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THE NEMEBTEANS W. CT MCINTOSH, M.D., E.R.S.E., F.L.S., ETC. LONDON: PRINTED FOR THE RAY SOCIETY. MDCCCLXXIII. MAY 3 19/7 PRINTED BY J. E. AD LARD, BARTHOLOMEW CLOSE. V 3B tiricat^ir TO THE MEMORY OF 3; THE AUTHOR'S ARTIST, FELLOW-OBSERVER, AND SISTER. <> PREFACE. The following fasciculus may be described as the First Part of a Monograph of the British Annelida, a department of native Zoology which more than any other required investi- gation, and whose neglected condition formed the author's chief inducement to attempt something for its improvement. So little was known in this country with respect to the Nemerteans, while their structure and zoological affinities opened up so many interesting questions, that they could scarcely be passed over in such a treatise. Accordingly they have been examined — both in the living and preserved conditions — with as much care as the circumstances of the author admitted. He hopes, moreover, that the publication of the skilful and laborious coloured drawings of the external configuration of these worms (which were so kindly executed by her to whom the work is dedicated) will assist in rescuing them from the comparative obscurity in which they have hitherto been involved in this respect, both in Britain and on the Continent. He has endeavoured to render the other parts of the treatise worthy of the delicacy and beauty of these figures. The species of the group are, on the whole, distinctly marked, so that comparatively little difficulty has been experienced in discriminating them ; indeed, the chief variation in the majority is in colour, which, of coarse, obscures none of the essential characteristics. Considerable additions may be expected to the list of species subsequently described (though the dredge has been used and the coast-line minutely examined at many points from the Shetland to the Channel Islands), and not a little new matter in regard to anatomy and development ; but, with such a field as the whole Annelida before him, the author could not devote more time to the group. As no freshwater species has yet been found in this country, such a habitat especially should be diligently explored. The author, however, will be satisfied if he has paved the way for a more extensive and accurate study of these beautiful and interesting forms, whose life-histories and structure so amply reward investigation. The Nemerteans have received so little attention from British zoologists that the author's list of contributions in this respect cannot but be small, and it is solely to the ceaseless care of a friend that he has been enabled to pursue the investigation with that completeness necessary for the elucidation of their anatomy and zoology, an investigation demanding an abundant and ever- ready supply of healthy living animals. Mr. Parfitt forwarded a few living specimens from the Devonshire coast, and Dr. Howden of Montrose, Prof. E. P. Wright of Dublin, Dr. Gray, xii PREFACE. Dr. Albert Giinther, and the late Dr. Baird of the British Museum, Mr. G. S. Brady of Sunderland, Dr. Carrington of Eccles, Mr. J. F. Whiteaves of the Natural History Society, Montreal, and Prof. Dickie, Aberdeen, have also aided him by the communication of preserved examples or otherwise. Mr. Gwyn Jeffreys included some in his rich collections of Zetlandic Annelids, and, in conjunction with Dr. Carpenter and Prof. Wyville Thomson in the celebrated " Porcupine-" Expeditions of 1869 and 1870, he secured a most valuable collection of Annelids and Nemerteans, which was most courteously placed at the author's disposal by these gentlemen. To all these he begs to return his sincere thanks for their valued assistance, and specially to Dr. A. Giinther, for his exertions in 1869. He has also to remember the many valuable hints in the microscopic department of this work received from the experienced hands of the late Dr. Eraser Thomson of Perth. Nor must he omit to acknowledge the steady encouragement given throughout these researches by Prof. G. Busk, whose cordial support at an early period was a source of the greatest satisfaction. He has further to thank Professors De Quatrefages of Paris, E. Grube of Breslau, Kolliker of Wurzburg, and Van Beneden of Louvain, Mr. Alex. Agassiz of America, and Dr. Malmgren of Helsingfors, for their esteemed aid, by the communication of papers and otherwise. Two others, unfortunately, have since been early lost to science, viz. Professors W. Keferstein of Gottingen and E. Claparede of Geneva. The former did much to place Nemertean anatomy on a proper basis, and his conscientious original investigations gave promise of great advances in this as well as in other departments. M. Claparede, again, was, perhaps, the most distinguished investigator of the Invertebrates, especially the Annelida, of his time, and his splendid work both with pen and pencil will make his name enduring. To the list of these losses he has now to add the lamented Dr. Baird, whose excellent labours amongst the collection of Annelida in the British Museum will long be remembered, no less than his genial and kindly aid to all interested in zoology. For the delay in the issue of this portion of the work — a delay originating in the printing of the Plates — the author is not responsible, since it was ready at the end of 1869. He has to thank the Council of the Bay Society for their liberality in regard to the Plates, and Mr. Ford for his masterly touch in their execution. Murthly; September, 1873. CONTENTS PREFACE .... GENERAL REMARKS Physiognomy of the Group Colour .... Relation of Colour to Sex HABITS . Native Haunts Modes of Progression Method of Preserving Alive in Glass Vessels Changes which ensue in Confinement PAGE vii 1 1 2 3 4 4 5 6 7 FOOD HISTORY OE THE LITERATURE ON THE NEMERTEANS ANATOMY AND PHYSIOLOGY OF THE GROUP Generalized Plan or Archetype I. ANATOMY OF THE ENOPLA 1. Cutaneous System 2. Body-wall . 3. Proboscidian Sheath . . •. 4. „ Aperture . 42 42 43 43 45 47 50 CONTENTS. 5. Proboscis a. Anterior Region b. Middle Region a. Marginal Stylet-sacs b. Ejaculatory Duct c. Central Stylet and its Apparatus d. External Granular Glands e. Reservoir c. Posterior Region /. Varieties in the Structure of the Proboscis : — Structure of the Proboscis in Anvphiporus pulcher A. spectabilis A. hastatus A. bioculatus Tetrastemma melanocephala T. Robertiance T. Candida . T. dorsalis . T. vermicula T. Jlavida Prosorhochmus Claparedii Nemeries gracilis N. Neesii N. carcinophila g. Review of previous Interpretations of the Proboscis d. Reproduction of the Proboscis 6. Digestive System a. Mouth b. (Esophagus c. Digestive Cavity proper 7. Vascular System 8. Nervous System a. Ganglia b. Great Lateral Nerve-Trunks 9. Eye-specks 10. Cephalic Furrows and Sacs PAGE 51 51 54 55 57 58 59 59 61 63 64 64 65 65 66 66 67 61 68 69 70 74 75 75 75 77 79 81 81 88 84 85 CONTENTS, XI 11. Generative System .... a, Male Organs b. Female „ .... 12. Phenomena of the Deposition of the Ova and Spermatozoa 13. Development ..... 87 87 88 89 90 II. ANATOMY AND PHYSIOLOGY OF THE ANOPLA 1. Cutaneous System 2. Body-wall in the Lineidce „ „ Carinellidce „ „ Cephalothricidce 3. Proboscidian Aperture . 4. „ Sheath and Chamber 5. Proboscis in the Lineidce . „ „ Carinellidce „ „ Cephalothricidce 6. Digestive System a. Mouth b. Oesophageal Division . c. Alimentary Cavity proper 7. Nervous System in the LineidcB „ „ Carinellidce . „ „ Cephalotkricidce 8. Cephalic Fissures 9. „ Sacs 10. Eye-specks 11. Vascular System in the Lineidce „ „ Carinellidce „ „ Cephalotkricidce 12. Organs of Reproduction a. Male Elements b. Female „ 13. Mode of Deposition of Ova 14. Development of the Lineidce „ „ Pylidium-form , } of Cephalothriw 95 95 97 98 99 101 101 102 104 105 106 106 106 107 109 110 110 111 112 113 113 114 114 116 116 116 117 117 120 123 xn CONTENTS. PAGE III. REPRODUCTION OF LOST PARTS AND THE ENTIRE ORGANISM FROM FRAGMENTS 125 IV. PARASITES V. CLASSIFICATION VI. SYNOPSIS OF FAMILIES, ORDERS, GENERA, AND SPECIES VII. HOMOLOGIES .... BlPALIUM .... Balanoglossus .... VIII. GENERAL DISTRIBUTION OF THE NEMERTEANS IX. DESCRIPTIONS OF THE GENERA AND SPECIES Amphiporus lactiploreus „ PULCHER „ SPECTABILIS „ HA STATUS „ BIOCULATUS Tetrastemma MELANOCEPHALA „ Robertian^e „ CANDIDA „ VERMICULA „ FLAVIDA „ dorsalis Prosorhochmus Claparedii Nemertes gracilis „ Nee si i „ CARCINOPHILA LlNEUS MARINUS „ GESSERENSIS „ SANGUINEUS „ LACTEUS BILINEATUS 128 130 134 138 142 144 151 153 156 158 160 162 163 165 166 167 169 170 172 174 176 178 180 181 185 188 190 191 CONTENTS. xiii PAGE Borlasia Elizabeths , 193 Cerebratulus angulatus . 195 Micrura FUSCA . 196 „ FASCIOLATA . 197 „ PURPUREA . 200 „ AURANTIACA . 201 Meckelia asulcata . 202 Carinella annulata . 203 „ LINEARIS . 206 Valencinia lineformis . 207 Cephalothrix linearis . 208 APPENDIX . 213a COUNCIL AND OFFICERS ELECTED 19th SEPT., 1873 SIE PHILIP DE MALPAS GEEY EGEETON, BAET., M.P., F.E.S. ©tjjer ftemto af totml Joseph Beck, Esq. Dr. Braithwaite, F.L.S. Dr. T. Spencee Cobbold, F.E.S. M. P. Edgewoeth, Esq., F.L.S. C. H. Gatty, Esq., F.L.S., G.S. Ferdinand Getjt, Esq., F.L.S. Dr. GtiNTHEE, F.E.S. Dr. J. B. Hicks, F.E.S. E. Hudson, Esq., F.E.S., G.S. J. Gwtn Jeeerets, Esq., F.E.S. H. Lee, Esq., F.L.S. Sir J. Ltjbbock, Bart., M.P., F.E.S. E. McLachlan, Esq., F.L.S. H. T. Mennell, Esq., F.L.S. F. P. Pascoe, Esq., F.L.S. Dr. P. H. Pye-Smith. Dr. P. L. Sclatee, F.E.S. H. T. Stainton, Esq., F.E.S. Chaeles Stewart, Esq., F.L.S. Professor Tennant, F.G.S. Capt. Chas. Ttlee, F.L.S. Dr. E. Haet Yinen, F.L.S. De. S. J. A. SALTEE, F.E.S., F.L.S., 1, Plowden's Buildings, Temple, E.C. EEV. THOMAS WILTSHIEE, M.A., F.L.S., F.G.S., 25, Granville Park, Lewisham, S.E. The Bay Society was founded in the year 1844, for the publication of works on Zoology and Botany. Each Person subscribing one Guinea is considered a Member of the Society, and is entitled to the Volume issued for the year to which the subscription relates. Subscriptions become due on the 1st of January in each year. The Back Volumes in Stock can be obtained on application to the Secretary, the Rev. Thos. Wiltshire, 25, Granville Park, Lewisham, London, S.E. List of the Bach Volumes in Stock, and the prices at which they can be obtained by Members. £ s. d. Reports on the progress of Zoology and Botany, translated by Messrs. Strickland, Macdonald, and Lankester . . . . . . .030 Reports and Papers on Botany, translated by Messrs. Busk, Macdonald, Henfrey, and Hudson . . . . . . . .030 Reports on the progress of Zoology, translated by Busk, Talk, and Haliday . .030 Reports and Papers on Physiological and Geographical Botany, translated by A. Henfrey . . . . . . . . .030 Oken's Elements of Physio-Philosophy, translated by A. Tulk . . .030 Letters of John Ray < . . . . . . .030 Botanical and Physiological Memoirs, including Braun on the Rejuvenescence in Nature, translated by A. Henfrey . . . . .050 A Synopsis of the British Naked-eyed Pulmograde Medusas, by Prof. E. 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I, II, III, and IV (the set) . . . . . . . . .100 A Monograph of the Sub-class Cirripedia, by C. Darwin, Vols. I and II (the set) . . . . . . . . . .100 A History of the Spiders of Great Britain and Ireland, by J. Blackwall, Parts I and II (the set) . . . . . . . . .220 (Part I, one guinea.) A Monograph of the British Nudibranchiate Mollusca, by Messrs. Alder and Hancock, Parts I, II, III, IV, V, VI, and VII (the set) * . . .660 (Parts V, VI, and VII may be obtained at one guinea each.) The Reptiles of British India, by Dr. Gunther, issued for the year 1863 . ,110 A Monograph of the British Spongiadae, by Dr. Bowerbank, Vol. I, issued for the year 1864 . . . . . . . . .110 The British Hemiptera Heteroptera, by Messrs. Douglas and Scott. A Mono- graph of the British Spongiadae, by Dr. Bowerbank, Vol. II, issued for the year 1865 (the set) . . . . . . , .110 The Miscellaneous Botanical Works of Robert Brown, Vol. I. Recent Memoirs on the Cetacea, by Professors Eschricht, Reinhardt, and Lilljeborg, translated by W. H. Flower. Nitzch's Pterylography, issued for the year 1866 (the set) .110 The Miscellaneous Botanical Works of Robert Brown, Vol. II. The Shoulder-girdle and the Sternum, by W. K. Parker, issued for the year 1867 (the set) . .110 The Miscellaneous Botanical Works of Robert Brown, Vol. III. Vegetable Teratology, by Dr. Masters, issued for the year 1868 (the set) . . . .110 A Monograph of the Gymnoblastic Hydroids, by Dr. Allman, Part I, issued for the year 1869 ..... . . . .110 A Monograph of the Gymnoblastic Hydroids, by Dr. Allman, Part II, issued for the year 1870 110 A Monograph of the Collembola and Thysanura, by Sir J. Lubbock, Bart., M.P., issued for the year 1871 . . . . . . .110 A Monograph of the British Annelids, Part I, the Nemerteans, by Dr. Mcintosh, issued for the year 1872 . . . . . . .110 THE NEMEETEANS. GENERAL REMARKS. The Nemerteans are elongated non-bristled worms very plentifully distributed on all our coasts ; yet, if not entirely overlooked, they have been generally regarded with a suspicion or aversion even more profound than that bestowed on the true Annelids ; apparently, on the one hand, from their supposed resemblance to the forms that live parasitically in the bodies of the higher animals ; and, on the other, from the intricacy of their structure, and the obscurity which shrouded their relations with surrounding groups. The appearance of the large species, indeed, has frequently given rise to feelings of superstitious wonder not unmixed with dread in the minds of the public ; and some authors even have been more careful to indulge in the same vein in their narratives, than to increase our knowledge of the structure and economy of these interesting animals. They have especially received slight notice from British zoologists. Cuvier first applied the name Nemertes 1 to designate the Lineus marinus of Montagu, and several subsequent writers have with propriety given the title Nemerteans to the Order, in which the name has been so long familiar. It is synonymous with the Teretularia of De Blainville, the Annelosi Polici of Delle Chiaje, the Cestoidina of (Ersted, the Mioccela of De Quatrefages, the Aploccda of Blanchard, and the Turhettaria Rliynclioccela of others. They have a soft, more or less elongated body, richly ciliated throughout, and the head is usually distinguished from the rest of the animal. The eye-specks and lateral slits (when pre- sent) are situated in the flattened snout. The Nemerteans for the most part frequent the sea, though a few aberrant forms occur in fresh water. The British species, so far as yet observed, are all marine ; one of them, moreover, having the semi-parasitic habit of a dweller in tubes attached to the hairs of the abdominal feet of female Carcini. This peculiarity amongst the Nemerteans was first noticed by Delle Chiaje, 1 Nemertes, one of the sea-nymphs (Mediterranean as distinguished from the Oceanides)— daughters of Nereus and Doris. 2 THE NEMERTBANS. who found his Folia tetrophthalma (a Tetrastemma with large eyes) in great abundance in the respiratory cavity of " Ascidia mammellata!' Leuckart and Pagenstecher also state that the former got at Nice a pale Tetrastemma in all the stages of egg, young and perfect animal — living parasitically in the body-cavity of Phallusia mamillaris ; such, however, in all probability, being only a confirmation of the foregoing. A. Agassiz, again, found a species of Planaria, which he thinks identical with the Planaria angulata of Miiller, on the under surface of the base of the tail in Limidus. This habit had also been observed in another Planaria, that frequents Velella in the Atlantic, by Lesson in his zoology of the ' Voyage autour du Monde sur la corvette La Coquille ;' and by Schneider in the case of Anoplodium parasita (one of the Rhab- docoela), which inhabits Holothuria tubulosa. Further observations will in all likelihood lead to the discovery of parasitic species in the Medusae. Such do not seem to be true parasites like the Entozoa, but may appropriately be grouped under the comprehensive title " Commensalisme," recently constituted by Prof, van Beneden — in an interesting lecture delivered before the Royal Belgian Academy. The animals included under this head do not prey upon the juices of their hosts ; but, like the Adamsia attached to the shell containing the Pagurus, or the accompanying JVereilepas, they simply live together for their mutual comfort and convenience. Comparatively few specimens, and these generally the largest forms, are to be found in our museums ; and even such examples, if named at all, are often specifically confounded, the same animal, e.g., Lineus marinus, being characterised by many names. In looking over such col- lections, indeed, one meets with a curious nomenclature ; thus I have found a large Sipunculus labelled ' Serpentaria,' a JBipalium ' Meckelia/ an elongated Sgnapta and a Tania respectively termed c Lineus,' and not a few distinguished by the ambiguous title of ' leech/ This confusion is partly due to the great changes that ensue on placing the animals in spirit. Specimens mea- suring feet or even yards in length shrink to short processes a few inches long, and the contour of the head is often indistinguishable on account of its retraction within the anterior portion of the body. Moreover, although the worm is in a manner preserved, it is generally unfit for dissection, and the colours frequently fade. While difficulties thus beset the investigator of specimens in museums, the obstacles to the satisfactory examination of the living forms are scarcely less per- plexing ; and though I would not fully endorse the description of Sir J. Dalyell, yet there is much truth in his observations : — "That many worms have no external prominences rising above the smoothness of their skin, or depressions sinking into it. That neither specks nor eyes, nor the position of the mouth can be discovered in the living specimens; that the student of animated nature cannot destroy his subject, and if perishing in his possession, it often goes so speedily to decay, that it is impossible, were he even a skilful anatomist, to avail himself of dissection." The colours of many species of the group are of such beauty as to attract even the casual observer, while in this respect also they widely deviate from their supposed allies the parasitic worms. The richest purples appear on velvety skins of deep brown or black, each of the soft and mobile folds giving shades that vary in intensity and lustre. Bright yellow contrasts with dark brown ; white with vermilion, brown and dull pink ; while individual uniformity is charac- terised by such hues as rose-pink, white, green, yellow and olive, the gradations of colour in the various parts of a single specimen being so subtle that enthusiasm as well as skill is necessary in the artist who sets himself to the task of faithful delineation. Our indigenous species as a whole do not seem to be less brilliantly coloured than those of warmer climates, if we may judge from GENERAL REMARKS. 3 Sclimarcla's plates, and the descriptions of other authors. Thus as regards beauty and variety of colouring the Nemerteans vie with any other group in the invertebrate series ; while in the silky sheen and ever-changing iridescence of the active cilia, with which their whole bodies are covered, they surpass in some respects their gaily tinted superiors — the true Annelids. The sexes of the Nermeteans do not appear to be distinguished by any peculiarity of shading, except where the ova or spermatozoa are observed through the translucent tissues of the adults. The reflections in regard to the bright colouring of these forms are somewhat cursorily treated by Mr. Darwin in his recent work. 1 These animals, he says, like many other invertebrates, " apparently stand too low in the scale for the individuals of either sex to exert any choice in selecting a partner, or for the individuals of the same sex to struggle in rivalry." The Nemerteans, however, are not devoid of sexual instincts, and the deposition of ova by a female, even at some distance from the male, gives rise to the immediate discharge of his special secretion. Thus Mr. Darwin would be furnished with the facts for stating that the best developed and most forward individuals would have most chance of securing numerous and healthy progeny. Their colours are not due to blood or bile, but are strictly skin-products, yet it would be as easy (or as difficult) to prove them advantageous to the creature as to demonstrate that the pale blood of some animals, the green or red of others, has been formed (as to colour) by natural or sexual selection. Indeed, there is scarcely a limit to the range of theory on such subjects, and it is hard to decide the one way or the other. The argument that the bright colours may be of use in leading their enemies to recognise them as unpalatable will scarcely suit, since fishes feed readily on some of the brightest. Neither can the proposition, available in the case of the soberly clad blind beetles, be of service, since some of the most gorgeously tinted {e.g., Carinella annulata and Linens bilineatus) are devoid of eyes ; nor are the animals coloured in any special manner so as always to resemble their surroundings, as may be noticed in the olive-green and reddish varieties of Linens g ess erensis. Tetrastemma Candida, on the other hand, assumes a greenish hue in certain instances amongst the littoral algae, and the food of the translucent Cepltalotltrix has a wonderful effect in colouring the cells of its alimentary region. Some of the most vividly tinted species live in obscure crevices and creeks, where light can rarely enter. The bright reddish ova, again, of Amphiporns pidcher, which shine through the pellucid integuments, must render the female for a period a more conspicuous object than the male or undeveloped animal. Though Prof. Grube's boatman saw the head of Linens marinus ' shine/ and Viviani states that Tlanaria retusa is uniformly luminous, none of the British Nemerteans show this property. There are, so far as at present known, thirty-one species of Nemerteans inhabiting the British Islands, and described in the following pages. The majority have been previously found ; a few are new to Britain or to science. 1 c rr\ The Descent of Man/ &c. HABITS, HABITS. In their native haunts these animals exhibit considerable diversity of habit. The majority, however, live under stones that lie on a muddy or sandy bottom, between tide-marks, either in pools or moist places, and, as scarcely a vestige of them is at any time seen unless a stone is upturned, their period of activity is probably during fall tide. As their haunts indicate, they are fond of the shade, but I do not know that for this reason they are to be called, after De Quatre- fages and others, nocturnal animals. Thus Lineus marinus is observed occasionally gliding amongst the seaweeds of a warm and sunny tide-pool. Hundreds of some of the common forms, such as Lineus gesserensis and Cephalothrix linearis, may be found under a single stone, sometimes in tangled masses, amidst the muddy sand so common in such places. Tetrastemma dorsalis is gregarious, in vast flocks, on Ceramium and other algse dredged in the Laminarian region ; and Prosorkockmus Claparedii is frequently found in groups in fissures of the rocks near low-water mark in the Channel Islands. Leidy, in his * Marine Invertebrata of Rhode Island and New Jersey/ also describes his Nemertes socialis as very abundant, often in masses, about the roots of corallines, between tides, at Point Judith. The larger and rarer forms occur either singly or in pairs, such as Nemertes Neesii and Micrura, which haunt the fissures of rocks near low-water mark. The great Lineus marinus, again, is often solitary, and the largest specimens almost always so, as well as limited in numbers — size, as in some of the higher forms of marine life, being thus inimical to profusion ; and it may be noticed that a diligent search for a lengthened period in one locality diminishes very sensibly the number of large examples. Other Nemerteans frequent the coralline ground or its neighbourhood, such as Micrura purpurea, Cerehratulus angidatus, Ampliiporus pidclier, and A. spectabilis, and they are partial to empty bivalve shells. Stones placed near the verge of low water, and covered with a profusion of algous and zoophytic life, furnish numerous specimens of the small Tetrastemmce, which apparently delight to crawl amidst the roots and branches, no doubt attracted by the abundance of the other animal organisms that like themselves seek shelter and safety in these miniature forests. One of the best modes of collecting such small forms is to chip off at the proper season — for their abundance is probably periodic — shelving fragments of rock, and carry them home for immersion in shallow vessels of sea- water, when the worms leave their retreats and crawl to the water-line of the basin, after the manner of Mssoce, Skenece, and other small Mollusca. The same may be said of the roots of the tangles dragged from the rocks near or beneath low-water mark, such treatment being often the only safe mode of procuring perfect specimens of Carinella annidata, Nemertes Neesii, and N gracilis, which generally inter- lace their lengthened bodies with the radicles. No richer ground for Nemerteans of rare size and beauty probably exists than the intricate roots of the vast tangles that envelop the muddy masses of horse-mussels in Bressay Sound, where Forbes and Jeffreys have each done such good work by aid of the old drag of the Zetlandic fishermen. Colonies composed of examples of different species, such as Lineus marinus, L. gesserensis, Micrura fasciolata, M. purpurea, Nemertes Neesii, and AmpJdporus pulcher, are occasionally met with in the same root; while the hollows of the rough roots of Laminaria bulbosa give shelter to select pairs or solitary individuals. HABITS. 5 Empty limpet-shells that adhere to the under surface of stones in tidal pools are also favourite lurking places for these animals. Although many of the smaller forms fashion gelatinous or membranous tubes with facility on sea-weeds and stones, one British species alone may be said to inhabit a tube or burrow not secreted by itself, viz. Borlasia Misabetha, which was found at Herm in a pit or burrow of clay ; and in this, as in other respects, the species is peculiar. A foreign example, the Stimpsonia aurantiaca of Girard, is also stated to dwell in vertical tubes in sand, near Port Johnston, Carolina. The group, as a whole, is composed of animals by no means inactive, for they glide swiftly about in their native sites, only their length sometimes proves a barrier to their rapid disappear- ance from a particular spot. Crustaceans, starfishes, and mollusks, indeed, are but clumsy athletes when compared w r ith the Nemerteans, whose bodies, deprived of all external protection, covered with cilia and endowed with exquisite sensibility, seem the very essence of mobility. On a solid surface, the chief mode of progression is by crawling, the body being thrown into a number of minute undulations, or else rendered more boldly moniliform by evident waves, which pass from the snout backwards. Some of the more active small species, again, such as Tetrastemma Candida, frequently glide over the surface of glass so smoothly that scarce a wrinkle is noticed in the soft outline of their bodies, which, for the time, seem to be propelled by an invisible agency. In progression, the body is extended in a rectilinear manner, or else thrown into one or more graceful curves ; while the snout is closely applied to the surface, or occasionally rolled from side to side. If a Nemertean, for example, Ampliiporus lactifloreus or Lineus gesserensis, is raised from the surface on which it crawls, it will generally be observed that it clings most pertinaciously by the anterior end ; indeed, it would appear that the lips exercise a kind of sucker-action, or, at least, that the under surface of the flattened snout does so. The bodies of several of the elongated forms resemble a semifluid yet coherent substance that can be drawn through any aperture, bent round any angle, and looped, coiled, or twisted in the most elaborate manner. In the more slender species, such as Cephalothrix linearis, the mobility greatly resembles that of the tentacular processes of the Terebellce, and I have been puzzled at least once, on lifting stones and sea-weeds from the dredge and placing them in water, by the independent and Nemertean motions of the spotted tentacles of T. nebulosa, the owner of which was for the time invisible. In the same species the living animals in confinement often group themselves into rounded masses, which become veritable Gorgon's heads when the constituent members push forth their straggling snouts. The larger kinds also, such as Nemertes Neesii and N. gracilis, follow a similar habit; and, when the water is changed, it is an interesting sight to watch the heads of the individuals sloAvly emerging, softly and w T ith ease, from the apparently inextricable coils. In few other groups of animals can such extreme conditions ensue between contraction and extension, and this not by the agency of sea-water, but by the extraordinary shrinking of the muscular substance, and the mobility of the other tissues of the animal. Specimens, measuring only a few inches in contraction, stretch with ease to the length of several feet; and irritants cause a large Lineus marinus, several yards in length, to shrink without injury into as many inches, while shorter forms become quite baccate. If a large example of the last-named Nemertean be held over spirit, the body seems to disappear swiftly on touching the liquid, and the hand with the shrunken mass rapidly approaches the surface. On viewing the motions of these animals, the observer will often be forcibly reminded of the graphic descriptions of the arms of Pleurobrachia, given by the elder Agassiz. 6 HABITS. Like many of the true Annelids they also progress by floating on the surface of the water, either crawling up the side of the vessel, and thereafter pushing their snouts outwards from the water-line ; or, if the water is shallow, raising their heads upwards from the bottom and gradually extending their snake-like bodies along the surface. As in the case of the Nudibranchiate Mollusca, a track of mucus is constantly left behind them in this position, and in the same manner they can be suspended by it. So abundant, indeed, is this mucus, that in jars containing numerous vigorous specimens of Linens gesserensis a perfect gelatinous mesh- work is formed near the surface of the water, and even throughout the entire vessel. I had carefully tested by personal observation the correctness of the explanation given by Messrs. Alder and Hancock of the modus operandi by which the Nudibranchs crawl on the surface of the water, and the same explanation is very evidently applicable to this class. The adhesion of the body to the mucus gives the animal sufficient purchase for the use of its facile muscles, for it need scarcely be mentioned that the water has no influence in lessening the attachment. Hence the remark of M. de Quatrefages, that Nemertes glides through the water by means of excessively fine vibratile cilia, which are protruded from every part of the surface of the body, cannot meet with our support. When anxious to view the ventral aspect to advantage, no difficulty has been experienced in making many thus float on the surface of the water in the shallow trough of a large dissecting microscope, for by constantly irritating the animals in their endeavours to crawl along the bottom of the vessel, and arresting their progress, they at last pushed their snouts upwards, and sought refuge by this mode of progression. While possessing the power of crawling and floating just mentioned, some species also swim freely through the water, and this habit in Britain is especially characteristic of the forms which inhabit deep water; indeed, I am not at present aware that littoral species exhibit it in any degree, though there is nothing inimical in their conformation. This habit has been noticed in the Cerebratulus marginatus of Nardo, the Meckelia aurantiaca of Grube, and by M. de Quatrefages, in his Folia bembioe, dredged off the coast of Sicily. Four British species, as far as at present known, show this mode of progression, viz. Amp/iiporus specfabilis, A. pidcher, Micrura fusca, and Cerebratulus angulatus. When irritated, each throws itself on its edge, and by alternate lateral strokes of the tail propels itself rapidly through the water with a serpen- tiform wriggle. Thus, their mode of swimming closely resembles that of the freshwater Nephelis, and differs from the horizontal flapping of their allies, the Planariae, which M. Duges compares to the motion of the Bays. The British species above noted are characterised by their somewhat short and broad form, and especially by the production of the lateral margins into a thin edge throughout the greater part of the body. Many of the Nemerteans, as M. de Quatrefages mentions, are very hardy in confinement, if the observer is at all experienced in the management of such animals. It is not by the well- calculated adaptation of plant to animal life, of nicely balanced conditions supposed to be favourable to the healthy continuance of marine existence in these artificial states, that the experiment is always successful. Pure sea-water in clean glass vessels, and, in some instances, a clean shell or empty Balaam, with a little sand or gravel on the bottom, constitute the most suitable aquaria. Unless the vessel is large, only one or two examples should be placed in each, and this is a point of great importance ; indeed, in the case of rare or valuable specimens, solitary confinement has generally been resorted to as most advantageous. I have thus been enabled to keep alive at a great distance from the sea-coast numerous individuals of Linens marinus, L. HABITS. 7 gesserensis, L. sanguineus, AmpJdporus lactifloreus, Micrura purpurea, M.fasciolata, and others, as well as to observe various interesting phases in their development. The vessels were always placed in a cool, and, if possible, in a darkened position, in accordance with the habits of the animals in their native sites ; but the sea- water was not changed more frequently than four or five times a year, and in some cases not at all. Such confinement generally blanched the snout of Lineus marinus, so as to render the groups of eyes visible. The pallor of the upper and under surfaces of the snout in this, species is peculiar, for the other parts of the animal are not affected. It occurs chiefly in the region of the cephalic sacs, across the entire breadth of the snout, and extends forward at the margins to the tip ; the pigment of the centre of the snout anteriorly, both dorsally and ventrally, and the reddish hue in the region of the cephalic pits remain. I have kept this species, indeed, so long that the snout has become completely etiolated, with the exception of the eye-specks and the reddish coloration of the cephalic fissures. Moreover, throughout an inch of the anterior part of the body, the ventral surface had assumed a pale pink colour, and the six dark stripes on the dorsum were separated by a ground-colour of the same pale hue, which, besides, here and there interrupted the longitudinal dark bands. In the instances, again, of AmpMporus lactifloreus and the pale Tetra- stemmce, the opacity of the cutaneous textures is considerably increased ; and as the two latter are generally best adapted for the investigation of certain minute details, it always became necessary to send to the rocks for a fresh supply. This opacity in the pale species is due to an increase of yellowish colouring matter in the cutaneous cells, and the deposition of brownish-red pigment, a change probably arising from a more frequent exposure to the sun's rays. In some specimens of A. lactifloreus under these circumstances, a general augmentation also occurs in the reddish pig- ment of the ganglia and anterior portions of the lateral nerves. A similar alteration ensues in other species, such as Carinella annulata and Lineus bilineatus, the former changing from pale brick- red to deep brownish red, and the latter from pale-pinkish buff to brown, thus intensifying the contrast with the pure white lines present in each case. This variety of tint, from exposure or seclusion, likewise occurs in their native haunts. Thus, for example, specimens of Nemertes Neesii, from a chink in the Gouliot Caves of Sark, have a much paler aspect than those from an ordinary tidal pool. The rule, however, has many exceptions, for in the same caves very dark olive speci- mens of Lineus gesserensis are found, while a variety of a pale reddish hue lives under stones beneath the open sky at the mouth of one of them. After protracted confinement without food, the longer forms generally lie coiled in an intricate mass on the bottom of the vessel, or, if only moderately elongated like Micrura, rest as a double band, and their bodies diminish in bulk to a very great degree. Under the same conditions the smaller species, such as Tetrastemma and Prosorhoclwius, are often found at the margin of the water, and some having receded too far from their element become dried on the side of the jar. The latter accident especially occurs amongst groups of recently captured specimens, which have not yet attained the experience necessary for their preservation in this artificial habitat. Some sustain life under almost complete abstinence for very long periods, such as a year or eighteen months, their bodies being apparently supported by the slow absorption of their own tissues, so that, as before mentioned, their size is greatly reduced. There is, indeed, no structure in the bodies of the majority that is not capable of such change, and thus decrease, in every respect, is easily attained. I have not sufficient facts to enable me to make generalisations on the subject of their longevity ; but the larger Nemerteans, e.g. Lineus marinus, L. gesserensis, and Z. sanguineus live for several years, even under very unfavourable circumstances, in confinement. With ordinary care, also, they can be 8 FOOD. carried alive from remote parts of the country, as from the Channel Islands to Scotland, and from Shetland, without the loss of a single example of any of the species. If, therefore, animals so large live for a protracted period in very limited supplies of salt water without a trace of food, our wonder is diminished at the apparent paucity of nourishment in the abysses of the Atlantic for the sustenance of the Eoraminifera and other minute organisms mentioned by Dr. Carpenter, since, putting aside for the moment the dissolving jellies and ciliated young of certain of their neighbours, they have free access to the trackless ocean and all its contained organisms. Under certain irritants, as, for instance, great impurity of the water in the case of recently captured animals, the common Linens gesserensis turns itself inside out, so that the inner surface of the digestive chamber can be viewed without dissection. This also occasionally occurs on placing it in alcohol. The extreme shrinking of Linens marinns on immersion in spirit is also some- times due to a literal doubling of its body, one fold of which is thrust within the other, the outer being in its normal position, but the inner having its alimentary surface external. Ceplwlothrix linearis is killed by fresh water in a few minutes, the body being swollen by contraction and con- torted. Amphiporus lactijloreus lives a little longer, though it never moves from the spot, and only thrusts its snout hither and thither for a short time, and dilates its mouth. Lineus gesserensis does not crawl after immersion, but lies helplessly on the bottom of the vessel, a swollen body- wave passing rapidly from before backwards for some seconds, as if sickly, then all is still. In most cases, as noticed by M. de Quatrefages, a copious exudation of mucus takes place, and disintegration speedily ensues, the specimens becoming pulpy in a few hours. They are not less hardy, however, than the higher Annelids under the same circumstances. POOD. The Nemerteans throughout are a carnivorous and predaceous race, either capturing living prey or devouring suitable portions of dead animals. Sir J. Dalyell observed Lineus marinus and his Gordius minor viridis feeding on fragments of mussel, the former also entering the tube of Amphitrite (Sabella) to devour the tenant, and M. de Quatrefages (after Cuvier and others), in his " Rambles," 1 narrates that the former species is nourished by sucking the Anomia, a feat, however, that seems to me to be involved in obscurity. The erroneous interpretation of the proboscis of the Enopla (which he took for an alimentary organ) of course exonerates M. de Quatrefages in a manner from criticism in regard to the feeding of the animals. It may be observed, however, that the thrusting out of the proboscis noticed by him in Folia mandilla (Amphvporus lactijloreus) may have been due to other causes than hunger, and that the adherence of the same organ to a Cyclops for a quarter of an hour may be otherwise explained than on the sup- position of suction. Mr. Kingsley gives a very graphic but not very accurate (since he says the proboscis assists in prehension) description of a specimen of the same species in the act of devouring a fish. Lineus marinus, indeed, would appear to have a very indiscriminate appetite, for not only does it devour its vertebrate and bristled superiors, but a specimen in the island of Herm swallowed an example of Ascidia intestinalis about an inch long and half an inch broad, which had been put into the same vessel. Mr. William Thompson, who did so much for the fauna of Ireland, 1 Excellently translated by the accomplished Miss E. C. Otte. London, 1857. HISTORY OF THE SUBJECT. 9 mentions that Captain Fayrer, R.N., got an individual of the same species holding on to a bait of Buccinum undaium on his long line, while fishing for cod off Portpatrick. In confinement the Lineidce readily feed on fragments of mussel. As soon as a specimen has come in contact with a suitable portion, the mouth is enormously dilated, the inner surface of the first part of the oesophageal region thrust outwards, and the bolus, although of considerable size, rapidly swallowed. The snout of the animal during this process is curved backwards, doubtless to afford assistance by its tactile properties, but there is no extrusion of the proboscis. They also feed on dead specimens of Nereis pelagica, Harmotlioe imbricata, and other annelids, ejecting the bristles and indigestible portions per (mum, and the only inconvenience which they suffer from the spines and bristles is an occasional perforation of the digestive tract and body-wall, and the formation of a vesicle in the cutaneous textures, through which the offending structures are by-and-by extruded. One specimen of L. gesserensis under examination boldly seized the head of a large Nepkt/igs, upwards of an inch longer than itself, and partially engulphed its prey. Many, moreover, greedily swallow their fellows, and hence it is dangerous to leave examples of rare specimens together in a vessel, as the larger generally make a meal of the smaller. While thus predatory and voracious,, they are in turn tolerant of much injury ; for instance, a specimen of L. gesserensis had its head and anterior portion seized and confined in the stomach of a Sagartia troglodytes for about ten minutes, yet the worm afterwards got free, and crawled about as if nothing had happened. In Cephalothriv the contents of the digestive tract are easily observed, and in confinement often consist of frag- ments of each other. I have not been so successful in seeing the Enopla feed, but they probably take similar nourishment. Several of the large forms, such as Lineus bilineai its, have been found in the stomachs of haddocks and flounders caught off St. Andrew's Bay. Their hardihood when confined in vessels without food has already been described. HISTORY OP THE LITERATURE ON THE SUBJECT. The early authors on Zoology, while conversant enough as a rule with a few of the con- spicuous Annelids, altogether omitted to notice the Nemerteans. Thus no mention is made of them by Linnaeus, Seba, Blumenbach, Swammerdam, and others. In 1758 the Rev. William Borlase, E.R.S., 1 introduced the Nemerteans to our Fauna by the following description of Lineus marinus :— "Fig. xiii, Plate xxvi, is the long worm found upon Careg-Killas, in Mount's Bay " (Cornwall), " which, though it might properly enough come in among the anguilli-form fishes, which are to succeed in their order, yet I chuse to place here among the less perfect kind of sea animals; it is brown, and slender as a wheaten reed; it measured five feet in length (and perhaps not at its full stretch), but so tender, slimy, and soluble, that out of the water it will not bear to be moved without breaking ; it had the contrac- tile power to such a degree that it would shrink itself to half its length, and then extend itself as before." A rough engraving of L. marinus accompanies this account. Certain « marine insects " from amidst Sertularians and other Corallines are represented in Tab. iv of Baster's " Opuscula," 3 vol. i, 1762, one of which, fig. 9, is a Nemertean, probably Tetrastemma Candida. No further mention is made of the animal. 1 < The Natural History of Cornwall,' p. 255, tab. 26, f. 13. Oxford, 1758. 2 Baster, < Opuscula Subseciva.' Haarlem, 1762. 