 84, 114-123; notopodial
chaetae, 41, 46-48; crotchets, 51,
53 ; gills, 59 ; septal pouches
absent, 62 ; Oesophageal glands,
63 ; ova, 72 ; development, 74 ;
relationship to other species, 157-
159.
Pygidium, 33 ; chaetiferous segments
formed immediately in front of,
37, 75.
Quatrefages, on classification, of
worms, 16, of Annelides, 19, 24.
Eapacia (Grube), 18, 24.
Ray, on classification of Insects, 4, 5.
Eedi, 4.
Reproductive organs, of Arenicola, 72,
73 ; of B. vincenti, 153.
Rondeletius, 3.
Rostrum of crotchet, of Arenicola, 48-
54; of B. vincenti, 151.
Relationships, of species of Arenicola,
156-159; of Arenicolidae, 159-
162; of B. vincenti with Areni-
cola, 155, 156, 159.
Sageblatter. 35 f.n., 45, 47, 48.
Savigny, on classification of Annelids,
12, 13, 15, 24 ; on Telethusae, 13,
26.
Scalibregmidae, affinities with Areni-
colidae, 159, 160, 161, 162.
Scoleciformia (Benham), 24.
Seba, 7.
Sedentaires (Lamarck), Sedentaria, 12,
16, 19, 20, 21, 24.
Segments, number and annulation of,
in Arenicola, 36 ; in B. vincenti,
149.
Sense-organs of Arenicola, 66-70.
General Index
169
Septa, of Arenicola, 61, 62, 75 ; of B.
vincenti, 152.
Septal pouches, of Arenicola, 62 ; ab-
sent in A. pusilla and assimilis,
62, and in B. vincenti, 152.
Serpuleae (Savigny), 13, 19.
Setipodes (Blainville), 14, 15.
Size, of A. marina, 97, loveni, 105,
cristata, 108, 109, glacialis, 114,
pnsilla, 121, assimilis, 130, ecau-
data, 135, 136, branchialis, 145,
.B. vincenti, 148.
Spermatozoa of Arenicola, 72.
Statocysts, of Arenicola, 67-70 ; varia-
tion in size of, 70 ; external aper-
tures of in marina, assimilis, gla-
cialis, 39 ; of post-larval marina,
78, cristata, 79, assimilis var.
affinis, 80, ecaudata, 81, bran-
chialis, 82.
Statocysts, absent in ^4. pusilla, 67,
and in B. vincenti, 153.
Statoliths of Arenicola, 67-70 ; differ-
ence in nature of, 69. See also
statocysts.
Sternaspidae, contrasted with Areni-
colidae, 160.
Sub-rostral process of crotchet, 48, 50.
Swimming, of A. marina, 97; of A.
ecaudata, 135.
Tail, of caudate species of Arenicola,
37, 38; of A. cristata, 109, 110.
Tail segments, site of production of, 38.
Telethusa, Telethusae, Telethuses
(Savigny), = Arenicolidae, 13-16,
24, 25, 26, 27, 159.
Tube, presence of as character of group
of worms, 11 ; enveloping post-
larval A. marina, 77, 78, cristata,
79, assimilis var. affinis, 80.
Tubicoles (Cuvier), 12, 16, 23.
Type specimens, remarks on, of A.
loveni, 105, glacialis, 113, 114,
pusilla, 117-119.
Variations, in nature of statoliths, 67-
69 ; in size of statocysts, 70 ; in
number of gills, of A. cristata,
109, pusilla, 122, assimilis, 130,
ecaudata, 136, branchialis, 145 ;
in number of nephridia of cristata,
110, assimilis var. affinis, 131,
ecaudata, 136 ; in number of
oesophageal glands of pusilla, 122,
assimilis, 131 ; in number of seg-
ments of ecaudata, 136, branchi-
alis, 145 ; in caudal processes of
cristata, 109, 110.
Ventral groove of Arenicola, 38.
Ventral nerve-cord of Arenicola, 66.
Vermes, 2-9 ; distinguished from " In-
secta," 9.
vincenti (Branchiomaldane), 147-159.