2 10 HISTORY OF THE SUBJECT. P. S. Pallas, 1 in the year 1766, described a Nemertean of a bluish-white colour under the name of Lumbricus oxyurus, which I am inclined to identify with Amphiporus lactifloreus, from a careful examination both of the figures and text. He mistook the proboscis for an intestine, as many subsequent authors have done, but he observed that the organ was bathed in fluid, thus recognising a very important element in the anatomy of these animals. He interpreted the stylet- region as the stomach, and detected three muscular bundles proceeding from the posterior end of the latter, so as to fix the organ to the integuments. The intestine, again, terminated in an anus at the anterior pore. The medulla or nervous trunk formed a simple white cord, he said, without ganglia. While there is much that is erroneous in the foregoing description, there is also a con- siderable amount of penetration and judgment evinced by the learned author, for he appears to have made out the proboscidian fluid, the dilated region of the stylets, and the muscular ribands; and it is clear that this observer would not have omitted to notice the mouth and lateral fissures if his specimen had been a typical form of the Anopla. In the same work 3 he also figures a Nemertean resembling Lineus gesserensis, but the only reference thereto occurs in the explanation of the Plate, viz., " Alia Lumbrici marini species, tota atra." The next important contribution was from the pen of the distinguished naturalist, Q. P. Miiller, 3 who in. the first part of his " Vermium," published in 1773, grouped the Nemerteans under the Second Division of his worms destitute of tentacles (Serpentes), and in the third head (Mutica). In his second part, published in 1774, they were included, along with Gordius, Ascaris, Hirudo and others, in the first subdivision (Mutica) of his Gens Helminthica. Three or four of the common species were for the first time described (some of them more than once) as Fasciolce. In the new edition of his " Natural History of Fresh and Salt Water Worms/' 4 published in 1800, the same author describes a single example of the IAneidm under the name of c Der Stro- mische Hod-Aat/ a species no doubt identical with Lineus gesserensis. He did not discriminate structure further than by supposing the lateral slits at the anterior end to be connected with the anus, and the ventral papilla (mouth) the male organ of generation. His figures are quite recognisable. This naturalist 5 in a subsequent publication (1776) enumerates the Nemerteans under his sixth Class (Vermes), and third Order — Mollusca. It is difficult to determine with precision the species referred to in this work, unless in those cases in which further mention in the " Zoologica Danica" confirms the diagnosis. He arranged them with the Planarise according to the number of eyes, but erroneously placed Lineus gesserensis, Amphiporus pulcher, and others, under the group of eyeless forms. The acute and painstaking Dutch naturalist, Martin Sfabber, 6 noticed a Nemertean, under the name of Gordius marinus, which is evidently one of the Anopla, having in his figure (where 1 P. S. Pallas, f Miscellanea Zoologica/ pp. 146—147, pi. 11, figs. 7 and 8. 2 Op. cit., p. 216, pi. 11, fig. 9. 3 O. F. Muller, 'Vermium Terrestrium et Fluviatilium.' Havnise et Lipsiae, 1773-4. 4 l Naturgeschichte einiger Wurm-Arten des siissen u. salzigen Wassers/ Neue Ausgabe. Ko- penhagen, 1800. 5 O. F. Muller, c Zoologise Danicse Prodromus/ Havnise, 1776. 6 ' Natuurkundige verlustigingen behelzende microscopise waarneemingen/ &c, Blad. 61, PI. 8, f. 1. Haarlem, 1778. HISTOKY OF THE SUBJECT. 11 the animal is seen on its edge) a conspicuous lateral fissure. It appears to be related to Mlcrura fuse a. In 1780, Otho Fabricius, 1 following 0. F. Muller, placed the Nemerteans in the genus Planaria, under his sixth Class "Vermes/ 5 He mentions Planaria angidata, P. rubra, P. viridis, P.fusca, P. caudata, and P. Candida, most of which had been previously described in the ' Zool. Danic. Prodr/ of O. F. Miiller. Under the head of Planaria fusca {Lineus gesserensis) he corrects certain statements of the latter author, who had only seen spirit-preparations. He con- sidered the aperture of the proboscis to be the mouth, and the tube itself the intestine. He also noticed that it lived in numbers under stones. Linnaeus seems to have had little or no acquaintance with Nemerteans, which were either unknown or confounded with other animals, and it was only after the labours of O. F. Muller and others had brought them into view that they were noticed in Gmelin's edition of the ' Systema Naturae/ 3 published in 1788. They were grouped by Gmelin along with the Planarians under the Genus Planaria, one of the divisions of his Class Intestina. They thus became associated with intestinal worms, Lumbrici, Sipuncnli, and leeches. They were classified as follows : — (1) Those without eyes -, (2) those with one eye ; (3) those with two eyes ; (4) those with three eyes ; (5). those with four eyes ; (6) those with many eyes. The animals, however, were so little under- stood that this arrangement is not to be depended on. Nothing new was introduced in Dr. Turton's translation of this edition of the c Systema.' 3 Otho Fabricius, returning to the subject in 1798 described 4 three Nemerteans under the names of Planaria angulata, P. fuscescens, and P. Candida, from Greenland. Like Pallas he considered the proboscis to be the alimentary organ, though he correctly interpreted the mouth in the Lineidce, and the anus in both. In the following year, 1799, Jens Rathke 5 alludes to six species of the group, viz., Planaria badia, P. lateritia, P. sanguinea, P. carnea, P. atrojmrpurea, and P. linearis. The first two I have not satisfactorily made out, the third probably refers to Lineus sanguineus, the fourth to a variety of L. gesserensis, the fifth may be L. marinus, while the sixth is Cephalothricc linearis. Three of the species are figured. Lamarck, in his ' Systeme des Animaux sans Vertebres ' 6 mentions only one Nemertean, viz., the Planaria rosea of O. F. Muller. L. A.'G. Bosc 7 classified the Nemerteans with the Planarians under the true worms with elongated articulated bodies, but without external organs, placing them with the Gordii and leeches. In regard to species he follows 0. F. Muller. Montagu was the next British naturalist after Borlase who paid attention to the Nemer- teans. 8 In 1804 he gave a good superficial description of the worm mentioned by the former, under the name of Gordius marinus 3 W\t\\ remarks on its habits. He was, moreover, the 1 Otho Fabricius, ' Fauna Grcenlandica/ Hafnia3 et Lipsize, 1780. 2 Gmelin's, l Linnseus Syst. Nat./ torn, i, pars, vi, p. 3087. Leipsise, 1788. Editio decime tertia, aucta, reformata. 3 London, 1802. 4 c Skrivter af Naturhistoire Selskabet/ 4de bind, 2det hefte, p. 52 et seq. Kiobenhavn, 1798. 5 ' ' Jattagelser henhorende til Jndvoldeormenes og Blddyrenes Naturhistoire." < Skrivt. af Natur- hist./ Selsk. v, 1 heft., pp. 83, 84. Kiobenhavn, 1799. 6 Paris, 1801. 7 < Hist. nat. des Vers. 5 Paris, 1802. 8 ' Description of several Marine Animals found on the South Coast of Devonshire/ Trans. Linn. Soc., vol. vii, pp. 72 and 73. 12 HISTORY OP THE SUBJECT. first to describe Carinella annulata. He followed previous authors in classing these and allied forms under the ' Intestinal The same species, termed respectively the Line-worm and the Hair- worm, appeared, from Montagus descriptions, in Dr. Turton's s British Fauna.' They were arranged in a similar manner under Class V, Vermes, and Order I, Intestina, but were placed under different genera, the former being alone, and the latter associated with Gordius aquaticus and G. argillaceus. It is from the interesting manuscript, however, which the relatives of Col. Montagu have placed in the Library of the Linnean Society, that we gather how much and how closely the esteemed observer examined the Nemerteans. In this work he describes more than a dozen species, not a few of them for the first time, and the majority so truly, that it is with a sense of relief and satisfaction that one rises from its perusal. Little can be added to his account of the external appearance and habits of the animals ; and, though he did not enter into their anatomy, he correctly interpreted the mouth and anus in the Anopla, and was too cautious an observer to locate the former organ in the same position in the Unopla. He explains that, though he termed the species above mentioned Gordii, this was only a provisional name until further discoveries of species should put him in a position to frame correct generic characters. To the description of the genus Lineus he appends the following remarks on the Nemerteans : — " Their use and general economy are little known, but we may conclude they contribute partly to the food of some fishes, and in their turn keep within bounds some smaller beings, and thus serve to support an equili- brium in the great scale of nature." A volume of carefully coloured figures, by the skilful hand of Miss E. Dorville, accompanies the manuscript. O. F. Miiller in his great work 2 described several new species, and gave figures of others mentioned in his previous works, grouping them still under the genus Planaria. Two of his forms, viz., Planaria viridis and P. rubra were communicated by the author of the f Fauna Grcenlandica -/ the others were P.filaris, P. rosea, P.Jlaccida, P. gesserensis, and in the fourth volume P. C. Abildgaard contributed another — Planaria dorsalis. The author observed the proboscis, the cephalic fissures, and the ventral slit in the Anopla, and likewise gave the correct position of the anus. This work then noticed seven species, most of them in a recognisable condition as regards description and figures, the latter especially deserving praise for their faith- ful delineation. In 1806 J. Sowerby 3 gave the title Lineus longissimus to the Black Line-worm, which now bears the name of Lineus marinus. He first heard of it from Col. Montagu, and afterwards from Mr. Simmons, who sent specimens from Edinburgh. In his description he correctly located the mouth, and observed the longitudinal streaks on the body, as well as the tendency of the broken posterior end to decay, while the anterior remained alive. He mentions that the fishermen pull them in as they would a rope, but never find the posterior extremity, and that they esti- mate their length at twelve fathoms. A coloured engraving of the animal accompanies the description. In 1811 Professor Jameson 4 included Lineus longissimus in his ' Fauna of the Frith of Forth/ mentioning that the worm was not uncommon on oyster-beds. 1 c British Fauna, containing a Compendium of the Zoology of the British Islands, arranged according to the Linnean System/ Vol. i. Swansea, 1807. 3 O. F. Muller, < Zoologica Danica/ Havniee, 1788—1806. 3 < The British Miscellany/ London, 1806, p. 15, plate 8. * ' Wernerian Memoirs/ Vol. i, p. 557. Edinburgh, 1811. HISTORY OF THE SUBJECT. 13 A very slight notice of the Nemerteans occurs in Pennant's ' British Zoology' (edit. 1812), two only being mentioned, and those previously described by Montagu. Some remarks on the habits of Lineus marinus were made by the Rev. Hugh Davies in 1815. He observed that the animal was sensitive to light, though he could not discover eyes. He also considered that the spiral form was purposely assumed by the worm during progression, for he could not perceive how its amazing length could otherwise be transported. He thought it by no means improbable that it reached the length of twelve or even fifteen fathoms. 1 An almost verbatim report of this paper appeared next year (1816) in the f London Medical and Physical Journal,' p. 207. In the same year Oken, 3 in his " Lehrbuch," brings in this well-known species [Lineus marinus) after Nais and Lumbricus, under the name of Borlasia anglite. He correctly describes the mouth, and gives a short resume of what was known with regard to the Devonshire specimens, and a small outline of the species. Lamarck, in his e Histoire Naturelle des Animaux sans Vertebres,' 1816, like other writers about this time, copies the arrangement of O. P. Midler. He did not think that the Planarise were annelids, but that they approached the leeches. 3 Cuvier, unaware of the names previously given to these animals by Sowerby and Oken, for the first time applied the term Nemertes^ in 1817 to designate the species described by Borlase. He groups the animal in the second class (of his Zoophytes) "Zes Intestinaux" {Entozoa, Rudolphi), and in the first order of this class, " Zes intestinauw cavit aires" along with very heterogeneous companions, such as Lemaea and others. He thus separated them from the Planarians, which he placed under the head of the " Zntestinaux parencJiymateuoc" The sole species known to him was the Nemertes Borlasii, Cuvier, which, he says, insinuates its anterior extremity (by which he in the first instance means the tail, since he mistook the anterior for the posterior end) into Anomise, for the purpose of sucking the contents, a feat, it appears to me, of somewhat dubious veracity. In his second edition he left the Prostomse amongst the Planarians, following, according to M. de Quatrefages, Duges in this respect. In Griffith's edition 5 of the ' Regne Animal ' of this author little further information is given. Of Nemertes it is said by way of description, " It is a worm extremely soft and elongated, smooth, slender, flattened, and terminated at one extremity by a large blunt point, pierced by a hole ; widened, and broadly opened at the opposite extremity, by which it fixes itself. Its intestine traverses the whole length of the body. Another canal, probably connected with generation, winds along its parietes, and finishes at a tubercle on the margin of the wide aperture. MM. Dorbigny and de Blainville, who have seen this animal living, assure us that the wide aperture is the mouth/' Besides repeating the remark about the sucking of the Anomia by Nemertes Borlasii, it is further explained that the animal remains sunk in the sand, and is " more than four feet long," neither of which observations adds in any way to our knowledge. The only point of interest in this description is the cautious correction of the mistake which Cuvier made in holding the anterior as the posterior end of the worm. In the illus- 1 'Some Observations on the Sea Long- Worm of Borlase, Gordius marinus of Monta/ Trans. Linn. Soc, vol. xi, p. 292. 3 « Lehrbnch der Naturgeschichte, Dritter Theil, Zoologie.' Erster Abtheil. &c. Jena, 1815, p. 365, tab. xi, fig. 4. 3 ' Hist. nat. des anim. sans vert/ Paris, 1816, &c. 4 Cuvier, f Regne Animal/ Tome iv. Paris, 1817. 5 Vol. xii, p. 468. London, 1834. 14 HISTORY OF THE SUBJECT. trated edition of the ' Regne Animal/ 1 by the disciples of the great master, M. de Quatrefages gives exactly the same description, and repeats certain of the figures — to be alluded to hereafter. Schweigger, in his ' Handbuch der Naturgeschichte, 5 follows Cuvier too closely, for he now describes Borlasia anglice as having a membranous disc posteriorly, and either occurring in a free state, or by aid of this disc adhering to Anomise. 3 Dr. Fleming, 3 in 1822, represents the Nemerteans by Linens, one of the genera of his family Gordiusidse, the other genus being Gordius. He correctly observes that in Linens the mouth is a longitudinal slit placed under .the snout, but makes no further remark than that several species inhabit this country. A very considerable increase to the knowledge of these animals was made by the investi- gations of the celebrated Italian naturalist Stefano Delle Chiaje, who, in the second volume of his 'Memorie,' 4 published in 1825, gave somewhat detailed descriptions of two Nemerteans for which he constituted the genus Folia, named after the comparative anatomist Giuseppe S. Poli. In his sketch of the anatomy of Folia sip/iunculus, he mentions two muscular coats under the skin, an inner of longitudinal fibres, and an outer of transverse (circular). From the mouth springs a muscular rugose gullet (speiserohre of the Germans), having an inner mucous coat and a fibrous layer. The alimentary canal has the same diameter, and extends throughout the entire length of the animal. In each articulation we have a right and a left sac or pouch in connection with the alimentary tube, into which the food may enter. Above the digestive tract is found a canal containing a long proboscis, which has four fibrous coats, and an internal mucous one covered with papillae. The proboscis, moreover, is fixed to the wall of its sac by a muscular band. He imagines this to be an organ of touch, and states that when free its motions are so vermiform that one might easily mistake it for a Lumbricus or Echinorhynchus. In regard to the circulation, he observes that two arteries arise from the triangular lobe of the head, and proceed along the sides of the body, while two sacs, which have the function of hearts, occur at their commencement. In the angle of the basis are three slight whitish elevations, in connection with a whitish thread, which runs down to the middle of each artery. From the end of the mouth springs a very small vein, which gives branches to the lateral sacs (of the digestive cavity). In his other species {Folia lineata) he describes a prehensile disc around the anus, and the occurrence of pores on the ventral surface, analogous to the respiratory sacs of Sipunculus, but the position of the form is doubtful. This author therefore has the merit of being the first to anatomise these animals in a scientific manner, and to interpret fairly the physiology of the parts. He recognised the true mouth of his examples (which belonged to the Anopla), the general arrangement of the digestive tract, and the presence of distinct muscular layers in the body-wall. The errors he fell into with regard to the circulatory system may be easily explained, since he worked only with dead animals, or, at least, not with those capable of being employed as transparent living objects. The anal " sucker" in P. lineata may have been due to some eversion of the digestive canal, if the species pertained to this order. 1 ' Regne Animal Illust/ Zoophytes, texte et atlas, p. 65, plates 33 and 34. Paris. 3 ( Handbuch der Naturgeschichte der skelettlosen umgegliederten Thiere/ Von Dr. August Friedrich Schweigger. Leipzig, 1820, p. 591. 3 ' Philosophy of Zoology/ vol. ii, p. 605. 4 S. Delle Chiaje, 'Memorie sulla storia e notomia degli animali senza vertebre del Regno di Napoli/ Napoli, 1823—1829. 4 vols. (Vol. ii, p. 406.) HISTORY OF THE SUBJECT. 15 In his third volume, published in 1828, he describes several other Nemerteans. Amongst these in all probability falls also his Planaria sipliuncuhs. I have not been able to identify his Folia punctata ; the size and colour of the proboscis, and the thin edges of the body in his figure, 1 would lead me to place it near Micrura fusca. His Folia oculata is allied to Lineus sanguineus, but the occurrence of eight large eyes on each side, and the somewhat wide and flat- tened nature of the snout in his enlarged figure, 2 make it doubtful. The identification of Folia ccerulescens is also difficult ; but his Folia geniculata is the Cerehratulus geniculatus of M. de Quatrefages. In 1829 the same author figures three species in his fourth volume, viz., Opkgocepkalus murenoides? Tuhulanus polymorphus? and Cerehratulus hilineatus? but I cannot find reference thereto in his text farther than the simple explanation of the plate. 0. murenoides may be a variety of Lineus marinus, or else a species with which I am unacquainted. Tuhulanus jiolgmorp/ius has a broad hastate head with lateral fissures. There are no stripes on the brownish ground-colour. In his description of the figure (9) of C. hilineatus he terms the everted pro- boscis " sifone genitale." In a section of the proboscis of this species, he shows at least external circular and median longitudinal fibres, although in some other respects he is obscure, since he speaks of an accessory cavity — probably from the invagination of the proboscis. A representation 6 and accompanying explanation are also given of the ovaries of Folia sipJiunculus, in which the author shows a general acquaintance with their position. An abstract of Delle Chiaje's observations was given in 1832 in Oken^s 'Isis.' 7 E. S. Leuckart 8 in. 1828 established the genus Meckelia for the reception of a species [Mechelia somatotomus) which he found in a runlet connected with the Mediterranean. This species was evidently a true example of the Anopla, from the description given of its cephalic fissures and mouth, and therefore it is wrong to apply the generic title to a family so diverse as that containing the Gordius annidatus of Montagu. In the same year Dr. George Johnston commenced a series of papers 9 on this department of British Zoology, and he proved a most able and persevering expounder of the habits and general structure of the group, rescuing them from the almost total obscurity in which they were shrouded in this country, and giving a fresh impetus to their investigation. Errors, doubtless, he made, but they were not more striking than those of many of his contemporaries, and not a few of his successors. He described on this occasion three species, viz. Flanaria flaccida, F. unicolor, and F. lactiflorea. The first refers to Nemertes Neesii. The second may be Lineus sanguineus, though he himself does not seem to have been quite sure as to what it was, since no notice is taken of it in his subsequent writings. The last is Jmp/iiporuslactifloreus. The first came from deep water, the last from the littoral region. M. Ant. Duges established the genus Frostoma, also in 1828, to designate what appears to 1 Op. cit., vol. iii, p. 172, tav. 43, f. 11. 2 Op. cit., tav. 44, fig. 1. 3 Op. cit., vol. iv, tav. 62, figs. 6, 7, and 13—15. 4 Op. cit., tav. 62, figs. 8 and 12. 5 Op. cit., tav. 62, figs. 9 and 16. 6 Op. cit., vol. iv, p. 37, and tav. 53, fig. 7. 7 Isis, 1832, heft. 6, p. 647, taf. 10, figs. 3—5, and ll 1 — ll 5 . ' Breves animalium quorundam maxima ex parte marinorum descriptiones, F. S. Leuckart/ HeidelbergEe, 1828. 9 ' Zoological Journal/ vol. iii, pp. 428 and 429. 16 HISTOEY OF THE SUBJECT. be a freshwater Nemertean {Prostoma clepsino'ides) , which he discovered in French streams. 1 He found that it differed entirely in type from the Planarians which he had been describing, since it did not possess their gastric ramifications, but had a simple alimentary tube (proboscis), forming several convolutions. The latter organ commenced in front by a probably exsertile mouth, and terminated posteriorly in a rounded anus. In the same year (1828) M. de Blainville 3 placed the Nemerteans along with the Planarians under the Class Bntomozoaires apodes ou Vers, in the Sub-class Parentomozoaires ou Sub-Annelid daires, and in his first Order Jporocepkala. He established his first Family, Teretularia, for their classification, but associated with them. Bonellia, a Gephyrean. His genera of true Nemerteans were Tubulanus (Renier), Op/tiocepkalus (Quoy and Gaimard), Cerebratulus (Renier), Borlasia (Oken), Lobilabrum (De Blainville), and Prostoma (Duges). He correctly described the mouth in the Anopla (to which group almost all his species, with the exception of Prostoma, belonged), and the general characters of the animals. His figures of Borlasia anglice in the Atlas are fair. Dr. G. Johnston 3 continued his observations on Planaria in 1829, describing Planaria octoculata, P. quadrioculata, P. bioculata, and P. filiformis. The first mentioned refers to Lineus sanguineus, the second to Tetrastemma Candida, the third to Z. gesserensis, and the fourth to Cephalothrias linearis. His accounts are short, but easily recognised. In 1830 M. Duges published descriptions 4 of four species of Prostoma, and gave certain anatomical details. One of these, however (now called P. clepsinoidemn), was mentioned in the previous paper • the second, P. lumbricoideum, is probably Tetrastemma Candida ; the third, P. candidum, Miiller, appears to be the same species ; and the fourth, P. armatum, has so many eye-specks that, if the description is correct, it is a species with which I am unacquainted. His anatomical investigations were made on the latter. He confounded the proboscis with the diges- tive system, and the nervous with the circulatory system. Professor Huschke 5 in a notice of the anatomy of Notospermus drepanensis {Cerebratulus geniculars, De Quatref.), from tufts of Corallina officinalis on the shores of Sicily, published at this time, mentions that there are two muscular coats under the skin, an external longitu- dinal and an inner circular; the inner longitudinal muscular coat having escaped observation. He truly interpreted the alimentary canal, with its post-ganglionic mouth and terminal anus, but mistook the proboscis for a male organ, which, however, he correctly located in a sheath between the muscles of the body-wall and the digestive tract. The lateral fissures of the head he likewise connected with the generative organs, and described and figured the nerves as semen-canals. This appears to be an example of the Anopla, and hence we are enabled to predicate as to its probable structure. In the same year (1830) Professor Leuckart, 6 in a further note on his Meckelia somatotomus, calls the aperture of the proboscis the genital organ, but he correctly names the mouth. He states that the genus Mechelia closely resembles Borlasia. In the following year (1831) our knowledge of the group received a considerable accession 1 f Ann. des sc. nat./ Ire S£r., vol. 15, p. 140, pi. 5, figs. 25 and 26. 2 ' Diet, des Sc. nat./ vol. 57, pp. 573—577. 1828. 3 ' Zoological Journal/ vol. iv, 1829, pp. 56 and 57. ^ < Ann. des sc. nat./ Ire Ser., vol. 21, p. 73, pi. 2, fig. 1—6. ' Beschreibung und Anatomie eines neuen an Sicilien gefundenen Meerwurms.' Isis, 1830, heft. 6, pp. 681—3, taf. 7, figs. 1—6. 6 Isis, 1830, heft. 6, p. 575. HISTORY OF THE SUBJECT. 17 from the labours of the illustrious Ehrenberg, 1 who formed them with others into a distinct class, which he termed Phytozoa Turbellaria. It is true he included under this head animals, such as the Gordii and Naidina, which are widely dissociated from the typical group, and, in his arrangement, placed apart genera allied in the closest manner, yet his contribution forms an epoch in the literature of the Nemerteans. He characterised the Turbellaria briefly as " E ver- tebrate apodous animals, creeping ; often with retractile vibratile hairs ; with a distinct intes- tinal tube ; separate vessels without hearts, rarely with a mobile dorsal and abdominal vessel ; hermaphrodite or with distinct sexes, oviparous and spontaneously fissile; excreting a copious mucus." The Nemerteans were placed entirely under his second order, Rhabdoccela, that is, Turbellaria with a simple cylindrical or conical intestine, having the mouth at one end and the anus at the other. The family Micrurea he grouped under the second section (Monosterea) along with the Gordii, but he more consistently classed all the other Nemerteans described by him under the third section, AmpMporina. His arrangement is thus, as follows : — Section II. — Monosterea. Earn. Micrurea. Gen. Disorus, Micrura, and Polystemma. Section III. — Gyratricina. Gen. Orthostoma, Gyratrix, Tetrastemma, Prostoma, Hemicyclia, Ommatoplea, Am- phiporus. Earn. Nemertina. Gen. Nemertes, Notogymnus. The want of an anatomical basis for his classification rendered errors unavoidable, but his descriptions of the species are characterised by care and lucidity, and his figures arc good. He erroneously considered the proboscis to be the intestinal canal, and its aperture the mouth, while the actual mouth in the Anopla he termed the genital opening. In the Enopla he could not of course find the latter. He correctly noticed the presence of an anus. Since he states that he saw a reddish viscus in Tetrastemma Jlavidum on each side in front of the proboscis (which reddish mass he took for an ovarium), it is probable he alludes to the ganglia. The stylet- region of the proboscis entirely eluded his notice. The arrangement of this author is implicitly followed in the twelfth edition of Lamarck's ' Histoire Naturelle des Animaux sans Vertebres/ 2 Dr. George Johnston described and figured 8 in 1833 Carinetta annulata under the name of Carinella trilineata. He was unacquainted with the previous description by Montagu in the 'Linnean Transactions/ Like many others he also called the proboscidian aperture the mouth, while the true mouth escaped his notice. He rightly stated that the anus was terminal. Quoy and Gaimardin the same year give an account, with figures, of several Nemerteans in their zoology of the ' Voyage de la Corvette 1' Astrolabe.' None of their species, however, seem to be 1 ( Symbolse Physicse. Anim. everteb. exclus. insectis.' Ser. prima. Berolini, 1831. 2 ' Hist. Nat. des Animaux sans Vert/ 12th edit., par Deshayes et H. M. Edwards, vol. iii, pp. 610—613. Paris, 1840. 3 Loudon's < Mag. Nat. Hist./ vol. vi, p. 232. 18 HISTOEY OF THE SUBJECT. identical with the British forms. They correctly interpreted the mouth in the Anopla, but erroneously considered the aperture of the proboscis a genital pore, representing, moreover, as a parasite (Plate m, fig. 14) the proboscis escaping from the mouth of a specimen of Borlasia tricuspidata. A Tetrastemma, with a deeply notched snout and four large eyes (" Borlasie a quatre points"), which they took in the sea, near Amboyna, was found inhabiting an Anatifa, but whether it occurred there accidentally or otherwise we are not informed. The worms are placed under the Zoophytes in the group " Vers Apocles." l In 1838 Dr. George Johnston published further interesting observations on the genus Nemertes? mentioning nine species as occurring on British shores. His general anatomy remains as before, the proboscis being described as the alimentary organ; but he rightly observed that one section of the worms had and another had not stylets in the proboscis ; and accordingly this formed the basis of his classification. He termed the true alimentary chamber the general cavity of the body, though he qualified this description by saying that the lateral cseca were parts of the digestive system. He also observed that the ova were independent of these cseca, and were developed between them and the skin. He, however, thought the mouth in Linens sanguineus a nerve-ganglion, and in the entire group called the ganglia "hearts." He discovered the gregariniform parasites infesting Lineus, though he could not make out their nature. Two plates of very fair figures accompany this paper, from the pencil of his accomplished lady. If M. de Quatrefages found that his species — Folia purpurea, ' Voy. en Sicilie/ ii, p. 122 — approached very closely the Nemertes or Borlasia purpurea of this author, it must have belonged to the Anopla, and have had lateral fissures. W. S. Macleay, in his remarks on the Annelida in Sir R. Murchison's ' Silurian System ' (1839), considered the Nemerteans as aberrant annelids, classifying them along with the Lumbrici and leeches, under the group Apoda, in which the body was without a distinct head or feet. The " Nemertina " were further characterised as aquatic, without eyes or antennae, and with indistinct articulations, which, indeed, were only visible in contraction. Special reference is made to the long vermiform impression in the Cambrian Bocks of Llampeter, which is termed Nemertites Ottivantii, Murchison ; but, so far as I can judge from the description and plate, this is a very doubtful Nemertean. 3 In 1840 Professor E. Grube 4 made some observations on the Nemerteans of the Adriatic, describing several species, two of which are figured, viz. Folia delineata, Delle Chiaje, and Meckelia annulata, Grube. The latter, however, is the Notospermus drepanensis of Huschke ; and, while I am not acquainted with the Borlasia annulata of Ehrenberg, another which he mentions, his Borlasia viridis appears to be allied to Lineus gesserensis. Under Ehrenberg's name Amphiporus, he also refers to what, in all probability, is an example of the Enopla ; but the identity of this form, or the succeeding new eyeless type Akrostomum Stannii, Grube, cannot be determined. This veteran investigator of the annelids and their allies recognised the correct situation of the apertures of the proboscis, mouth, and anus. He observed that the 1 ' Voyage de decouverts de 1/ Astrolabe — sous le commandement de M. J. Dumont D'Urville/ Zoologie, par MM. Quoy et Gaimard, tome quatrieme. Paris, 1833. 2 cc Miscellanea Zoologica," 'Mag. Zool. and Bot./ vol. i, pp. 529 — 538, pis. xvii and xviii. 3 Murchison's ' Silurian System/ vol. ii, p. 699, pi. xxvii, f. 4. 4 'Actinien, Echinodermen und Wiirmer des Adriatischen und Mittelmeers/ pp. 57 — 60, figs. 7, 7 a, 8, and 8a. Konigsberg, 1840. HISTORY OF THE SUBJECT. 19 former had a special sheath, and that it was not connected with the alimentary system, which lay beneath it. During the same year (1841) the valuable 'Descrizione e Notomia Animali Invertebrali/ of Delle Chiaje, was published at Naples, containing further and important observations on the Nemerteans. It has, indeed, been aptly said by the lamented Professor Claparede, that the productions of this author form zoological mines, from which succeeding investigators may quarry out much that is new and rare. In this fine work the author describes the Nemerteans as Annelosi Folici, and considers they offer certain analogies with the leeches, on account of the structure of the alimentary canal, while in the form of their bodies they approach the Planariae. A good description is given of the digestive tract and its "hepatic sacs/ 7 with their varying arrangement, e.g. " pinnatifid-bifurcate " in Folia delineata, and bifid in Folia rosina ; but he falls into the error of regarding the stylet-region of the proboscis in the Enopla as the stomach, and exhibits an imperfect and inverted figure of the region (Tab. 104, fig. 22; vol. v, p. 42) in the Frostoma candidum of Duges. He, however, correctly interpreted the relations of the proboscis to its sheath, the anatomy of the generative organs, and showed an elaborate series of branching transverse arteries between the dorsal and lateral vessels in Folia sifoncello. Many species are described and figured, and for the first time he notices the semi-parasitic habits of Folia tetrqph- t/mlmata, which he found in the respiratory cavity of " Ascidia mammellata" Besides the new species, the descriptions and remarks concerning the old enable us to determine more clearly their nature and relationships. 1 Mr. W. Thompson 3 contributed at this time, under the head of " Additions to the Fauna of Ireland/' an account of some species of Nemerteans, viz. Nemertes gracilis, JV. lactiflorea, Carinella trilineata, and Gordius annulatus. The two latter refer to the same species, viz. Carinella annidata, the one being Dr. Johnston's name, the other Montagu's prior title. In P. Gaimard's c Voyages en Scanclinavie, en Laponie/ 3 &c, considerable attention is devoted to the Nemerteans; but, as only the plates of this work could be procured in the British Museum, its examination is incomplete. However, as none but he who is conversant with the anatomy of the parts can correctly represent in a drawing so minute and complex structure as is found in the proboscis of the Enopla, we may with propriety make a few remarks on these plates. In Plate c, most of the figures, from 1 to 20, seem to pertain to Amphiporus pulcher, and therefore the slit which is shown behind the ganglia in fig. 9 is erroneous. The entire animal is well represented in fig. 20. Figs. 23, 24, and 28 belong to a species resembling Nemertes gracilis. Fig. 1 of Plate d would do for Amphiporus lactifloreus. The whole of Plate e is devoted to the Nemerteans, and in this the structure of the proboscis of the Enopla is detailed. In Plate f a curious form is delineated (figs. 1 and 3), with a spear-shaped snout, a flattened body and widened tail. It appears to be an intermediate type between the Nemerteans and Planarians, and probably is a swimmer. The drawings were made by G. Boeck. (Ersted, 4 in the fourth volume of ' Kroyer's Naturhistorisk Tidsskrift' for 1842-43, wrote 1 ' Descrizione e notomia animali invertebrali della Sicilia citeriore osservati vivi negli anni 1822— 1830/ da S. Delle Chiaje. Napoli, 1841. 2 ' Ann. Nat. Hist./ vol. vii, 1841. p. 482. 3 'Voyages de la Commission Scientifiqne duNord en Scandinavie, en Laponie, au Spitzberg et aux Feroe, sur la corvette La Recherche.' Paris, 1842, &c. 4 Kroyer's ( Naturhistorisk Tidsskrift/ Fierde Bind. Kiobenhavn, 1842—1843. 20 HISTORY OF THE SUBJECT. a paper on Planaria and Nemertes, promulgating those views, which afterwards were given at length in his ' Entwurf/ and w r hich therefore need not be further alluded to here. The Nemer- teans especially are curtly dealt with. H. Rathke, in a very excellent structural chapter in 1843, 1 amended the errors of Dr. Johnston in regard to the mouth in Lineus, and described correctly the digestive system, the position and relations of the proboscis and other points. He was inclined to think the proboscis an organ of touch. In the same year (1843) we have the forerunner of a series of elaborate investigations by M. de Quatrefages, 2 who notified to the Academy that he had found separate sexes in the Nemerteans, with the development respectively of ova and spermatozoa, as in the Annelids. He promised to make known the complete results at a future period. M. Milne Edwards, 3 in reporting on the papers of M. de Quatrefages, in 1844, states, with regard to the Nemerteans, that the latter found that they approached the Annelids in the general distribution of their vascular system, the leeches in the structure of their buccal apparatus, and other points in their organisation ; yet their reproductive organs were analogous to those of many helminths. Their nervous system he compared to that of the " Lingules," and he likened their digestive system (with a csecal termination) to that of the lower helminths and zoophytes. The majority of these homologies are placed on no reliable data. In 1844 A. S. CBrsted contributed a valuable addition to our knowledge of the Nemerteans and allied genera. 4 He classed the Nemerteans as the fourth sub-order {Cestoidina) of his order Apoda, the others in their respective positions being (3) Trematodina (Hirudinea and Planariea), (2) Acanthocephalina (Siphunculacea), and (1) Nematoidina (Gordiea). The sub-order Cestoidina was thus characterised : — " Body linear, rounded rather than flattened, much longer than broad, indistinctly marked by soft annulations, covered with vibratile cilia; distinct muscles, but no true nerves (?). Eyes 2, 4, 6, 8, 10, many or none. Respiratory organs absent or in the form of lateral fissures on the head, which conduct the water to the proximity of the hearts. Complete circulation with two hearts. Digestive tube simple, with the aperture of the mouth situated ventraliy (rarely terminal), and a terminal anus. Sexes separate ; in each a stimulating copulating organ. Testicles and ovaries similar in structure except as regards contents (ova or spermatozoa), numerous, and placed laterally in each segment." The author thus confounded the ganglia with hearts, and hence was led to believe that the cephalic fissures were connected with respiration, in so far as they permitted a closer relation between the sea- water and the contents of the supposed hearts. He had a fair notion of the digestive system, but he misinterpreted the physiology of the proboscis, He arranged the sub-order into two families and eight genera, thus : — 1 ' Beitrage zur Fauna Norwegens,' &c, pp. 231—237. 2 ( Comptes Rendus/ torn, xvii, Dec, 1843, p. 424. s ( Ann. des sc. nat./ 3eme ser., torn, i, pp. 20-21. 4 ' Entwurf einer systematischen und speciellen Beschreibung der Plattwurmer/ &c. Copenhagen, 1844. HISTORY OF THE SUBJECT. 21 I. Fam. Nemertina. Mouth inferior ; anus terminal. (1) Body filiform, equally attenuated at either extremity (head indistinct) ; no respiratory fissures. a. Mouth and ovaria or testicles considerably removed from the snout. Genus 1. Cephalotlirix. b. Mouth and ovaria or testicles not much removed from the snout. Genus 2. Astemma. (2) Body linear, rounded, more or less dilated anteriorly (head distinct), respiratory fissures distinct or none. a. Head distinguished from the body, no respiratory fissures. Genus 3. Borlasia. b. Head not distinguished by a constriction from the rest of the body, respiratory fissures more or less distinct. a. Eyes in groups. Genus 4. Folystemma. /3. Eyes 8 — 16, biserial. Genus 5. Nemertes. y. Eyes 4. Genus 6. Tetr astemma. (3) Body linear-oblong, flattened, equally obtuse at either extremity, respiratory fissures distinct. Genus 7. Cerebratulus. II. Fam. Amphiporina. Aperture of the alimentary tube terminal. Genus 8. Ampldporus. The foregoing classification, being founded on external appearances, could not be expected to stand, the more so as the writer's knowledge of the anatomy of the groups was imperfect. In this author's ' Inaugural Dissertation' 1 (for M.A.), published about the same time, mention is made of the Nemerteans and other marine animals occurring in the Sound — in the various zones, viz. those of the Trochi, Gynmobranchs and Buccini (corresponding with the Littoral, Lamiuarian and Coralline of Eorbes). Little or no additional information on the subject is obtained in this work, mainly on account of the difficulty in recognising his species. He does not note the presence of any in the Laminarian zone. Mr. H. Goodsir, in 1845, made some remarks on certain of the Anopla, viz. Serpentaria fragilis and "Nemertes gracilis" but his observations are characterised by serious structural defects, apparently from too limited observations. 2 He termed the nerve-ganglia and cords the testicles, and this upon the faith of his microscopic researches. He considered the alimentary canal, again, a space common to the respiratory, digestive, and generative systems ; his digestive tract being the proboscis. He thought that in Serpentaria each of the "annuli/' or fragments, contained all the elements of the perfect or original animal, viz. a male and female generative apparatus, the 1 ' De regionibus marinis.' Havnise, 1844. 2 "Descriptions of some Gigantic Forms of Invertebrate Animals from the Coast of Scotland," < Ann. Nat. Hist./ vol. xv, p. 337, pi. 20, f. 1—3. 1845. 22 HISTORY OP THE SUBJECT. cavity common to the generative, digestive, and respiratory functions, and a small dorsal vessel analogous to the intestinal canal of Nemertes. A very interesting brochure on the Nemerteans 1 was contributed by Prof. Kolliker in 1845, a paper, I may remark, which has received too little attention from some continental writers. After indicating the ordinary characters of the group, the author gives a general account of their anatomy, correctly describing the mouth, alimentary canal and anus, the situations of the ganglia and the branches of the lateral nerves. Pie also notes the occurrence of lenses in the eyes of certain species. He is in error, however, when he states that he found two hearts with coloured blood in the head of Nemertes roseus ; and that the proboscis is attached to the wall of the body posteriorly. He observed the stylet-apparatus in several species. His classification of the Nemerteans was founded, somewhat curiously, upon the presence or absence of a sheath to the proboscis, thus : — (1) With the proboscis floating freely in the body-cavity; body ciliated, and smoothly rounded. (2) With a smooth body, and the proboscis confined in a sheath. The latter group he again subdivided into (a) those with a flattened head and lateral furrows, and (b) those having neither a flattened head nor lateral furrows. He describes ten species, most of which are stated to be new. One of these is the strange Nemertes carcinopldla, which he found in an apparently parasitic condition amongst the ova of the common shore-crab. Dr. Johnston, in his 'Index to the British Annelides ' 3 (1846), described a few additional Nemerteans ; but this paper does not require further mention at present, except to observe that he arranged his species under five genera, viz., Borlasia, Zineus, Serpent aria, Meckelia, and Prostoma, which were comprehended by the Sub-family Linince of the Family Planariada, Tribe Nemertinea and Order Apoda. In the same year (1846) M. de Quatrefages published his observations on the Nemerteans, 3 but as a more complete edition of his acute and comprehensive labours (especially as regards figures) subsequently appeared, I shall in the meantime reserve further criticism. A notice of this paper, with an appendix of his classification, was given in Proriep's ( Neue Notizen/ 4 Before the appearance of the foregoing, he had also made some remarks on the proboscidian fluid and circulation of the Nemerteans in his " Note sur le sang des Annelides " in the previous volume (V) of the ' Annales.' This author observes 5 that he had found in the rocks of Solenhofen certain imprints which he considered difficult to attribute to other than Nemerteans. The impressions indicate cylindrical coiled animals, resembling these worms after immersion in alcohol. In the chips of stone from Strasbourg he thought the forms referable to the Genus Borlasia, and especially resembling Zineus marinus. In 1847 the celebrated J. Miiller 6 described and figured Pylidium gyrans, as a larva from Heligoland ; but he did not then find out its connection with the Nemerteans, and indeed was in doubt as to its actual relations. 1 e Verhandlungen der Schweizerischen Naturforschenden geseilschaft bei ihrer Versammlung zu Chur, 1844/ pp., 89—93. Chur, 1845. 2 l Ann. Nat. Hist./ vol. xvi (Supplement), pp. 433—462, pi. xv. 3 " Etudes sur les types inferieurs de rembranchement des anneles. Memoire sur la Famille des Nemertiens" (Nemertea). e Ann. des sc. nat./ 3eme ser., Zool., torn, vi, pp. 173 — 303, pis. viii — xiv. 4 Froriep's ' Neue Notizen/ bd. xxxix, 1846, p. 276. From the < Institut/ No. 660, 26 Aug., 1846. 5 " Soc. Philom. Extr. Proces verb. 1846/' < I/Institut/ xiv, 1846, No. 664, p. 154. 6 < Archiv fur Anat./ 1847, p. 159, taf. vii, f. 1—4. HISTORY OF THE SUBJECT. 23 Dr. Joseph Leidy 1 in the same year (1847) published notes on what appears to be a small freshwater Nemertean (Prostoma marginatum), but his remarks are so indefinite that they are of comparatively little value. Prey and Leuckart next made some excellent observations, in their ' Beitrage ' (1847), on the structure of the Nemerteans. 3 They described the ciliated coating, and pointed out that in these animals the spike-cells (Nesselorgane) present in the Planarise were wanting. They mentioned two muscular coats — an outer longitudinal and an inner circular coat, and that the nerve-trunks lay on the inner side of the latter. The differences in regard to the ganglia of Tetrastemma and Borlasia were shown, the authors demonstrating the shape of the organs in the former by a drawing from Tetrastemma variabilis, of which, however, no additional mention is made. The cephalic sacs in Borlasia {Linens) were thought to be appendages of the ganglia. They did not enter into the structure of the proboscis further than to mention that it has longitudinal and circular muscular fibres ; but they correctly observed that its muscular ribbons were attached to the wall of its sheath, within which sheath a fluid with corpuscles existed. They did not know whether the generative products escaped through the body-wall, or by rupture at the posterior end, as in Arenicola ; and at any rate rupture of the body-wall might ensue for this purpose, for it was not very likely that these products escaped into the body- cavity. Lastly, they compared the Nemerteans with the Flukes and Trematocla. On the whole they correctly appreciated most of the structures detailed by them. The only book of Renier's which I have been able to examine is the posthumous volume on the zoology of the Adriatic, edited by Professor G. Meneghini (1847). 3 In this work the mouth of the Anopla is thought to be the genital opening, and the aperture for the proboscis the mouth. Little attention is paid to the proboscis, and the anatomy of the group in general is much less precise than that of Delle Chiaje. The drawings, also, which accompany the text, are indifferent. Six species are described, only one of which, however, appears to be British, viz., Siphonenteron elegans (Renier), which Meneghini avers is identical with the Valencinia ornata of De Quatrefages, and therefore with the common Carinella annulata of Montagu. E. Blanchard in 1S47 gives a brief but important notice of the structural position of the Nermertina, Ehrenberg. 4 After having shown the principal differences between the Anevormes [Bdellomorpha, Dendroccela, and Trematocla), the Cestoidea and the Plelminths, he contrasts the whole with the Nemerteans. (1) In regard to the Nervous system. He considers the cephalic ganglia of the Nemerteans analogous to the sub-intestinal ganglia of the other annelids ; and states that their disposition quite differs from that of the Anevormes in general, and the Planarians in particular. They have no closer analogy with the Nematoidea in this respect. (2) The Circulatory system, he observes, presents nothing in common. (3) Digestive system. He follows M. de Quatrefages in describing the digestive canal (proboscis) as simple in the Nemerteans, whereas in the Planarians it is branched. (4) Generative system. He agrees with the former author also in regard to his designating the Planarise and Trematoda Turbellaria monoiques, 1 < Proceed. Acad. Nat. Sc. Philadelph./ vol. iii, 1847, pp. 251-2. 2 "Zur Kenntniss vom Bau der Nemertinen/'' ( Beitrage zur Kenntniss Wirb. Thiere/ &c, pp. 71—8 and 150, taf. i, f. 14-16. Braunschweig, 1847. 3 ' Osservazione postume di Zoologica Adriatica del Professore Stefano Andrea Benier/ edited by Prof. G. Meneghini. Venezia, 1847. 4 ' Ann. des sc. nat./ 3eme ser., Zool., torn, viii, pp. 123—127, pi. ix_, f. 5. 24 HISTORY OF THE SUBJECT. while the Nemerteans are Turbettaria dioiques. As regards the separation of the sexes, the Nemerteans approacli the Nematoda, but the configuration of their organs is entirely dissimilar. He hints at other differences in connection with the teguments and form of the body, but adds that in a rigorous examination these are of secondary importance. He concludes with the following remarks : — "Thus having shown how the Nemerteans differ from the Planarians in their entire organization, having exhibited these differences to be profound and characteristic, havino- demonstrated how far they diverge from the Nematoda in essential structure, we arrive at the necessary conclusion that the Nemerteans constitute a group quite unlike those with which Ave have been contrasting them, and that their affinities do not link them more closely to the Nematoda and Anevormes in general than to the Planarians in particular." The author thus rather exaggerated the gulf between the latter and the Nemerteans, being misled by the erroneous observations of M. de Quatrefages on the digestive system. In the same paper M. Blanchard goes on to describe Cerebratidus lij/uricus, one of the Anopla, chiefly with respect to its circulation. He mentions that on account of the delicacy of Nemertean tissues he had to add a small proportion of a salt of mercury to the sea- water, so as to enable him to inject the vessels. He states that the dorsal vessel shows no ramifications, but passes forwards to the cephalic region to unite with the two lateral vessels by the communications around the proboscis and nerve-centres, the latter being bathed by the circulating fluid. He contrasts this arrangement with the observations of M. de Quatrefages, but he was not aware that essential differences exist in this respect between the Anopla and Enopla. He saw trans- verse ramifications between the lateral vessels, and appears to have noticed the network in the oesophageal region, though he speaks of an internal lateral vessel, of whose presence we are unacquainted. He thought that transverse ramifications of the longitudinal vessels existed in all the Nemerteans, for he also observed them in Folia geniculata, Delle Chiaje, and in a Valencinia of undetermined species ; and agreed with M. de Quatrefages as to the presence of proper walls to the vessels. The Nemerteans, therefore, have a vascular network comparable with that in the Anevormes, presenting nevertheless differences in anatomical disposition. The circulatory apparatus in these worms is perhaps more complete than that of the Aporocephales (Planarians) or the Trematoda ; for the dorsal vessel seems to carry the blood forwards, and the lateral backwards, though the oscillations are irregular. He would place the Nemerteans, consequently, in a division adjoining the Anevormes, both on this account and the higher development of their nervous system. Yon Siebold, 1 in 1848, took the bold step of severing the Nemerteans from the Planarians by the intervention of the Rotatoria ; and though we would not approve of such disjunction, the soundness of his decision in separating them from the Helminths can scarcely be questioned. He arranged them as the first Order of the Ringed worms : — Order I. Apodes. — Body without bristles. Sub-order 1. Nemertini. — Body posteriorly without an anus (Ausangeorgane) ; head often with lateral respiratory fissures. His information is derived from Rathke and other observers. This author subsequently gave abstracts of various papers on the Nemerteans in the c Archiv fur Naturgeschichte.' 2 1 c Lehrbuch der Yergleichenden Anatomie/ von Y. Siebold u. Stannius. Berlin, 1848. 2 ' Archiv fur Naturgeschichte/ 1850, p. 382, &c. HISTORY OF THE SUBJECT. 25 In a subsequent paper in the e Annates' for 1849/ M. Blanchard adopts the general anatomy of the Nemerteans given by M. de Quatrefages, and agrees with the latter in thinking that the affinities of the group lie rather with the Helminths than the Planarians, on account of the erroneous view with regard to the csecal nature of the digestive tract. Moreover, in all the known Aporocephales (Planarians) the sexes are united in one individual, whereas in the Nemerteans they are separate. The latter likewise have a veritable oesophageal collar, which is wanting in the former. He proposes the name Ajploccela as distinctive of the characters of the group (the simplicity of their intestine), and thinks that the title Nemerteans should be applied only to a tribe or family. No fresh observations are produced in this paper, and the errors in regard to the digestive system are rendered more conspicuous. M. cle Quatrefages at this time published his valuable and extensive observations, begun at the lies Chauseg in 1841, and carried on subsequently at St. Malo, St. Vaast-la-Hougue, Brehat, Sicily, &c, on the anatomy and zoology of the order, with additional coloured plates, in the second volume of the c Voyage en Sicilie/ the joint work of Milne Edwards, Blanchard, and himself. 3 The author, after giving an account of the history of the group, proceeds to treat of their characteristics and classification thus : — ■ Nemertians. — Nervous system distinct, composed of two lateral lobes united above by a slender commissure, beneath by a broad sub-cesophageal commissure, and giving origin to two isolated longitudinal nervous trunks. Circulatory system shut; circulation complete. Alimentary tube simple ; proboscis exsertile ; intestine csecal. Sexes separate ; reproductive organs placed at the sides of the abdominal cavity, and occurring throughout the entire length of the body. Surface quite smooth, covered with vibratile cilia. He distinguishes his six genera as follows : NEMERTIANS Nerve-trunks entirely- lateral in position f Month subterminal, inferior Valeneinia. f Very flat .... Borlasia. Body very long ~{ l^ More or less rounded Nemertes. Mouth terminal < C Very proteiform . . Polia. __ Body short -{ (^ Form less variable . Cerebratulus. Nerve-trunks sublateral (Erstedia. This arrangement, from the inaccuracy and limited extent of his observations in regard to the position of the nerve-trunks in the various groups, is useless ; and the subordination into genera rests upon an equally unreliable basis. Not a few in his list of thirty-two species are forms previously known, though described as new worms — several more than once ; and it is to be remarked that some of the very common specimens, e.g. Lineus gesserensis and L. sanguineus, are not mentioned, or else are so described as to be unrecognisable. He characterises the animals as chiefly nocturnal in their habits, with the exception of Polia 1 "Recherches sur T organisation des Vers/' 'Ann. des sc. nat./ 3me ser., Zool., torn, xii, pp. 28—35. 2 f Recherches Anatomiques et Zoologiques faites pendant un Voyage sur les cotes de la Sicilie et sur les divers points du littoral de la France/ par MM. H. Milne Edwards, A. de Quatrefages, et Emile Blanchard ; deuxieme partie, pp. 85—220 ; pis. ix— xxiv, par A. de Quatrefages. Paris, 1849. 4 26 HISTORY OP THE SUBJECT. mandilla (Amphiporus lactifloreus) 9 and notices the ease with which the latter species can be kept in confinement. He remarks that his captive specimens thrust out their proboscides and stylets, probably for the purpose of capturing the Infusoria that swarmed in his vessels. Moreover, he also saw a little Folia attack a Cyclops. I am, however, of opinion that all the interesting motions he witnessed in such cases were accidental, and not due to predaceous habits. There is no wonder he found no debris of food in the proboscis, since this is not at all an alimentary organ. He observed their tolerance of pressure between glasses under the microscope, and the fatal result of immersion in fresh water, but gave no remarks of importance in regard to the reproduction of lost parts. In the second division of the memoir he discourses on the anatomy of the Nemerteans, and it may suffice at present only to allude to his results. He was certainly one of the first to anatomise the animals in a truly scientific manner, and his drawings of structure, though scarcely accurate, are very beautiful. He is wrong in averring that a fibrous layer exists in connection with the dermal tissues ; his muscular coats of the body-wall (external longitudinal and internal circular) agree neither with the arrangement in the Enopla nor with that in the Anopla ; the description of the general cavity of the body is obscure and misleading, and he located the corpuscular fluid there instead of in the proboscidian sheath; he altogether went astray in his interpretation of the proboscis, which he took for a digestive system (dividing it into proboscis, oesophagus, and intestine), and even his anatomy of the organ (proboscis), as it exists, is erroneous. He only examined the circulation in the Enopla. He confounded the generative with the true digestive system, and, indeed, fell behind the early observations of Duges in this respect. In the third part he treats of the analogies and zoological affinities of the Nemerteans, which he regarded as the degraded representatives of a more elevated type. While descanting on their general structure and relations, he observes that the organic apparatus presents the same complication in the large Linens as in the minute Tetrastemma, but the elements (of such structure) undergo a degradation in the latter ; a statement which is somewhat obscure, since the types of the forms differ entirely. Eor the same reason his comparison of the integuments of Borlasia anylice, Nemertes balmea, and Folia filum, is fallacious. He points out that no part of the vascular system is in immediate contact with the respiratory surface, while the vessels are always plunged in the liquid of the abdominal cavity, which he therefore considers as the active agent in nutrition. He compares this corpuscular fluid to the chyle, for, he says, into it the products of digestion are transmitted directly from the alimentary tube (proboscis) ; further, it resembles the lymph, because it receives the internal products of the organism ; finally, it is like the blood, because it is the direct agent in the nutrition of the eggs, and, since it bathes the muscular coats of the body, it is also charged with their nourishment. With so formidable an array of functions for this (proboscidian) fluid, it is no wonder he asks — whether the contents of the blood-vessels merit the name of blood ? tie was not aware, however, that this fluid is enclosed within a special muscular sheath, and nowhere comes in contact either with blood-vessel, body-wall, or ovaries. With regard to systematic arrangement, M. cle Quatrefages retains the class Turbellaria of Prof. Ehrenberg, exclusive of Gordius and Nais, and which he would apparently link on to the Trematoda of M. Milne Edwards. He does not altogether place the Planaria?, and Distomse together, but mentions that if further researches should reveal the same vascular apparatus in the HISTORY OF THE SUBJECT. 27 former as M. Blanchard lias found in the latter, then there is no obstacle to their sequence. He regarded the Rliabdoccela as intermediate between the Planarians and Nemerteans ; resembling the former by the general disposition of their genital organs, the union of the sexes, and the organs of the senses; the latter by the simplicity of the digestive canal and the disposition of the vascular and nervous systems. He places the Nemerteans under the second sub-class of the Turbellaria, for which he advances the term Miocmla} thus : Class. Sub-classes. Orders. f f Intestine ramified . . . Dendroccela. | Turbellaria "Monoiques" *\ TURBELLARIA ■{ L Intestine simple . . . Bhabdoccela. [^ Turbellaria "Dioiques" Mioc beneath the basement-layer of the cutis (which in the fragmentary specimen was almost absent), is a coat of circular fibres (e). Within the latter is a very powerful layer of longitudinal fibres ( are probably associated with the ovaries. A trace of the excretory tubes appears at the oral sucker. In a specimen of Cephalothrix filiformis several examples of an Opalina occurred, but such on the whole seem rare in the Scottish Nemerteans. V. — Classification. As might have been expected in the case of animals whose anatomical structure was either unknown or much misunderstood, great diversity has prevailed in the classification of the Nemerteans. The early writers, such as 0. P. Miiller, 0. Pabricius, and Gmelin generally placed them amongst the Helminths or intestinal worms (under the genus Planaria) ; and even Cuvier associated them with the same group. Others, such as Oken and Fleming, ranged them near Gordius and Lumbricus. De Blainville, again, established the family Teretularia for their reception, the title being^founded on the external appearance of the animals. Ehrenberg next 1 c Der K. Gesellsch. der Wissensch. vorgelegt, am 4, Jaimar, 1868.' CLASSIFICATION. 131 constituted the class Phytozoa Turbellaria for them and the Planarians, as described in detail in the 'History/ Other authors, such as Quoy, Gaimard and Macleay, placed them under the group " Vers Apodes," without any definite basis of classification. Dr. G. Johnston first pointed out the important fact, that one group of the Nemerteans had and that the other had not stylets, and thus he has partly the credit of the classification promulgated by Max Schultze. They constituted, again, the Annelosi Polici of Delle Chiaje ; and the fourth sub-order (Cestoi- dina) of the Apoda of (Ersted. Kolliker's division of the Nemerteans, according to the presence or absence of a sheath for the proboscis, rests upon a misunderstanding, as the sheath is present in all. De Quatrefages adopted Ehrenberg's classification with amendments, placing the Nemerteans under the third order Mioccela, and founding his subordinate groups on the position (lateral or sub-lateral) of the nerve-trunks, and the situation of the mouth. Von Siebold ranged them as the first order of his ringed worms (Apodes), and separated them from the Planarians by the intervention of the Rotatoria. Blanchard formed the term Aploccela for the group, and thought the term Nemerteans should be restricted to a tribe or family, but the author was mis- led as regards the true alimentary organ. Diesing's arrangement is sufficiently alluded to in the Zoography, and rests on no secure basis. Girard wished to class them with the mollusks, an idea which found no other supporter. Max Schultze divided Ehrenberg's class Turbellaria into the sub-classes Aprocta and Proctucha, the Nemerteans being grouped under the latter. This author afterwards split the order Nemertinea into the Enopla and Anopla, according to the armed or unarmed condition of the proboscis. Stimpson's classification was based on the presence or absence of the ventral fissure, and other external characters, and therefore failed where it was most wanted. The same may be said of Schmarda's arrangement, where the characters of the sub-orders are founded on the "respiratory" fissures. Keferstein establishes the primary divi- sion of the order on the same basis as Max Schultze, but enters much more minutely into the subject. His families rest on characters derived from the fissures of the head and the arrange- ment of the ganglia. There is little new matter in the classification adopted in the Catalogue of the British Museum. In his ' Handbuch der Zoologie,' J. V. Carus arranges the Nemerteans as the first division (Turbellaria) of his fifth class (Platyelminthes) of the Vermes, the second division being formed by the Trematoda, to which he states the Planarians lead, and the third division by the Cestodes. Similar views prevail in several text-books of zoology. The inquiry into the structure of the British Nemerteans rendered it apparent that consi- derable modifications of the existing schemes would be requisite, yet great care has been taken to interfere only where absolutely necessary. With these brief remarks on the chief classifications already in existence, I may now proceed to explain the appended scheme. 132 CLASSIFICATION. Order. Sub-Orders, 1 ENOPLA Class Turbellaria. 1 Families. Sub- Families. * Amphiporid^e '< Amphiporince Nemertinae . ANOPLA Line idte Carinellid^e { Cephalothricid^e Genera. I. Amphiporus. II. Tetrastemma. III. Prosorhochmus. IV. Nemertes. V. Lineus. VI. Borlasia. VII. Cerebratulus. VIII. Micrura. IX. Meckelia. X. Carinella. XI. Valencinia. XII. Cephalothrix. The characters of the order Nemertinea may be concisely described as follows : — Worms with more or less elongated, soft, ciliated bodies ; nervous system composed of two conspicuous ganglia connected by a double commissure and two main lateral trunks ; digestive system a ciliated canal with two apertures ; circulatory system consisting of a series of closed contractile vessels. The proboscis forms the most typical organ in the group, is surrounded by a special muscular sheath, within which it glides in a corpuscular fluid, and passes in front between the commis- sures of the ganglia, while the digestive tract is placed inferiorly. Sexes separate in the majority, oviparous or ovo-viviparous. The order may most naturally be divided into two great sub-orders, distinguished from each other by the presence or absence of stylets in the proboscis or typical organ of the group ; the former being called after Max Schultze (but with amended characters) Enopla, 2 and the latter Anopla. 3 The sub-order Enopla is characterised further by the globular and somewhat double nature of the nerve-ganglia, and by the fact that the lateral nerve-trunks are placed within the proper muscular walls of the body. The mouth, moreover, opens on the ventral surface of the snout in front of the commissures of the ganglia. The blood-vessels are more differentiated than in the Anopla. The young, so far as known, do not undergo any noteworthy metamorphosis in their growth. In the Enopla there exist one great group and a subordinate one, which latter, however, retains so many of the characters of the former that it conveniently forms a sub-family. In the chief division (Amphiporin;e) of the family Amphiporld;e the animals have two muscular layers in the body- wall, an external circular and an internal longitudinal ; the proboscis is composed of three divisions, anterior, middle, and posterior, the former having in the typical species seven coats, viz. external elastic, external longitudinal, reticulated, inner longitudinal, circular, basement and 1 Turbella, a little bustle or turmoil, referring to the ciliated integument of the animals. 2 ri and"07rXa, arms. s a an d"0-Xa, without arms. CLASSIFICATION. 133 glandular layers. The middle region bears the stylets, and the posterior forms a long sac with two muscular coats, external circular and internal longitudinal. There are three great longitudinal vascular trunks, two lateral and one median, besides a cephalic arch. The cephalic sacs or glands are accompanied by long tubes or ducts. The animals as a whole have comparatively short and thick bodies, with proportionally large proboscides. The sub-family Nemertinje has the characters of the foregoing, with the exception of the last, since they possess more or less elongated bodies, and proportionally short proboscides. It is right to mention that I have not been able to procure a specimen of Prorhynchus, but from the diminished size of the proboscis and other particulars, it would seem to follow closely on Nemertes carcinophila, Kolliker, one of the species in the previous sub-family. The sab-order Anopla, again, is further distinguished by having the nerve-trunks generally placed between the muscular layers of the body-wall. The mouth opens on the ventral surface behind the commissures of the ganglia. The blood-vessels are somewhat less differentiated than in the Enopla. The young in the most conspicuous families undergo a remarkable meta- morphosis. This second sub-order has several families, the most typical of which is that of the Lineim;,, characterized by the more or less elongated shape of the ganglia (the arrangement with the commissures having the form of a horseshoe). The muscular covering of the body is composed of three layers, external longitudinal, circular, and internal longitudinal. The proboscis is fur- nished with five coats, viz. external elastic, external longitudinal and accessory band, circular, basement and glandular layers. The circulatory system consists of three great longitudinal trunks, two lateral and a dorsal, which frequently anastomose by transverse branches, form a rete mimbile in the oesophageal region, and unite in lacunae behind the ganglia. The head has a deep lateral fissure on each side in connection with the cephalic sac, which is rounded, and devoid of long tubes or ducts posteriorly. The curious specimen from Herm forms the type of a group that would perhaps require to be raised to the rank of a sub-family, but as no more than one specimen has yet been found, it is thought advisable to postpone this at present, and distinguish it only generically. In this animal the proboscis is extremely slender in proportion to the bulk of the body, and differs from the typical Lineup in having no accessory band cut from the longitudinal layer. Externally the organ has an elastic investment, then a longitudinal, a thin circular and a glandular coat. The reddish colour of the muscles of this species, and the tinted circulation, are likewise quite characteristic. A more distinct sub-family of the Lineidce than the foregoing, perhaps, might be formed by Meckelia, but for the present generic separation will suffice. The anatomy of the body-wall agrees with Linens, but there are no cephalic fissures. The structure of the proboscis is also peculiar, for there is externally no distinct superficial layer, the outer coat consisting of spiral muscular fibres closely interwoven, within which lies a longitudinal layer, with the glandular coat on its inner surface. The CARiNELLiDiE are a very characteristic family. The general structure of the nervous system agrees with Lineus, but the lateral nerve-trunks are placed between the basement-layer and the circular (external) muscular coat of the body-wall, that is, quite without the two muscular layers in the typical form, and just within the circumference of the outer muscular layer in the other. There are no cephalic fissures. The circulatory system consists of two great 134 SYNOPSIS OP FAMILIES, GENERA, AND SPECIES. lateral trunks. The proboscis has externally a double elastic layer, a thick longitudinal coat, and lastly, a glandular layer. The family of the Cejphalothricidm deviates still more from the typical group. The arrange- ment of the ganglia differs, and the commissures are separated by a considerable antero-posterior interval. The lateral nerve-trunks lie between the longitudinal muscular coat and an isolated inner band of fibres having the same direction. The proboscis is supplied with acicular papillae, and seems to have an external circular and internal longitudinal layer. The snout is devoid of fissures. The circulatory system is composed of two great longitudinal trunks, whose contents communicate behind the ganglia and at the tail. Oviparous ; the young undergoing no distinct metamorphosis, though they have eyes, whereas the complete animal is generally eyeless. VI.— SYNOPSIS OP FAMILIES, GENERA, AND SPECIES. Order.— NEMERTINEA. Sub- Order.— ENOPLA. Proboscis furnished with stylets. Fam. I. AMPHiPORiDiE. — Ganglia rather rounded. Lateral nerves within the muscular layers of the body-wall. Mouth opening in front of the ganglionic commissures. Sub-Family, AMPHIPORIN^. Proboscis proportionally large. Genus I. Amphiporus, Ehrenberg. — Eyes more or less numerous, but never arranged in a square. Body rather short, sometimes flattened. 1. A. lactifloreus, Johnston. — Eyes grouped in two series on each side; body white, roseate, or greyish. 2. A. pulcher, Johnston. — Eyes well defined and numerous, irregularly grouped on each side, A central reserve-stylet in the proboscis. Cephalic furrows slightly branched. 3. A. spectabilis, De Quatrefages. — Head spathulate, peculiarly narrowed posteriorly. Eyes forming two long rows on each side. Cephalic furrows conspicuously branched. Longitudinally striped with brown on the dorsum. 4. A. hastatus, n. s. — Snout short and hastate, with a grooved dorsal ridge. Eyes indistinct. Brownish-yellow, with white grains on the snout. 5. A. bioculatus, n. s. — Snout acutely pointed, with a cephalic furrow — forming an angle directed forward on the dorsum — at its posterior boundary. Two eyes at the tip of the snout. SYNOPSIS OF FAMILIES, GENEBA, AND SPECIES. 135 Genus II. Tetrastemma, Ehrenberg. — Eyes four; arranged so as to indicate a square or oblong. 1. T. melanocep/iala, Johnston. — A large black pigment-mass between the anterior and pos- terior pairs of eyes. Marginal stylet-sacs placed somewhat in advance of the central apparatus. 2. T.Bobertiance, n. s. — Head furnished with a brown collar, which sometimes hides the posterior (smaller) pair of eyes. Body longitudinally striped with two brown and a median white line. 3. T. Candida, 0. F. Miiller. — Head flattened, wider than the rest of the body ; eyes distinct. Stylets large. Pale yellow, greenish or reddish brown. 4. T. vermicula, De Quatrefages. — A longitudinal dark patch between (and connecting) the eyes of the respective sides. 5. T.flavida, Ehrenberg. — Head not wider than the rest of the body. Anterior and posterior pairs of eyes widely separated. 6. T. dorsalis, Abildgaard. — Body short, thick and rounded ; speckled with yellow and brown j sometimes with a pale median stripe on the dorsum. Genus III. Prosorhochmus, Keferstein. — Eyes four ; not forming a square. Snout dimpled and furnished with a transverse superior lobe. Ovo-viviparous. 1. P. Claparedii, Keferstein. — Snout blunt; eyes placed far back, the space between the anterior pair being widest. Yellowish. Sub-Family, NEMERTIN^. Proboscis proportionally small. Genus IV. Nemertes, Cuvier. — Body more or less elongated, while the proboscis is very much diminished, the anterior region especially being shortened so as to cause the stylets to approach the ganglia. 1. N. gracilis, Johnston. — Eyes numerous. Snout broader than the rest of the body. Central stylet with a very long basal apparatus. Greenish or olive. 2. If. Neesii, (Ersted. — Eyes numerous. Stylets short and grooved. Streaked on the dorsum with purplish brown. 3. If. carcinophila, Kolliker. — Eyes two. No marginal stylet-sacs. Body pinkish. 136 SYNOPSIS OP FAMILIES, GENERA, AND SPECIES. Sub-Order.— ANOPLA. Proboscis without stylets. Family II. Lineim. — Ganglia elongated. Muscular layers of the body-wall three in number, viz. external longitudinal, circular, and internal longitudinal. Proboscis furnished with five coats, viz. external elastic, longitudinal and accessory bands, circular, basement and glandular layers. Snout with a deep lateral fissure on each side. Genus V. Lineus, Sowerby. — Body more or less elongated, rounded or somewhat flattened, and tapered posteriorly. Head distinct, spathulate, and generally truncate in front. Eyes numerous, arranged along the sides of the snout anteriorly ; rarely absent. Mouth in the form of a conspicuous longitudinal slit on the ventral surface. Other characters as in the Family. 1. Z. marinus, Montagu. — Eyes numerous, deeply set in a marginal row on each side of the snout, Of a dull olive or blackish colour, more or less distinctly striped longitudinally. 2. Z. gesserensis, 0. F. Muller.— Eyes numerous, marginal. Snout distinctly wider than the rest of the body. Greenish-olive or reddish-brown. 3. Z. sanguineus, Jens Rathke.— Eyes more regularly arranged than in the former; snout narrower. Body more elongated, and of a reddish or reddish-brown hue. Regenerates easily. 4. Z. lacteus, Montagu, MS.— Snout similar to the foregoing, but the mouth is separated from the ganglia by a much longer interval. Body reddish anteriorly, pale posteriorly. 5. Z. bilineatus, Delle Chiaje. — Snout rounded anteriorly; eyeless. Body of a pale brown or dull pinkish colour, with a white stripe on each side of a dorsal median line. Gems VI. Borlasia, Oken. — Characters as in Lineus, but the proboscis is extremely slender, and has only four coats, viz. elastic, longitudinal, circular, and glandular. 1. B. Elizabeths, n. s. — Snout pointed anteriorly; eyeless. Body generally contracted into a rugose mass posteriorly. Head pale, faintly streaked with greenish brown. Body marked with deep madder-brown. Genus VII. Ceuebratulus, Renier.— Body generally flattened, and thinned at the margins. Eyes in the usual position, but obscure. Proboscis with a cross of fibres at each pole in transverse section. 1. C. angulatus, 0. F. Muller. — Snout somewhat pointed. Body much flattened ; brownish. HOMOLOGIES. 137 Genus VIII. Micrura, Ehrenberg.— Characters as in Linens, with the addition of a soft, filiform caudal process, capable of attachment. 1. M.fu8ca,Ti. s. — Eyes small, from four to eight on each side; body much flattened and thinned at the edges ; caudal process often moniliform ; colour pale brown or yellowish, speckled with brownish grains, especially in front. 2. M.fasciolata, Ehrenberg. — Eyes marginal, placed towards the anterior part of the snout ; body various shades of brown, generally barred with white belts. 3. M. purpurea, Dalyell. — Eyeless. A bright yellow patch at the tip of the snout; body of a uniform rich dark brown colour. 4. M. aurantiaca, Grube. — Eyeless. A white patch at the tip of the snout ; body rounded and of a fine brick-reel hue. Genus IX. Meckelia, Leuckart. — Structure of the rounded body-wall as in Lineus. Cephalic fissures absent. Proboscis furnished with only three coats, viz. external spiral, longitu- dinal, and glandular. 1. M> asulcata, n. s. — Eyeless. Body thick and round; of a uniform pinkish hue. Family III. Carinellid.e. — Lateral nerves placed between the basement-layer of the cutis and the external (circular) muscular coat of the body- wall, or in the substance of the longitudinal layer close to the circular. There are only two muscular coats. The pro- boscis has four layers, viz. external elastic, circular, longitudinal and glandular. Genus X. Carinella, Johnston. — Body elongated, tapering from the front backwards. Snout wider than the rest of the body, bluntly rounded in front ; mouth sometimes small. 1. C. annulata, Montagu. — Eyeless, with a white patch on the snout ; body round, of a rich red colour, striped longitudinally and banded across at somewhat regular intervals with white belts. Rarely pinkish throughout. 2. C. linearis, Montagu, MS. — Eyeless. Head spathulate, somewhat pointed in front; milk- white. Genus XL Valencinia, De Quatrefages. — Structure of the proboscis as in Carinella. The lateral nerves lie in the longitudinal muscular coat of the body-wall. The snout is shaped as in Lineus lacteus, and furnished with a row of eyes on each side. The mouth forms a distinct fissure a considerable distance behind the ganglia. 1. Valencinia lineformis, n. s. — Roseate in front, yellowish white posteriorly. Family IV. CephalothriciDjE. — Commissures of the ganglia separated by a distinct antero- posterior interval. Lateral nerves placed between the longitudinal muscular coat and an 18 138 HOMOLOGIES. isolated inner band of fibres. Proboscis has an external circular (or elastic), an internal longitudinal, and a glandular layer supplied with acicular papillae. Genus XII. Cephalothrix, OErsted. — Head nearly cylindrical, slightly tapered in front ; eyeless, or with a few obscure pigment-specks. Cephalic fissures and sacs absent. 1. C. linearis, Jens Rathke. — Body extremely attenuate. Of a pale yellowish or skin-colour, often with reddish grains towards the tip of the snout. VII. — Homologies. The majority of the early investigators of the Nemerteans correctly associated them with the Planarians, and generally linked them to the Intestinal worms, Lumhrici, or Gordii, as a single genus — Planaria. Other animals, however, which had no affinity either in form or structure, were grouped with them, often in a perplexing manner. Lamarck thought the Nemerteans approached the leeches, while Cuvier amalgamated them with his Entozoa. Ehrenberg, again, while he took the wise step of forming a class {Turbellaria) for them and the Planarians, does not seem to have had a very definite idea of their relationship to other animals, and, more especially, to other Vermes. This author's class appears to me to be a very natural one, and though a considerable hiatus exists between the Planarians and Nemerteans, as will afterwards be pointed out, the gap is very much less than that which separates the Turbellaria from the other groups of animals, and especially from the Trematoda. Delle Chiaje considered they had certain homologies with the leeches, on account of the structure of the " alimentary canal/' but that in regard to the form of their bodies they approached the Planarians. Duges, De Quatrefages, and Frey and Leuckart, were inclined to link on the Turbellaria to the Trematoda, though the second author was of opinion that further researches as to the vascular system of the Planarians were needed to render the relationship distinct. In his report on the memoirs of De Quatrefages, M. Milne-Edwards observed that the Nemerteans approached the Annelids by the general disposition of their vascular system, the leeches by the structure of their buccal system and other parts of their organization, but that their reproductive and digestive organs were homologous with those of the helminths. He compared their nervous system to that of the " Lingules." The statement with regard to the digestive system, however, is founded on erroneous observations, since both reviewer and reviewed mistook the proboscis for the alimentary canal, and thus instead of the latter forming a blind tube, it is open at both ends, and very different from that of any helminth. (Ersted, again, placed them after the Leeches, while M. Blanchard, misled by the observations of M. de Quatrefages, exaggerated the gulf between the Nemerteans and the Planarians so much that he thought their affinities lay rather with the helminths than with the latter. Dr. Thomas Williams considered his closed alimentary chamber (digestive canal) the homologue of the spongy mass in Taenia, but this is open to doubt. He HOMOLOGIES. 139 also drew a resemblance between the Nemertean reproductive organs and the " ovarian or female series " in the leeches. So struck was this author by the differences between the Nemerfceans and the Planarians (which he affirmed were only allied by the ciliated integument), that he proposed to separate the former from the " true Turbellaria" under the name of the Cestoid Annelids. I think, however, that we are scarcely warranted on structural grounds in making so radical a change. Amongst recent writers, Dr. Cobbold, it appears to me on somewhat insufficient data, has grouped the Turbellaria under the class Helmintha, which he conveniently widens to allow them, as he thinks, to be near their allies the Trematoda. But it is to be observed that, while the Planarians perhaps do approach the Trematoda, the Nemerteans diverge so much that the relationship is very difficult to discover. The outline of the ovate and flattened Planarian somewhat resembles that of the Distomes and their allies ; but there is nearly as much similitude between the former and an Elgsia or Limaponiia, or again between a Sagitta and a Pish. The cutaneous texture of a Trematode (for instance, Fasciola liepatica), according to Dr. Cobbold, is covered with minute chitinous processes or spines, and is composed of an outer transparent epidermis, and an inner fibrous cutis. In the Planarian, on the other hand, we have the ciliated epidermis and the characteristic soft, cellular cutis, so conspicuous for its secretion and its tendency to diffiuence under examination. " In the Fasciola the next layer is composed of numerous bands of muscular fibres, in which four separate groups may be recognized more or less distinctly. They have been described as so many layers, but they are not readily separated from one another." Such is the description this author gives of the muscular system. In the Planarian the muscular layers form distinct coats, which cannot be confounded, and moreover they seem to be formed after a different type. I would, however, remark that in a transverse section of Ccmvpula oblonga, Cobbold, a Distome from the bile-ducts of the Porpoise, there is below the chitinous cutis a delicate layer of circular fibres — slightly indented by the bulbs of the chitinous spines, and having a thin coat of longitudinal fibres underneath. Such therefore agrees with what Prof. Owen found in Distoma clavatum. Dr. Cobbold also speaks of soft parenchymatous tissue filling up the general cavity of the Fluke, and though not averse to such a disposition as a proof of further divergence of type, yet in the Distome just mentioned (Campula oblong ci) transverse and longitudinal sections show a complex arrangement of fibres and cells — only inferior to the more differentiated muscular bands, fibrous tissue and cells, the presence of which in the Planarian is so intimately connected with the physiology of the parts. In the case of the digestive system there is apparently some analogy in form, since both Planarians and Plukes have branched, csecal, alimentary organs, but then Vortex, and the whole of the Nemerteans to which the Planaria Dendroccela are linked, deviate in a still greater degree from the parasites. The oral sucker of the fluke has little homology with the protrusible proboscis of the Planarian, and still less with the mouth of Vortex or the Nemertean. Moreover, the microscopic structure of the digestive ramifications of the Planarian agrees very closely with the same organ in the Nemertean, while it differs entirely from that of the fluke, with its " fibrous wall" and " columnar cellules," or, as I should call them, papillae. Such differences probably depend much on the divergent character of the food. Dr. Ehlers, in his arrangement of Worms, separates the Nemertinea (Class V) from the Turbellaria, Ehrenberg, s. str. (Class IV), and interpolates the round worms and Gephyrea between them and the Annelida. It is doubtful if the Gephyrea are a higher type than the Nemertinea, and they certainly do not approach the true Annelida 140 HOMOLOGIES. more closely. Prof. Huxley, again, groups the Nemerteans amongst the Scolecida, charac- terising the " water- vascular system" of this heterogeneous class as having ciliated tubes throughout. This, of course, cannot apply to the Nemerteans, and not even to the Planarians. The branched water-vascular system (which Prof. Owen regards as excretory) of the Pluke has no counterpart in the Planarian, and cannot be supposed to be closely allied to the vessels of the Nemerteans. A decided difference is apparent in regard to the nervous system, which is much more conspicuous in the Planarian than the Pluke ; indeed, observers who are familiar enough with other parts of the structure of some species of the latter have not seen such at all. It is described by Prof. Owen in Distoma clavatum as in the form of a pair of cephalic ganglia connected together by a thin commissural filament above the pharynx, and giving off two main lateral nerves. Two much larger ganglia occur in the Planarians, connected by a broad commissure, and the branches to the surrounding parts are more distinctly arranged. Prof. Owen states that pigment-specks, called "eye-specks," are present in the Polystoma of the urinary bladder of the toad and frog, as in the locomotive ciliated larvae of most Trematoda ; but as a whole the special organs of sense are much more highly developed in the Planarian. In regard to reproduction there is some resemblance between the groups, both Flukes and Planarians having male and female organs developed in the same animal. Both are oviparous, and the ova produce ciliated embryos; but the young of the fluke soon lose the cilia, and represent only the first stage of a series of metamorphoses which occur before reaching maturity. The embryo of the Planarian, while, perhaps, undergoing metamorphoses in some cases, comes out of the egg in others nearly in the same form as the adult, and never loses its cilia at any period. Besides, too much reliance cannot be placed on this common metamorphosis, for we may as readily arrange the Echinoderms with the Nemerteans on account of the Pilidium- development, as class the Planarians with the Trematoda on this account. The habits and motions of the two groups, it is well known, are widely different. Having thus indicated some of the chief points of divergence and affinity between the Planarians and the Trematoda, we may now examine the relationship between the former and the animals with which we have more particularly to deal, viz. the Nemerteans. In regard to the general structure of the cutaneous textures there is much resemblance. Both have a ciliated cuticle, a soft, easily disintegrated cutis, chiefly composed of cells and areolae, and capable of secreting abundant mucus. In the skin of no Nemertean, however, have I seen any urticating or " stabformigen" bodies. The muscular coverings are similarly grouped into definite layers of longitudinal and circular fibres. On the ventral surface of the Planarian, however, we sometimes have an inner layer not represented on the dorsum, a fact that has been overlooked by Professor Keferstein in his recent valuable remarks on the Planarians. 1 The digestive systems, though apparently divergent, are really allied in an intimate manner. The mouth in the Planarians follows the habit of the organ in the Anopla in opening behind the ganglia, but more posterior in position. The large proboscis in the Planarians is probably homo- logous with the oesophageal division of the digestive tract in the Nemerteans ; and in the typical Idneidce amongst the latter the oesophageal region is frequently everted during feeding in the form 1 f Beitriige zur Anat. u. Entwicklung. einiger Seeplanarien/ &c, 1868. HOMOLOGIES. 