Willis, 4.
Willughby, 5, 91.
Wotton, 2.
DESCRIPTION OF PLATES I-XV
LIST OF REFERENCE LETTERS
A.B.S. .
Acic.
Bl.V. .
Br.1 .
Ch.SegS
D. . . .
D.V. . •
Ep.. .
Gon.
Gon.V..
H. . .
M. . .
M.Circ.,
M.Long.
M.Gr. .
Mo. .
N.C. .
Neur .
Neur.1 .
N.O. .
N.O.1 .
Not. .
Not.1 .
Not.Pr.,
Not.Eetr.
Not.S. .
Nph.1 .
, Achaetous body-segment.
. Aciculnm.
Blood-vessel.
First gill.
First chaetiferous seg-
ment.
, Diatom (as statolith).
Dorsal blood-vessel.
Epideraiis.
Gonad.
. Gonadial blood-vessel.
Heart.
Muscle-band.
^Circular and longitudinal
/ muscles of body-wall.
Metastomial groove.
Mouth.
Nerve-cord.
, Neuropodium.
First neuropodium.
External opening of ne-
phridium.
, External opening of first
nephridium.
, Notopodium.
First notopodium.
^Protractor and retractor
/ muscles of notopodium.
Notopodial chaetal sac.
, First nephridium.
Nph.F.D.
NpJi.F.V.
N.Sh. .
N.St. .
Nuc. Gr.
(E. . .
(E.Conn.
CE.Gl. .
P. . .
Per. .
Prost.,
or Pr.
81, S2, S3
S.P. .
S.P.O. .
St. . .
Sth. .
St.O. .
Stom. .
St.T. .
Tent. .
Ves.
Dorsal lip of nephridia
funnel.
Ventral lip of nephridial
funnel.
Nervous sheath of stato-
cyst.
Nerve to statocyst.
Nuchal groove.
Oesophagus.
Oesophageal connective.
Oesophageal gland.
Pit (possibly sensory).
Peristomium.
>Prostomium.
First, second
and
third
septa.
Septal pouch.
Opening of septal pouch
into coelom.
Statocyst.
Stomach.
Opening of statocyst to
exterior.
Stomodaeum.
Tube from statocj'st to
exterior.
Tentacle.
Vesicle, or bladder, of
nephridium.
PLATE I.
Arenicola marina (Linnaeus). Light- and dark-coloured examples, taken, at
the same time, from the beach at Musselburgh, Firth of Forth.
Fig. 1. — A typical light -coloured example. The buccal mass and pharynx are
protruded.
Fig. 2. — Anterior end of a similar specimen ; dorsal aspect.
Fig. 3. — A dark-coloured example.
Fig. 4. — Anterior end of a similar specimen, with buccal mass and pharynx
protruded ; dorsal aspect.
172 Description of Plates
PLATE II.
Fig. 5. — A. bnincldaliis Audouin and Edwards (.4. grubii Claparede), from
Plymouth.
Fig. 6. — ^1. branchial is, anterior end, dorsal aspect. The first notopodium was
wanting, a condition not uncommon in this species.
Fig. 7. — A. ecaudata Johnston, from Plymouth. .
Fig. 8. — A. ccaudata, anterior end, dorsal aspect.
PLATE III.
Fig. 9. — A. loveni Kinberg, from Saldanha Bay, Cape Colony.
PLATE IV.
Figs. 10, 11. — Dissections of the anterior portions of A. marina (Linnaeus)
(Fig. 10), from Musselburgh, and A. loveni Kinberg (Fig. 11), from
Saldanha Bay. The specimens were opened along the mid-dorsal
line. Compare their septal pouches and nephridia. The septal
pouches of the specimen of A. marina were dilated ; they are
usually rather smaller than they are here represented.
PLATE V.
A. cristata Stimpson.
Fig. 12.— A specimen from Naples, with full number of tail-segments.
Neuropodia were absent in the first two chaetiferous segments.
Fig. 13.— Last chaetiferous segment and tail (consisting of only eight
segments) of a specimen, from Wood's Holl, Mass., to show the
caudal processes, one of which — on the first tail-segment — is branched
end gill-like.