141 of a rugose prehensile organ. The ramose nature of the digestive caeca, which are all connected with a central cavity, is but a modification of the pinnate organ in the Nemerteans, the pinnae in certain of the latter being even slightly branched. Moreover, the microscopic structure of the walls of this system (with perhaps the exception of the inner coating of cilia) is similar, and in both cases appears to combine the biliary with the intestinal system proper. In the Planarians, however, there is no anus, while such is present in all the Nemerteans. The system as a whole shows a higher degree of advancement in the latter, the connecting links apparently occurring in the Anopla, whose mouth opens behind the ganglia as in the Planarians. The nervous systems of the groups are also related. The cephalic ganglia are two in each, but those of the Nemerteans are connected by two commissures, a dorsal and ventral, whereas in the Planarians there is only a single large commissural band, which is homologous with the ventral of the Nemerteans. The separation of the ganglia in the latter is more distinct than in the former, though this does not necessarily imply a higher type ; indeed concentration of nervous matter is generally considered to be so. The senses in the groups are somewhat similar ; over the entire surface touch is as exquisite in the one as in the other ; the organs of vision consist of two well-marked series in each, viz. those with and those without apparent lenses or capsules, so that the pre-eminence in this respect is hard to adjudge, though I am inclined to give it to the Nemerteans. There is some doubt about auditory corpuscles or otolites in either group, though Grafe and Keferstein mention their occurrence in certain Nemerteans. I have never seen such. The function of the special cephalic pits and neighbouring glands in the same animals is involved in obscurity. They may represent the segmental organs of the higher Annelids, or, perhaps, with greater probability, may be taken as the homologues of the water-vascular system. In the circulatory system the Nemerteans much excel the Planarians. In none of the latter is there any circulation in distinct vessels, while in the former group all possess such, the vessels being filled with a more or less corpuscular fluid. It is true that a water-vascular system is described by O. Schmidt in certain freshwater Turbellaria, and that Max Schultze mentions a system of canals in Thysanozoon and Tolycelis, but I agree with Professor Keferstein, after a careful examination of spirit-preparations, in considering farther investigation necessary, and that in the present state of our knowledge we cannot admit this in the ordinary Planarians. Considerable divergence occurs between them in regard to the organs of reproduction, the Planarians being hermaphrodite, while almost all the Nemerteans have the sexes separate. In regard to the complexity of the sexual system the former excel the latter, whose organs consist simply of a series of sacs placed along the sides of the body — for the development of ova or sper- matozoa. Moreover, where hermaphroditism appears, as in Borlasia hermapkroditica and B. Kefersteinii, respectively described by Professor Keferstein and A. P. Marion, one part of the body has its sacs filled with spermatozoa and another with ova, or the male and female elements occur in the sacs without definite order as regards position, so that the type of structure remains unaltered, and essentially different from the arrangement in the Planarians. The development of the young in the two groups has certain features in common, others at variance. Thus the ova of the Planarians in some instances produce ciliated embryos that have at birth more or less the form of the parent, — which form they retain throughout. The group Enopla of the Nemerteans agrees with the former ; while in the division Anopla the young either emerge from a ciliated covering inside the egg-capsule, or they are produced from the Pylidium4ovm in the free state. Moreover, some of both great Nemertean groups are viviparous, the ova being 142 HOMOLOGIES. long enough retained in the ovisacs to develop their contents, after impregnation through the lateral (sexual) pores. In the homologies of no organ, however, does the separation between the Planarians and Nemerteans become more apparent than in those of the proboscis, which, with all its adjuncts, appears to be a structure purely Nemertean. 1 Its definite aperture in front, its relation to the ganglionic commissures (between which it passes), its remarkable microscopic structure, and distinct muscular sac or sheath containing the highly organized corpuscular fluid, all point it out as an organ mi generis, and apparently without prototype or homologue in the Planarians or their allies. As already mentioned, I am inclined to consider the proboscis of the Planarian as the analogue and homologue of the oesophageal division of the digestive tract in Linens and Anpkiporus, and the " Schlund" of Vortew. The diminished size and atrophied condition of the proboscis in Brorhynchus seem to lead on the Nemertean type to certain of the Rhabdoccela. Both groups are characterized by great recuperative powers after injury, new parts and organs replacing those that have been cut off; while mere fragments not infrequently grow into perfect animals. Both consist for the most part of predatory and carnivorous creatures, that, notwithstanding their general deprivation of organs of offence and defence, manage to prey on animals much higher in the scale of organization than themselves, such as the Annelida. Their habits are also in many respects similar. Bipalium. I thought that considerable light might be thrown upon the affinities of the Planarians and Nemerteans by an examination of Bipalium, whose elongated body and central mouth indicated the probability of its intermediate position. In Bipalium 2 there is externally (in the preserved condition) a rather dense cellular cutis, similar in structure to the same coat in the Planarians and Nemerteans, though less defined from the subjacent investment, which consists in this case of a thin belt of circular muscular fibres. There next occurs a longitudinal muscular layer, split into isolated fasciculi, between which certain pigmentary and cutaneous elements and connecting fibres lie. Thus the coat in transverse section presents a barred appearance, especially in the dorsal region, where the pigment is most marked, the dark band being interrupted by the pale longitudinal fasciculi. In super- ficial longitudinal sections, also, the same aspect is caused as in Linens by the intrusion of the pigmentary and cutaneous elements amongst the muscular. The intermediate region below the coat just mentioned has numerous cells and granules amongst the fibres which connect it with the next layer and the general stroma of the body-cavity. There are also many cells, often of a flask-shape, with the narrow end external, filled with long and somewhat spindle-shaped 1 It is probable some further light will be thrown on the homologies of this organ in the anatomy of the Annelida. 3 I am indebted to Prof. E. P. Wright, of Dublin, for the opportunity of examining this form, which was kindly placed in my hands along with many foreign Annelida collected by himself. His genus Dunlopea is synonymous with Bipalium. HOMOLOGIES. 143 filamentous processes, which are termed by Schmarda " stabchenformigen Korpern." The most prominent features of the complex muscular arrangement filling up the body-cavity after the full bulk is attained are the following : — Within the intermediate layer all round the body are many longitudinal muscular bundles clasped in isolated fasciculi by divergent or curved fibres. Thus, with the exception of the central digestive cavity, the whole mass of the body is filled up by these interlacing, longitudinal, and other fibres. For some distance at the tip of the snout the stroma quite fills the region, but shortly a differentiation ensues, caused by the prominence of three transverse bands of muscular fibres, which pass across the snout at a distance from each other, so as to leave spaces occupied by fibres which have more or less a vertical direction. At first the arrangement is merely indicated, but it steadily gains so distinct a character that at last a series of spaces is left in transverse section in the dorsal division. In their fully developed condition these spaces have a thick layer of cellulo-granular matter, forming an inner lining or investment, which is so consistent that, in some fine sections which have been torn, it remains as a ring, with a well-marked outer margin. There is much opaque granular matter, also, between the vertical fibres. The channels — now larger and better defined — become continuous with the anterior part of the digestive chamber. They are about twenty in number in the snout. The long pale area (in transverse section), which forms with the preceding in the snout, though streaked by the vertical granular bands, presents a much more translucent appearance. Towards the tip it is a simple transverse pale belt, wider in the middle, tapering at the ends, and passing entirely across the snout, the usually opaque cutaneous margin being more translucent opposite the ends in such a view. At first it is more conspicuous than the dorsal belt, but after the three vertical bands previously described appear, the two areas are nearly equal in breadth. No aperture, however, occurs in that now under consideration. It becomes gradually more transparent and wider in the middle ; and by-and-by there is a tendency to enlargement on each side of the median line, while the vertical fibres forming the latter increase in prominence. A pale ventral region also makes its appearance, at first faintly marked, then more distinctly; the cutaneous textures, moreover, being included in the pallor. This causes the trans- lucent region on each side of the median line to assume a long club -shape, and then — as an increase of the opaque fibro-granular matter occurs in the centre — a wedge-shape. The central septum afterwards (proceeding backwards) gets wider, a ventral prominence becomes distinct, and the wedge of pale tissue shortens and assumes a somewhat ovoid form. Some pale fibres stretch across the septum between each ovoid space. With a few changes as to size and separa- tion this arrangement continues to the posterior end of the worm, where it gradually ceases. So far as I can make out, the pale bands (just described in transverse section) are not composed of nervous tissue, for which they appear to have been mistaken by Schmarda. The proboscis of the animal is Planarian in structure, having a glandular investment, with subjacent circular and longitudinal muscular fibres — the former being most conspicuous immediately below the mucous surface, and an intermediate and apparently erectile tissue. The digestive tract throughout is also Planarian. It is branched in front and laterally, and towards the posterior end becomes divided by a perpendicular septum into a right and a left division. The structure of the generative system as described by M. Claparede 1 shows a wide divergence from the Nemerteans. 1 'Mem. de la Soc. de Phys. et d'Hist. Nat. de Geneve/ tome xvi, 2eme partie, pp. 293— 312, 1862. 144 HOMOLOGIES. This animal, therefore, leans to the Planarian rather than the Nemertean type ; and on the whole it would appear that, while the affinities of these groups are sometimes in accordance, there can be little doubt as to the higher position of the latter in almost every respect. Balanoglossus. Two species of Balanoglossus dredged in the last cruise of the "Porcupine" (1870), in the one instance by Mr. Jeffreys outside the Strait of Gibraltar, to the south of Tangier, in 128 fathoms, 1 and in the other by Dr. Carpenter off the Algerine coast, at a point intermediate between Capes Falcon and Tenes, in 51 fathoms, 2 gave me an opportunity of investigating an apparently intermediate type of much interest. Unfortunately, none of the specimens were in good condition, either from rapid decay before being placed in spirit, or some other cause. None of the fragments exceeded If inch in length, and the diameter at the collar or widest portion was about f-ths of an inch. The general appearance of those dredged by Dr. Carpenter resembles the penis, the short conical anterior end or " proboscis," with the overlapping collar behind, closely imitating the glans penis, with its prepuce retracted. On the dorsum the "proboscis" is marked by a furrow at its base, and, continuous with this on the body, two well-marked ridges course along the median line. On the ventral aspect is a deep median furrow, a groove also being present on the head in the same line. The body is rounded anteriorly, flattened posteriorly. The " proboscis " exhibits various appearances, from the bluntly conical form in contraction to a more elongated and pointed contour in partial extension ; and it is evidently a very mobile muscular organ. On reaching the collar, its base becomes contracted all round, so as to be connected with the trunk only by a narrow pedicle, which is attached just over the anterior opening or mouth, the whole having the appearance of an operculum or plug. The anterior end or " proboscis " has lost its dermal layers in all the preparations, showing externally a tough, translucent and slightly granular membrane, probably the representative of the basement- membrane of the cuticular tissues. A considerable belt of circular muscular fibres forms the next investment. In transverse section a large number of vertical lamellae are observed to be arranged within the latter coat, in a divergent manner with regard to the central space. These can readily be split from each other in a longitudinal direction, yet so intimately do the fibres mix that in longitudinal sections their main direction is longitudinal, while they follow a trans- verse direction in transverse section. Prom the shape of the region the lamellae become narrowed in front and widened posteriorly. The nature of the specimens did not warrant a decision as to the presence or absence of a terminal pore, but, from an examination of specimens in the living condition, other authors, such as Delle Chiaje, 3 Keferstein, 4 Kowalewsky, 5 and Willemoes-Suhm, 6 have observed one. The posterior end of the "proboscis" in contraction fits into a kind of cup 1 No. 36, surf, temp., 75° ; bottom, 55° Fahr. 3 No. 50, „ 75°; „ 54° 7'. 8 c Memorie sulla storia e not. degli/ &c, vol. iv, p. 117. 4 ' Untersuchungen ueber nied. Seethiere/ p. 91. 5 ' Mem. de FAcademie imp. des sc. de St. Petersbourg/ vii e ser., torn, x, No. 3, 1867. 6 c Zeitsch. f. w. Zool./ Bd. xxi, 3, p. 383. HOMOLOGIES. 145 formed by the fleshy collar of the body, which projects after the manner of that in Terebella, but without the break or fissure. In his excellent account of the anatomy of Balanoglossus clavigerus and B. minutus, Kowalewsky describes the chief muscular fibres of the "proboscis" as longitudinal, and the circular as insignificant. This does not quite agree with the state of the parts in the foregoing examples. Structure of the Body-wall. Few traces of the cutaneous elements remain in any of the specimens, but the structure of fragments in the furrows demonstrates that it is allied in the closest manner to that of the Nemerteans. The cutis consists of a multitude of cells and globules in a gelatinous inter- cellular substance, the skin on section being streaked and loaded with circular and elongated granular masses, as in the former group. Indeed, the ease with which almost the whole cutaneous elements had separated from the subjacent tissues corroborated the relationship. A tough and continuous basement-membrane, having a finely streaked appearance, intervenes between the former and the next coat, which is a thick layer of longitudinal fibres, most developed, perhaps, on the ventral surface. The interfascicular substance is slightly marked, but there are many intersecting fibres which radiate inwards from the outer margin of this investment, through the next layer, to the wall of the digestive chamber. In longitudinal sections the longitudinal coat has, therefore, a transversely streaked aspect. It also presents three well-marked dorsal gaps anteriorly, viz. a median and two lateral, while ventrally a single hiatus exists in the centre. The circular muscular coat, which comes next in order, is moderately developed. The space between the latter and the wall of the digestive canal is partly occupied by the divergent fibres previously mentioned, the glandular or " liver"-tissue, and a few cells and globules. The examination of living specimens enabled Kowalewsky to see the cilia with which the whole integuments are covered, and he further describes a fine " cuticula " but, so far as an examination of preserved specimens warrants me in affirming, this structure is not more differen- tiated than in the Nemerteans, and therefore not demonstrable histologically as a special layer. In his anatomy of the body- wall he places the circular muscular coat to the exterior of the longitudinal — beneath our basement-membrane, and thus his specimens deviate in type from the foregoing. 1 Within the circle formed by the collar a conical process having a filiform terminal append- age projects from the truncated anterior extremity of the body, and fits into the hollow at the base of the " proboscis." This structure is supported upon a somewhat enlarged firm base, round which the tough basement-membrane of the "proboscis" is fixed. Below the line of attachment of the latter the process is again narrowed, and presents just over the opening of the 1 There would seem to be considerable variety in the structure of the body-wall of these forms. Another species dredged in 125 fathoms off Cape Rosier, in the Gulf of St. Lawrence, by Mr. J. F. Whiteaves, shows (in the spirit-preparation) underneath the glandular lining of the digestive chamber all round a dense and almost cartilaginous layer marked on its inner surface by regular transverse striae, but there is no specialization of chitinous tissue as in the Mediterranean examples. 19 146 HOMOLOGIES. mouth a smooth eminence of cartilaginous density, tinted of a reddish-brown hue. This terminates posteriorly in two brown chitinous rods, which diverge along the margin of a firm valvular process (forming on each side part of the lips of the oral aperture) and support the axis to which the " proboscis" is attached. A pointed and somewhat dense papilla lies at the fork of the chitinous processes. On the dorsal aspect of the valves and in the central line of the animal a series of transverse bars or ridges commences on each side. They are arranged in a double row, separated by a well-defined median furrow, which corresponds with the groove between the dorsal ridges externally. When first observed these firm bars had somewhat the appearance of a vertebral column — split as in a dried fish, and this special chitinous skeleton might therefore furnish the modern theorist with as good grounds as usual for the demonstration of the true stepping- stone to the vertebrate series. They are upwards of seventy in number, commencing by a well-marked chitinous bar just behind the fork of the axial processes, and, from the gradual diminution of the rows, terminating in a somewhat pointed extremity. Generally the whole structure may be separated into two divisions, viz. septal and branchial proper. Each septum is furnished with a brownish chitinous rod, which is conspicuous throughout its entire length in front, but is chiefly observed towards the median line posteriorly. These septa mark off the branchial spaces, since by splitting and uniting with others at the outer extremity, a branchial furrow is completed. Erom a point a little exterior to the median line each septal rod passes outwards to bifurcate as already mentioned, its course being easily seen anteriorly on account of the brownish hue of the process. This colour, however, is really confined to the central part of the flattened organ, which has throughout a thin translucent edge above and beneath, and is densest near the fork of the branchial lamella. Erom each side near its base is given off a translucent lamina, which, with another from the adjoining septum, forms the support of the branchial sabre. The junction of these laminae with the septal process is interesting, for in transverse section the base presents the form of an anchor. The septal rod, elevated on a fold of the basement- and mucous membrane, constitutes the strong central support (shank) of the T-shaped structure, while the branchial laminae, passing from the transverse bar as long recurved processes, correspond to the flukes. At the junction of the septal rod with the transverse portion is a slight swelling of the former, having the brown chitinous part in the centre, the rest of the process, as well as the branchial laminae, being quite translucent. As the sections proceed outwards, however, a slightly brownish hue from the presence of dense chitinous matter is seen at the base of the branchial laminae where they join the septal rod. The latter is marked almost from the commencement by a vertical median line, showing its double composi- tion. The branchial laminae at this part touch at the lower edges, but gape at the upper, so as to make a triangular channel, which is completed by the thick membrane of the region. Eurther outwards the branchial arches stand freely in their grooves, their supporting chitinous laminae being enlarged at the upper end and bent inwards in transverse section, and the tunnel completed by the membrane formerly described. The supporting chitinous rods gradually taper from the median line to the outer edge, as also do those of the septal regions ; thus the diminu- tion in the former case has to be compensated by an increase of the soft parts of the tunnel. After the branchial lamella forms an independent sabre in the groove, the septal process is found (in transverse section) elevated on a still higher fold of the mucous membrane as a club-shaped structure, the central brown chitinous part — somewhat triangular in shape — appearing in the rounded summit. The next change is the increase of the brown hue in the chitinous supports HOMOLOGIES. 147 of the branchial lamellae. The double nature of the septal process also becomes more evident, even from the fold of membrane upwards. The summit, however, is still uniformly coated by the investing membrane of the branchial region j by-and-by the papilla on which it is placed shortens, and the pale chitinous tips of the rods split to form the arch at the boundary. The laminae of the branchial processes diminish into slender pale chitinous rods, which lie towards the inner (lateral) margin of the canal, and each soon terminates in a closed extremity. Over the whole of the processes just described a thick mucous layer, probably ciliated during life, is spread. In ultimate structure it is glandular in appearance, being finely streaked in vertical section and minutely granular. A peculiar fibrillated condition is observed in that forming the wall of the branchial lamella, and also at the base of the chitinous supports of the septa. This mucous layer rests upon a basement-membrane, from which numerous divergent fibres pass to the exterior muscular coat of the body- wall, here and there enclosing spaces for the fatty " liver "- structure found in this region. The foregoing account, of course, is only meant to convey a description of the framework of the branchial apparatus, which in other respects has received careful treatment from the excellent Russian naturalist Kowalewsky. The arrangement of the system in this form shows a close approach to that of Balanoglossus clavigerus. Accessory Glands to the Digestive By stem. Anteriorly a considerable space occurs between the dorsal surface of the branchial apparatus and the body-wall, which is occupied for the most part by transversely arranged sacs of the yellowish fatty " liver "-tissue. These bodies are surrounded by a distinct membrane, enclosing a vast number of compound fatty globules and granules, similar in minute structure to the same tissue in the Nemerteans. In transverse section the contents seem to fall out of the centre, but a thick layer of globules still adheres to the wall of the sac. These saccate glands occur under the branchial lamellae, and generally in the space between the inner muscular layer and the wall of the digestive tract anteriorly. As soon as the branchiae cease, however, they become much more prominent. The digestive and respiratory functions are thus performed in one chamber anteriorly, and the structure and arrangement throw considerable light on the condition of the same part in the Nemerteans, where a characteristic distinction exists between the two regions of the digestive system. Kowalewsky shows a folding of the branchial region in his species, so that a special chamber is separated from the general alimentary cavity. The digestive would therefore not intrude on the respiratory function. Digestive Cavity Proper. This chamber commences at the oral aperture, and continues in the form of a wide tube to the posterior end of the animal, which, however, is incomplete in all our examples. It is supported and held in position by the radiating fibres that pass inwards from the external muscular coat of the body-wall. Anteriorly the glandular mucous membrane, which forms its inner coat, presents 148 HOMOLOGIES. a frilled appearance, from the rugae, which, as in the Nemerteans, often assume an arborescent appearance, owing to the extrusion (under pressure and preparation) of their cellular and granular elements. The wall of the canal is somewhat thinner in front, while the glandular lining is largely developed. Behind the branchial region, however, the following structure is clearly seen : — Externally the radiating fibres from the outer coat of the body- wall pass into a well- marked layer of circular muscular fibres, upon which the continuous basement-membrane and its glandular lining rest. The latter is thinner than in front. The structure on the whole closely approaches the Nemertean digestive tract. Kowalewsky mentions that the surface of the digestive chamber is richly ciliated. His specimens occurred on sandy ground, as might be expected from the nature of their food. Circulatory system. Two vessels only could be satisfactorily made out by an examination of the specimens. A large longitudinal dorsal vessel lies over the fibrous band connecting the branchial septal rods across the median furrow. At this point it has externally only the circular muscular coat, the basement-membrane and cutaneous tissues, since there is a hiatus in the longitudinal muscular layer. The vessel is continued to the posterior end of the specimen over the wall of the digestive tract. Exactly in the median line on the ventral surface a similar vessel occurs, with the same relations to the cutaneous and alimentary textures. Both trunks have distinct walls. Besides the elaborate arrangement of vessels in connection with the branchial lamellae, Kowalewsky shows a lateral vessel on each side, and various minute twigs from the larger trunks. A single imperfect example of the other form of Balanoglossus was dredged by Mr. Jeffreys as above mentioned. In general features and size it resembles the foregoing, but certain ana- tomical differences merit special notice. The "Proboscis" consists of a bluntly conical mass, which has lost its cutaneous elements. Externally, instead of the basement-membrane and circular fibres of the former type, there is a coat of longitudinal fibres, or, rather, of fibres whose direction is chiefly longitudinal, for they are felted firmly together. Within is a belt of circular fibres, from which the vertical lamellae of the central region spring. The lamellae consist of fleshy columns, which are fixed to the outer wall all round, but have a free margin internally. In transverse section, thus, the region some- what resembles the kind of fruit called hesperidium, such as that of the orange, only the carpels are enormously increased. The columns are composed of densely felted fibres — longitudinal, oblique, and radiating, besides circular fibres towards the inner free margin. The whole must therefore form a powerful squeezing or propelling organ, after the manner of the heart of the higher animals. This region is attached to the body by an elongated, chitinous, process which has a broad basis at the mouth, and sends four divergent chitinous spurs into the tissues for support, the posterior pair coursing along the borders of the dorsal valves or lips, as in the HOMOLOGIES. 149 previous form. The broad, fleshy collar has two powerful conical bands of fibres (continuous with the dorsal belts) attached to the chitinous process on the dorsum, while ventrally a special bundle of fibres passes from the collar to the anterior margin of the trunk. The dermal layers of the body agree in both species, as also does the external (longitudinal) muscular coat; but though certain circular muscular fibres lie under the latter, they are so indistinct as scarcely to merit the name of a special layer. A considerable difference is apparent on opening the body-cavity, as at first sight the branchial arrangement characteristic of the former examples seems to be absent. On careful inspection, however, many minute, transparent, chitinous processes are found in the somewhat thickened membrane behind the dorsal valves. These processes have the form of a pointed molar tooth with very long fangs, and a fissure passing up the centre of the tooth to the crown. Some of the fangs or processes are bifid at the tip, each division diverging with a curve from the main stem. In all probability they form a short double row, after the type of the former species ; but the specimen is not in a condition to bear searching investigation. The digestive canal and accessory glands have a similar character to those in the foregoing species ; the former being distended with muddy sand containing many Foraminifera and other microscopic organisms, the latter chiefly grouped along the dorsal area. This species would not seem to approach any yet described. In reviewing the several features presented by these curious forms, and contrasting them with what is known of Nemertean anatomy and physiology, the following reflections occur : — In both the cutaneous tissues have the closest similitude as regards ciliation and minute structure. In Balanoglossus, however, the basement-membrane underneath the latter is more differentiated, and assumes a slightly fibrous appearance. In the arrangement and histology of the muscles of the body-wall they much resemble each other. The digestive system is similar. Both have a ciliated chamber divided into two great regions, represented by the first or branchial, and the succeeding division in Balanoglossus, and by the oesophageal and alimentary cavity proper in the Nemertean. The peculiar rete mirabile over the oesophageal region of the Nemertean, and the elaborate branchial circulation of Balano- glossus are apparently homologous. The minute structure of the proper wall of the chamber is closely allied. Moreover, while the " liver "-tissue is separated into elongated sacs in Balano- glossus, and simply diffused over the alimentary region in the Nemertean, its histological features are nearly identical. The mouth and anus are also similarly arranged. With regard to the " proboscis " of Balanoglossus and that of the Nemertean I fear there is no homology \ indeed, I would be inclined to regard the anterior region in Balanoglossus rather as the homologue of the Nemertean snout. The pore at the tip in the former would therefore correspond with the aperture for the proboscis in the latter, the mouth in both being placed a considerable distance backwards. A great divergence happens in regard to the nervous system. It is not yet sufficiently understood to enable us to form a correct idea of its relations in Balanoglossus, while it is con- spicuous in the Nemertean. There is considerable similitude in the circulatory system. Both have a main dorsal and two 150 HOMOLOGIES. lateral trunks, the blood in each group flowing from behind forward in the dorsal. The much greater differentiation of the branchial region in Balanoglossm necessitates a corresponding com- plexity of the vessels, yet there is a connecting link in the elaborate plexus in the oesophageal region of the Nemertean. In regard to generation and development there is also a parallelism. The reproductive elements are developed in sacs in both, and the sexes are often distinct. Certain of the young in each case undergo a kind of metamorphosis, as shown on the one hand by the description already given, and on the other by the interesting observations recently made by E. Metschnikoff on Tomaria} apparently the early condition of Balanoglossus. The occurrence of eye-specks in the anterior region (" proboscis ") in the latter would seem to indicate that the above view of its homologies is correct. Having thus examined the relations and homologies of the Nemerteans with their inferiors and apparent equals in the scale, we may next inquire into their affinities with the higher annelids. Here, however, there is room for very diverse opinions, since, so far as known, there are no intermediate forms through which they may be linked on to any higher group. Their relationship would rather appear to be with the Leeches than with the Gephgrea or Scoleidce of Prof. Allman's classification, although a considerable gulf intervenes. Thus, in regard to the cutaneous system the cilia are not present in the leeches, though the exudation of the cutis proper is abundant enough. The muscles of the body-wall are less definitely arranged in the latter {e.g. Nephelis), the internal longitudinal bundles for instance being placed in the body- cavity, and separated by regularly arranged vertical fasciculi at the lateral regions. The external coat is composed of circular fibres, within which lie a decussating series. The digestive system opens by a mouth in front of the ganglia, after passing through a nervous collar, and the muscular oesophageal region is distinguished from the more glandular stomachal portion, as in the Nemerteans. There are no cilia in the alimentary chamber, but it is occasionally furnished with csecal processes. The alimentary canal adheres as much to the body- wall in the Leeches as in the Nemerteans, which in this respect differ from the higher Annelids. The dorsal and the two great lateral vessels of the leech are probably homologous with the three vessels of the Enopla, but the ventral is additional. In regard to the nervous system, the superior lobes of the Nemertean brain seem to correspond with the supra-oesophageal ganglia of the leech, and the inferior (from which the great lateral trunks arise) with the sub-cesophageal. If in the Enopla the two ganglia were separated, and the lateral nerve-trunks thrown together in the median line of the body, the alimentary canal would become dorsal in position, and would perforce pass through the nervous system to open ventrally, while the lateral vessels would remain in their usual situation. Thus a partial resemblance to the state in the leech would ensue. A much greater amount of branching of course would occur after the concentration of the nervous system. The two cephalic sacs and coiled ducts in the Enopla may be the homologues of the segmental organs in the leech. 1 < Zeitsch. f. w. Zool./ Bd. xx, p. 131, taf. 13, 1870. DISTRIBUTION OF THE NEMERTEANS. 151 There is a considerable difference in regard to the reproductive organs, for the Leeches are hermaphrodite, whereas the Nemerteans are chiefly unisexual. The capsule of mucus for the ova in Lineus is homologous with the cocoon of the leech ; the latter being apparently due to the same abundant secretion poured forth by the general cutaneous surface, and is not necessarily connected in any way with the numerous segmental organs. Some of the higher Annelids, again, agree with the Nemerteans in discharging the generative products through lateral pores, e.g. Harmothoe and Fhgllodoce. As in the Enopla, no metamorphosis occurs in the embryo of the leech. All the latter are oviparous, whereas some of the former are ovo- viviparous. There is no feature to connect them with the Brachiopoda, which Mr. Morse 1 thinks should be classed with the true Annelida; indeed, we are not prepared at present to admit the relationship until we are more acquainted with the grounds on which the American author bases his conclusions. I would be inclined to place the Turbellaria next the true Annelida, without the usual interpolation of the Rotatoria. General Distribution of the Nemerteans. The Nemerteans have a very wide geographical range, extending from the arctic seas to those of the equator, and it is probable they occur on every suitable sea-beach, as well as in the surrounding depths. The forms adapted for swimming generally frequent the latter, and perhaps only approach the shallow water at the extreme limit of their range, and in a somewhat modified form, especially as regards size. Moreover, examples of the two great types (Enopla and Anopla) are common both to the arctic seas and the antipodes. The range of the freshwater species is involved in obscurity ; they have been found in various parts of the world, but not yet in this country. With regard to the distribution of the British species, some forms are cosmopolitan, such as Anvphiporus lactifloreus, Tetrastemma melanocepkala, Candida, and dorsalis, Nemertes JSfeesii, Lineus marinus, L. gesserensis, Cerebratulus angulatus, and Carinella annulata, extending from the Zetlandic seas along both eastern and western shores to the Channel Islands, and, in addition, radiating widely all round. Thus I have received A. lactifioreus from Greenland, and apparently the same form is described by M. de Quatrefages from the Mediterranean. Tetra- stemma melanocephala, T. Candida, and T. dorsalis range from the latter to the extreme north of Europe. Lineus gesserensis, again, appears to be even more widely distributed, for besides being prevalent in the European seas, it (or a form almost identical in every respect) extends to the shores of the United States. Cerebratulus angulatus attains greater dimensions in the seas of Greenland and the Boreal province generally than it does in the Channel Islands. In other forms, however, e. g. Lineus marinus, I have observed no apparent difference in bulk between those from Shetland and those from Guernsey ; though at the same time it must be stated that nowhere have the Nemerteans occurred of greater size and beauty than amongst the sheltered tangle-forests of the i l Ann. Nat. Hist./ 4 ser., vol. vi, p. 267. 152 DISTRIBUTION OF THE NEMERTEANS. Zetlandic seas. Carinetta annulata stretches from the north of Shetland to the Mediterranean, and a very similar species is found at the Cape of Good Hope. Others, again, have a more southerly range, and have not yet been found in the northern portions of the British Islands ; but on this point I would not speak dogmatically, for very much yet remains to be done in regard to the distribution of marine animals. A. spectabilis, Borlasia Mizabetlice, and Micrura aurantiaca may be instanced as specially southern forms. Some of the Nemerteans live at a depth of many fathoms and at a considerable distance from land, as well as between tide-marks, for example, Nemertes JVeesii, Zineus marinus, and bilineatus, Micrura purpurea and Carinetta annulata. Amphiporus pulcher and Cerebratulus angulatus are rarely found elsewhere than in deep water, the limits being from 5 to 120 fathoms. Amongst the Nemerteans procured in the dredgings of the " Porcupine" in 1869 and 1870, no new form, so far as can be ascertained from the spirit-preparations, occurs. It is interesting, however, to notice that the Anopla much exceed the Enopla in number, the most abundant form being Micrura fusca, with its flattened and oar-like posterior extremity. Tetra- stemma Candida, again, was found at a depth of 420 fathoms, its usual site being the laminarian and litoral regions. Representatives of the Anopla come from the great depth of 795 fathoms off the coast of Portugal. The Planarians accompany them in these sites, and there is no reason why both should not be found at yet greater depths. A. lactifloreus, all the Tetrastemmce, ProsorhochmuSy Nemertes carcinopkila, many of the Linei and Micrura, and Cephalothricc, have their habitat between tide-marks, though sometimes at the extreme border of the litoral zone ; indeed, as a rule, Tetrastemma dorsalis is a laminarian form. M. de Quatrefages states that he has seen imprints in the rocks of Solenhofen and Strasbourg, which he thinks belong to Nemerteans, in the latter case especially to the " genus Borlasia;' and palaeontologists have expressed similar opinions. The fossils in the lithographic stone of Solenhofen recently noticed by Prof. Ehlers 1 under the name Legnodesmus bear a close resemblance to such as might be caused by the Nemerteans ; but a perusal of his excellent descriptions and drawings leaves an impression so indefinite that further and more extensive investigations are evidently necessary before a safe decision can be arrived at. The most interesting part of this paper is the account of his finding stylets in the Legnodesmus figured in taf. xxxvii, figs. 1 and 2. My acquaintance with the living animals leads me to entertain doubts as to their connection with the so-called fossil Nemerteans (Nemertites) of the Cambrian rocks ; at least, those coils I have seen suggest the following ideas : — Since they are simply casts without organic remains, the worms which made them could only have done so in shallow water, so as to have raised the snout to the surface, and crawled off in the usual manner (by floating). Any other mode of departure would have blurred the tracks in a deposit so soft as to receive such impressions. Moreover, I have often observed similar contorted tracks in the soft muddy sand in tidal pools — tracks made by litoral univalves in their daily wanderings. 1 c Ueber fossile Wiirmer aus dem lithographischen Schiefer in Bayera/ Cassel, 1869. DESCRIPTION OF THE GENERA AND SPECIES OF THE BEITISH NEMEETEANS 20 GENERA AND SPECIES OF THE NEMERTEANS Sub-Order.— ENOPLA. Proboscis furnished with stylets. Family I. — AmphiporidjE.* Sub-Family. — Amphiporin^:. Proboscis proportionally large. Genus I. — Amphiporus. Ehrenberg, 1831. Before the time of Ehrenberg the species of this group had chiefly been included under the genera Fasciola and Planaria. In his f Symbolse Physical/ published in 1831, this author established three genera, viz., Polystemma, Ommatoplea, and Amphiporus, for the reception of animals probably belonging to the present type ; and, while there is room for doubt with regard to the exact nature of the first two genera, as illustrated respectively by the examples Polystemma adriaticum and Ommatoplea tceniata, it is quite clear to every observer that his Amphiporus albi- cans from the Red Sea is a characteristic representative of the Fnopla, closely allied to A. lacti- Jloreus. I have therefore deemed it right to use for the typical forms that generic name about which there can be no misunderstanding, and which name, moreover, is contemporaneous with the others. Usage, perhaps, inclined me to favour the adoption of the generic title Ommatoplea, but in the present state of our knowledge this nomenclature would not have been strictly appro- priate, and by the discovery of the typical form from which Ehrenberg drew up his description it might be our misfortune to find that it is one of the Anopla, since there is nothing decisive in his account or figure. The name here adopted is not free from faults, for the Anopla as well as the Enopla have a pore at either end ; but the term Ommatoplea stands in the same position, nume- rous eyes occurring in the one group as often as in the other. In his description of the genus, Ehrenberg, although noting and figuring the glandular papillae of the proboscis, omitted to observe the stylets, and did not truly comprehend the situation and relations of the mouth, as he mistook the proboscidian aperture for the latter. The name Polia instituted by Delle Chiaje, and 1 'Aju^t and iropog, an aperture. !56 AMPHIPOEUS LACTIFLOREUS. adopted for this genus by M. de Quatrefages, was applied by its founder to examples of the Anopla. In distinguishing the species of Jmpkiporus the chief characters are drawn from the arrange- ment of the eyes, the nature of the cephalic furrows, and the structure of the stylet-region of the proboscis. Generic character.— Eyes more or less numerous and large, but never arranged in a square. Body rather short, and often flattened. 1. Amphiporus lactiploretjs, Johnston. Plate I, figs. 1 and 2. Specific character.— Eyes grouped in two series on each side. Body whitish, roseate or grayish. Synonyms. 1776. Lumbricus oxyurus, Pallas. Miscell. Zool., p. 146, tab. 11, f. 7 and 8. 1828. Planaria lactiflorea, Johnston. Zool. Journal, vol. iii, p. 489. 1837. Nemertes lactiflorea, Johnston. Mag. Zool. and Bot., vol. i, p. 535, pi. 17, f. 2 and 3. 184 1. „ „ W. Thompson. Ann. Nat. Hist., vol. vii, p. 482. 1843. Borlasia? alba, W. Thompson. Eep. Brit. Assoc, 1843, p. 271. 1844. Polystemma roseum (partim), (Ersted. Entwurf Plattwur., p. 92. » » „ } , Ibid. De Regionibus marin., p. 80. 1845. Nemertes glaucus (?), Kolliker. Verhandl. d. schweiz. nat. Gesellsch. zu Chur im Juli, 1844, p. 89. „ Borlasia alba, W. Thompson. Ann. Nat. Hist., vol. xv, p. 320, with woodcut. „ Planaria rosea, Ibid. Op. cit., p. 321. 1846. Borlasia? alba, Johnston. Ann. Nat. Hist., vol. xvi, p. 434 (Index). „ Prostoma lactiflorea, Ibid. Op. cit. (Index), p. 435. „ Prostoma ? rosea, Ibid. Index, p. 436. „ Polia mandilla, De Quatrefages. Ann. des sc. nat., 3 rae ser., Zool., torn, vi, p. 203, tab. 8, f. 1 and la, and tab. 9, f. 2. mutabilis, Ibid. Op. cit., p. 205, tab. 10, f. 2. violacea, Ibid. Op. cit., p. 210. berea, Ibid. Op. cit., p. 211. glauca, Ibid. Op. cit., p. 206, tab. 10, f. 3. mandilla, Ibid. Voyage en Sicilie, vol. ii, p. 115, pi. 15, f. 1, a b. mutabilis, Ibid. Op. cit., p. 117, pi. 15, f. 4 and 5. violacea, Ibid. Op. cit., p. 122, pi. 16, f. 16, and pi. 17, f. 1. berea, Ibid. Op. cit., p. 123, pi. 15, f. 13. glauca, Ibid. Op. cit., p. 118, pi. 15, f. 7—9, var. 1850. Nemertes glaucus, Von Siebold. Archiv fur Naturges., ii, p. 382. „ „ mandilla, Diesing. Syst. Helm., vol. i, p. 275. „ Omatoplea mutabilis, Ibid. Op. cit., p. 252. „ „ violacea, Ibid. Op. cit., p. 253. „ „ berea, Ibid. Op. cit., p. 252. „ „ glauca, Ibid. Op. cit., p. 253. „ „ alba, Ibid. Op. cit., p. 252. 1853. Gordius albicans, Dalyell. Pow. Creat., vol. ii, p. 73, pi. 10, f. 5a and 6. 1849. AMPHIPORUS LACTIFLOREUS. 157 1862. Ommatoplea mutabilis, Diesing. Revision der Turbell., p. 257. „ „ violacea, Ibid. Op. cit., p. 257. „ „ berea, Ibid. Op. cit., p. 257. „ „ glauca, Ibid. Op. cit., p. 25 7, bis. „ „ alba, Ibid. Op. cit., p. 257. „ Nemertes mandilla, Ibid. Op. cit., p. 303. „ Borlasia mandilla, Keferstein. Zeitsch. fiir wiss. Zool., Bd. 12, p. 58, Taf. 5, f. 1 — 7. 1863. Ditactorrhochma mandilla, Diesing. Nachtrage zur Revis. der Turb., p. 11. 1865. Omatoplea rosea, Johnston. Catalogue Brit. Mus., p. 23, pi. Ha, I 2, 2* 2** 3, and 3*. „ „ alba, Ibid. Op. cit., p. 23. 1865-6. Polia mandilla, De Quatrefages. Hist. Nat. des Anneles, pi. 4, f. 3. 1866. Ommatoplea rosea, Lankester. Ann. Nat. Hist., 3d Ser., vol. xviii, p. 388. „ „ alba, Ibid. Op. cit., p. 388. 1867. „ „ Mcintosh. Bept. Brit. Assoc., 1867 ; Trans. Sect., p. 92. 1868. „ „ Ibid. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. 1869. „ „ and var. rosea, Mcintosh. Trans. Roy. Soc. Edinb., vol. 25, pt, ii, p, 323 et seq. Habitat. — Under stones between tide-marks and in the laminarian region; abundant. Generally distributed — from the Arctic Seas probably to the Mediterranean. Body rounded on the dorsal surface, flattened on the ventral, not much tapered towards the tail, which is rather blunt. In newly spawned specimens the body is much flattened, but in those bearing ova it is rounded. Length one to three inches, and occasionally even reaching four inches ; breadth three lines. Colour.— Various shades of white or pinkish white, with a translucent streak along the centre of the dorsum — caused by the proboscidian chamber. Specimens with the generative organs well developed assume a grayish aspect. There are two conspicuous pink or reddish-pink spots indi- cating the ganglia in front. The under surface has the same colour as the dorsum, and during the quiescent state of the reproductive organs is distinctly marked by the pinnse of the digestive chamber. A specimen found at St. Peter Port, Guernsey, had the body of a pale greenish hue, like that usually seen in Tetrastemma melanocephala ; while in the Bight of Vatsland (to the north of Bressay Sound) in Shetland a variety with the pigment everywhere increased abounds on a sandy bottom. Head spathulate, flattened, and slightly pointed ; furnished with numerous eyes placed in two or three groups on each side, the anterior generally forming a marginal row ; the posterior arranged in front of or sometimes over the ganglia, and three often forming a triangle. In the pale brownish variety from Shetland an eye-speck on each side in front of the ganglia is larger and more conspicuous than the others. Cephalic furrows. — Midway between the tip of the snout and the anterior border of the ganglia a furrow runs inwards and slightly forward on the dorsum, ceasing before it reaches the middle line. On the ventral surface is a similar though shorter furrow, the two meeting on the side at a richly ciliated dimple, which leads into the cephalic pit. A short distance behind the ganglia two other superficial furrows exist, each slanting backwards and inwards to meet its fellow of the opposite side in the middle line. These furrows are also continued inferiorly, but with a slightly altered direction, so that they meet under the ganglia. The two sets of furrows are indicated in the flattened head by lateral notches. 158 AMPHIPORUS PULCHER. This is a very common animal, generally lurking under stones between tide-marks, whether these rest on sand, gravel, or sandy mud, and sometimes the latter is odoriferous ; thus at Herm it frequently lives amidst crushed and blackened fragments of Zostera marina and sea-weeds under stones. In such situations it generally resembles in contraction a cream-coloured larva, but when placed in sea-water it readily extends itself and crawls with a slow gliding motion, and likewise progresses on the surface of the water with the ventral region uppermost. It lives well in confinement, and numerous broods can be reared from captive specimens. The white ova are deposited in a free condition from January to April, and the young are from the first furnished with two eyes. I have not been able to see this species feed in confinement, but the rapid fattening in the free condition after spawning shows that it takes nourishment greedily. The skin presents an acid reaction to test-paper, and the mucus secreted thereby is of a most tenacious description, the animal, indeed, rapidly forming an investment by this means when placed in a vessel containing a little sand. Considerable confusion has prevailed with regard to this very abundant and widely distri- buted species. Johnston, CErsted, and others have considered the Planaria rosea of 0. F. Miiller referable to this form, but, as will be noticed elsewhere, a careful consideration of all the facts has led me to a different conclusion. When descriptions and figures are so vague and uncharacteristic, it is impossible to clear away all doubts, but such uncertainty cannot be laid to our charge. The earliest reliable account of the species is, perhaps, that given by Pallas in his ' Miscellanea Zoo- logica/ but the specific name {pxyurus) there given is objectionable, and I have consequently adopted another. Dr. Johnston, amongst modern authors, first clearly described this common worm, and since his period less difficulty has been encountered in regard to its discrimination. This author changed the name originally applied by him to the species from various causes, none of which, however, interfere with our following the usual laws of zoological nomenclature. For some time I was inclined to include the Amphiporus albicans of Ehrenberg under the synonyms, as it has many characters in common, but it approaches A. pulclier in others, and the arrange- ment of the eye-specks in his figure is so different that I have struck it off. For the same reason the Planaria elongata of Montagu (MS. p. 231) was not included. The Polia manclilla of De Quatrefages, from St. Vaast, probably belongs to this form, and there is nothing in the slight differ- ences noted in Polia mutabilis, P. violacea and P. berea to distinguish them from the same worm. The P. glauca of this author is also, in all likelihood, a dark variety of the species. 2. Amphiporus pulcher (0. F. Miiller), Johnston. Plate I, fig. 3, and PL XIV, fig. 11. Specific character. — Eyes well-defined and numerous, irregularly grouped on each side. A central reserve-stylet in the proboscis. Cephalic furrows slightly branched. Synonyms. 1774. Fasciola rosea, O. F. Miiller. Verm, terrest. et fluv. hist., i, 2, p. 58. 1776. Planaria rosea, Ibid. Zool. Danic. Prodr., p. 221, No. 2679. 1788. „ „ Ibid. Zool. Danic, ii, p. 31, tab. 64, f. 1 and 2. 1865. 33 3) 1866. 33 3. 1868. 33 3. )} 33 3 1869. 33 3. AMPHIPORTTS PTTLCHER. 159 1788. Planaria rosea, Linnaeus. Syst. Nat. (GmehVs), torn, i, pars vi, p. 3088. 1827. „ „ Bosc. Hist. Nat. des Vers., i, p. 256. 1837. Nemertes pulchra, Johnston. Mag. Zool. and Bot., vol. i., p. 536, pi. 17, f. 6. „ Polystemma roseum, CErsted. Kroyer's Nat. Tids., iv, p. 579. „ „ pulchrum, Ibid. Ibid., p. 580. 1844. „ „ CErsted. Entw. Plattw., p. 93. 1846. Prostoma pulchra, Johnston. Ann. Nat. Hist., vol. 16, p. 436. 1850. Omatoplea rosea (partim), Diesing. Syst. Helm., vol. i, p. 251 et postea. „ „ pulchra. Ibid. Ibid., p. 252. 1853. Vermiculus rubens, Dalyell. Pow. Creat., vol. ii, p. 89, pi. 10, f. 13 — 18. 1862. Ommatoplea pulchra, Diesing. Revis. der Turbell., p. 257. Johnston. Catalogue Brit. Mus., p. 24, pi. ii a, f. 6 and 6*. Lankester. Ann. Nat. Hist., 3rd ser., vol. 17, p. 388. Mcintosh. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. Ibid. Kept. Brit. Assoc., 1868, p. 340. Ibid. Trans. Roy. Soc. Edinb., vol. 25, pt. ii, p. 337 et seq. Habitat. — Generally diffused round the British coasts in water eight to thirty fathoms deep, and specimens were dredged by Mr. Jeffreys off Unst, Shetland, even at a depth of 120 fathoms. It frequently occurs amongst shells and other debris brought from the coralline region by the fishermen. Body one to three inches and a half long, and three to five lines broad ; flattened, thinned at the edges, slightly narrowed behind the snout ; of nearly equal diameter throughout the middle region when stretched, but the anterior part is often narrowed, while the posterior forms a broad flattened oar. In extreme contraction, the body resembles an fflysia or Limapontia, or even becomes baccate. Colour. — During the period of reproductive quiescence the animal has a general dull pinkish hue, pale at the snout, along the margins, and at the tail. The pinkish tint proceeds forward in the centre of the snout in front of the ganglia. The under surface is pale pinkish. In the ripe females the lateral regions are enlivened by the rich reddish hue of the ova, which shine through the transparent integuments, so that, from their somewhat symmetrical disposition, the animal has a segmented appearance, from the termination of the oesophageal region nearly to the tip of the tail. In specimens which have lived a considerable time in captivity the dorsum becomes freckled with brownish-red grains, especially towards the snout. Head broadly spathulate, pointed at the tip, flattened ; the snout clearly defined from the rest of the body by a well-marked furrow, which notches each side, and passes inwards almost to the middle line. The tip is furnished with a distinct central papilla, from which an opaque line generally proceeds backwards to the central glandular mass. Some distance behind the transverse furrow another oblique groove coming from the ventral surface slants backwards and inwards — meeting its fellow of the opposite side in the middle line of the dorsum, so as to form an acute angle. There are numerous large, well-defined eyes, which form somewhat irregular groups on each side, to the number of about twenty-three in all, three or four lying behind the transverse furrow. These are much more distinct in some specimens than in others. On the under surface the furrows are continued straight inwards towards a dimple (Plate XIV, fig. 11), then curve forward and inwards to the middle line. Numerous longitudinal grooves slant from the front 160 AMPHIPORUS SPECTABILIS. towards these furrows so as to produce a similar appearance to that in Amphiporus spectahilis, Quatref., but less marked in the lateral regions. The ganglia lie quite behind the trans- verse furrow, as indicated by the shading in the figure. This species is often found in crevices of the coils of Serpulce attached to shells and stones from deep water, and it is one of the most interesting of the group. It glides over the bottom of the vessel with considerable speed, almost without a wrinkle of its body ; and when irritated a healthy example turns on its edge, and, by sw T ift lateral strokes of the oar-like posterior extremity, swims rapidly through the water like a Nephelis or a horseleech, so that not infrequently the uninitiated mistake it for a species of the latter. In contraction the head is drawn within the anterior portion of the body, the neck forming a kind of collar through which the organ slips inwards. It rapidly secretes a tough sheath of transparent and iridescent mucus, under which it remains for days. The skin presents an alkaline reaction to test-paper. The ova are developed in the beginning of May and are nearly ripe towards the end of June, but though many ova have been discharged in the vessels, I have hitherto been unable to watch their development. While, for a time, of opinion that the Tlanaria rosea of 0. F. Miiller {' Zool. Danica') might refer either to this or the previous form, I now think that in all probability this species has the preference in the description and figure. He says, "Body elongate, sub-equal, convex above, of a rosy colour, marked with black points and lines (not distinct in some) ; flat beneath, of a pale red interrupted with transverse striae, posterior end blunt, anterior produced into an angular head; the latter is marked on each side by a semicircle of black points." The figure (which has its anterior end downwards) bears a considerable resemblance to this form, especially in the head and position of the eyes. His remark, however, that it is common everywhere leaves a certain degree of doubt, and I have therefore chosen Dr. Johnston's title. The latter author was the first to give a proper account of the species, from specimens procured amongst corallines and old shells in deep water off the coast of Berwickshire. He noted the appearance of the ova in the female, describing them as a series of bright scarlet spots along the sides. Sir J. Dalyell men- tions a stripe, generally yellowish, which runs down the back, and a broader stripe along the ventral surface, but these probably refer to the colour of the digestive canal. Pair figures of the structure of the proboscis and the external appearance of this species are present in Gaimard's ' Voyages en Scandinavie, en Laponie/ as mentioned in the zoography. I have not thought it necessary to include all the synonyms given by CErsted and Diesing, since it is doubtful to what species they refer. 3. Amphiporus spectabilis, De Quatrefages. Plate III, figs. 2, 7, and 8. Specific character. — Head spathulate, peculiarly narrowed posteriorly. Eyes in two long rows on each side. Cephalic furrows conspicuously branched. Longitudinally striped with brown on the dorsum. AMPHIPORUS SPEOTABILIS. 161 Synonyms. 1846. Cerebratulus spectabilis, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., p. 219, tab. 10, f. 7. 1849 - „ „ Ibid. Voyage en Sicilie, vol. ii, p. 131, pi. 17, f. 12 and 13. 1850. Nemertes spectabilis, Diesing. Syst. Helm., vol. i, p. 272. 1852. Cerebratulus spectabilis, Max Schultze. Zeitsch. f. wiss. Zool., Bd. iv, p. 183. 1861. „ „ Grube. Ein Ausflug nach Triest, &c, pp. 80 and 129. 1862. Nemertes spectabilis, Diesing. Revision der Turbell., p. 299. „ Borlasia splendida, Keferstein. Zeitsch. f. wiss. Zool., Bd. xii, p. 59, taf. v, f. 10—18. 1863. Ptychodes splendida, Diesing. Nachtrage zur Revis. der Turb., p. 12. 1864. Cerebratulus spectabilis, Grube. Die Insel Lnssin u. ihre Meeresf., p. 94. 1869. Cerebratulus (Ommatoplea) spectabilis, Mcintosh. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, pp. 342 and 355. Habitat. — Dredged off St. Peter Port, Guernsey, at a depth of 18 — 20 fathoms, in a fissure of Eschara foliacea. Sicily, the Adriatic and St. Vaast-la-Hougue ; generally in the crevices of shells. Body rather more than three inches in length, and about a fifth of an inch in breadth, flat- tened ; dilating rather abruptly behind the snout, and again diminishing towards the tail. The margins are thin. Colour brownish, with six longitudinal brown stripes on the dorsum, and five pale inter- mediate lines. The two bands on each side of the central line are somewhat dark in colour, wide in front, narrow and somewhat closely applied posteriorly. The two adjoining brown belts become considerably wider towards the tail. Besides the foregoing there is also a marginal brown stripe, which is somewhat wider posteriorly. The tip and edges of the snout are pale, the four central brown bands of the dorsum being continued thereon, the two lateral becoming indistinct over the pigmentary region, the two central almost reaching the tip of the snout. All the four stripes are much narrowed and more closely approximated after passing the cephalic furrows, and the two lateral are in addition bent inwards towards the middle line at the latter. The under surface has a uniform pinkish colour, slightly marked within each border by a reddish coloration from the vessel. Head narrower than the rest of the body, somewhat conical, defined posteriorly by a very distinct notch on each side. The region assumes various shapes according to the motions of the animal, sometimes presenting a blunt tip with a notch in the centre and almost cylindrical, at others a dilated tip and a constricted posterior portion. In the recently captured animal the eye- specks are not very evident on the dorsum, but after it has been blanched by captivity, they are observed to form two rows on each side, the central having about ten eye-specks, and the lateral a larger number. The former are best seen on the dorsal, the latter on the ventral surface, or from the side, and they proceed further forward than the central, indeed, almost to the tip of the snout. In the inner rows the eyes are nearly equal in size, while in the outer there are some larger ones towards the front. Cephalic furrows. — Prom the notch, which on each side marks the posterior boundary of the snout, a well- marked furrow proceeds inwards and backwards, and is joined by eight or nine deep grooves which occupy the slightly dilated region immediately in front of the oblique furrow. These accessory grooves have in general a longitudinal direction, but they are curved in various 21 162 AMPHIPORUS HASTATUS. ways, and are of different lengths. On the under surface of the snout the lateral furrow follows a different course, being directed forward and inward on each side. This animal lives well in confinement; the sole specimen procured at Guernsey in the end of July survived till the middle of November. At this time it discharged a vast number of ova and perished in their midst, so that the effort of spawning had been too much for its health, or the water had become vitiated by the fluids exuded during the process. When irritated it swam rapidly through the water like A. pulcher, but generally lay quiescent on the bottom of the vessel surrounded by a delicate mucous investment, the body being shortened and thickened, but the head narrow and papilliform. It has strictly the structure of the Amphiporidce, the longitudinal bands of the reticulated layer of the pinkish proboscis being very apparent. The blood is reddish-pink. The species was first described in a recognizable manner by M. de Quatrefages, and though his drawing of the complete animal and its head are not quite accurate, their identity is satisfac- torily made out. He does not say anything about the blood of this form, but he mentions that in Cerebratulus crassus it is reddish, and this with other points at one time inclined me to unite the species. The arrangement of the eyes is, at any rate, very similar, and if more pigment is added to the dorsum of the present form, the distinction only rests on the author's account of the stylets, on which comparatively little reliance can be placed. It was erroneously described as a new species by the lamented Prof. Keferstein under the name Borlasia splendida, and as having the mouth behind the ganglia ; but he correctly interpreted the structure of the stylet-region of the proboscis. Prof. Grube accepted the anatomy given by M. de Quatrefages, and did not dissect the animal himself. The Folia pusitta of Delle Chiaje (Descrip. e Notom., &c, torn, iii, p. 126, tav. 103, figs. 13 — 15) is a closely allied species. Amphiporus hastatus, n. s. Plate VIII, fig. 2. Specific character. — Snout not wider than the succeeding portion of the body, with a grooved median ridge; ungulate when viewed laterally, hastate when seen from the dorsum. Eyes somewhat indistinct. Brownish yellow, with white grains on the snout. Habitat. — In seven fathoms Bressay Sound, Shetland, amongst tangle-roots attached to horse-mussels. Body about an inch and three fourths long, and a seventh of an inch broad, rather rounded, gently dilating from the snout backwards, a slight diminution only occurring at the tail, which is thick and broad. The edges of the body are not thinned off, as in A. pulcher and others. Colour pinkish ; very much resembling that variety of A. lactifloreus, the hue being deepest in front, behind the reddish spots caused by the ganglia. The snout is paler than the subsequent portion of the body, and shows a series of whitish grains on the upper surface. The proboscis and proboscidian fluid are visible in the median line of the body. The mouth (woodcut, fig. 9) has some grayish-brown pigment-grains along its margins, and there is a curved band of the same hue a little behind the tip of the snout on each side. The under surface of the body is generally paler than the upper. AMPHIPORUS BIOCULATUS. 163 Head with a snout narrower than the succeeding portion; bluntly pointed, and similar in shape to the head of a short spear or harpoon. In the median line is a grooved ridge, which, although cut by the cephalic furrow, is continued some distance along the dorsum of the body. On each side of the ridge is a longitudinal hollow on the snout. The eye- specks are placed a little behind the tip of the latter, and from their deep ~piG. 9. situation are somewhat indistinct. When viewed laterally the peculiar tapering of the snout resembles the hoof of a horse. The mouth is marked on the under surface, either as a slit like a key-hole, or as a linear depression (fig. 9) — ren- dered conspicuous by its pigment, according to the degree of contraction : in few species, indeed, is it so well seen. Cephalic furrows. — At the posterior border of the snout a well-marked groove proceeds inwards and slightly forward on each side to the median ridge, where a A-shaped process is formed by a sudden turn of the furrow inward and forward. The groove is continued on the ventral surface in a similar manner, and also has a slightly developed median angle at the mouth. Under surface of the This curious form combines the hardihood of A. lactifloreus with the irrita- anterior region of bilityof A. pulcher. It is exceedingly contractile, becoming quite baccate AmpHporusMsta- when stimulated ; the head being withdrawn through a collar of the body, as krged. in the latter species. The grooves of the snout during the various movements become much exaggerated, and give the animal a very characteristic appearance. In minute anatomy it belongs strictly to the Amphiporidce, the large proboscis, moreover, being furnished with four marginal stylet- sacs. Amphiporus bioculatus, n. s. Plate VIII, fig. 3. Specific character. — Dull orange ; snout acutely pointed, with a distinct cephalic furrow forming an angle directed forward at its posterior boundary. Eyes two, placed at the extreme tip of the snout. Habitat, — Amongst tangle-roots attached to horse-mussels, in eight fathoms, Bressay Sound, Shetland. Body about an inch in length, and rather more than a line in breadth, rounded, increasing in diameter from the pointed snout almost to the posterior third. The tail is rather blunt. Colour dull orange, or pale brownish, inclining to reddish in front, especially in the region of the snout. Under surface somewhat pale. Head with a small, pointed snout, which is bounded posteriorly by an angular furrow (woodcut, fig. 10). The mouth is indicated on the ventral surface by a streak running forward from the arch of the latter (woodcut, fig. 11). Two eyes, consisting of simple masses of black pigment, are observed at the tip of the upturned snout (woodcut, fig. 10). Cephalic furrows. — Viewed from the dorsum the furrow passes from each side of the snout inwards and forward, so as to form an angle. On the ventral surface, again, it makes an arch with the convexity directed forward, the slit for the mouth springing from the centre. The 164 TETRASTEMMA. course of the dorsal and ventral furrows is such that when the snout is seen in profile, a somewhat acute angle is formed at their junction on the side. This is another interesting species supplied by the rich tangle-roots on the mussel-ground of Fig. 10. Fig. 11 Outline of the anterior dorsal region of Amphiporus bioculatus. Enlarged. Ventral surface of the anterior region of A. hioculatus. Bressay Sound. It lives well in confinement, and it can be observed that, instead of the usual gliding progression of its allies, this form moves its snout in a boring manner. The specimens were loaded with fully-developed spermatozoa in the beginning of August. Genus II. — Tetuastemma, 1 Bhrenberg, 1831. Like many others of the race, the species of this genus were included amongst the Fasciolte by 0. F. Miiller, the first who, in the ' Zoologica Danica,' clearly described a species (Fasciola Candida). Ehrenberg, in establishing his genus Tetrastemma, in 1831, seized upon a very constant character; but we must dissociate it from many of the genera which formed along with it the anomalous Family Gyratricina. Though he describes the proboscis as being exserted from a transverse fold of the snout in his typical species, and hence apparently connecting it with Keferstein's Prosorhochmus, an attentive examination of the other parts of his description and his figures has convinced me that he alludes to a form identical with one not uncommon in Britain, viz., Tetrastemma flavida. Generic character. — Eyes four ; arranged so as to indicate a square or oblong. 1 Terpag, four, otejUjUci, a crown. TETRASTEMMA MELANOCEPHALA. 165 1. Tetrastemma melanocephala, Johnston. Plate II, fig. 1. Specific character. — A large mass of black pigment between the eyes. Marginal stylet-sacs placed considerably in front of the central apparatus. Synonyms. 1808. Planaria unipimctata, Montagu. MS., p. 236, tab. 55, f. 5. 1837. Nemertes melanocephala, Johnston. Mag. Zool. and Bot., vol. i, p. 535, pi. 17, f. 5. 1842-3. „ „ (Ersted. Kroyer's Naturhist. Tidskr., iv, p. 577. 1844. „ „ Ibid. Entwurf. Plattw., p. 88. 1846. Prostoma melanocephala, Johnston. Ann. Nat. Hist., vol. 16, p. 436. „ Nemertes melanocephala, W. Thompson. Ann. Nat. Hist., vol. xviii, p. 387. „ Polia coronata, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 213. „ ,, pulchella, Ibid. Op. cit., p. 214. 1849. „ coronata, De Quatrefages. Voyage en Sicilie, vol. ii, p. 125, pi. 13, f. 6—9. „ „ pulchella, Ibid. Op. cit., p. 126, pi. 16, f. 7 and 8. 1850. (Erstedia pulchella, Diesing. Syst. Helm., vol. i, p. 248. „ Nemertes melanocephala, Ibid. Op. cit., p. 270. „ „ coronata, Ibid. Op. cit., p. 271. 1859. Loxorrhochma coronatum, Schmarda. Neue wirb. Thiere, i, i, p. 39. 1862. Tetrastemma menalocephalum, Diesing. Revis. der Turbell., p. 291. „ Loxorrhochma coronatum, Ibid. Op. cit., p. 295. 1865. Omatoplea melanocephala, Johnston. Catalogue Brit. Mus., p. 23, pi. na, f. 5 and 5*. 1866. „ „ Lankester. Ann. Nat. Hist., 3rd ser., vol. 17, p. 388. 1867. Cephalotrix unipunctata, Parfitt. Catal. Annel. Devonsh., p. 5. „ Omatoplea melanocephala, Ibid. Ibid., p. 7. 1868. Ommatoplea „ Mcintosh. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. 1869. „ „ Ibid. Trans. Boy. Soc. Edinb., vol. xxv, pt. ii, p. 333 et seq. Habitat. — Under stones between tide-marks, in crevices of rocks near low-water mark, and ranging to twenty fathoms off Guernsey. Coast of France, and Sicily. Body two to two and a half inches in length, somewhat flattened in progression, rounded in contraction, gently dilating behind the head, then continuing of almost equal calibre until near the tail. Colour dull yellow, greenish yellow, or dull green ; occasionally with minute brownish pig- ment-grains along the sides. A large and somewhat quadrate black patch on the snout, in some cases with one faintly marked band of white pigment in front, and another— more distinct— posteriorly. In a specimen from deep water off Guernsey the dark spot on the head was nearly invisible, and the whitish pigment indistinct. The fluid in the proboscidian sheath causes a pale streak along the centre of the dorsum. Head flattened, much wider than the succeeding portion of the body, famished with a notch in front. The first two eyes are placed some distance behind the tip of the snout, and incorpo- rated with the anterior border of the black patch, so that they are not at first observed. The posterior eyes lie quite behind the pigment-patch, the white band, when present, intervening. 166 TETRASTEMMA ROBERTIAK.E. The pairs are equidistant. Rarely the single specks are represented by two or three smaller pigment-patches. Cephalic furrows, — An oblique furrow runs from the margin on each side inwards and backwards towards the posterior eye, and behind the latter two other grooves meet at an angle, as in A. lactifloreus, in the middle line of the dorsum. On the under surface of the snout a furrow passes from the cephalic pit inwards on each side ; and there is a continuation of the posterior furrows, as in the last-mentioned form. It is less hardy than A. lactifloreus in confinement, but can readily be kept several months. It remains chiefly at the water-line in a silky sheath of the tough transparent mucus. Almost every specimen in the free state in the Channel Islands was furnished path the latter, though the case was less transparent on account of the adherent debris. The skin gives an acid reaction to test-paper. I have not yet seen a specimen of this species with ova or spermatozoa, so that it must breed very late or very early. The young soon acquire the black patch on the snout, and other characteristics. It was absent from the rocks at St. Andrews in April and May. This species was first discriminated by Col. Montagu under the name Planaria unipunc- tata, though Dr. Johnston's title has the priority by publication. The former described the species, which he procured on the south coast of Devonshire, as follows : — " Body filiform, with a black subquadrangular spot that nearly covers the head, behind which are two minute black eyes, distant from each other." The Planaria ascaridea of the same author had the " body long, linear, white, with a square black spot close to the anterior end," and in all probability is to be referred to the same species. Length one inch. Moreover, though he describes the square black spot of Planaria filum as situated between the pairs of eyes, this too can scarcely be any other animal than that now under discussion. (Ersted remarks that there is a transverse brown bar between the eyes of his Tetrastemma rufescens, but there is no other character to connect it with this form. It is probable Professor Kolliker refers to the same species under the name Nemertes Knochii (Krohnii?), as he describes a transverse brownish-red band of pigment on the head. There is no doubt of the identity of the present species with the Polia coronata of M. de Quatrefages, from Brehat, though his figure of the head is faulty, and the colour peculiar, since he states that the spot between the eyes has a violet hue. The Polia pulchella of the same author, from Sicily, seems to be a greenish variety, in which the pigment- patch on the head is separated from the eyes in front and behind by a larger interval than usual. 2. Tetrastemma eobertiais 1 ^, n. s. Plate III, fig 1. Specific character. — Anterior pair of eyes larger than the posterior, which are sometimes quite hidden in 'the pigment-belt; body longitudinally striped with two brown and a median white line. Habitat, — Dredged in four fathoms in Lochmaddy amongst tangles, and from the roots of the same seaweeds in Bressay Sound at a depth of six to eight fathoms. Body about l|th inch long, flattened, rather narrowed in front, then gently dilating towards the tail, which is slightly tapered, and furnished with a somewhat thin margin. TETRASTEMMA CANDIDA. 167 Fig. 12. Colour a uniform dull pinkish or pinkish-brown, marked on the dorsum by three stripes — a central white and two lateral brown belts. The latter commence at a ring of the same colour which surrounds the posterior boundary of the snout, and proceed backwards to the tail, where they join ; and the central white line follows a similar course. They are not close to each other, but a stripe of the usual ground-colour of the dorsum intervenes. The abdominal surface has a pale pinkish-brown hue throughout, with the exception of the ventral portion of the brown ring in front. Head wider (in its greatest transverse diameter) than the succeeding portion of the body, spathulate, furnished with four black eyes, the anterior pair of which is the larger, while the posterior specks are closer and just in front of the transverse pigment-belt. The mouth is a well-marked longitudinal slit, in the usual position on the ventral surface. Cephalic furrows. — These pass inwards and backwards from the prominent angles of the snout on the dorsum towards the posterior pair of eyes. The lateral notch is seen on the ventral surface, but the direction of the furrows thereafter (if such exist) is indistinct. In a pale example from Shetland the brown ring anteriorly appears only on the dorsum, and the central white line is somewhat faint. In the coloured drawing (Plate III, fig. 1) only two eyes are visible, the posterior pair being covered by the great development of the pigment-belt. The ordinary condition is represented in the woodcut fig. 12. CErsted describes a Tetrastemma bioculata, but the snout in his species is peculiarly acuminate, and he indicates no stripes or other colouring of note. Dorsal view of the an- terior region of Te- trastemma Bober- tiance. Enlarged. 3. Tetrastemma Candida, 0. F. Mutter, 1774. Plate II, figs. 2 and 3. Specific character. — Head flattened, wider than the rest of the body ; eyes distinct. Stylets large. Colour pale yellow, greenish, or reddish. Synonyms. 1774. Fasciola Candida, O. F. Muller. Verm, terrest. et fluv. hist., i, ii, p. 71. 1776. Planaria Candida, Ibid. Zool. Dan. Prodr., p. 223, No. 2704. 1780. „ „ O. Fabricius. Fauna Grcenlandica, p. 327. 1788. „ }i Linnaeus (Gmelin). Syst. Nat., torn, i, pars vi, p. 3094. 1798. „ „ O. Fabricius. Skrivt. af Naturhist. Selskab., iv, p. 62, tab. 11, f. 11 1828. „ „ Bosc. Hist. Nat. des Vers., i, p. 262. 1829. Planaria quadrioculata, Johnston. Zool. Jour., vol. iv, p. 56. 1837. Nemertes quadrioculata, Ibid. Mag. Zool. and Bot., vol. i, p. 535, pi. 17, f. 4. „ Tetrastemma varicolor (partim), CErsted. Kroyer's Naturhist. Tids., iv, p. 575. 1844. „ candidum, Ibid. Entw. Plattw., p. 88. „ „ varicolor (partim), Ibid. Op. cit., p. 85, f. 41 and 44. „ „ „ Ibid. De Region, marin., p. 79. 168 TETRASTEMMA CANDIDA. 1846. Prostoma quadrioculata, Johnston. Ann. Nat. Hist., vol. xvi, p. 436. „ Polia quadrioculata, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 216, pi. 11, f. 1 . 1847. „ „ Prey u. Leuckart. Beitrage z. Kennt. wirb. Thiere, p. 150. 1849. „ „ De Qnatrefages. Voyage en Sicilie, vol. ii, p. 128, pi. 16, f. 10 and 11. 1850. Tetrastemma varicolor, Diesing. Syst. Helm., vol. i, p. 257. „ „ grcenlandicum, Ibid. Op. cit., p. 259. „ „ Krohnii, Siebold. Archiv fiir Naturges., ii, p. 382. 1851. „ varicolor, Maitland. Descrip. syst. anim. Belg. septent., p. 190. 1853. Vermiculus coluber? var., Dalyell. Pow. Creat., vol. ii, p. 91, pi. 10, f. 24. „ Planaria alga, Ibid. Op. cit., p. 117, pi. 16, f. 24 and 25. 1858. Polia quadrioculata, Williams. Philos. Trans., 1858, p. 131. 1859. Tetrastemma algce, Leuckart. Archiv fiir Naturges., ii, p. 188. 1860. Polia obscura (partim), Van Beneden. Mem. Acad. Belg., torn, xxxii, p. 23, pi. 4, f. 2, 4, &c. „ „ capitata, Ibid. Op. cit., p. 28, pi. 4, f. 12, &c. „ „ farinosa, Ibid. Op. cit., p. 29, pi. 4, f. 17. 1861. Tetrastemma varicolor? Claparede. Recher. Anat. snr les Annel. Turb., &c, p. 81, pi. 5, f. 6. 1862. „ „ (partim), Diesing. Revis. der Turbell., p. 289. ,, „ obscurum (partim), Ibid. Op. cit., p. 291. „ „ capitatum, Ibid. Op. cit., p. 292. „ „ grcenlandicum, Ibid. Op. cit., p. 293. „ „ farinosum, Ibid. Op. cit., p. 293. „ Loocorrhochma obscurum, Ibid. Op. cit., p. 295. 1863. Tetrastemma varicolor, Diesing. Nachtrage zur Revis. der Turbell., p. 10. „ „ algae, Ibid. Op. cit., p. 11. 1864. Polia quadrioculata, Grube. Die Insel Lussin u. ihre Meeresf., p. 96. 1865. Tetrastemma varicolor (partim), Johnston. Catalogue Brit. Mus., pp. 20 and 289. „ „ algce, Johnston. Op. cit., p. 20. 1865-6. Polia quadriocellata, De Quatrefages. Hist. Nat. des Anneles, pi. 4, f. 2. 1869. Tetrastemma algae, Mcintosh. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 339 et seq. Habitat. — Not uncommon under stones near low-water mark, especially amongst the algae and corallines which cover their surfaces, and, indeed, one of the best modes of procuring the species is to immerse portions of such stones in sea-water, when the animals seek the water- line and are easily observed. It extends from the Shetland to the Channel Islands. Body one to one and a half inch long, and nearly a line in breadth ; somewhat flattened, narrowed behind the head, and again tapered towards the tail. Colour. — Various shades of grass- or siskin-green, but females bearing ova have a dull grayish aspect. Some varieties, also, are pale yellow. The head is usually paler than the rest of the animal. Two dull red spots indicate the ganglia. A Zetlandic variety occurs in Bressay Sound of a reddish-brown colour, and in some a few white grains are situated between the anterior pair of eyes. Head much flattened, spathulate, wider than the succeeding portion of the body, with a pale streak in the median line anteriorly, where there is also a slight notch. Eyes four, forming a square ; by the lengthening of the snout, however, they are placed at the corners of an oblong. Cephalic furrows. — The two oblique anterior furrows course inwards near the posterior pair of eyes, and cause a notch at the margin of the snout in front of the latter. The posterior pair were TETRASTEMMA VEKMICULA. 169 only examined in small examples, and they were very indistinct, but they probably have the same direction as in other species. A variety was dredged off St. Peter Port, Guernsey, in 10 fathoms, with the eyes of large size, very pale, and with whitish grains from the tip of the snout backwards between the pairs. The stylet- region had the posterior border of the muscular investment nearly transverse, but pro- bably this was abnormal, as in all other respects it agreed with that of T. Candida. This is a very restless species, constantly gliding about with considerable speed ; indeed, it is one of the most active of the group. It is tolerably hardy, and will survive more than twenty- four hours on a moist stone in a room. In Bressay Sound the variety above mentioned abounds amongst Obelia geniculata about half-tide mark, as well as amongst Corallina bored by Leucodore at the extreme verge of high-water. Whether the variety shown in Plate III, fig. 5, and having a pale orange hue, will prove to be specifically different on further investigation, I am at present unable to say, as the drawing was the sole remembrance brought by my sister in one of her excursions. It was procured from the deep water off St. Andrews Bay. The ova are developed in April and May, as well as in autumn. I am inclined to refer the Fasciola Candida of 0. P. Miiller to this common and variable form. It was discovered by 0. Pabricius under stones on the shores of Greenland, and his specimens were unusually large, viz. from two to three inches, the only doubtful feature in the description. (Ersted's Tetrastemma varicolor, again, seems to include both this species and T. dor salis. The occurrence of a single stylet-sac in the example of M. de Quatrefages is purely accidental. The Vermiculus coluber of Sir J. Dalyell is probably a pinkish variety of this form, and not T. melanocepkala. M. van Beneden included this along with others under his Folia obscura, and the Polia farinosa of the same author presents no feature different from the young of this species. M. Claparede's T. varicolor comes under the same head, a view supported by his figure of the stylet -region. This is the only Nemertean mentioned in Maitland's ' Pauna Belgii septentrionalis.' 4. Tetrastemma vermictjla, JDe Quatrefages. Plate III, fig. 3. Specific character. —A longitudinal dark patch between the eyes of the respective sides. Synonyms. 1846. Polia vermiculus, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 214. 1849. „ „ Ibid. Voyage en Sicilie, vol. ii, p. 126, pi. 14, f. 12 and 13. 1850. Nemertes vermiculus, Diesing. Syst. Helm., vol. i, p. 270. 1862. Tetrastemma vermiculus, Ibid. Revis. der Turbell., p. 290. 1869. „ „ Mcintosh, Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 339 et seq. Habitat. — Not uncommon under stones between tide-marks, and occasionally dredged in the laminarian region, from the North of Scotland to the Channel Islands. Coast of France (Brehat). 22 170 TBTEASTBMMA FLAVIDA. Body. — Three fourths to one inch in length, and about a line in breadth, moderately elon- gated, dilating very gradually behind the head, continuing for some distance of considerable diameter, and again diminishing towards the tail. Colour. — Dull. whitish, salmon, or pinkish, with two elongated dark spots on the head. In a specimen from St. Peter Port, Guernsey, the digestive tract was pale siskin-green. There was also a faint white streak on the middle of the dorsum, commencing between the posterior pair of eyes, and proceeding a short distance backwards. Bead wider than the succeeding portion of the body, flattened, having its greatest diameter in the middle, and marked by the cephalic furrows. Eyes four, the pairs separated by a con- siderable interval, which on each side is nearly filled up by a longitudinal patch of dark pigment. The latter is widest anteriorly, and often does not quite reach the posterior eye, which is thus prominent, while the anterior is indistinct. There is sometimes an opaque whitish patch between the anterior pair of eyes, and this is continued faintly along the central streak. Cephalic furrows. — A little in front of the posterior pair of eyes is the groove connected with the cephalic pit, which (furrow) passes inwards and slightly backwards on each side and soon terminates. Somewhat behind the posterior pair of eyes another furrow slants inwards and backwards, and meets its fellow of the opposite side in the middle line. T. vermicula in its lively and restless habits much resembles T. Candida. Many perish by crawling out of the water and being dried on the side of the vessel. The ova are deposited in a free condition about the beginning of May. I have placed this pretty species under the name of M. de Quatrefages, but with amended characters. He erroneously states that the head is not distinguished from the rest of the body, and that the marginal stylet-sacs are situated on the " dorsal and ventral " aspects of the pro- boscis. His figure, also, of the entire animal is too elongated, and his remark that the pigment- patch between the eyes of each side is violet can only refer to the aspect under transmitted light. Stimpson has a Tetrastemma (?) vermiculus in his 'Prodromus' (ii, p. 19), but its identity with the present form is doubtful. 5. Tetrastemma flavida, Bhrenberg. Plate IV, fig. 1. Specific character. — Head not wider than the rest of the body. Anterior and posterior pairs of eyes widely separated. Synonyms. 1831. Tetrastemma flavidum, Ehrenberg. Symb. Phys., Phyt. Turb., No. 25, tab. 5, f. 3, a— d, and a* — #; 1844-5. „ longecapitatum, (Ersted. Kroyer's Naturhist. Tids., i, p. 418. „ „ flavidum, Ibid. Op. cit., iv, p. 576, in note. Ibid. Entwurf Plattw., p. 87. 1846. Polia sangmrubra, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 208, tab. 11, f. 3 and 7; tab. 12, f. 1. 1849. „ „ Ibid. Voyage en Sicilie, voUii, p. 120, pi. 15, f. 11 and 12. TETRASTEMMA FLAVIDA. 171 1850. Tetrastemma flavidum, Diesing. Syst. Helm., vol. i, p. 257. „ Nemertes haematodes, Ibid. Op. cit., p. 270. 1860. Folia obscura (partim), Van Beneden. Mem. Acad. Belg., torn, xxxii; Recher. sur les Turb. (sep. copy), p. 23, pi. 4, f. 10. 1862. Tetrastemma flavidum, Diesing. Revis. der Turb., p. 289. „ , y sanguirubrum, Ibid. Op. cit., p. 290. „ „ longecapitatum, Ibid. Op. cit., p. 293. 1869. ,, varicolor, Mcintosh. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 339 et seq. Habitat. — Under stones between tide-marks and in fissures of rocks ; less common than T. Candida. From Scotland to the Red Sea. Body one to one inch and a half in length, attenuated, flattened, nearly of equal diameter throughout, except where slightly tapered towards head and tail. Colour pinkish or pale peach, from the hue of the digestive tract. The snout is translucent, with a slight opacity between and rather in front of the posterior pair of eyes, and a pale patch from the ganglia behind them. The lateral margins are pale. Head rather indistinctly defined, bluntly rounded at the tip, from the centre of which the usual pale streak proceeds. The eyes are equidistant in each pair, and the latter are separated from each other by a much longer interval than exists in T. Candida and the others. The anterior eyes have the larger masses of pigment. Cephalic furrows. — The openings of the cephalic sacs are placed nearly opposite the first pair of eyes, so that the anterior furrows are carried far forward. They slant inwards and back- wards just behind the eyes, while inferiorly they are nearly transverse. The posterior furrows lie a little behind the last pair of eyes, and, proceeding inwards and backwards, meet in the centre of the dorsum. They have a direction forward and inwards on the inferior surface, but less obliquely than on the dorsum ; thus, while the dorsal meet towards the posterior part of the ganglia, the ventral coalesce near the anterior border of the latter. The two sets of furrows are indicated by lateral notches. This species is more sluggish than T. Candida, and much more delicate. It resembles Nemertes carcinophila in the slow, gliding manner in which it moves about the vessel, a very gentle undulatory motion of the head and body taking place. The ova are developed in May. Prof. Ehrenberg first gave a description and drawing of this species. The equidistant eyes, with the pairs widely separated, and the cephalic furrows passing inwards nearly opposite the first pair, are fairly represented. The Tetrastemma assimile of (Ersted, no doubt, has the anterior and posterior pairs of eyes widely removed, but this is the only character which can be identified with the present species. The Folia sanguirubra of De Quatrefages, again, appears to be a variety with tinted nuclei to the proboscidian discs (a phenomenon probably due to refrac- tion of the rays of light), and the Sicilian Folia baculus of the same author differs only in the somewhat more attenuated condition of the snout. His Folia armata is also closely allied in external characters, but the presence of four stylet-sacs, if not accidental, is a distinguishing feature. Two of these marginal stylet-sacs, according to this author, occur a considerable way in front of the central stylet, or at the anterior part of the elongated stylet-region, and two behind, opposite the basal apparatus of the central organ. M. van Beneden seems to have included 172 TETRASTEMMA DORSALIS. specimens of this species under his Folia obscura. In the absence of more definite characters I have not thought it proper to place the Tetrastemma sanguirubra of Stimpson amongst the synonyms. 