PLATE VI.
Fig. 14. — A. glacialis Murdoch. Type specimen. Note the presence of an
eighteenth neuropodium. The buccal mass and pharynx are fully
protruded. The tail is, in the specimen, strongly contracted ; it
has been represented in the figure in a condition of more normal
extension.
PLATE Vn.
Fig. 15. — A. 2)usilla Quatrefages (A. claparcdii Levinsen), from Naples.
Fig. 16. — A. assimilis Ehlers, from Uschuaia, Beagle Channel. Co-type from
Naturhistorisches Museum, Hamburg.
PLATE VIII.
Fig. 17. — A. cristata Stimpson, from Naples. Dissection of the anterior portion.
The specimen was opened along the mid- dorsal line. Note especially
the nephridia, the small oesophageal glands, and the septal pouches.
Fig. 18. — A. pusilla Quatrefages (A. claparedii Levinsen), from Naples. Dis-
section of the anterior portion. The specimen was opened along
the mid-dorsal line. Note especially the nephridia, the oesophageal
glands (five pairs), and the absence of septal pouches.
Description of Plates 173
PLATE IX.
Fig. 19.— A. ecaudata Johnston, from Plymouth (August, 1910). Dissection of
the anterior portion of a mature male example. The specimen was
opened along the mid-dorsal line. The portion of the oesophagus
between the glands and the hearts is unusually extended and dilated
with food. The testis on the fifth left nephrklium is produced into
two thin outgrowths, one overlying the other, and the testis borne
by the third right nephridium presents a similar condition ; each of
the other testes bears only one such outgrowth (see PI. XV. Fig. 53).
Fig. 20. — A. branchialis Audouin and Edwards (A. grubii Claparede), from
Plymouth. Dissection of the anterior portion of a mature specimen ;
the reproductive organs are small (see PL XV, Fig. 51).
PLATE X.
Figs. 21-25. — A. pusilla Quatrefages (A. claparcdii Levinsen).
Fig. 21. — Larva, about thirty hours after fertilisation of the egg; ventral aspect
(see p. 74).
Fig. 22. — Larva, dorsal aspect ; about forty hours older than the preceding,
and on the point of forcing its way out of the vitelline membrane,
through the thin area in the upper part of the same.
Fig. 23. — Larva, one day after hatching ; dorsal aspect. The larva was
slightly compressed under the cover-glass, and therefore appears a
little too broad. The first notopodial chaetae have been formed.
Fig. 24. — Larva, twelve days after hatching ; right aspect. The middle portion
of the gut still contains yolk. Note the two kinds of notopodial
chaetae and the crotchets.
Fig. 21-24 were drawn, in Naples, from living larvae, which had
developed from eggs fertilised artificially.
Fig. 25. — One of the eyes of the larva shown in the preceding figure. Note the
cup-shaped group of pigment-spherules, and the lens (see p. 70).
Figs. 26-28. — A. marina (Linnaeus), from Plymouth (see p. 77).
Fig. 26. — Post-larval example, 4' 7 mm. long, in its mucous tube, as found in
the plankton.
Fig. 27. — Post-larval example, about 6 mm. long ; anterior end, dorsal aspect.
Fig. 28. — -Left.aspect of the anterior portion of a stained and cleared post-larval
specimen, 4'5 mm. long.
Fig. 29. — A. assimilis Ehlers var. affinis Ashworth. Left aspect of the anterior
portion of a stained and cleared post-larval specimen, 11 mm. long,
from the Falkland Islands (see p. 80).
Fig. 30. — A. cristata Stimpson. Post-larval specimen, 6 mm. long, from
Wood's Holl, Mass., showing the full number of tail-segments and
the incipient gills (see p. 79). The neuropodial crotchets are
indicated by vertical series of white dots.
174 Description of Plates
PLATE XI.
Figs. 31-33. — Branchiomaldane vincenti Langerhans, from
near Cherbourg.
Fig. 31. — Adult, but rather contracted, specimen, 8 mm. long (see p. 148).
Fig. 32. — Anterior portion of an adult specimen, about 10 mm. long, stained
and cleared (see p. 152).
•Fig. 33. — Posterior portion of a well-extended specimen, 10 • 5 mm. long, showing
the characteristic bi-armulate segments, in which the anterior ring
is chaetiferous and the posterior branchiferous.
Figs. 34, 35. — A. ecaudata Johnston, from near Cherbourg.
Fig. 34. — Young, abranchiate post-larval specimen, 4'6 mm. long (see p. 80).
Fig. 35. — Fifteenth to twentieth segments of a late post-larval stage, 11 mm.
long, seen from the left side ; showing the gills on the sixteenth and
succeeding segments. Note that the gills are situated on the
respective chaetiferous annuli (cf. Fig. 33), and that the neuropodia
are much longer than those of Branchiomaldane (cf. Figs. 31, 33).
PLATE XII.
Figs. 36-38. — Nereis cultrifera Grube, from Plymouth.
Figs. 36, 37. — Dorsal (Fig. 36) and ventral (Fig. 37) views of the anterior end,
to show the pre-oral prostomium (Pr.), with its eyes, tentacles and
palps, the peristomium (Per.), with its cirri and the mouth, and the
first two chaetiferous segments, with their parapodia.
Fig. 38. — Parapodium or " foot," consisting of a basal piece and two distal,
lobate processes — the iiotopodium and neuropodium — each of which
bears a sensory cirrus, a bundle of chaetae (the tips of which project
from the mouth of the sac in which the chaetae were formed;, and
an aciculum, which serves as an internal skeleton.
Figs. 39, 40. — A. marina (Linnaeus).
Fig. 39. — Transverse section, passing through a parapodium, showing the noto-
podial chaetal sac, with its chaetae and its protractor and retractor
muscles, and the neuropoclial chaetal sac, with its crotchets
(see pp. 34, 35).
Fig. 40. — Anterior end, dorsal aspect; showing the buccal mass protruded, the
prostomium, nuchal groove, metastomial groove, and the openings
of the statocysts. From a specimen preserved with the anterior
end fully distended.
PLATE XIII.
Figs. 41, 42. — A. cristata Stimpson (175 mm. long). The dorsal axis of the first
gill (Fig. 41) and of the fifth gill (Fig. 42). Pinnate type of gill (see
p. 58).
Fig. 43. — A. marina (Linnaeus), littoral form (120 mm. long), second left gill.
Fruticose or bushy type of gill (see pp. 58, 59). Most of the gill-
axes have been cut away near their origins.
Fig. 44. — A. pusilla Quatrefages (A claparedii Levinsen), from California.
A portion of the alimentary canal, at the junction of oesophagus and
stomach, to show the multiple oesophageal glands (see p. 63). The
posterior part of the oesophagus is contracted, and the glandular
caeca form a cluster.
Description of Plates 175
Fig. 45. — A. assimilis Ehlers, var. affinis Ashworth, from Table Bay, Cape
Colony. A portion of the alimentary canal, at the junction of
oesophagus and stamach, to show the multiple oesophageal glands.
The posterior part of the oesophagus is unusually extended.
Fig. 46. — A. marina (Linnaeus). Dissection of the anterior end, from the dorsal
surface ; the buccal mass and pharynx have been cut away to show
the prostomium, oesophageal connectives, statocysts and soptal
pouches.
PLATE XIV.
Fig. 47. — A. marina (Linnaeus). Section of the statocyst and the tube leading
to the exterior. The statoliths are naked irregular bodies, chiefly
quartz -grains ; one (D) is a diatom (see p. 67).
Fig. 48. — A, marina (Linnaeus). Fourth left nephridium, dorsal aspect. The
ventral lip (Nph. F.V.) of the funnel is seen through the dorsal
one (see p. 71).
Fig. 49. — A. pusilla Quatrefages (A. claparedii Levinsen). Ventral aspect
of anterior portion of third left nephridium of a large specimen
(160 mm. long.) fi-om Unalaska ; M. Band of muscle which binds
the funnel to the body-wall.