6. Tetrastemma dorsalis, Abildgaard. Plate I } fig. 4, and Plate III, fig. 4. Specific character. — Body short, thick and round, little tapered towards either extremity. Speckled with yellow and brown, or with a single dorsal stripe. Synonyms. 1806. Planaria dorsalis, Abildgaard. Zool. Danic, vol. iv, p. 25, tab. 142, f. 1 — 3. 1844. Tetrastemma fuscum, (Ersted. Kroyer's Naturhist. Tids., iv, p. 575. „ „ „ Ibid. Entw. Plattw., p. 86, woodcut 14. „ „ „ Ibid. De Region. Marin., p. 79. 1846. (Erstedia maculata, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 222, tab. 8, f. 2. „ „ tubicola, Ibid. Op. cit., p. 223. 1849. „ maculata, Ibid. Voyage en Sicilie, vol. ii, p. 134, pi. 17, f. 15 — 17. „ „ tubicola, Ibid. Op. cit., p. 135, pi. 17, f. 18 and 19. 1850. „ maculata, Diesing. Syst. Helm., vol. i, p. 247. „ „ tubicola, Ibid. Op. cit., p. 247. „ Tetrastemma fuscum (partim), Ibid. Op. cit., p. 257. „ „ varicolor (partim), Ibid. Op. cit., p. 257. 1853. Vermiculus variegatus, Dalyell. Pow. Creat., vol. ii, p. 91, pi. 10, f. 25 and 26. ! 1859. Tetrastemma variegatum, Leuckart. Archiv fur Naturges., ii, p. 188. 1862. (Erstedia maculata, Diesing. Revis. der Turbell., p. 263. ' „ „ tubicola, Ibid. Op. cit., p. 263. „ Tetrastemma fuscum, Ibid. Op. cit., p. 289. 1863. „ variegatum, Ibid. Nachtrage zur Revis. der Turbell., p. 10. „ „ marmoratum, Claparede, Beobach. iiber Anat. u. Entwicklung., &c, p. 24, taf. 5, f. 14. 1865. „ variegatum, Johnston. Catalogue Brit. Mus., pp. 20 and 289. 1866. „ „ Lankester. Ann. Nat. Hist., 3rd Ser., vol. 17, p. 388. 1868. „ „ Mcintosh. Rept. Brit. Assoc, 1868, p. 340. 1869. „ „ Ibid. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 339 et seq. Habitat. — Abundant in the laminarian region, in three to ten fathoms, where it haunts Ceramium rubrum and other algae. It is also occasionally found under stones at extreme low water. Extends from Shetland to the Channel Islands. Body half to three quarters of an inch in length, and rather more than half a line in breadth. It is so round as to be nearly circular in transverse section, with the exception of a little flattening on the ventral surface ; very slightly tapered at either extremity. Colour. — On the coasts of Scotland two varieties are especially common. The most abun- dant form is of various shades of brown or reddish-brown, speckled with groups of yellowish- white granules, often of considerable size, which are placed along the centre of the dorsum from one TETRASTEMMA DORSALIS. 173 end of the body to the other, but they do not form a continuous stripe. In some there is also a distinct brown lateral line. The other variety is reddish -brown, with a pale yellow dorsal stripe from snout to tail. The sepia-brown grains of the dorsum are placed on a reddish- brown ground. As soon as the pigment of the body becomes dark enough, a fine purplish lustre is produced by the play of light on the cilia, and the animal assumes a rich velvety aspect. In these dark examples, with a reddish-yellow central stripe, the under surface of the snout generally presents two pale symmetrical ovoid spaces a little behind the line indicating the mouth. In some cases the yellowish grains are scattered over both dorsal and ventral surfaces, and are quite characteristic of the species. In a large example dredged in Bressay Sound the dorsum was curi- ously variegated with patches of cinnamon-brown on a general ground-colour of pale brown speckled with yellowish grains, the pale brown of the ventral surface having a few specks of the same hue as the dorsum. The ventral surface is somewhat pale in all cases, and occasionally assumes a dull brownish-orange posteriorly. When floating with the ventral surface uppermost, a brownish margin is generally visible. Young examples are occasionally reddish-orange. Head somewhat truncate and even notched in front, slightly narrowed posteriorly towards the cephalic furrows, and very little flattened. Eyes four, nearly in a square, the first pair being further from the tip of the snout than the last are from the cephalic furrows. They are deeply situated, and somewhat lateral in position — from the roundness of the snout when seen from above, and in profile appear considerably below the dorsal line. A variety from the harbour of Symbister, in Whalsay (Shetland), has the head somewhat pointed and better defined than usual, and the tail is also more tapered. Cephalic furrows. — The anterior furrows are not visible on the dorsum. The posterior slant inwards and slightly backwards some distance behind the posterior eyes, meeting in the middle line. On the ventral surface they are directed slightly forward. T. dorsalis is a marine rather than a littoral form, and sometimes occurs in vast numbers clinging to the debris of various seaweeds dredged in the laminarian region. It is hardy in con- finement, either gliding with scarcely an undulation of its body, or rolling its snout from side to side in a peculiar manner as it progresses along the glass. It is also fond of enclosing itself in a tough transparent sheath, which is fixed to the wall of the vessel at the water-line. The sheath is highly elastic, and, while remaining perfectly transparent under a high power, is yet minutely streaked with translucent granules or specks, which are not due to fine creases or folds. The animal often reverses itself in the tube, and is sometimes doubled therein. It is curious to watch the pertinacity with which it progresses in a definite direction to stretch itself along the water-line. The ova are deposited in the beginning of September, but some latitude is necessary in this respect, since specimens from deep water produced ova in June. This species was brought into notice by P. C. Abildgaard in the fourth volume of 0. F. Mutter's celebrated * Zoologica Danica ;' and though he did not observe the eyes, his account is otherwise good. He terms it an eyeless brown ' Planaria/ with a pale ventral surface and a white dorsal line, and which constantly twists itself and loves to swim on its back. M. de Quatrefages, again, made a distinction between two varieties of this species, one of which {(Erstedia tubicola), he said, formed a tube, while the other (0. maculata) did not. Moreover, he elevated them into a new genus— characterized by the sublateral position of the nerve-trunks, and their cylindrical bodies. Their structure, however, is in all respects strictly conformable to 174 PKOSORHOCHMUS CLAPAEEDIL the type of the Enopla. The large size of 0. maculata (3 to 3| in.) from the shores of Sicily is peculiar. Sir J. Dalyell says it is rare, and that its colour is universally variegated red and white, with a white line down the back, but his drawing shows only interrupted specks along the dorsum. This excellent author held the opinion, which I cannot endorse, that the Planaria dorsalis of Abildgaard referred to a fragment of Lineus bilineatus. The Tetrastemma marmoratum of M. Claparede, from the coast of Normandy, is the present species. The cylindrical form of the body had previously been known. Genus III. — Prosorhochmus, 1 Keferstein, 1863. The typical species of this genus was first mentioned by Col. Montagu (MS., Library of the Linnean Society), who, however, was inclined to refer it to the Planaria Candida of O. F. Muller. It is unlikely that so common a species escaped the notice of observers from the foregoing period up to 1863, the date at which Professor Keferstein published his descriptive characters of the genus in his ' Untersuchungen/ but it is probable that it was confounded with other forms. The four eyes which are characteristic of the previous genus are retained, only they do not form a rectangle. I would not place much weight (generically) on the ovo-viviparous character, as this is a condition which further investigation will probably extend to many genera. Generic character, — Eyes four, not forming a rectangle ; snout dimpled and furnished with a transverse superior lobe. Ovo-viviparous. Prosorhochmus Claparedii, Keferstein. Plate II, fig. 4. Specific character. — Snout blunt ; eyes placed far back, the space between the anterior pair widest ; yellowish. Other characters as in the genus. Synonyms. 1808. Planaria flava, Montagu. MS., p. 237, tab. 35, f. 2. 1846. Poliafumosa, De Quatrefages. Annal. des sc. nat., 3 me ser., Zool., vi, pp. 206-7. ? 1849. „ „ Ibid. Voyage en Sicilie, vol. ii, p. 118, pi. 14, f. 9—11. ? 1862. Prosorhochmus Claparedii, Keferstein. Zeitsch. f. wiss. Zool., Bd. xii, p. 61, taf. 6, f. 1 — 5, 1863. „ „ Diesing. Nachtrage zur Revis. der Turbell., p. 10. „ ,, „ Claparede, Beobach. uber Anat. u. Entwick., p. 23, taf. 5, f. 10 — 12. 1869. „ „ Mcintosh. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 344 et seq. Habitat. — Under stones, and in fissures of rocks between tide-marks, on the southern shores of England, and in the Channel Islands. Body an inch to an inch and a half in length, and three quarters of a line in breadth, flat- tened, somewhat narrowed behind the head, then gradually dilating, continuing for some distance of nearly equal diameter, and again diminishing towards the tail. In those examples in which the ovisacs are filled with developing young the body is round. The anus is very distinct. 1 7rpoo-w, the front, and pwxi^og, a fissure. PEOSOEHOCHMUS CLAPAEEDII. 175 Colour pale yellow, or, in some, pale orange, with two translucent spots behind the eyes, marking the situation of the ganglia. Long confinement increases the number of the dull orange grains on the dorsum. The young have numerous orange pigment-specks in their skins at birth. Head wider than the succeeding portion of the body, though not distinctly defined poste- riorly, broadly spathulate as well as somewhat truncate in front, and with a well-marked central notch from which a pale streak proceeds some distance behind the ganglia. Just behind the notch is a transverse furrow, furnished with very long cilia, which have a radiate appearance under the microscope. Eyes situated considerably behind the tip of the snout, the anterior pair being the larger, and while those of opposite sides are widely apart, those on the same side are closely approximated. The anterior pair under pressure often present a crescentic margin in front, and I have seen a clear globule in connection with them, which may represent a lens. In profile the two halves of the snout in front form a pair of large and prominent lips, with the mouth underneath and behind— in the shape of a well-marked elliptical or ovoid slit, while a third lobe, less prominent, occurs on the dorsum. The trilobed condition of the snout is well seen in small specimens placed between glasses separated by a chip. Cephalic furrows. — A very slight notch is observed opposite the first pair of eyes, which indicates the opening of the cephalic pit, and an indistinct furrow runs from this point inwards. P. Claparedii is not so active and restless in its movements as some of its allies, but it is the most hardy four-eyed example of the Enopla I have yet seen, even more so than T. dorsalis. The specimens bore a journey from the Channel Islands to Scotland without the loss of one, or rather with a considerable increase, since the adults gave birth to numerous young individuals. It is interesting to see the comparatively large embryo moving in the interior of the adult, with- out interfering with its comfort in any way. They are observed in the bodies of their parents in July, and some remained there till October, having meantime considerably increased in size. Under pressure the embryos sometimes escape per anum. Both young and old are fond of leaving the water and remaining on the side of the vessel in the open air, and dozens of the former are frequently found floating on the thin whitish film which gathers on the surface of the sea-water after long keeping. They appear to be somewhat social animals in the free condition, as groups of adults (from ten to fifteen in number) are occasionally found in fissures of the rocks at St. Peter Port, Guernsey. If the indefatigable Col. Montagu had published his notes and figure of this species it now would have borne his name. He describes it as " long, filiform, yellow, with the front rounded and slightly bifid. Pour eyes placed quadrangular." Pive were found entwined together on the coast of Devon. He thought it might be the Planaria Candida of Muller, but the arrangement of the eyes and other points in his figure, together with the description, show its real nature. CErsted remarks that the anterior pair of eyes in his Tetrastemma subpellucidum are widest apart, but we are otherwise left in doubt as to the actual species he describes. The Polia fumosa of M. de Quatrefages has certain close resemblances to this form, such as the arrangement of the eyes and the truncated snout, and it is difficult to see to what species the author refers if not to this. The colouring of the figure (op. cit., fig. ix, a, b) is much too dark, and the outline not at all characteristic. The enlarged anterior end, however, in fig. x, though not accurate, can scarcely apply to any other species. He found it in fissures of the rocks at St. Vaast and Brehat. It was not till more than half a century after the English naturalist's observations 176 NEMERTES GRACILIS. that Prof. Keferstein published his account of the animal from specimens collected at St. Vaast- la-Hougue. His statement, however, that its mouth is behind the ganglia is erroneous, and it may be remarked that the position of the mouth is more easily seen in this species than usual. The occurrence of three marginal stylet-sacs in some examples is evidently accidental or abnormal. The notched condition of the anterior border of the snout, so characteristic of this species, is very conspicuous in a large and flattened member of the Enopla, from New Zealand, in the British Museum. The specimens (in spirit) are about three inches long. Sub-Family — Nemertin^s. Proboscis proportionally small. Genus IV. — Nemertes, Cuvier, 1817 (Char, emend.). Cuvier founded this genus for the description of Lineus marinus, which previously had received other names, and therefore the new title ought to have lapsed. But being set abroad by a zoologist so distinguished, it naturally came to be much employed in describing numerous and often diverse genera, as well as used by subsequent authors as the title of the entire order. Though the genus was first established, therefore, for the reception of one of the Anopla, yet the name has very frequently been bestowed on forms belonging to the Enopla, and, besides, claims attention from its priority, both as a generic title and as applied to one of the typical forms {Nemertes gracilis) of this genus. Generic character. — Body more or less elongated, while the proboscis is very much diminished, the anterior region of the organ especially being shortened, so as to cause the central stylet to approach the ganglia. 1. Nemertes gracilis, Johnston. Plate II, fig. 5. Specific character. — Eyes numerous; snout broader than the rest of the body; central stylet of proboscis with an extremely long basal apparatus. Greenish or olive. Synonyms. 1837. Nemertes gracilis } Johnston. Mag. Zool. and Bot., vol. i, p. 534, pi. 17, f. 1. 1841. „ „ W. Thompson. Ann. Nat. Hist., vol. vii, p. 482. 1844. Polystemma gracile, (Ersted. Entw. Plattw., p. 93. 1846. Prostoma gracilis j Johnston. Ann. Nat. Hist., vol. xvi, p. 435. „ Nemertes balmea } De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 197 ; tab. 9, f. 3—6 ; tab. 11, f. 2, and 4 ; and tab. 12, f. 2. 1849. „ „ Ibid. Voyage en Sicilie, vol. ii, p. 109, pi. 10, f. 6 and 7, and pi. 19, f. 3—6. NEMERTES GRACILIS. 177 1850. Omatoplea balmea, Diesing. Syst. Helm., vol. i, p. 249. » » gracilis, Ibid. Op. cit., p. 250. 1862 - » balmea, Ibid. Revision der Turbell., p. 255. » » gracilis, Ibid. Op. cit., p. 255. 1865 - » » Johnston. Catalogue Brit. Mus., p. 22, pi. ii a, f. 1 and 1*. 1869 - w « Mcintosh. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 334 et seq. Habitat. — Frequent under stones between tide-marks, and especially abounding under tangle-roots at low water. No example, however, was met with during an excursion to the Channel Islands. Body.— Eight to twenty inches in length, and about a line in breadth, flattened in progression, and thrown into ever-varying wrinkles, dilatations and contractions. The diameter is nearly uniform for a considerable distance behind the head, and then the body gradually tapers towards the tail. It is occasionally attenuated to a mere thread. Colour.— Dull greyish-green on the dorsum, deepest in front, and somewhat duskier in the centre from the hue of the alimentary tract. Some incline to bluish-green anteriorly, others are dull olive throughout. There are two reddish specks (due to the ganglia) behind the head. In some specimens the dorsum for a short distance posterior to the latter is marked with minute pale specks or with black pigment-grains, the latter occasionally continuing to the tip of the tail. The under surface is greyish-white, dappled in the ripe females with dull whitish spots from the ova. The reddish colorations from the ganglia are best observed on this surface, and there is also a pale streak in the oesophageal region. Head. — Somewhat spathulate, flattened, rather blunt at the tip, and slightly dilated laterally, so as to be wider than the rest of the body. Eyes arranged in two or three groups on each side, the anterior cluster containing the larger number, and being situated just within the pale border of the snout. The number of eyes in this series ranges from five to nine, but, as usual, it is variable. The next group is placed distinctly posterior, nearer the middle line of the head, and consists of three, four, or five eyes, which in some are transversely arranged. The third cluster lies at the anterior border of the ganglion, or, occasionally, proceeds backwards along the outer border of the latter. The first-mentioned groups are visible from the ventral surface. Cephalic furrows. — There are no evident furrows on the dorsum of the head, and inferiorly there is only the central slit of the mouth. This species lives a considerable time in confinement. Sometimes, when it has stretched its snout beyond the water-line, while its tail reaches the bottom of the vessel, it assumes a very regular spiral arrangement. If the snout be loosened from its attachment, the body is at once gracefully shortened, like the stalk of a Vorticella or a coiled spring. It can also attenuate itself to an extreme degree. It secretes a very tenacious, transparent mucus, especially when irritated, and envelopes itself therewith, apparently for protection. The fine threads of this secretion are so tough that they support the animal when lifted above the surface of the water. The skin is acid to test-paper. Nemertes gracilis spawns in May. This animal was discovered by Dr. Johnston on the coast near Berwick, a region that became so rich in novelties under his patient and searching scrutiny. It was re-described many years later by M. de Quatrefages under the name Nemertes balmea, from Brehat. The French 23 178 NEMERTES NEESII. author did not observe any cephalic furrows, or " genital aperture" (mouth), and therefore he concluded that the latter was a temporary orifice. Its mouth occupies the usual position. 2. Nemertes Neesii, CErsted. Plate III, fig. 6 ; and var., Plate VII, fig. 6. Specific character. — Eyes numerous. Stylets short and grooved. Streaked with purplish- brown on the dorsum. Synonyms. 1828. Planaria flaccida, Johnston. Zool. Journ., vol. iii, p. 488. 1844. Amphiporus Neesii, CErsted. Kroyer's Naturhist. Tids., iv, p. 581. „ „ „ Ibid. Entw. Plattw., p. 95. 1846. Borlasia? flaccida, Johnston. Ann. Nat. Hist., vol. xvi, p. 435. „ „ camillea, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 194, tab. 9, f. 1, and tab. 14, f. 3. 1849. „ „ Ibid. Voyage en Sicilie, vol. ii, p. 106, pi. 10, f. 4 and 5. „ Amphiporus Neesii, Leuckart. Archiv fur Naturges., i, p. 149. 1850. „ „ Diesing. Syst. Helm., vol. i, p. 245. „ Nemertes camillea, Ibid. Op. cit., p. 274. 1853. Gordius fuscus, Dalyell. Pow. Creat., vol. ii, p. 83, pi. 9, f. 15 to 17, and pi. 12. 1859. Amphiporus Neesii, Leuckart. Archiv fur Naturges., ii, p. 187. 1862. Borlasia Neesii, Diesing. Revis. der Turbell., p. 249. „ Emplectonema camillea, Ibid. Op. cit., p. 306. 1865. Serpentaria fusca, Johnston. Catalogue Brit. Mus., pp. 28 and 298. 1865-6. Borlasia Camilla, De Quatrefages. Hist. Nat. des Anneles, pi. 4, f. 14. 1866. Serpentaria fusca, Lankester. Ann. Nat. Hist., 3rd ser., vol. xvii, p. 389. 1868. Ommatoplea purpurea, Mcintosh. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. „ „ „ Ibid. Report Brit. Assoc, 1868, p. 340. 1869. „ „ Ibid. Trans. Roy. Soc. Edinb., vol. xxv, p. 336 et seq. Habitat. — Under stones between tide-marks, in crevices of rocks and tangle-roots near low water, and in fissures of the Gouliot caves, Sark. It also occurs on the tangle-ground in Shetland, and in deep water off the east coast of Scotland. Ranges from Iceland to the Channel Islands. Body. — Pour to eighteen inches in length, and, in large specimens, about a quarter of an inch in breadth, elongated, much flattened, appearing almost of equal diameter throughout, though in reality slightly tapering towards the posterior end. It is generally thrown into numerous equidistant transverse wrinkles, which are only obliterated in extreme extension. Colour. — -Variously speckled madder-brown, with a faint purplish iridescence from the play of light on the cilia. Towards the anterior part of the body the specks are more marked, and the general colour somewhat paler, especially on the head. Behind the latter the dorsum assumes a streaky appearance, brown being the predominant hue, with longitudinal flesh- coloured stripes, all of an interrupted character. The lateral regions abound with brown NEMERTES NEESII. 179 specks. Towards the tail the colour again becomes paler, and the dorsal specks more numerous. The entire under surface is pale pinkish -white, or skin-coloured. In the darker specimens the streaks are less numerous, though more boldly marked. Some examples are of a very pale brownish hue, the dorsum having only pale brown pigment-grains and no streaks. Other varieties, again, are very curiously mottled, like polished rosewood or walnut, or of a faint yellow, speckled with brown. Young specimens from deep water are occasionally almost white, or faint skin-colour, and some have a uniform dull orange hue, from the digestive chamber. The proboscis in the latter examples is pale pink. Young specimens, and those from dark recesses, are generally pale. Head. — Spathulate, wider than the rest of the body, with a pale margin, and a central streak from the notch or dimple in front backwards. Eyes numerous, arranged in two dense clusters on each side — a little behind the tip of the snout. Unless in pale specimens, they are distinguished with difficulty on account of the dark coloration of the dorsum. They are larger than the eye- specks of N. gracilis. Cephalic furrows. — The snout is bounded posteriorly by two dorsal transverse grooves, which also mark a slight constriction. On the under surface two furrows slant outwards and backwards from the mouth, a short distance behind the tip of the snout, and from these the openings of the cephalic pits proceed. They are visible as two curved lines, which do not reach the lateral margin of the body, and thus are wholly ventral. N. Neesiiis rather plentifully distributed on our coasts, four or five being occasionally pro- cured under one stone, or in a fissure of the shelving rocks. The facility with which it coils and twists its body in all directions is most interesting. Sometimes the posterior part of the animal lies in a tangled knot, while the anterior extends outwards as a long screw, the alternate dark and light shades of the dorsal and ventral surfaces forming a very agreeable contrast ; and from the frequency with which it assumes this attractive position one might be excused in attributing to the animal some sense of the splendour with which nature has endowed it. It floats with ease on the surface of the water, the body being thrown into various undulations, as when progressing on the surface of the ground, though, of course, more slowly and less distinctly. It is killed by immersion in fresh water, the body before death being surrounded by a tough coating of mucus, like many of its allies and the Dorides. The skin is alkaline to test- paper. In one specimen of a pale brick-red hue, from Guernsey, the muscular investment of the basal apparatus of the central stylet was abnormal (a state that could scarcely have resulted from dege- neration, for it was examined on the third day after capture), being elongated posteriorly and split into processes like rootlets, from the peculiarities of the fibres. It spawns in March and April. The Linens maculosus of Montagu (MS., p. 274) can scarcely refer to any other British form than the above. It is described as "rufous-brown, mottled, beneath white, resembling L. marinus. Length more than a foot, and not larger than Gordius aquaticus." Dr. Johnston, however, first published an account of the species, from a specimen coiled in a valve of Saxicava rugosa, from deep water in Berwick Bay. The Amphiporus Neesii of (Ersted, as R. Leuckart mentions, is clearly synonymous with the Gordius fuscus of Dalyell (the present species), and as GErsted's specific title is free from the objections connected with Johnston's, it has been chosen. Sir J. Dalyell noticed its tendency to coil in knots. His examples spawned in April, the ova t80 NEMERTES CARCINOPHILA. merely lying in a " thin albuminous matter" (probably mucus), and covering the bottom of a vessel two inches in diameter. He hazarded the opinion that the mouth was apparently in the anterior part. There is nothing to indicate specific distinction from the present form in the description and figures of the Borlasia camillea of De Quatrefages. I cannot, however, make the same statement with regard to the Emplectonema camillea of Stimpson and the Nemertes camillea of Williams. Two specimens in the British Museum, from Greenland, have very short, thick bodies, and the proboscis in each is proportionally large ; but these appearances may be due in some respects to the mode of preparation. This species has sometimes been confounded with " Serpentaria fragilis" (Cerebratulus angulatus). 3. Nemertes carcinophila, Kolliker. Plate I, fig. 5. Specific character. — Eyes two ; proboscis furnished with a central stylet only. Body of a pale pink colour. Synonyms. 1845. Nemertes carcinophilos, Kolliker. Verhandl. d. Schweiz. naturf. Gesellsch. in Chur., p 89. 1850. „ „ Von Siebold. Archiv far Naturges., p. 382. 1860. Folia involuta, Van Beneden. Keener, sur les Turbell. (sep. copy, from Mem. Acad. Belg., torn. xxxii), p. 18, pi. 3. 1862. Cephalothrix involuta, Diesing. Revis. der Turbell., p. 254. „ Nemertes carcinophila, Ibid. Op. cit., p. 298. 1869. Polia involuta (Nemertes carcinophila, Kolliker), Mcintosh. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 309 et seq. Habitat. — Abounds in tubes attached to the abdominal hairs of female specimens of Carcinus mcenas bearing ova. Messina and the Coast of Belgium. Body. — One to two inches long, scarcely so thick as a thread during extension, flat- tened, nearly equal in diameter throughout, or very slightly tapered at head and tail. Colour. — Pale skin or slightly pinkish; pale rose-pink in contraction or when coiled en masse. There is a pale patch behind the snout, indicating the region of the proboscis. Head. — Slightly tapered towards the anterior end, not defined from the rest of the body, and ending in a blunt snout. Eyes two, situated considerably behind the tip of the latter. It is a somewhat sluggish animal, lying doubled in its sheath, or when removed gliding about the vessel in a slow, feeble manner. It is also less hardy in confinement than the majority of the group. N. carcinophila spawns in April, and it is easy to watch the development of the young. Prof. Kolliker first found the worm in its usual position on a small crab at Messina, and his account of it is quite characteristic. This paper, however, escaped the notice of M. van Beneden, who re-described it as a new species from " Cancer mcenas" many years subsequently. It is not strictly a parasite of the shore-crab, but, like diverse annelids in other sites, it seems to find the hairs of the abdominal feet of females bearing ova a convenient position for its sheaths, and LINEUS MARINUS. 181 probably for protection and a proper supply of food. In the same way the Tetrastemma before mentioned frequents the branchial chambers of the Ascidians, the Planaria angulata of Agassiz (not Miiller) the under surface of Zimulus, and the Planaria the cavities of the Medusas ; or, as Harmothoe imbricata, Polynoe areolata, and others, live in harmony with Chcetopterus norvegicus in its tube, and Polynoe scolqpendrina with Marphysa sanguinea and Terebella nebulosa in their tunnels. Prof, van Beneden, however, correctly indicates its affinity with the Prorhynchus stagnalis of Max Schultze, a freshwater species, and gives an interesting if not strictly accurate account of its development. Sub- Order— ANOFLA. Proboscis without stylets. Family II. — Lineid^e. Genus V. — Lineus, 1 Sowerby, 1806. The typical species of this genus was one of the first Nemerteans known to~ science, viz. the Gordius marinus of Montagu. The generic name employed by the latter, however, as he himself was well aware, could not stand ; and while he was waiting till the discovery of other species would enable him to give a more comprehensive description of the genus, Sowerby published ' The British Miscellany/ in which the generic name above mentioned was bestowed on the same characteristic species. Generic character. — Body more or less elongated, rounded or somewhat flattened, and tapered posteriorly. Head distinct, spathulate, and generally truncate in front. Eyes numerous, arranged along the sides of the snout anteriorly ; rarely absent. Mouth in the form of a con- spicuous longitudinal slit on the ventral surface. Other characters as in the family. 1. Lineus marinus, Montagu. Plate IX; and Plate XVIII, figs. 1 — 3. Specific character. — Eyes numerous, deeply set in a marginal row on each side of the snout. Of a blackish or very dark olive colour, more or less distinctly streaked longitudinally. Body rather rounded. Synonyms. 1758. Sea-Long Worm, Borlase. Nat. Hist. Cornwall, p. 255, tab. 26, f. 13. 1804, Gordius marinus, Montagu. Linn. Trans., vol. vii, p. 72. 1806. Lineus longissimus, T. W. Simmons. Sowerby's Brit. Misc., p. 15, pi. 8. 1 Linea, a line. 182 LINEUS MARINUS. 1807. Lineus longissimus, Tur ton's British Fauna, p. 130. 1808. „ marinus, Montagu. MS., p. 271. 1811. „ longissimus, Jameson. Wernerian Memoirs, vol. i, p. 557. 1812. Gordius marinus. Pennant's British Zoology, vol. iv, p. 74. 1815. Borlasia anglice, Oken. Lehrbuch, &c., p. 365, tab. xi, f. 4. „ Gordius marinus, Davies. Trans. Linn. Soc, vol. xi, p. 292. 1816. „ „ Ibid. Lond. Med. and Phys. Jour., xxxvi, pp. 207-9. 1817. „ „ Ibid. Extr. in Isis, 1817, pp. 1054-56. „ Nemertes Borlasii, Cuvier. Reg. An., tome iv, p. 37. 1828. Borlasia anglice, De Blainville. Diet, des sc. nat., 57, p. 575 -, ibid., Atlas, Parentomozoaires, f. 1 a—\ d. 1834. Nemertes Borlasii. Griffith's Cuv., vol. xii, p. 468. 1836. Borlasia longissimus, Templeton. Loud. Mag. Nat. Hist., vol. ix, p. 236. 1838. Nemertes Borlasii, W. Thompson. Charlesworth's Mag. Nat. Hist., vol. ii, p. 21. 1843. Borlasia striata, Bathke. Beitr. z. Fauna Norweg. (Nov. Act. Nat. Curios., xx), p. 231. 1842-3. „ angli(B, OErsted. Kroyer's Naturhist. Tids., iv, p. 572, in nota. 1844. Nemertes Borlasii, Ibid. Entw. Plattw., p. 92. „ „ striata (Bathke), Ibid. Op. cit., p. 92. 1845. „ gracilis, H. Goodsir. Ann. Nat. Hist., vol. xv, p. 378, pi. 20, f. 3. 1845.? „ Borlasii, De Quatref. Eegne An. illust. (Zoophytes, 12 e livraison, pi. 83). 1846. Lineus longissimus, Johnston. Ann. Nat. Hist., vol. xvi, p. 435. „ „ gracilis, Ibid. Op. cit., p. 435. „ Borlasia anglice, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 192, tab. 8, f. 4 and 5 ; tab. 10, f. 8 ; tab. 12, f. 3 and 4 ; and tab. 13, f. 1—3 and 5—9. 1 849. „ „ Ibid. Voyage en Sicilie, vol. ii, p. 104, pi. 9, f. 7 ; pi. 11 ; and pi. 12, f. 2, &c. 1850. Meckelia Borlasii, Diesing. System. Helm., vol. i, p. 265. „ „ gracilis, Ibid. Op. cit., p. 268. „ Nemertes striata, Ibid. Op. cit., p. 274. 1851. Lineus longissimus, Williams. Eept. Brit. Assoc, 1851, p. 244, f. 64 (?) 1853. Gordius maocimus, Dalyell. Pow. Creat., vol. ii, p. 63, pi. 8, and pi. 9, f. 1. 1855. " An ascaroid or planarian worm." North Brit. Eeview, No. 43, p. 38. 1856. Borlasia nigra, Byerley. Fauna of Liverpool, p. 98. 1857. Nemertes Borlasii, De Quatrefages. Eamb. of a Naturalist, Eng. edit., vol. i, p. 116. 1859. „ „ Kingsley. Glaucus, p. 124, pi. 3, f. 1. „ Borlasia anglice, Leuckart. Archiv fur Naturges., ii, p. 187. 1860. Nemertes Quatrefagii, Van Beneden. Eecher. sur les Turb., &c, p. 15, pi. 2, f. 5— 9, var. 1862. Meckelia Borlasii, Diesing. Eevis. der Turbell., p. 285. „ „ gracilis, Ibid. Op. cit., p. 303. „ „ Quatrefagii, Ibid. Op. cit., p. 304. 1863. „ Borlasii, Diesing. Nachtrage z. Eevis. der Turbell., p. 8. 1865. Borlasia striata, Johnston. Catalogue Brit. Mus., pp. 22 and 291. „ „ longissimus, Ibid. Op. cit., pp. 25 and 293. „ „ gracilis, Ibid. Op. cit., pp. 26 and 295. „ „ lineatus, Ibid. Op. cit., pp. 26 and 295. „ „ murenoides, Ibid. Op. cit., p. 26. „ „ fasciatus, Ibid. Op. cit., pp. 26 and 295. 1866. ,, longissimus, Lankester. Ann. Nat. Hist., 3d ser., vol. xvii, p. 389. LINEUS MAKINUS. 183 1866. Borlasia gracilis, Ibid. Op. cit., p. 389. „ „ lineatus, Ibid. Op, cit., p. 389. 1867. „ longissimus, Parfitt. Catal. Annel. Devon, p. 8. „ „ lineatus, Ibid. Op. cit., p. 8. 1868. „ longissimus, Mcintosh. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. ,, j, „ Ibid. Proceed. Linn. Soc, vol. x, p. 251. „ „ „ Ibid. Rept. Brit. Assoc, 1868, p. 340. 1869. „ „ Ibid. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 374 et seq. Habitat. — Not uncommon under stones between tide-marks, either in or out of tidal pools, in fissures of rocks, amidst tangle-roots in the laminarian zone, and occasionally in deep water. Body, — Fifteen to thirty feet to as many yards in length, and from one to four lines in breadth, rather rounded, slightly narrowed behind the head, continuing of nearly equal calibre throughout the greater part, and then gradually narrowing towards the tail. Colour. — Blackish- brown, relieved throughout by the fine purplish iridescence of the cilia. The tip of the snout is pale or whitish, and there are three pale bands from this region backwards. The central passes along the body a considerable distance, but gradually becomes indistinct, and the two lateral, which follow a similar course on the dorsum, vanish sooner. In addition to the foregoing, a very distinct pale stripe commences on each side at the posterior part of the cephalic fissure, and courses along the infero-lateral region of the body to the tip of the tail Another well-marked stripe commences on the ventral surface at the centre of the snout, and continues along the middle nearly to the termination of the body. There is not much difference in colour between the dorsal and ventral surfaces. In young examples the brown is much paler, assuming an olive-brown or olive hue, and the stripes are more numerous and conspicuous; indeed, there is considerable variety in this respect. Generally, a reddish coloration is observed on both surfaces in the ganglionic region. The stripes exist on many good spirit- preparations, those on the head being especially distinct, and the slight eversion of the mouth causes a pale margin (or lip) all round. In dark specimens the lateral lines of the body are the most conspicuous. The rich dark colour of many shows that they are not unused to light in their native haunts. Head. — Wider than the succeeding portion of the body, narrowed towards the anterior and posterior borders. The tip of the snout is generally bilobed, with a distinct papilla in the centre and two small ones on each lateral eminence. On each side is a deep lateral fissure with large lips, the superior being often rolled or curved inwards. The fissures have the usual reddish hue posteriorly. There is a dense group of eyes on each side of the anterior margin of the snout, arranged in a longitudinal manner, or rather their outline forms a long wedge — narrow anteriorly and wide posteriorly. In very dark examples these eyes are not easily seen, indeed they have escaped the notice of many observers ; but if the animals are kept in confinement a long time, the bleaching of the snout renders them conspicuous, as may be noticed by contrast- ing the large coloured figure in Plate IX with Plate XVIII, fig. 1, which (latter) represents the head of the same specimen upwards of a year after its capture. In young animals the eyes are easily seen from the dorsum. This is unquestionably the giant of the race, and even now I am not quite satisfied about the limit of its growth, for after a severe storm in the spring of 1864 a specimen was thrown on shore at St. Andrews which half filled a dissecting jar eight inches wide and five inches deep. Thirty 184 LINETTS MARINUS. yards were measured without rupture, audyet the mass was not half uncoiled. It chiefly delights to lurk under stones not far from low- water mark, or in tidal pools, and is occasionally found looped like a living string of caoutchouc amongst the seaweeds fringing the sides of the latter. It is useless in such a case to attempt to capture the worm by pulling at the free end, for, although it resists considerable tension, rupture is apt to follow : it should be allowed to contract itself, and then lifted or rolled in a mass into the vessel. At first sight it seems strange that nature should have fashioned an animal so soft and apparently so helpless as this, devoid of arms either of offence or defence throughout its extreme length, and which, moreover, can be so easily ruptured. Yet the facility with which reproduction can take place in wounded examples on the one hand, and the shelter afforded by its site on the other, give it sufficient protection in the struggle for existence as an adult form, while the enormous powers of increase in the ordinary way by ova render the continuance of the species doubly secure. There is something remarkable in the movements of a large specimen of this huge worm, as its quivering body emerges from a dark creek in one of the little caverns that abound amongst the tidal rocks. No useless bustle warns its companions of its approach, but it glides silently forward with its exploratory snout, and scatters the smaller inhabitants by the very stealth and suddenness of its appearance. Some may even be excused in reckoning it the evil genius of the pool — dark, slimy and mysterious, moving hither and thither, as it were, by an invisible^agency, and whose ways, like the inextricable knots and coils of its serpentiform body, are difficult to find out. It is not to be more harshly judged, however, than the young Cotti, Shannies, and Cyclojpteri, that shelter themselves from its approach amidst the blades of the trailing tangles, the Hippolytes and Mysidce that reconnoitre it from under the fringes of Corallina, Ulva and Cramium, the Idoteidce and Caprellidce that climb monkey-like on their branches, or than the sluggish Doris adherent to the variously tinted Halichondria. All are equally pre- datory, and subserve the special ends for which they live ; and if the elongated worm preys by stealth and not by swift and open attack, this is due to its physical constitution, and not to any acquired vice or degradation. If it swallows its prey alive, it is, at any rate, devoid of instruments of laceration or torture, such as the jaws of its higher allies or the thread-cells of the Hydrozoa. Z. marinus lives well in confinement, and, without receiving any food, will survive for years, though the body greatly diminishes in size, both as regards length and thickness. Indeed, as in other examples, the insensible consumption of the formed tissues supports the animal under circumstances so abnormal, for we cannot place any weight upon food derived from microscopic organisms in so limited a supply of salt water, and one so rarely or never changed. Sickly specimens die from behind forward piece by piece, a fresh portion being thrown off at intervals until the head is reached. It is fond of taking refuge in tubes ; thus a small one captured at Herm thrust out the rightful owner (a Protula), coiled itself therein, and is now preserved in situ. Several have also been found with the body looped through a broken Trochus or Littorina, which formed a kind of anchor in the runlets of sea-water in which their protecting stones lay. Not only do some fragmentary specimens, when put in spirit, turn themselves inside out, as Sir J. Dalyell saw in the living animal in salt water, but more than once I have been puzzled when making transverse sections by finding one part of the body doubled quite within the other, and this for a considerable distance. The entire skin gives a marked acid reaction to test-paper. The breeding season would seem to be in June, but spermatozoa have been found fully LINEUS GESSERENSIS. 185 developed in May and September. Sir J. Dalyell had a specimen which discharged innumerable white ova in May. This Nemertean was first noticed by the Rev. W. Borlase, under the name of the Sea-Long Worm, but it received its scientific title from Col. Montagu. If subsequent writers on the Nemerteans had had the privilege of consulting the manuscript of this author, great confusion would have been avoided, and this not more conspicuously than in the present instance. He had observed the variable colours — from dusky to rufous-brown, and striped more or less plainly — of adults and young specimens. His description, on the whole, is excellent, though, in common with many other naturalists, he omitted to notice the eyes ; and in his early account in the ' Linnean Transactions' it is probable he thought the proboscis the excreta. He makes the curious remark, that " It is not fragile unless contracted by spirits, for we have generally measured the length by winding upon a cylinder of wood of known circumference, suffering five or six feet of the animal to be pendent, in order to ascertain as nearly as possible the utmost length. In this state they have been suffered to die, and rarely break by contraction. " Prof. Jameson observes that it was " noticed many years ago by my friend Mr. Neill, afterwards transmitted by the late Mr. Simonds to Mr. Sowerby, who has figured and described it ... in his e British Miscellany/ ' He calls it the Black Worm of the Newhaven fishermen. The Rev. Hugh Davies did not see the eyes, and rather vaguely conjectured that it advanced by coiling its " amazing length into a compact spiral, each volution of which assisted in the act of progression," a supposition only less wide of the truth than that of M. de Quatrefages, who mentions that it glides through the water by means of excessively fine cilia. Sir J. Dalyell, again, considered that small examples floated less by their specific levity than by the repulsion of the lubricating matter investing the body, a method somewhat involved in obscurity. I am not satisfied that the Opkiocephalus murenoides of Delle Chiaje is this species ; indeed, the flattened form and pointed snout shown in a figure in his ' Descrizione 5 point this out rather as allied to Cerebratulus angulatus, Miiller, than to the present species. The so-called specimens of Lineus murenoides, also, of British naturalists, are all referable to L. marinus. I have included M. van Beneden's Nemertes Quatrefagii under the same head, for it seems to be only a pale and young variety, with the stripes distinctly marked. The arrangement of the eyes, as noted by this author in regard to his supposed new form, is equally characteristic of L. marinus. 2. Lineus gesseuensis, 0. F. Mutter. Plate IV, fig. 2; and Plate V, fig. 1. Specific character. — Eyes numerous, marginal. Snout distinctly wider than the rest of the body. Greenish, olive or reddish-brown. Synonyms. 1766. Alia Lumbrici marini species, tota atra, Pallas. Miscell. Zool., p. 216, tab. 11, f. 9. 1771. Der Stromische Rod-Aat., O. F. Miiller. Wurm-Arten des sussen u. salzigen W., p. 118, tab. iii, figs. 1—3. ] 774. Ascaris rubra, O. F. Miiller. Verm, terrest. et fluv. Hist., vol. i, ii, p. 36. 1776. „ „ Ibid. Zool. Danic. Prodr., p. 213, No. 2587. 1780. Planaria fusca, O. Fabricius. Fauna Greenland ica, p. 324. 24 186 LINEUS GESSERENSIS. 1788. Planaria gesserensis, O. F. Muller. Zool. Dame, ii, p. 32, tab. 64, f. 5 — 8. ), „ 33 Gmelin. Linn. Syst. Nat., torn, i, pars vi, p. 3093. 3 798. „ fuscescens, O. Fabricius. Skriv. af Naturhist. Selsk., iv, ii, pp. 58—62, tab. 11, f. 8—10 (?) 1816. „ gesserensis, Lamarck. Hist. Nat. des an. sans vert., vol. iii, p. 179. 1827. „ „ Bosc. Hist. Nat. des vers, i, p. 262. 1829. „ bioculata, Johnston. Zool. Jour., vol. iv, p. 56. 1837. Nemertes (Borlasia) olivacea, Johnston. Mag. Zool. and Bot., vol. i, p. 536, pi. 18, f. 1. 33 33 purpurea, Ibid. Op. cit., p. 537, pi. 18, f. 3. 1843. Borlasia rufa, Rathke. Beitrage z. Fauna Norweg., p. 234 (?). „ Meckelia olivacea, Ibid. Op. cit., p. 234. 1842-3. Planaria gesserensis, (Ersted. Kroyer's Naturhist. Tids., iv, p. 572, in nota. „ Nemertes olivacea, Ibid. Op. cit., p. 578. „ „ purpurea, Ibid. Op. cit., p. 579, in nota. 1844. Tricelis gesserensis, (Ersted. Entw. Plattw., p. 27. „ Nemertes olivacea, Ibid. Op. cit., p. 89. „ „ fuscescens, Ibid. Op. cit., p. 92. „ „ purpurea, Ibid. Op. cit., p. 91. 1846. Borlasia olivacea, Johnston. Ann. Nat. Hist., vol. xvi, p. 434. „ 33 33 W. Thompson. Op. cit., vol. xviii, p. 388. „ „ purpurea, Ibid. Op. cit., p. 388. 1847. „ rufa, Frey u. Leuckart. Beitrage z. Kennt. wirb. Thiere, p. 72, tab. 1, f. 15 and 16; var. 1849. Nemertes fusca, Leuckart. Archiv fur Naturges., i, p. 152. 1850. Notospermus gesserensis, Diesing. Syst. Helm., vol. i, p. 260. „ Meckelia olivacea, Ibid. Op. cit., p. 264. „ „ fusca, Ibid. Op. cit., p. 266. „ Nemertes rufa, Ibid. Op. cit., p. 271. „ „ olivacea, Ibid. Op. cit., p. 273. „ „ purpurea, Ibid. Op. cit., p. 275. 