Fig. 50. — A. assimilis Ehlers. Ventral aspect of anterior portion of second right
nephridium, showing that the ventral lip of the funnel is thrown
into folds or frills (see p. 71).
PLATE XV.
Fig. 51. — A. branchialis Audouin and Edwards (A. grubii Claparede). Fourth
left nephridium, dorsal aspect. The deeply-notched ventral lip
(Nph. F.V.) of the funnel is seen through the dorsal one.
Fig. 52. — A. ecaudata Johnston. Female specimen from Plymouth ; fifth right
nephridium with mature ovary, dorsal aspect (see p. 73).
Fig. 53. — A. ecaudata Johnston. Male specimen, from Plymouth ; tenth left
nephridium, with mature testis, dorsal aspect (see p. 73). The
deeply notched ventral lip (Nph. F.V.) of the funnel is seen through
the dorsal one.
LONDON :
PRINTED BY WILLIAM CLOWKS AND SONS, LIMITED,
DL'KK STREET, STAMFORD STREET, S.E., AND GREAT WINDMILL STREET, W.
CAT. CHAETOPODA BRIT. MUS.I.
Prost.
N.OJ
Plate I.
Fig A. x2.
—Prost.
Fig. 2. *3.
A.K Maxwell del.
Arenicola marina (Linnaeus)
Ltghb-and dark- coloured examples.
E.Wflson,Cambndge
CAT. CHAETOPODA BRIT. MUS. I.
Plate II.
Br
Fig. 5. ArenicoLcu grukiL Clouparede, x1 '/a
---Jfeur'
Fig . 6. A .grubii Clop.
x3
Fig. 8 . A .^couudotoL. Johnst.
x3
For Arenicola grubii plaparede, read Arenicola branchialis Audouin and
Edwards (see pp. 141-3, and p. 143, footnote).
Figi. 7. Arenucola, eacumdaubai Johnston x 1'/s
A.K.MajcweU.del. E Wilson .Cambridge.
CAT. CHAETOPODA BRIT. MUS. I.
Plate II.
yppi^^^^W^GUBB^I^^^^^B
Fig.5. Arentcolugrubu, Glaparede, x1'/a
.—Proat.
---Neur' ffewr'--
Ftg.6. A.grubit, Clop.
Fig.8 . A .zcoujdata- Johnst.
x3
Fig. 7. Ar&nLcola, eaaudata, Johnston x T/s
A.K.M«xwell,del. E Wilson .Cambridge
5*1
CAT. CHAETOPODA BRIT. MUS.I.
Plate IV.
Arenicola marina (Linnaeus.)
AX.Maxwell del.
Arenicola Loveni Kinberg.
E.Wflson,Carabridge .
IMMIIMM
fe: O,
: -
o
3
CAT. CHAETOPODA BRIT. MUS.I.
Plate VIII.
S.P.
CE.Gl.—
Nph? —
'
Arenicola cristata Stimpson.
A.K.Maxwell del.
Arenicola pusilla. Quatrefages.
E.Mson, Cambridge .
CAT. CHAETOPODA BRIT. MUS. I .
Plate IX.
S.P--
-S.P.
Arenicola branchlaLis.
Aiuiouin & Edwards.
ArenlcolOL ecaudLcLta Johnston.
Male specimen.
A. K.Maxwell del.
E.Wilson, Cambridge.
X
5
E
m
OAT. CHAETOPODA BRIT. MUS.I
Nuc.Gr
Plate XI.
31.
AKMaxwell.del.
E.WUson,C«nbridge.
IAT. CHAETOPODA BRIT. MUS.
Plate M.
A K Maxwell, del
CAT. CHAETOPQDA BRIT. MUS.T.
PI ate Kill.
«. Not!
A.K.Maxwell, del.
E.Wlson.Cambndge.
CAT. CHAETOPODA BRIT. MUS.l
Plate XIV.
AJC Maxwell i
J H.Ash'vrorth.del.
D.
E Wilson, Cambridge.
JHAETOPODA BRIT. MQS. I
Plate XV
Nph.FD
AK.Maxwell,del.
EWilson.Gambridge.
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