1852. „ olivacea, Max Schultze. Zeitsch. f. wiss. Zool., iv, p. 178. 1853. Gordius minor viridis, Dalyell. Pow. Creat., vol. ii, p. 72, pi. 9, f. 2 — 7. „ „ gesserensis, Ibid. Op. cit., p. 73, pi. 10, f. 5. „ Vermiculus lineatus, Ibid. Op. cit., p. 90, pi. 10, f. 19 and 20 (young with two eyes). 1857. Cerebratulus oleaginus, Stimpson. Proceed. Acad. Nat. Sc. Philad., p. 160. „ Nemertes olivacea, Max Schultze. Icones Zootom. (V. Carus), tab. 8, f. 14. 1859. Meckelia olivacea, Leuckart. Archiv fur Naturges., ii, p. 187. „ Gordius gesserensis, Ibid. Op. cit., p. 187. „ Nemertes olivacea, Ibid. Op. cit., p. 187. 1860. „ flaccida, Van Beneden. Recher. sur les Turb., &c, p. 14, pi. i, f. 14—17 (?) 1862. Meckelia oleagina, Diesing. Revis. der Turbell., p. 280. „ „ fusca, Ibid. Op. cit., p. 285. „ Nemertes rufa, Ibid. Op. cit., p. 298. „ „ gesserensis, Ibid. Op. cit., p. 299. „ „ purpurea, Ibid. Op. cit., p. 299. } , „ olivacea, Ibid. Op. cit., p. 300. „ „ „ Keferstein. Zeitsch. fur wiss. Zool., Bd. xii, p. 66. } , Meckelia olivacea, Diesing. Nachtiage zur Revis. der Turbell., p. 8. „ Gordius gesserensis, Ibid. Op. cit., p. 14. „ Nemertes olivacea, Ibid. Op. cit., p. 14. LINEUS GESSERENSIS. 187 1865. Borlasia olivacea, Johnston. Catalogue Brit. Mus., pp. 21 and 289, pi. lib, f. 1 and 1*. „ ,, gesserensis, Ibid. Op. cit., pp. 21 and 290. y , Lineus viridis, Jbid. Op. cit., pp. 27 and 296. 1866. Borlasia olivacea, Lankester. Ann. Nat. Hist., 3rd ser., vol. xviii, p. 388. 1867. „ „ Mcintosh. Jour. Micros. Sc. ; Trans., p. 39. 1868. „ „ Ibid. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. 1869. „ „ Ibid. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 371 et seq. Habitat. — Abundant on all our shores under stones between tide-marks, and in the laminarian region, from the Shetland to the Channel Islands. Body. — Pour to nine inches in length, breadth a line and a half or more, flattened, tapered towards the head, and more distinctly towards the tail ; marked by numerous pale transverse wrinkles, somewhat regularly disposed, and most conspicuous in pale specimens. Colour. — Two very distinct hues are characteristic of this species, viz. reddish-brown and dull olive, while pale reddish and green varieties are also occasionally met with. The pigment is generally darkest in front, before and behind the reddish mark in the ganglionic region, the rest of the body being uniformly tinted except towards the tail, which is paler. The snout is sur- rounded by a broad pale margin, as far back as the termination of the fissures. The ciliation gives the body under certain conditions either a purplish or an opalescent hue. The sides are often marked with numerous pale spots, from the generative apertures. The ventral surface is paler than the dorsal, especially towards the snout, which is also reddish posteriorly. The mouth is surrounded by a pale margin. Party-coloured varieties are sometimes found, the anterior region, for instance, being dark green mottled with white, while the posterior half is quite pale. Such bleaching is different from that caused by parasitic attacks. Head. — Somewhat elongated, flattened, spathulate, rather truncate in front, with a small central and two lateral papillae, and having on each side — from the tip of the snout backwards — a deep fissure with pale edges and a pinkish bottom, the latter hue being most distinct posteriorly. It tapers slightly anteriorly, and is decidedly wider than the succeeding portion of the body, on account of the lips of the lateral fissures. The eyes are situated at the anterior central pig- mentary portion of the snout, and number from three to six or more on each side, the largest being generally in front. They are not always symmetrical ; three, for example, occurring on one side, and occasionally eight on the other, besides some indistinct grains. The mouth opens as a longitudinal slit a short distance behind the ganglia. L. gesserensis progresses in an easy, graceful manner, with slight undulatory motions of the head, its body being marked with successive contractile waves, which proceed from before back- wards. The specimens frequently herd together in the water, which they are prone to leave, and remain attached to the side of the glass a considerable time. They are very easily kept in confinement for years ; but, as with many of their allies, great diminution of bulk occurs, from deprivation of the natural supply of food. When recently captured specimens are placed in a jar containing injured Annelida, numerous faecal masses, consisting of the bristles of Nereis pelagica, and other annelids and digested matter, are found lying on the bottom of the vessel, showing how greedily they have fed ; a fact, indeed, very easily ascertained by actual observation. It is also frequently noticed that specimens confined in vessels along with the deep green Eulalia viridis assume a similar hue, probably from feeding on the rejected debris of those animals, if not upon the latter themselves. In their native haunts the stones under which they lie 188 LINEUS SANGUINEUS. are often placed on dark, muddy and highly odoriferous sand or gravel, and the water cannot be otherwise than brackish at the estuary of a river. The skin of this species gives an acid reaction. The ova are deposited in gelatinous sheaths from January to May, and abound under stones in pools and moist places between tide-marks. The want of precision in the descriptions of authors has burdened the literature of the present group of animals with diverse synonyms, especially as regards this widely distributed species. Though 0. F. Miiller's specific name rubra has the priority, and fusca comes next in order, yet, as each of these terms implies something at variance with the true description of the species, as contrasted with others, or retains some elements of doubt, I have chosen the suc- ceeding title, viz. gesserensis (of the same author), as more appropriate. His description of the form under the latter name, and the accompanying figure, leave no room for uncertainty, even the pale specks for the exit of the reproductive elements being noticed on the sides. Miiller's Ascaris rubra was probably a small specimen of the same worm. Tor some time I was inclined to include Planar ia viridis under the present species, but the thick or almost baccate appear- ance of some of the figures in the * Zoologica Danica' gives rise to so much doubt that I have not deemed it prudent to unite them. The Planaria carnea of Jens Rathke (' Skrivter af Naturhist. Selskabet,' &c, 5 te Bd., p. 83, tab. iii, f. 10, a, b) appears to be referable to this common form. It is doubtful whether the Lineus oculatus of Montagu (MS.) applies to L. gesserensis or to L. sanguineus. Dr. Johnston first described the species as having two eyes, but, as OErsted states, the author had only seen a young specimen. He afterwards gave it four eyes, but the number of the latter is of little moment, since the animals are so liable to vary in this respect. Dr. Johnston also observed the presence of the gregariniform parasites for the first time, though he did not correctly interpret their nature. The Nemertes obscura of E. Desor, from the coast of the United States, is allied in the closest manner to this species, and the Nemertes flaccida of M. van Beneden is either a pale variety of the same or L. sanguineus. 3. Lineus sanguineus, Jens Bathke. Plate V, fig. 2. Specific character. — Eyes more regularly arranged than in the foregoing ; snout narrower. Body more elongated, and of a reddish or reddish-brown hue. Regenerates easily. Synonyms. 1799. Planaria sanguinea, Jens Rathke. Skrivter af Naturhist. Selsk., vol. v, i, p. 83. 1828. „ unicolor, Johnston. Zool. Jour., vol. iii, p. 488 (?) 1829. „ octoculata, Ibid. Op. cit., vol. iv, p. 56. 1837. Nemertes (Borlasia) octoculata, Ibid. Mag. Zool. and Bot., vol. i, p. 537, pi. 18, f. 2. „ „ „ (Ersted. Kroyer's Naturhist. Tids., iv, p. 579, in nota. „ Planaria sanguinea, Ibid. Op. cit., pp. 572 and 579, in nota. 1844. Nemertes octoculata, Ibid. Entw. Plattw., p. 91. „ „ sanguinea, Ibid. Op. cit., p. 92. 1846. Borlasia octoculata, Johnston. Ann. Nat. Hist., vol. xvi, p. 434. LINEUS SANGUINEUS. 189 1846. Borlasia octoculata, W. Thompson. Ann. Nat. Hist.,, vol. xviii, p. 388 (?) 1850. Nemertes octoculata, Diesing. Syst. Helm., vol. i, p. 276. „ „ sanguinea, Ibid. Op. cit., p. 276. 1856. „ octoculata, Byerley. Fauna of Liverpool, p. 98. 1860. „ communis, Van Beneden. Recher. sur les Turb., p. 7, pi. i, f. 1 — 13. 1862. „ octoculata, Keferstein. Zeitsch. f. wiss. Zool., Bd. xii, p. 63, taf. 7, f. 1 and 2. „ „ communis, Diesing. Bevis. der Turbell., p. 302. „ „ octoculata, Ibid. Op. cit., p. 305. „ „ sanguinea, Diesing. Op. cit., p. 305. „ „ octoculata, Ibid. Nachtrage z. Bevis. der Turbell., p. 14. 1865. Borlasia octoculata, Johnston. Catalogue Brit. Mus., pp. 21, 287, and 290, pi. ii b, f. 2 and 2*. 1866. „ „ Lankester. Ann. Nat. Hist., 3rd ser., vol. xvii, p. 388. 1867. „ „ Mcintosh. Jour. Micros. Sc. ; Trans., p. 39. 1868. „ „ Ibid. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. „ „ „ Ibid. Proceed. Linn. Soc, Zool., vol. x, p. 251, tab. 7. 1869. „ „ Ibid. Trans. Boy. Soc. Edinb., vol. xxv, pt. ii, p. 374 et seq. Habitat. — Under stones between tide-marks; less abundant than Lineus gesserensis, but having a similar range in the British Islands. Body. — Four to eight inches long, and about a line and a half in breadth, flattened, of nearly equal diameter for some distance behind the head, and then gradually diminishing towards the tail. It is always proportionally much longer and more slender than Lineus gesserensis. The dorsum is crossed, sometimes at rather distant intervals, by transverse lines, which cause a dimple at each side, and it is probably at these furrows that rupture so frequently occurs. Colour. — Various shades of red and brown. Some specimens anteriorly are of a very bright red, which becomes fainter posteriorly, the caudal region being pale brown. In the dark brown examples the ganglionic region (not the ganglia) is bright red, the succeeding portion of the dorsum dull brownish-red, and then dark brown, the latter gradually becoming paler towards the tip of the tail. The under surface is somewhat paler. Head. — This differs from that of the former species by being scarcely wider than the suc- ceeding portion of the body. Its posterior boundary can just be distinguished dorsally by the slight indentations at the termination of the cephalic fissures. The whole region is narrow, flat- tened, slightly tapered towards the tip, which is pale, and furnished with a central and two lateral papillae, or, as the case may be, with a notch and two lateral papillae. The eyes are placed further back than in L. gesserensis, are more distinctly defined, and form a regular row on each side, to the number of three or four. The lateral fissures have narrow lips, and extend from the tip of the snout backwards. The mouth opens in a pale space some distance behind the ganglia. The worm is much longer and more slender than L. gesserensis, from which it is at first sight distinguished by the fine reddish coloration anteriorly. It is also a less active and restless species, and is prone to seek shelter under shells and stones, or in fissures and tubes, where it remains in a quiescent condition for weeks. It frequently lies coiled as a firm ball amongst the debris in the vessel, or loosely on the bottom, so that when the vessel is held obliquely the speci- mens roll from side to side. On account of these retiring habits it is somewhat difficult to get a good view of the animal. This may, however, be accomplished by transferring ^the hidden or coiled worm to another vessel of salt water, when the change of element generally causes it to 190 LINEUS LACTEUS. move out of its shelter or unroll. It readily reproduces heads or other portions in fragments of its body, so that the irritation and discomfort of a long journey in a jar is found occasionally to increase rather than diminish the number of specimens. The skin is acid to litmus-paper. Z. sanguineus feeds on Harmothoe imbricata and other annelids in a decaying or at least dead condition. The ova are developed in October. After some hesitation I have referred the Planaria sanguinea of Jens Rathke to this species. The Planaria unicolor of Dr. Johnston may also be the same animal; indeed, so far as can be made out, it does not approach any other form. His preparation of Borlasia purpurea in the British Museum belongs to the same species. This author does not seem to have been aware that several varieties of Lineus gesserensis have a reddish-brown colour, when he described this hue as distinctive of the present species, yet he probably had the true Z. sanguineus before him. M. van Beneden remarks that his Nemertes communis is distinguished from L. gesserensis by the length of the body and the double row of eyes. The latter character occurs in both species ; and while his form, probably, differs from Z. gesserensis, he does not satisfy us as to its separation from Z. sanguineus. I have made Prof. Keferstein's Nemertes octoculata synonymous after some doubt, since there is little in his description to distinguish it from a pale variety of Z. 4. Lineus lactetjs, Montagu, MS. Plate V, fig. 3. Specific character. — Snout similar to the foregoing, but the mouth is placed much further behind the ganglia. Body reddish anteriorly, pale posteriorly. Synonyms. 1808. Lineus lacteus, Montagu. MS., p. 275. 1867. Borlasia lactea, Mcintosh. Quart. Jour. Micros. Sc. ; Trans., p. 39. „ „ „ Parfitt. Catal. Annel. Devon. (Ext. Trans. Devonsh. Assoc, for the Advancement of Sc, &c), p. 6. 1868. „ „ Mcintosh. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. 1869. „ „ Ibid. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 372 et seq. Habitat. — South coast of England, under stones between tide-marks. Body. — One to two feet in length, rather less than a line in breadth, flattened, almost insensibly tapered from head to tail, and marked by pale transverse lines. In contraction it is rounded, and very frequently the animal advances with its body thrown into various stiff wrinkles and dilated portions. Colour. — Uniform dull whitish or cream-yellow, with the regions before and behind the ganglia (three quarters of an inch or more) of a fine rose-pink, which gradually fades posteriorly. The coloured region behind the ganglia corresponds to the long circulatory space in front of the mouth. Snout and tail translucent. Head. — Elongated, very slightly broader than the succeeding portion of the body, and in many positions narrower, tapered anteriorly, with the tip rather rounded, and furnished with three papillae. It is distinguished posteriorly by a slight incurvation at the termination of the cephalic LINEUS BILINEATUS. 191 fissures, which are rather shallow. Eyes forming a nearly parallel row on each side, distinctly separated, and to the number of six or eight in each row r . They are not symmetrically arranged, and a considerable translucent space exists between their commencement and the tip of the snout. The mouth is situated much further back than in Lineus sanguineus, to which it is other- wise closely related. Seven or eight specimens were sent me, in October, 1866, by Mr. Parfltt, of the Devon and Exeter Institution, in a tin box, and a few are still alive (Dec, 1871), so that they exhibit the usual hardihood in confinement. In progression the head is often ribbed in a longitudinal manner. When irritated, the extended worm contracts, generally in a spiral or closely coiled manner, and sometimes in a form so regularly twisted as to resemble a rope with its strands. It advances by gentle undulations of the body, and frequently the head is rolled from side to side. The worm also readily forms itself into a knotted mass, as well as stretches to an extreme degree of tenuity. The skin presents an acid reaction. This is one of the many discoveries made by the acute and persevering Montagu on the southern coast. There are few external characters in the description of the animal that had escaped him. It is doubtful whether Prof. Grube's Nemertes lactea from Villafranca ('Archiv fur Naturges.,' 1851, p. 151, taf. 7, f. 3 and 4) coincides with our species. His enlarged drawing of the head has certainly many more eyes, and the orange specks on the dorsum are quite different. Moreover, it is scarcely to be supposed that this author would not mention so impor- tant a point as the distance of the mouth behind the ganglia. He states that the " mouth is rounded/' and about two millimetres from the snout. Dr. Johnston's preparation of Lineus aldus, Dalyell, in the British Museum, resembles the present species very closely. 5. Lineus bilineatus, Delle Chiaje. Plate VI, fig. 1. Specific character. — Head rather rounded anteriorly ; eyeless. Body pale brown or dull pinkish, with a white stripe on each side of a dorsal median line. Synonyms. 1841. Folia bilineata, Delle Chiaje. Descr. e Notom. deglianim. invert., torn, hi, p. 126, tab. 103, f. 11 and 12. 1844. Nemertes bilineata, (Ersted. Entw. Plattw., p. 91. 1850. Meckelia bilineata, Diesing. Syst. Helm., vol. i, p. 264. „ „ cerebratulus, Ibid. Op. cit., p. 269. 1853. Gordius taenia, Dalyell. Pow. Creat., vol. ii, p. 70, pi. 10, f. 1 — 4. 1860. Cerebratula (Erstedii, Van Beneden. Eecher. sur les Turbell., p. 16, pi. 2, f. 1—4. 1862. Cerebratulus bilineatus, Ibid. Op. cit., p. 273. „ Meckelia (Erstedii, Diesing. Revis. der Turb., p. 286. „ „ cerebratulus, Ibid. Op. cit., p. 286. 1865. „ taenia, Johnston. Catalogue Brit. Mus., pp. 28 and 298. 1866. „ „ Lankester. Ann. Nat. Hist., 3rd ser., vol. xvii, p. 389. 1868. Cerebratulus taenia, Mcintosh. Kept. Brit. Assoc, 1858, p. 340. 1869. „ bilineatus, Ibid. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 374 et seq. 192 LINEUS BILINEATUS. Habitat. — Generally occurs in somewhat deep water on coralline ground, or oyster-beds, but also under stones and in cracks of oyster-shells between tide-marks. The largest specimen I have seen was procured from the stomach of a haddock caught off St. Andrews Bay. Body. — A few inches to a foot and a half in length, and of variable breadth ; not much flattened, except on the ventral surface, widest in front and gently tapering towards the pos- terior extremity. Colour. — Various shades of pale madder-brown, chocolate or reddish-brown, darkest in front, and gradually fading posteriorly. Prom the centre of the snout, just within the pale border, a white or yellowish stripe commences by a wide origin, which occupies nearly the whole breadth of the region, and proceeds to the tip of the tail along the middle line of the dorsum. It is widest anteriorly, and is rendered double by a dark central streak. Sometimes a young specimen presents an opaque white pigment-patch on each side of the usual central bands of the snout, so that by transmitted light the organ seems furnished with two large eyes. In a variety the anterior third was very pale, the rest of the body being of a bright rose or carmine colour. The under surface of the body is paler than the upper, especially towards the middle line and the region of the mouth. Specimens found in exposed places between tide-marks are darker than those from more sequestered regions. Head. — Flattened and somewhat spathulate, rather blunt anteriorly and.somewhat narrowed posteriorly at the termination of the .cephalic fissures, from which a slight depression slants inwards and backwards towards the central stripes. The lateral fissures are deep, and tinted of a vivid red colour towards the pit posteriorly. The narrowing of the snout anteriorly and poste- riorly gives it a somewhat elliptical or ovoid appearance. There is no trace of eyes or eye-specks. The mouth opens a short distance behind the ganglia. L. bilineatus is rather a sluggish species in confinement, but is easily preserved alive for years. It progresses with a rolling motion of the head, but will remain for weeks in a dormant condition under a shell or in a mass of hardened mucus. The skin is strongly acid to test-paper. I have not found specimens containing developed generative organs, but Sir J. Dalyell relates of his captives that a vast quantity of white ova, amidst a thin glairy matter, appeared in the vessel in June. I have little doubt the Folia bilineata of Delle Chiaje refers to this species ; and since he describes the Cerebratulus (Opkiocephalus) bilineatus of Renier as quite a different form, probably the same as the Nemertes peronea of De Quatrefages, with two dorsal black lines, I have omitted Renier's name altogether from the synonyms, for I have not been successful in seeing a copy of his early work. It is unlikely that so acute an observer as Delle Chiaje would confound the two species, especially as the published description of the first form was in his own language. Sir J. Dalyell thought the Planaria dorsalis of Abildgaard (Tetrastemma dorsalis) was pro- bably a mutilated fragment of this worm. M. van Beneden, again, not long ago described it as a new species from deep water off the Belgian coast. I have not been able to verify this author's remark, that there are three divisions in the alimentary canal, nor have I ever seen it or any other Nemertean " threatening its prey with its proboscis." In his c Nachtrage zur Revision der Turbellarien' Diesing erroneously places Dalyell's Gordius tcenia (the present form) under Omniatoplea jperonea. BORLASIA ELIZABETHS. 193 Genus VII. — Borlasia, 1 Oken, 1817. The genus Borlasia was formed by Oken in his ' Lehrbuch der Naturgeschichte' for the previously named Lineus marinus of Montagu, and therefore very properly was disused in that instance. Instead of applying the title to represent forms belonging to the Enopla, as Prof. Keferstein and others have done, I have chosen rather to bestow it on the present new type of the Anopla, a type, indeed, not far removed from that to which the name was originally given. Generic character. — Body round and massive, not tapered posteriorly. Snout acutely pointed. Proboscis extremely slender, furnished with elastic external, longitudinal, circular, and glandular coats. There are no accessory bands at the poles in transverse section. Circulatory fluid and muscles tinted reddish. Borlasia Elizabeths, n. s. Plate VII, figs. 1 and 2. Specific character. — Eyeless ; snout much tapered anteriorly. Posterior part generally contracted into a thick rugose mass. Head pale, faintly streaked with greenish brown ; body mottled with deep madder-brown. Habitat. — In a pool near low- water mark to the north of Rat Island, Herm. Body. — About a foot in length and a fifth of an inch in breadth, rounded in extension, flattened in contraction, tapering towards the snout, and also slightly towards the tail, which ends bluntly ; indeed, the posterior end generally forms a dilated mass with a dimple in the centre, and coarsely marked by transverse wrinkles. The body is seldom free from numerous longitudinal furrows, which are especially distinct anteriorly. Colour. — The head throughout two thirds of its length anteriorly is pure white, with olive-green specks ; for rather more than the posterior third, however, the deep purplish-brown and white touches of the dorsum occur. The speckled dorsum is marked at somewhat regular intervals by belts of pinkish white, which entirely surround the body. Some of the pale rings are broader than others, but there does not seem to be any regularity in this respect. They continue to the tip of the tail, but gradually grow faint posteriorly. The colours are brightest anteriorly, the greater part of the body being of a speckled olive-brown hue. A very slight reddening is noticed over the ganglionic region. The pale olive specks of the snout pass into the anterior part of the cephalic fissures, while the posterior end of each is deep red. The snout continues pale to a similar extent ventrally, while the olive-green specks are few and indistinct. The ventral surface of the body generally is somewhat paler. Captivity does not seem to affect these hues very soon. Head. — Not distinguished posteriorly from the rest of the body, except in certain positions, when the slight elevation of the posterior fold of the cephalic fissure indicates a separation. It tapers rather abruptly to a somewhat narrow tip, furnished with a central papilla. Prom the angle of the tip on each side a deep lateral fissure runs to the posterior border of the snout, where 1 In honour of the Rev. W. Borlase, the natural historian of Cornwall. 25 194 CEREBRATTTLUS. the dilated termination is conspicuous on account of its reddish coloration. A groove generally present on the side of the body is continuous with the end of the latter, but such a furrow, of course, is only one of the variable longitudinal rugae of the body. The lips of the cephalic fissures are usually kept in apposition, except at the posterior dilated portion. The mouth commences just behind the ganglia, and forms a considerable longitudinal slit. On turning over a large stone in the litoral pool above mentioned a piece of the tenacious grayish-white clayey mud so characteristic of the locality, and which was furnished with a smooth groove, adhered to a corner on the under surface ; and on searching the now muddy pool from which the stone had been raised, the rest of the firm clayey groove and a purplish or dark madder- brown body about two inches long were found. The latter very much resembled the rough siphons of a bivalve mollusk, being flattened, transversely rugose, somewhat abruptly truncated at each extremity, hard and resilient under the touch. On placing this curious structure in pure sea-water, the head of the animal was by-and-by pushed out from the dilated mass, not by the gradual elongation of the whole, but as if an invisible power were drawing caouchouc through a fixed aperture. It was transported to Scotland without difficulty, and lived there until dissected, pushing its anterior end slowly about the bottom of the vessel, and seldom completely extending itself. Indeed, the remarkable dilatation of the posterior end, which was often enve- loped in mucus, was characteristic. Sometimes, however, the stretched tail was attached to mucus at the bottom, while a dilated mass of the body remained about an inch in front of it, the rest of the animal being attenuated, and perhaps laid along the water-line. Its habits on the whole were sluggish, and corresponded with its native situation. On taking the animal out of the water after several months' confinement it contracted itself firmly, an elliptical rent appeared on the ventral surface, and in a few seconds it ruptured into four pieces. The anterior fragment with the head lived several months longer, and during this time the posterior end had become considerably enlarged and paler, and there is no doubt the original size and shape would have been gradually attained under favourable circumstances, while its lost fragments were mounted as microscopic preparations. The skin gives an acid reaction to test-paper. An allied species was dredged by Mr. Jeffreys in the "Porcupine" Expedition, 1870, off Cape Pinisterre, at a depth of 80 fathoms. Genus VII. — Cerebratultjs, 1 Benier, 1804. The species upon which this genus in the present work rests was probably known to 0. F. Miiller as Planaria angulata. Renier in 1804, in his e Prospetto della classe dei vermi,' established the genus Cerebratulus for a worm which appears to have been allied to the present form, and certainly one of the Anopla, if we may judge from Diesing's reprint of the characters given by this author. I have chosen rather to run some risk in using Renier's name than to aid in perpetuating the profuse nomenclature which arose chiefly from insufficient acquaintance with the literature and anatomy of the subject. Generic character. — Body generally flattened, and thinned at the margins. Snout pointed 1 Cerebrum, the brain ; probably from the fancied resemblance of the respective tissues. CEREBRATULUS ANGULATUS. 195 in front. Eyes obscure. Proboscis with a cross of fibres at each pole in transverse section. Cerebratulus angulatus, 0. F. Muller, 1774. Specific character.— Snout pointed. Body much flattened, brownish. Synonyms. 1774. Fasciola angulata, O. F. Muller. Verm. Terrest. et Fluv., vol. i, part ii, p. 58. 1776. Planaria angulata, Ibid. Zool. Danic. Prodr., p. 221, No. 2680. 1780. „ „ O. Fabricius. Faun. Greenland., p. 323, No. 303. 1788. „ „ Gmelin. Lin. Syst. Nat., p. 3088, No. 9. 1798. „ „ O. Fabricius. Skriv. af Naturhist. Selskabet, 4 te Bind, 2 det hefte, p. 52, &c, tab. ii, f. 1—7. 1844. Cerebratulus ? angulatus, CErsted. Entw. Plattw., p. 94. 1845. Serpentaria fragilis, H. Goodsir. Ann. Nat. Hist., vol. xv, p. 377, pi. 20, f. 1 and 2. 1850. Meckelia serpentaria, Diesing. Systema Helm., vol. i, p. 266. 1853. Gordius fragilis, Dalyell. Pow. Creat., vol. ii, p. 55, pis. 6, 7, and 7 (bis). 1857. Lineus Beattim, J. E. Gray. Proceed. Zool. Soc, pt. xxv, p. 210, pi. 48. 1858. „ longissimus, W. Beattie. Op. cit., pt. xxvi, p. 307. 1859. Meckelia serpentaria, Leuckart. Archiv fur Naturges., ii, p. 187. „ Lineus longissimus, Beattie. Ann. Nat. Hist., 3rd ser., iii, p. 160. 1862. Meckelia serpentaria, Diesing. Bevis. der Turbell., p. 281. „ „ Beatticei, Ibid. Op. cit., p. 285. 1863. „ olivacea (Ratlike), Diesing. Nachtrage z. Hevis. der Turbell., p. 8. 1865. Serpentaria fragilis, Johnston. Catalogue Brit. Mus., p. 28. Habitat. — Generally in deep water throughout the British coasts. Greenland. Body. — Fifteen inches to three feet long, and about an inch in breadth ; flattened, bluntly and rather suddenly tapered in front, more gradually posteriorly, and thinned at the margins all round, so that a transverse section of the contracted body is elliptical. Colour. — Universally gray, darker on the dorsal, paler on the ventral surface, and with a pale margin. Sir J. Dalyell's figure has a brown stripe commencing at the anterior third, and conti- nuing to the tip of the tail, and the divisions of the alimentary organ are indicated inferiorly, but of course we must be cautious in making deductions therefrom. This author also observes that in one of his specimens a portion of the edge was reddish, a colour in all probability due to the nerve-trunk and its surroundings. Mr. Goodsir states that his example was of a slate-blue colour, with a yellowish edge. Head. — Tapered to a blunt snout in front, with a cephalic fissure on each side, and apparently without eye-specks. Mouth forming a large slit on the ventral surface in the usual position. I have referred this species to the Planaria angulata of 0. F. Muller, from a careful con- sideration of all the circumstances connected with its history, including the examination of several examples from the north sea, and named by northern naturalists. Muller's account of its size, the pointed nature of its snout, its colour and other points, can scarcely apply to any other species \ and in the preparations the flattened body, thinned edges, and the structure of the 196 MICRURA FUSCA. proboscis are quite characteristic. The late Mr. Harry Goodsir mentions that, " when swimming, the animal is very active, and advances with considerable rapidity by means of an undulatory serpentine motion. When handled it throws itself into various contortions, and instantly casts off numerous annuli from the posterior part of its body, each of which, immediately upon its separation from the original, begins to move in a similar manner." Sir J. Dalyell afterwards made like observations, and noted that the animal was full of a yellow substance, a remark which probably applied to the wall of the digestive cavity, the same colour being present in Micrura fusca. He also found numerous white ova discharged from a fragment in May. The Lineus Beattim of Dr. Gray, and the L. longissimus of Mr. Beattie, appear to belong to this species, if we may judge from the preparation of the former and the proboscis of the latter in the British Museum. Mr. Alex. Agassiz mentions that he found the Planaria angulaia of 0. P. Miiller on the under surface of the tail of Limutus, but of course this refers to quite a different form, probably to a Planaria. This species is very closely allied to Micrura fusca; and if the structure of the proboscis had not deviated so distinctly I should have been inclined to unite them. Genus VIII. — Micrura, 1 Mrenberg, 1831. As has occurred in several instances, the typical form was known to the veteran naturalist 0. P. Miiller, as well as to Col. Montagu. Ehrenberg, however, separated the genus from others for the first time in his ' Symbolse Physical and gave a good figure of M. fasciolata, though he was unaware that the same form had previously been observed by others. Generic character. — Body not much elongated. Head distinctly marked, snout truncated. Other characters as in Lineus, with the addition of a caudal process or style capable of attachment. 1. Micrura fusca, n. s. Plate VI, fig. 3. Specific character.— -Eyes four to eight on each side, small. Body much flattened and thinned at the edges ; speckled with brownish grains on the head and anterior region. Synonym. 1869. Micrura, Mcintosh. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 376, &c. Habitat. — Not uncommon amongst the debris from the coralline ground in fishing boats, amidst oysters and tangles in the laminarian region in Shetland, under stones between tide-marks at Herm, and at a depth of 795 fathoms off the coast of Portugal. Body. — Two to four inches in length, slightly tapered towards either extremity, flattened both 1 Macpbg, small or slender, and ovpa tail. Strickland applied the same title to a genus of Certhidas in 1841 ('Ann. Nat. Hist/). MICRURA FASCIOLATA. 197 dorsally and ventrally, and furnished with a pale caudal filament. It is frequently marked by transverse lines or slight furrows. Colour. — Pale skin, ash or brownish ; dorsum speckled with pale brown touches, especially distinct over the head, which has also a well-marked reddish hue in the ganglionic region. A little within the pale margin of the body a pinkish streak occurs on each side from the coloration of the nerve-trunks. Posteriorly the lateral divisions of the dull yellowish digestive tract shine through the skin. Ventral surface of a pale skin-colour, also enlivened by the coloration of the nerves, and in some cases with a few pale brownish specks anteriorly. The caudal style occasionally shows a few white grains in the central line towards the base. Head. — Spathulate, but much pointed towards the tip, dilating from the latter backwards to the termination of the cephalic fissures, the whole region being peculiarly hastate. Eyes small, black, grouped on each side of the pointed snout, and varying in number from four to eight on each side. The lateral fissures are deep, and have the reddish hue very brightly marked posteriorly. This is one of the flattest among the shorter species of the group, both before and after preservation in spirit. During life it swims through the water on its edge, with an eel-like wriggle, similar to that of A. pitcher, but somewhat less vigorously. When progressing the margins of the body are often very prettily frilled, the reddish longitudinal lines just within the pale border increasing the effect. It is rather irritable, throwing out its yellowish proboscis when touched, or breaking into several fragments. The former clings closely to the finger by means of its tenacious secretion. It fixes the tip of its caudal process as in M. fasciolata, and elongates it so as to resemble a very fine thread, which, however, is slightly moniliform. It agrees in minute structure with the foregoing, and, when detached from the worm, much resembles a long Opalina, or other ciliated organism, in facile and independent movements. The skin presents an acid reaction to test-paper. I at first thought that this form was only a small variety of the great Gordius fragilis of Daly ell (the previous species), and future investigators may establish a closer relation between them than I have been able to make out. I did not feel justified, however, in uniting them, on account of the remarkable difference in the structure of the proboscis, which in M.fusca has the anatomy characteristic of Lineus, while the double isolated longitudinal bands at one of the poles in transverse sections of the organ in C. angulatus exhibit quite a new feature. No author, so far as I am aware, has mentioned the caudal process in the last species, but this is a point which may have been easily overlooked. Whether the young animal shown in Plate VI, fig. 4, is an early condition of this or an allied species I am unable to decide. It was one of the novelties found by its artist during one of her trips to St. Andrews in the spring of 1866. 2. Micrura fasciolata, Mrenberg. Plate VI, fig. 2. Specific character. — Eyes marginal, placed towards the anterior part of the snout. Body various shades of brown, generally barred with white belts. 198 MICRURA FASCIOLATA. Synonyms. 1788. Planaria filaris, O. F. Muller. Zool. Danic, ii, p. 38, tab. 68, f. 18—20. » >, ,> Gmelin. Linnseus Syst. Nat., torn, i, pars vi, p. 3093. 1808. „ lineata, Montagu, MS. tab. 56, f. 5. 1831. Micrura fasciolata, Ehrenberg. Symb. Phys., Phyt. Turb., No. 15, tab. 4, f. 4, a—i. 1827. Planaria filaria, Bosc. Hist. Nat. des Vers., i, p. 261. 1844. Nemertes pusilla, CErsted. Entw. Plattw., p. 90. a „ fasciolata, Ibid. Op. cit., p. 91. w a pusilla, Ibid. Kroyer's Nat. Tids., iv, i, p. 578 (partim). 99 99 99 Ibid. De Region. Marin., p. 80. 1847. Pylidium gyrans (young form), Muller. Archiv fur Anat., p, 159, taf. 7, f. 1—4. 1850. Micrura fasciolata , Diesing. Syst. Helm., vol. i, p. 261. „ Nemertes pusilla, Ibid. Op. cit., p. 271 (partim). 1851. Pylidium gyrans, Busch. Beobacbtungen iiber Anat., &c., p. 107, taf. 16, f. 1—8. „ Alardus caudatus, Ibid. Op. cit., p. Ill, taf. 11, f. 8. 1853. Gordius fragilis spinifer, Dalyell. Pow. Creat., vol. ii, p. 79, pi. 11, f. 5 (var.). „ „ fasciatus spinifer, Ibid. Op. cit., p. 80, pi. 11, f. 6—15. „ Alardus caudatus, Muller. Abbandl. Berl. Akad. (1852), p. 59. 1854. Pylidium gyrans, Gegenbauer. Zeitscb. fur wiss. Zool., v, p. 345. Muller. Arcbiv, p. 75, taf. 4, f. 2—8. „ Alardus caudatus, Ibid. Op. cit. 1858. Pylidium gyrans, Krohn. Miiller's Arcbiv, p. 289. „ Alardus caudatus, Ibid. Op. cit. „ Micrura filaris, Muller. Archiv, p. 330 (note) . 1861. Pylidium gyrans, Claparede. Becher. Anat. sur les Annel., Turb., &c, p. 54, pi. 5, f. 3 and 4 (?) 1862. Micrura fasciolata, Diesing. Bevis. der Turbell., pp. 258—260. „ „ filaris, Ibid. Op. cit., p. 260. „ Meckelia cceca, Ibid. Op. cit., p. 286. „ Nemertes pusilla, Ibid. Op. cit., p. 298. 1863. Micrura fasciolata, Diesing. Nachtrage z. Bevis. der Turbell., p. 7. 1865. Stylus fragilis, Johnston. Catalogue Brit. Mus., pp. 24 and 293. „ „ fasciatus, Ibid. Op. cit., pp. 24 and 293. 1869. Micrura fasciolata, Mcintosh. Trans. Boy. Soc. Edinb., vol. xxv, pt. ii, p. 374. Habitat. — In fissures of the rocks near low water, in the coralline region, and oyster-beds. Ranges from the Shetland Islands to the Adriatic. Body. — Four to six inches in length, and about a line in breadth, flattened on the ventral surface, about as much tapered anteriorly as posteriorly, and with a slender styliform process attached to the tail. Colour. — Fine reddish brown of various shades, banded across with white belts at somewhat regular intervals, and with the tip and sides of the snout pale. The styliform process is pale and translucent. Ventral surface paler than the dorsal, but also inclining to reddish brown, and marked by distinct lines or furrows, which are continuous with the white dorsal bands. The first white dorsal belt usually occurs a little behind the termination of the cephalic fissures, but occa- sionally the presence of some dark red pigment near the tip of the snout cuts a stripe off the pale portion. The white bars are sometimes lozenge-shaped, from a dilatation in the middle. Some specimens from the coralline ground off St. Andrews are of a very pale brown or fawn colour on the dorsum, darkest in front, without white stripes, the only markings being the transverse MICRURA FASCIOLATA. 199 wrinkles of the body. The pale portion at the tip of the snout, and especially its margins, are increased in breadth ; the latter, indeed, being continuous with a pale lateral border (not due to the cilia) throughout the entire length of the animal. The under surface in such examples is of a dull whitish hue, with the exception of the reddish ganglionic region. A dull olive variety of large size (six to ten inches) also occurs in the recesses of the tangle-roots in the Shetland Islands. Some of the examples with white bands have also a whitish ventral surface; and occa- sionally the bands, even when present, are very inconspicuous. Head. — Somewhat spathulate, flattened, tapered towards the front, which is rounded and furnished with a central papilla, wider than the rest of the body. There is a deep lateral fissure on each side, with a reddish coloration posteriorly. Just within the pale margin of the snout are numerous eyes, those in front being best seen from the dorsum, especially in pale specimens, and also from the cephalic fissures. They form a single converging row on each side, to the number of eight or twelve. Young specimens are famished with two conspicuous eyes only. The mouth occupies the usual position behind the ganglia. This is one of the most beautiful Nemerteans, from the striking contrast in its colours and the soft and velvety aspect of its skin. It is evidently a dweller in crevices, and has a great tendency to hide under debris or other shelter in glass vessels ; and if this protection be denied it, the animal frequently coils itself in a mass, either with or without enveloping mucus. Some are hardy in confinement and live for years, others are irritable and fragile, breaking themselves on the slightest interference into many fragments, the separation almost always occur- ring at the white belts. This rupture often takes place before they are removed from the collecting-bottle, especially if they do not have it all to themselves. Fragments of the posterior end of the body turn slowly in the vessel, and live a long time. Of the two well-marked varieties, viz., the banded and the uniformly tinted, the latter are the less fragile, and their bodies are more flattened. The styliform process at the tail can be elongated to an extreme degree. The skin presents an acid reaction. The spermatozoa are fully developed in the beginning of November, causing pale trans- verse bars at the sides of the males. The same elements are fairly matured in Zetlandic examples in August. It is doubtful whether the Fasciola caudata of 0. F. Miiller has any connection with this species, especially as it was found by 0. Fabricius gregariously associated amongst litoral fuci on the shores of Greenland. The same author's Fasciola fiaccida has closer resemblances both in description and figure ; though, as regards the transverse white lines, it is to be remembered that he gives the same account of F. viridis. His figure and the remark concerning the fragility of the species show a close affinity. The Flanaria Jilaris of this author, again, may be regarded as a young specimen, though he represents the tail too elongated. He found it on Madrepora jprolifera. Montagu observes that the colour of his specimens {Flanaria lineata, Mont. MS.) was " rufous brown, with about ten white lines across the back. Beneath pale, without the lines." The Flanaria rvfa of the same naturalist (MS., p. 232) is either a uniformly tinted example of this species, or a variety of Lineus gesserensis. It was found on a large oyster. Ehrenberg gave a good description and figure of the animal from specimens found in the Adriatic. He mentions the presence of five eyes on each side, and that the ovarian aperture (mouth) lies under the second dorsal white bar. He also alludes to the copious exudation of mucus with which it forms a sheath. I have followed J. Miiller in including the young form, Fylidiwn gyrans, under this 200 MICROTIA PURPUREA. species. Dalyell observed that his specimens [Gordius fasciatus spini/er) had a tendency to rup- ture at the white belts. Moreover, his examples reproduced bodies to the anterior regions, but no heads on the posterior fragments, though he did not doubt that regeneration would ensue in every case under more favourable circumstances. His G.fragilis spinifer is probably a specimen of this species uniformly tinted, and its subsequent fracture into many pieces is corroborative of this view. I am in doubt, however, whether his G. viridis spini/er (op. cit., p. 78, PI. XI, f. 1) is a distinct form or only a variety of this or the succeeding species. The MecMia annulata of Grube, and the M. Kneriioi Diesing, are closely allied to the fore- going. The absence of the caudal process in the former may have been accidental, while, as regards the latter, Prof. Grube may be wrong in supposing such only a reproduced tail. 3. Micrura purpurea, BalyelL Plate VII, fig. 3. Specific character.— Eyeless. A bright yellow patch at the tip of the snout. Body of a uniform rich dark brown colour. Synonyms. 1853. Gordius purpureus spinifer, Dalyell. Pow. Creat., vol. ii, p. 78, pi. 11, f. 2 — 4. 1858. Micrura purpurea, J. Muller. Archiv, p. 300. 1862. „ „ Diesing. Revis. der Turbell., p. 260. 1865. Stylus purpureus, Johnston. Catalogue Brit. Mus., pp. 24 and 293. 1868. „ „ Mcintosh. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. 1869, Micrura purpurea, Ibid. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 374, &c. Habitat. — In fissures of rocks near low water, and between the valves of empty shells, or other crevices of the debris from the coralline ground on the east coast of Scotland. It seems to be generally diffused, and occurs of large size off the Shetland Islands. Body. — Five to eight inches in length, flattened, slightly narrowed behind the head, and gradually tapered towards the rather blunt tail, from which the styliform process arises. Colour. — Rich dark brown with a purplish lustre on the dorsum. The tip of the snout is pale, and immediately behind is a well-defined crescentic granular yellow patch. The convexity of the latter is directed forward. In some specimens the anterior margin of the patch only is yellow, while the rest is yellowish white or pure white. There is a slight reddish hue at the ganglionic region. The styliform process is pale brown. The ventral surface is very slightly paler than the dorsal, and from the translucency of the snout the yellow pigment-patch on the upper surface shines through. Head. — With a truncate anterior margin which is also broad, so that it has a peculiar spade- shaped appearance, slightly wider than the succeeding portion of the body, and with three papillae in front, a central and two lateral, the latter being small and inconspicuous. The lateral fissures are deep and well marked, the bottom tinted red posteriorly, and having anteriorly some yellowish grains continued from the pigment-patch of the snout. There is no trace of eye-specks, Micrura purpurea appears for the most part to be a deep-water species. In regard to MICRURA AURANTIACA. 201 colouring it is one of the most striking of the group, the bright yellow patch in front and the ever-varjing purplish lustre of the cilia on the deep brown body forming manifold contrasts, at once pleasing and novel. It is active and voracious, and it is dangerous to leave two in the same vessel, especially if there is disparity in size, as the stronger devours the weaker. Like many of its allies, grave injuries are borne with impunity; thus a specimen which had been so severely wounded in January that it divided itself behind the head, reproduced early in May a small but complete body, furnished with the usual caudal styliform process, and this without a single renewal of the sea-water in the vessel. The head had diminished much in bulk, but was still the widest part of the animal. The body measured an inch and a half after nine months' growth. The introduction of a fresh and hungry specimen from the coralline region proved fatal to this example. The posterior end of the ruptured worm also lived many months, turning slowly round on the bottom of the vessel, and showing a pointed process above the aperture of the digestive chamber in front, while the ova in its interior had arrived almost at complete development in April. Sir J. Dalyell procured the first specimen of this species from Shetland, and so introduced it to science and our fauna. He also figures an example with reproduced (pale) anterior and posterior extremities. Few authors seem to have observed this form, the above, indeed, being the only published notice I have been able to identify. This is the more remarkable, as it has frequently been sent from St. Andrews in the debris of the fishing boats on their return from deep water. 4. Micrura aurantiaca, Grube. Plate VII, fig. 4. Specific character. — Eyeless. A white patch at the tip of the snout. Body rounded, and of a fine brick-red hue. Synonym. 1855. Meckelia aurantiaca, Grube. Archiv fur Naturges., p. 148, pi. 7, f. 1. Habitat. — Under stones in tide-pools to the north of Rat Island, Herm. Body. — Three or four inches long, rather rounded on the dorsum and flattened inferiorly. A small caudal process or filament, as indicated in the figure, was noticed during delineation, but this was not present when I examined it subsequently. Colour. — Dorsum fine brick-red, with a roseate lustre here and there from the cilia, and having a white patch a little behind the anterior border of the snout. The reddish pigment in front of the white spot is somewhat deeper in tint than the rest of the body. The under surface is pinkish-white. Head, — Scarcely wider than the succeeding portion of the body, somewhat flattened, slightly narrowed towards the front, and with rather shallow lateral fissures, the upper lip of the latter projecting over the lower. No eye-specks are visible. The mouth forms an indistinct slit in the usual position. In minute anatomy this species strictly agrees with the Lineidae. The cells of the cutis are very distinctly marked, and the subjacent pigmentary region has a fine reddish hue on the dorsum. 26 202 MECKELIA ASULCATA. The layer of longitudinal fibres underneath the latter is powerful. The proboscis is white, and furnished with small glands, somewhat like those in L. gesserensis. Several specimens were brought alive to Scotland, but from their fragility they were in an imperfect state. After surviving a fortnight they deposited eggs, and died about the middle of September. It was interesting to observe the change of colour which ensued in certain fragments after rupture 5 inferiorly they were dull brownish-red, with the pinkish-brown ova projecting in masses, but by-and-by the latter were extruded, and the ruptured ends and the inferior surface resumed the usual whitish hue of the walls of the digestive chamber. On the whole they were inert animals, generally fashioning tubes on the side of the vessel and remaining therein. I have incorporated the British form with Prof. Grube's species from Villafranca. His description is as follows: — " Body rounded, not changeable, 1—1-5 inch long, contracting into 7*5 lines long, and then ringed and wrinkled, 0*5 of a line broad. Orange-red, or sometimes brick-red, sides and under surface white ; head white, only at the tip of the snout there is a violet spot, and then a broad white belt. The body tapers towards the posterior end, and terminates in a much thinner process, probably a short reproduced tail. The head is not pointed: lateral fissures and eyes not noticed." He had overlooked the lateral fissures, which are shallow. The description of the " growing tail" quite corroborates the correctness of my sister's drawing, for the styles had fallen off when I examined the specimens. Grube's figure shows a broader white belt anteriorly than I observed in the British forms, but such may have been due either to variation or want of scientific accuracy in his artist. Genus IX. — Meckelia, 1 Leuckart, 1827. (Char, emend.) For the curious form described in the following paragraphs I have thought it better to appropriate the title of a genus established in 1827 by Leuckart in his 'Breves Animalium,' and set at liberty by the undisputed claim of priority. The name, it is true, was given to a form differing in some respects from the following ; but the literature of the subject is already so burdened with generic names which have been fashioned on insufficient and unreliable data, that it is almost a duty to resent any addition thereto if it can be avoided. Priority, also, gives the present title a certain claim on our consideration. Generic character. — Structure of the rounded body-wall as in Linens. Cephalic fissures absent. Proboscis furnished with only three coats, external spiral, longitudinal, and glandular. Meckelia asulcata, n. s. Specific character. — Eyeless. Body thick and round. Of a uniform pinkish hue. Habitat. — St. Magnus Bay and adjoining seas, Shetland ; and between tide-marks, Herm. 1 Named in honour of Prof. Meckel. The same name was in 1830 given by Robineau-Desvoidy ( f Essai sur les Myodaires') to a genus of Diptera. CARINELLA ANNULATA. 203 This species can be only imperfectly described at present, as its distinction was not recognized on the sole occasion on which it was seen alive. The specimen found at Herm was of a rose-pink colour in front, pale posteriorly. There are no lateral fissures on the head. The mouth lies on the ventral surface some distance behind the tip of the snout, and in the preserved specimens forms a small puncture or dimple. The worm appears to attain the length of four or five inches. Numerous specimens of an elongated example of the Anopla without lateral fissures occur in a collection brought by the Rev. L. Guilding from the West Indies, and now in the British Museum. All have a peculiarly corrugated and thickened anterior end, and a small round mouth like a puncture. Some measure about fifteen inches long. Family III. — Carinellid^). Genus X. — Carinella, Johnston, 1833. Before the time of Dr. Johnston the typical animal of this genus, the Gordius annulatus of Montagu, had not been sufficiently distinguished from its congeners ; and though he named the species in ignorance of the prior observations of Montagu, yet his generic title is more appro- priate than that of MecMia, in favour of which the original name was suppressed. The latter term was given to one of the Lineidse, while the type here is totally different. Carinella, as its originator says, labours under the disadvantage of being a name which the scholar may " in vain puzzle himself" to find out "from what, and whence, it is derived." At first sight it seems to be a diminutive of carina, a keel. Generic character. — Body elongated, tapering from the front backwards. Snout wider than the rest of the body, bluntly rounded anteriorly. Mouth sometimes small. 1. Carinella annulata, Montagu, 1804. Plate VII, fig. 5 ; and Plate VIII. Specific character. — Eyeless, with a white patch on the snout. Body rounded, of a rich red colour, striped longitudinally and banded across at somewhat regular intervals by white belts. Occasionally pinkish throughout. Synonyms. 1804. Gordius annulatus, Montagu. Linn. Trans., vol. vii, p. 74. 1807. „ „ Turton. Brit. Fauna, p. 130. 1808. Lineus annulatus, Montagu. MS., p. 273, tab. 9, fig. a. 1812. Gordius annulatus, Pennant. Brit. Zool., vol. iv, p. 73. 1833. Carinella trilineata, Johnston. Loudon's Mag. Nat. Hist., vol. vi, p. 232, woodcut, f. 24, a. b. 1841. „ „ W. Thompson. Ann. Nat. Hist., vol. vii, p. 482. „ Gordius annulatus, Ibid. Op. cit., p. 482. „ Polia crucigera, Delle Chiaje. Descriz. e Notom. anim. invert., &c, torn, v, p. 40, tab. 174, f. 15 — 18, and tab. 176, f. 17. 1866. a 1867. )> 1868. )> 1869. » 204 CAEINBLLA ANNULATA. 1846. Meckelia trilineata, Johnston. Ann. Nat. Hist., vol. xvi, p. 435. „ Valencinia ornata, De Quatrefages. Ann. des sc. nat., 3 me ser., Zool., torn, vi, p. 187, tab. 10, f. 4 and 5. 1849. „ „ Ibid. Voyage en Sicilie, vol. ii, p. 99, pi. 10, f. 1—3. 1850. „ annulata, Diesing. Systema Helm., vol. i, p. 244. } , „ ornata. Ibid. Op. cit., p. 244. 1853. Gordius anguis, Dalyell. Vow. Creat., vol. ii, p. 85, pi. 10, f. 7—10, and pi. 13. 1854. Valencinia ornata, M tiller. Archiv, p. 83. 1859. „ „ Leuckart. Archiv fur Naturges., ii, p. 187. 1861. „ „ Grube. Ausflug nach Triest u. dem Quarnero, pp. 35 and 129. 1862. „ „ Diesing. Revis. der Turbell., p. 252. „ „ annulata. Ibid. Op. cit., p. 253. 1863. Valencinia ornata, Diesing. Nachtrage z. Revis. der Turbell., p. 6. 1864. „ „ Grube. Die Insel Lussin u. ihre Meeresfauna, p. 94. 1865. Meckelia annulata, Johnston. Catalogue Brit. Mus., pp. 27 and 296-8, with woodcut, as in 1833. „ Lankester. Ann. Nat. Hist., 3rd ser., vol. xvii, p. 389. „ Parfitt. Catal. Annel. Devon, p. 8. „ Mcintosh. Kept. Brit. Assoc, 1868, p. 340. „ Ibid. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 372 et seq. Habitat. — Under stones near low water, in obscure fissures of rocks, and also dredged in somewhat deep water. Often cast on shore amongst debris from the laminarian region. Gene- rally diffused round the British coasts and the shores of France. In laminarian and coralline regions it prefers tangle-roots, the inner surface of bivalve shells, or the tubes of Terebellce, Serpulce, and other annelids. Body. — Seven to thirty inches long, and about a line in breadth, somewhat narrowed behind the cephalic furrows, and gradually tapering to the tail. Dorsal surface rounded, ventral flattened. Colour. — Various shades of brick-red, brownish-red or vandyke-brown (garnet-red, Montagu), and with a very regular arrangement of white stripes. The snout usually has a patch of white, with a crescent ic margin anteriorly and posteriorly, so as to be narrowed in the middle, with a coloured portion in front. From the former a white central line proceeds backwards on the dorsum to the tip of the tail. A short distance behind the ciliated furrows of the head a circular white belt environs the body, and from each side of this ring a white stripe passes along the lateral aspect to the tip of the tail. At certain intervals, only two of which in front are distant, the body is encircled by white rings, which give a somewhat regularly segmented appearance to the elongated worm. Posteriorly, indeed, they are often equidistant, and in many there is a pale intermediate ring, sometimes faintly indicated by whitish pigment on the dorsum. Every alternate white ring in most of the specimens is double ; that is, divided by a slight furrow. Col. Montagu mentions 220 as the number of white rings after the third, and Sir J. Dalyell counted 200 belts in a specimen eighteen inches long. There are likewise in many a series of white specks above the lateral white lines, generally commencing at the fourth or fifth space behind the cephalic furrows, though occasionally some occur on the third. These indicate for the most part the points at which the products of the generative organs escape. The under surface is CARINELLA ANNULATA. 205 paler than the upper. The ventral aspect of the snout has a white patch continuous with, but narrower than, that on the dorsum. The only other markings on this surface are caused by certain pale lines and the circular white belts ; but in a characteristic variety a median white stripe passes along the entire belly from tip to tip. The space behind the first white circle is usually paler than the rest. In a very large dark specimen, sent from Montrose by Dr. How den, the white stripes anteriorly had a beautiful rose-pink shade. Pale red examples from fissures of rocks, when placed in glass vessels, gradually become brownish-red or quite brown by exposure to light. Head. — Horseshoe shaped, wider than the rest of the body, not much flattened, and with- out eye-specks. Posteriorly it is gradually narrowed to the cephalic furrows, where a slight shoulder occurs. There is a curved streak in the bend of each ciliated furrow on the dorsum, perhaps in connection with the cephalic sac. These furrows are continued straight inwards on the ventral surface, so as to meet just at the anterior part of the mouth. The latter forms a longi- tudinal slit somewhat less distinct than in Linens. A well-marked southern variety occurs in the island of Herm. The head is peculiarly flattened, larger in proportion than in the common form, and pale at the tip. At first sight the body appears to be dull orange throughout, but minute inspection shows a pale lateral line on each side, with a series of minute pale spots above it, and traces of faint transverse bars on the dorsum. This species, one of the most handsome and graceful of the whole order, lives a long period in confinement, constructing on the bottom and sides of the vessel numerous hyaline transparent tubes, in which it lies either doubled or coiled in various ways. The tube or case has a fine silky lustre or iridescence, appearing under a high power as an almost structureless membrane with a few minute adherent granules, and irregularly streaked with fine lines, from microscopic folds of the very thin tissue. The animal progresses somewhat slowly ; and though devoid of eyes, it needs but a touch to become aware of the proximity and apparently the nature of any object, so that, for instance, it at once enters head foremost or backs into a tube. Small fragments of the body survive a long time, and move slowly about. In these the anterior end is somewhat pointed. Probably they develop into perfect animals under favourable circumstances. The skin gives a marked acid reaction. This is another addition to our marine fauna for which we are indebted to the industry and enthusiasm of Col. Montagu. He distinguished the common form and that with the ventral median white line, as well as noticed the white specks at the sides and the broader nature of some of the circular white belts. In the variety with the ventral longitudinal line he states that " the first annulation of white is very close to the anterior end, the second is distant about an inch, and the rest (about 220) are nearly equidistant." The drawing accompanying the manuscript by some accident shows dark instead of white lines on the dorsum. Four succeeding authors of note, viz. Dr. Johnston, Sig. Delle Chiaje, M. de Quatrefages, and Sir J. Dalyell, each described the same animal as a new species. M. de Quatrefages based the distinction of his Valencinia ornata from Col. Montagu's form on the fact that the latter did not note the remarkable enlarge- ment of the head, and because his specimens came from the laminarian region, Montagu's from the coralline. Such data, of course, are unsatisfactory. Moreover, since we observe that a species so prominently barred as Micrura fasciolata occasionally presents none of these charac- 206 CARINELLA LINEARIS. teristic markings, and that the variety of Carinella annulata from Herm showed few traces of stripes, we may be forgiven if we harbour some doubts as to the specific distinction of De Quatre- fages' two species ornata and splendida. It is possible that Tubulanus elegans and T. polgmorpkus of Renier, Delle Chiaje, and others, may also have some connection with this species. Sir J. Dalyell compares C. annulata to a regular snake in miniature, of delicate form and proportions, and decked in lively colours. He observes that the mouth is at the very extremity, and opens by a wide horizontal gape, as if the creature had an upper and an under jaw, statements due to some erroneous recollections. He notices that a large number of reddish-brown ova were discharged from a specimen in June. M. de Quatrefages, again, mentions that specimens of his Valencinia splendida from Brehat were loaded with ova in September and October. 2. Carinella linearis, Montagu, MS. Specific character. — Eyeless. Head spathulate, somewhat pointed in front. Milk-white. Synonym. 1808. Lineus linearis. Montagu, MS., pp. 274-5. Habitat. — South coast of England, and Lochmaddy in the Hebrides, amongst sand at low water. Body. — Eive to six inches long, less than a line in breadth, flattened, slightly tapered towards the front, diminishing more decidedly posteriorly. Colour. — Pure milk-white, with translucent margins towards the tail. Fig. 13. Eig. 14. Anterior extremity of Carinella linearis. Carinella linearis with the anterior end somewhat contracted. Head. — Spathulate, assuming various aspects, sometimes pointed (woodcut, fig. 13), at VALENCINIA LINEFORMIS. 207 others blunt and rounded (woodcut, fig. 14). The snout has an opaque- white central streak. No pigment-specks are present. The species was procured whilst digging for Triapulus caudatus and Annelids at Lochmaddy. Its habits and motions are like those of other species. As usual with white forms, immersion in spirit gives a yellowish hue. On transverse section its anatomy is found to agree with the foregoing, and especially with the variety from Balta having the bifid proboscis, for the inner (longitudinal) muscular coat of the body-wall shows a marked tendency to separation in the middle line of the dorsum. I was inclined to consider this species a doubtful variety of Carinella annulata until I saw the manuscript of the accomplished Montagu containing the description of u Linens linearis" He says — " L. linearis, with a cream-coloured body. Long, slender, considerably extensible and tenacious ; the anterior end largest, sometimes clavated and flattened, at other times pointed ; frequently that part is observed to be alternately inflated and contracted, while the rest of the body is quiescent. Length 5 or 6 inches when extended, but usually contracted to 3 or 4. This species inhabits the sandy shore at Dawlish, about five or six inches beneath the surface at low water. Like the marinus, its motion consists of contortion and variation in size of different parts of the body at the same time. A tenacious slime exudes from its body, which, collecting sand, readily forms a covering like a Sabella." The Valencinia longirostris of M. de Quatrefages has certain affinities with this form, although the snout, as shown in his figures, is much more pointed. It is to be remembered also that he found his species in a similar region and medium (sand and mud) at the ties Chausey. The Linens albus in the British Museum is one of the Lineidce from Cornwall. The shape of the head of this animal, the absence of eyes, its habit of residing amongst sand, and other points, make it clear that there are grounds for specific distinction. Genus XL — Valencinia, Be Quatrefages. (Char, emend.) This genus was instituted by M. de Quatrefages for the typical and other forms of the previous genus, but lapses in virtue of the priority of other names. Since the term was applied to an allied form, it may not inappropriately be used for the description of the present species. The genus Folia, perhaps, has prior claims, but it is already employed by the entomologists. Generic character. — Structure of the proboscis as in Carinella. The nerves lie in the longitudinal muscular coat. The snout is shaped as in Linens lacteus, and furnished with a row of eyes on each side. The mouth forms a distinct fissure a considerable distance behind the ganglia. Valencinia lineformis, n. s. Specific character. — Roseate in front, yellowish-white posteriorly. Habitat. — Amongst shell-gravel and the fine purplish ramose form of Corallina officinalis in five fathoms, Bressay Sound, between the Point of Scotland and the Green Head. 208 CBPHALOTHEIX LINEARIS. Body. — Six to eight inches or more in length, and about a line in breadth, generally resembling that of Linens lacteus, except in the greater tendency to encircling furrows. Colour.— Richly roseate in front, the rest of the body being pale pinkish-yellow or yellowish-white. Head. — Spathulate, as in the above-mentioned species, the lateral fissures, of course, being absent. The eyes are also fewer in number and smaller, but similarly arranged. The mouth is large and situated far backwards, the position and size being equally interesting in this group. So like was this species to Linens lacteus (Plate V, fig. 3), that most examples were consigned to spirit before a more critical examination discovered the essential differences. Those specimens; even, which were destined for transmission southward proved so delicate as to break into short fragments in a day or two. The structure of the body-wall and the proboscis at once distinguishes it from the Lineidce, while the fact that the nerves in the longitudinal muscular coat do not quite reach its outer border separates it from its ally Carinella linearis. Family IV. — Cephalothricimi. Genus XII. — Cephalothrix, 1 (Ersted, 1844. This genus was established by A. S. (Ersted in his ' Entwurf Plattwurmer' for the reception of animals identical with the Planaria linearis of Jens Rathke. The typical form was distinguished by several names, and a variety included also under the genus Astemma of the same author, for I consider the distinctions as to the presence or absence of eye-specks and the vague remarks about respiratory fissures of little consequence. Generic character. — Head cylindrical, slightly tapered in front ; eyeless, or with a few obscure pigment-specks. Cephalic fissures and sacs absent. Mouth situated a considerable distance behind the snout. Cephalothrix linearis, Jens Bathke. Plate IV, figs. 4 and 5. Specific character. — Body extremely attenuated, pale yellowish or skin-colour ; often with reddish grains towards the tip of the snout. Synonyms. 1799. Planaria linearis, Jens Rathke. Skrivter af Naturhist. Selsk., v, p. 84, tab. 3, f. 11. 1829. „ filiformiSj Johnston. Zool. Jour., vol. iv, p. 56. 1837. Nemertes (Borlasia) rufifrons, Johnston. Mag. Zool. and Bot., vol. i, p. 538, pi. 18, f. 4 and 5. 1844. Cephalothrix bioculata, (Ersted. Entw. Plattw., p. 81, woodcut 12. „ „ caeca, Ibid. Op. cit., p. 81, tab. 3, f. 39. „ „ linearis, Ibid. Op. cit., p. 82 (note under C. caeca) . 1 KrfaXrj, the head, and SpiZ a hair. There is a genus of Lamellicorn beetles (established by Hope in 1837) called Cephalotrichia. CEPHALOTHRIX LINEARIS. 209 1844 Astemma rufifrons, (Ersted. Op. cit., p. 82, woodcut 13 (?) Cephalothrix bioculata, Ibid. Kroyer's Nat. Tids., iv, p. 573. „ caeca, Ibid. Op. cit., p. 574. Planaria linearis, Ibid. Op. cit., p. 573. Astemma rufifrons, Ibid. Op. cit., p. 574. „ longum, Ibid. Op. cit., p. 574. „ rufifrons, Ibid. De Region. Marin., p. 79. Cephalothrix bioculata, Ibid. Op. cit., p. 79. 1846. Borlasia ? filiformis, Johnston. Ann. Nat. Hist., vol. xvi, p. 434, pi. 15, f. 1, a, b. 1850. „ rufifrons, Diesing. Syst. Helm., vol. i, p. 241. „ „ longa, Ibid. Op. cit., p. 241. „ ,, cephalothrix, Ibid. Op. cit., p. 241. » » filiformis, Ibid. Op. cit., p. 242. » „ linearis, Diesing. Syst. Helm., vol. i, p. 242. „ Cephalothrix (Erstedii, Ibid. Op. cit., p. 246. 1853. Gordius gracilis, Daly ell. Vow. Creat., vol. ii, p. 74, pi. 9, f. 8—11. 1859. „ „ Leuckart. Archiv f. Naturges., ii, p. 187. 1861. Cephalothrix lineata, Claparede. Recher. Anat. sur les Ann., Turb., &c, p. 82. 1862. Borlasia longa, Diesing. Revis. der Turbell., p. 249. „ „ rufifrons, Ibid. Op. cit., p. 249. „ „ cephalothrix, Ibid. Op. cit., p. 250. „ „ filiformis, Ibid. Op. cit., p. 250. „ „ linearis, Ibid. Op. cit., p. 250. „ Cephalothrix (Erstedii, Ibid. Op. cit., p. 254. „ Meckelia caeca, Ibid. Op. cit., p. 286. „ Cephalothrix ocellata, Keferstein. Zeitsch. f. wiss. Zool., Bd. xii, p. 63, taf. 6, f. 11 — 16. « „ longissima, Ibid. Op. cit., p. 65, taf. 6, f. 6 — 10. 1863. Borlasia linearis, Diesing. Nachtrage zur Revis. der Turbell., p. 5. „ „ ? longissima, Ibid. Op. cit., p. 6. „ Ommatoplea ocellata, Ibid. Op. cit., p. 7. „ Gordius gracilis, Ibid. Op. cit., p. 15. 1865. Astemma rufifrons, Johnston. Catalogue Brit. Mus., pp. 19 and 288. „ „ filiformis, Ibid. Op. cit., p. 19. 1866. „ rufifrons, Lankester. Ann. Nat. Hist., 3rd ser., vol. xvii, p. 388. „ ,, filiformis, Ibid. Op. cit., p. 388. „ Cephalothrix lineatus, Ibid. Op. cit., p. 388 (?) 1867. Astemma rufifrons, Parfitt. Catalogue Nat. Hist. Devon., Annelids, p. 5. „ Cephalothrix filiformis, Mcintosh. Rept. Brit. Assoc, 1867, Trans. Sect., p. 92. 1868. „ ,, Ibid. Ann. Nat. Hist., 4th ser., vol. ii, p. 293. 1869. „ „ Ibid. Trans. Roy. Soc. Edinb., vol. xxv, pt. ii, p. 376 et seq. Habitat. — Under muddy stones between tide-marks, often in great numbers, and on oysters and other shells and ascidians in the laminarian region. Ranges from Shetland to the Channel Islands. Body. — About three or four inches long, flattened, tapering towards the snout, and much more towards the tail ; most variable in appearance, now stretched to a mere thread, and again shortened to a worm of some volume, or thrown into alternate dilatations and contractions. It is marked along the centre by the pale streak of the proboscidian sheath. 27 210 CEPHALOTHRIX LINEARIS. Colour. — Variable. Sometimes the animal is of a pale cream-colour throughout, with no special pigmentary accumulation. A patch of yellowish pigment occurs in other cases on the snout, and the oesophageal region is yellowish ; or the yellowish, orange or reddish pigment is increased towards the tip of the snout, and the oesophageal region is reddish-orange. The suc- ceeding part is also faintly tinged in those most deeply coloured, the rest of the animal being of the usual dull whitish or skin colour, and more opaque than the former. In a female specimen laden with ova, sent from the St. Andrews rocks in April, the entire digestive cavity was of a fine dark green hue (Plate IV, fig. 5), a condition probably due to the absorption of colouring matter from the food, as specimens kept in vessels beside the ova of Phyllodoce maculata, Johnst., become similarly tinged towards the posterior part of the digestive tract. Head. — Rounded, slightly tapered to a blunt point, not distinguished from the rest of the body ; without eye-specks, and devoid of furrows or fissures. The mouth forms a conspicuous slit a little behind the commencement of the oesophagus, and the pouting lips would seem to be occasionally used as a kind of sucker, since a jerk occurs on raising the body from this point. C. linearis is easily kept in confinement, moving about actively, or reclining at ease along the vessel as a slender thread. It is fond of associating with fellows of the same or a similar species, forming a tangled bunch or grouped as a radiating series of living filaments. In progression the mobile snout is used as an exploratory organ, being thrust hither and thither with ceaseless energy under a glass cover, and pushing aside its own yielding body in any direction. The latter is also frequently drawn through a loop of mucus like a thread of coherent yet fluid substance, which becomes thickened or attenuated by each successive contractile wave; and it is sometimes bent in a peculiar manner from twists round loops of mucus or the bodies of others. The skin is strongly acid to test-paper. The ova and spermatozoa are ripe from January to June. I have taken the Planaria linearis of Jens Rathke to be the present species. It was noticed by Col. Montagu and afterwards by Dr. Johnston in Britain. The Lineus spiralis of the former (MS.) is probably a variety to which the description exactly applies, with the exception of the " red spiral intestine." The proboscis may occasionally be tinted. The presence of pigment- or eye-specks does not seem to be of sufficient weight to separate (Ersted's C. bioculata and C. cceca, if, indeed, the former is to be included in this genus at all. The Astemma rufifrons of the same author is only a variety of the present species with a greater development of pigment in the snout. The woodcut (op. cit., fi.g. 13), however, very much resembles a com- pressed anterior region of Lineus bilineatus viewed as a transparent object. It is somewhat doubtful if his Astemma longum (' Kroyer's Naturhist. Tidskrift') is a Cefthalothrix, though he places it next A. rufifrons. Sir J. Dalyell was the first to notice the development of this species, which he saw producing a rope of spawn in June. He correctly describes the young as having two eyes. The Poliafilum of De Quatrefages has much resemblance to C. linearis; indeed, his remarks can only apply to this form or to Nemertes carcinopMla, and the probability is in favour of the former, though he had omitted to notice the mouth. The enlarged drawing of the ganglia given by this author still further indicates the connection. This arrangement is never seen in an example of the Enopla. The C. lineata ((Erst.) which M. Claparede found at Skye is evidently this common species. There is also nothing in the descriptions and figures of Prof. Keferstein's C. ocellata and C. longissima to distinguish them from each other or from CEPHALOTHEIX LINEARIS. 211 this form. The presence of dark pigment-specks is of no greater value specifically than the anterior red pigment in the British examples. There is considerable variation, but no character of sufficient importance to merit specific distinction. The form of the papillae of the proboscis (which are stated to be hook -shaped) and other minute points in the author's descriptions require confirmation. EXPLANATION OF THE LETTERS USED IN THE PLATES. The following letters have been employed both in the Enopla and Anopla to designate similar structures : — a. Proboscis. /. Superior ganglionic commissure. g. Inferior do. do. j. (Esophageal region. f. Digestive canal proper. k. General stroma of the snout. m. Cephalic sac. in! . Duct of do. n. Great lateral nerve. o. Proboscidian sheath. ov. Ovaries, ova, or their indications. p. Dorsal blood-vessel. r. Lateral do. w. Mouth. z. Anus. \p. Muscular ribbon of proboscis. Letters confined to the Enopla. ac. Reflection of the proboscis in front of the ganglia. b. Epidermis. ab. Channel in the snout for the proboscis. c. Cutis. d. Circular muscular coat. e. Longitudinal do. h. Superior lobe of the ganglion. i. Inferior do. do. I. Cephalic blood-vessel. q. Anastomotic do. a. First region of the proboscis. b. Second do. do. c. Third do. do. 214 €. Globule in marginal stylet-sac. j3. Stylets in do. do. 8. Duct of do. do. f. Muscular chamber behind the floor of the anterior region of the proboscis. rj. Floor of the anterior chamber of the proboscis. 6. Muscular investment of the granular basal apparatus. A. Granular basal apparatus. ft. Ejaculatory duct. ft. Aperture of do. into chamber £. v. Marginal stylet-sacs. 7T. External granular glands. c. Reservoir. a. Glands of do. r. Spiral muscular fibres of the walls of the reservoir. to. Longitudinal do. do. tp. Duct of communication with the posterior chamber. X- Wall of the posterior chamber. Letters used in describing the anatomy of the Anopla. ao. Tube for the proboscis in the snout. b. Cephalic fissures. c. Ciliated epidermis. d. External layer of cutis. d\ Basement-layer. d" '. Pigment-layer in Linens gesserensis. e. External (longitudinal) muscular layer. e' '. Circular muscular layer. e". Inner (longitudinal) do. do. h. Ganglia. A'. Superior lobe of the ganglion. h" . Inferior do. do. s. Vascular lacunae behind the ganglia. u. Vascular meshes around the oesophageal region. v. Larger vascular space at each side of the sheath for the proboscis in front. y. Constriction between the oesophageal and succeeding alimentary regions. PRINTED BY J. E. ADLAED, BAETHOLOMEW CLOSE. 213a APPENDIX. The delay which has taken place in the preparation of the coloured plates has enabled me to make a few remarks on certain recent papers bearing on the subject. Several of these are by A. F. Marion, who has already (p. 40) been alluded to as the discoverer of an hermaphrodite Nemertean, which he found, with developed generative organs, in the month of March in the Mediterranean. 1 In a communication entitled < Histologic du Systeme nerveux des Nemertes' 2 the author describes the lateral nerve-trunk as enveloped in a fine membrane, and gives an interesting account of the fibres after they have entered the ganglia. He mentions that the nerve-cells in the latter are chiefly elliptical and apolar, though multipolar are also present. He further notes that in certain forms a pulpy granular mass occurs between the external sheath and the internal fibres of the lateral nerve, probably referring to the fibro-granular matrix described on page 110, and shown in Plate XXI, fig. 6, ri, of the present work. In these forms, moreover, the cephalic ganglia are composed of the same pulpy mass, without a trace of cells. Another French author, M. Leon Vaillant, 3 next advances certain remarkable opinions con- cerning contested points in the Nemerteans. He revives the idea, as he says, of Max Schultze and De Quatrefages, that the proboscis is the digestive organ. The works of the latter author have already been fully gone into, but I am unacquainted with the paper in which the former has propounded this erroneous idea; indeed, the contrary opinion has been taken in the review of his labours (see pp. 28, 29, &c). His assertion that the marginal stylet-sacs furnish the stylet for the central apparatus through the ducts of the former organs has already been disposed of (pp. 57 and 67). His remarks that the posterior chamber of the proboscis has an aperture leading into "the general chamber of the body" (the proboscidian sheath being unknown), and that Valencinia longirosiris (one of the Anopla) takes nourishment by the proboscidian aperture, scarcely require refutation. A. F. Marion published an important article on the subject in his recent ' Recherches sur les Animaux inferieurs du golfe de Marseille,' 4 which, indeed, mainly consist of an account of an hermaphrodite Nemertean named Borlasia Kefersteinii, already alluded to in the " Zoography" (p. 40). The form was dredged by the author at the above-mentioned locality amongst the roots of sea- weeds, and, in conjunction with three other species of similar organization, its examina- 1 ' Comptes Eendus/ torn. 69, 1869 2 Ibid., torn. 68, 1869, p. 1474. 3 ' La Revue scientifique de la France et de l'Etranger/ &c., 2e serie, 21st Sept., 1872. I am much obliged to Mr. Waterhouse, of the Zoological Department, British Museum, for a perusal of this note. 4 'Ann. des. sc. nat./ v e ser., tome xvii, Nos. 3 & 4, 1st March, 1873. 28 2135 APPENDIX. tion afforded, he says, an opportunity of giving a very complete description. He follows Prof. Keferstein in his classification, and therefore the observations on this head in the " Zoography" are equally applicable here. He is also rather behind date in his remarks on the value of the stylet -region in the discrimination of species. In what he calls the granular coat of the skin he found small brilliant bodies, sometimes in the form of prisms, sometimes in the form of buckles. This peculiar condition has not been observed in the British Nemerteans. Only longitudinal muscular fibres were present in his species, but he does not say that he made any transverse sections. In consonance with the .structure of the Enopla, to which the form belongs, there ought to be external circular as well as internal longitu- dinal fibres. I cannot agree with his proposition that naturalists generally consider the proboscis an organ of offence and defence, for observations on the living animal, and the anatomy and phy- siology of the organ in both Enopla and Anopla, render this view quite theoretical. He is safe, however, in objecting to the interpretation of his countryman, M. Leon Vaillant, previously narrated. A vital discrepancy is the affirmation that the mouth in his species (one of the Enopla) opens behind the ganglia, because in every example (British and foreign) of this group seen by me the position of the oral orifice is quite in front of the ganglia and ganglionic commissures, and thus, very properly, forms one of the most important distinctions between them and the Anopla, in which (latter) the mouth invariably opens behind the ganglia. As an accompaniment tp this erroneous view the author has quite overlooked the characteristic oesophagus, which forms a lon- gitudinally plaited ciliated sac (essentially differing in appearance from the rest of the digestive chamber) behind the ganglia. The oral slit shown in his figure might pass for one of the longi- tudinal rugae of the organ. It is by no means easy to arrive at an accurate knowledge of the anatomy of these animals, and hence the greatest care and patience are necessary. He further observes that the proboscis is fixed to the wall of the " general cavity of the body," a position it does not occupy, since it is enclosed in its special sheath of two coats, and to the inner surface of which the terminal ribands are duly fixed. M. Marion's interpretation implies a total want of this sheath, which, I am sure, a single transverse section would at once render apparent. He next narrates that the anterior region of the proboscis is covered with papillae, but he would have been more exact if he had mentioned that these organs are internal, for on glancing at his figure (PI. 17, fig. 3, op. cit.) it is difficult to say whether they are wholly internal or also common to the external surface. To have got the figure the organ must have been turned inside out at its anterior part. The basal apparatus of the central stylet is described as brownish. It is only so by transmitted light — from the dense mass of white granules. The terminations of the ducts of the marginal stylet-sacs have never, in any form observed by us, been close to the aperture for the central stylet in the floor of the anterior chamber, but at some distance therefrom. The statement, also, that below the stylet-sacs the fibrous tissue is furnished with fine pigment-granules is not sufficiently comprehensive, Tor no mention is made of the regularly arranged circlet of granular glands (?r in our figures), neither is any help on this point obtainable from the plate. Another discrepancy is the arrangement of the duct from the reservoir (his jpoclie de reserve du liquide venimeuw), which canal he describes and figures as extending forward to open into the floor of the anterior chamber near the point of the central stylet. If the author had watched an organ under careful pressure he would have seen the granular gland-cells from the posterior APPENDIX. 213c chamber (his region glandulaire de la trompe) roll forward into the reservoir, and find exit singly into the muscular cavity (e in our figures) behind the floor of the anterior chamber, and which the author actually represents without comment. Moreover, that afterwards they passed into the cavity of the anterior chamber by the aperture for the central stylet. With regard to his discussion concerning the venomous nature of the fluid in the reservoir, I would not, for my part, say that it is poisonous. It is clear, from the minute anatomy of the organ, that the fluid cannot enter a wound inflicted by the stylet until the latter is withdrawn ; and, as stated previously (p. 62), the proboscis is a somewhat precarious aggressive weapon. The jerking movements observed by the French author in the protruded proboscis are common enough in a structure so muscular and mobile, but they may be explained otherwise than on the supposition of attacking prey. My experience of the organs in the Anopla, also, does not coincide with his observation that they subserve the same function, viz. the secretion of poison. Neither has anything been observed to support the view that other marine animals, such as Crustacea, manifest great repug- nance to the Nemerteans, nor is it probable that nature furnished the latter with cilia (in lieu of urticating organs) to warn their fellows of their deadly approach. The author admits that he has only imperfectly examined the organs of circulation, a fact apparent from his remark (and figure) that a central dorsal vessel springs from the middle of the cephalic arch at the tip of the snout. As formerly shown (p. 79), the dorsal vessel arises from the two lateral — by the anastomotic — behind the ganglia. He indicates the discovery of a curious species, having small clear processes like buckles in its cutis, and analogous to the bodies in the muscles of Echinoderms ; hence he calls it Borlasia ecliinoderma. The basal apparatus of the central stylet in this species is truncate posteriorly, as in Prosorhochmus Claparedii. Some interesting details are given of its nervous system, amongst others the curious fact that the first eleven pairs of lateral nerves (from the great lateral trunks) go to a series of eyes furnished with refracting globules. The anterior eyes are supplied, as usual, by branches from the ganglia. The paper concludes with an account of the reproductive organs of Borlasia Kefersteinii. The statement that on attaining full development the ova and spermatozoa burst their envelopes and escape into the " general cavity of the body" is not in accordance with our observa- tions. The apertures along the sides, which the author failed to see in this small species, render such a supposition unnecessary, though, of course, not impossible. His asking if, like Keferstein, we are to consider the cephalic sacs and " fossettes cephaliques" the channels whereby the reproductive products are expelled, is not in keeping with a thorough knowledge of the subject. In the viviparous Prosorhochmus Claparedii even the largely developed young are confined to certain definite spaces in the body of the parent, but their actual mode of exit in this species is still involved in obscurity. It is to be remembered in connection with the subject that in Nemertes carcinqphila, also occasionally a viviparous species, the sexes are separate. The author's allusion to the literature of the subject is meagre, and though several of his views are nearly identical with, or modifications of, those promulgated long ago by his distin- guished countryman, M. de Quatrefages, he does not even mention his name. The plate of figures accompanying the paper is considerably behind date in accuracy. An important memoir (an abstract of which has only been published) in connection with the homologies of the subject is that f On the Anatomy and Histology of the Land-Planarians of 213rf APPENDIX. Ceylon/ 1 by Mr. H. N. Moseley, now one of the naturalists in the " Challenger" expedition. The author specially examined the genera Bipalium and Bhynchodemus ; and since my observations on the former had been made some years ago, and printed off several months before the above paper reached the Royal Society, a comparison of the results will be interesting. He agrees with me in affirming that the skin closely conforms to the Planarian type. The flask-shaped cells filled with " stabchenformigen Korpern" below the cutis he thinks homologous with the "nail-like bodies of the Nemertines " but if he means by the latter expression the proboscidian stylets, the homology is not very apparent, any more than the conjecture concerning their possible alliance with the bristles of the Annelida. He makes the curious statement that " it is commonly said that whilst in all other Vermes the external muscular layer is circular, and the longitudinal internal, in Turbellarians the reverse is the case ;" but he might have observed, in a paper on the " Anatomy of the Nemerteans/' 2 that considerable differences exist in the arrange- ment of the muscular coats of the great groups — for example, between the Enopla and Anopla, the external muscular layer in the former being circular, while in the latter it is longitudinal. With regard to the nature of the pale areas described on p. 143, and which Mr. Moseley calls primi- tive vascular trunks, I was in doubt after the examination of my specimen, though I could not see anything nervous about them. If such be a water-vascular system it is totally different from the circulatory trunks in the Nemerteans, which I hold to be the blood-vessels of the animals. Some interesting theoretical remarks are appended to the communication. The latest publication pertaining to the subject is by M. E. Zeller, 3 on the " Structure of the Proboscis of Borlasia Kefersteinii" Marion, the author having worked under the direction of the latter. He is of opinion that the species must be united with that parasitic on the branchial tissue of Bhalksia mamillata. It is therefore probably a similar — if not the same — form as Delle Chiaje or Leuckart and Pagenstecher long ago described (see p. 2, &c). Unfortunately the author is not more precise than M. Marion with regard to the anatomical position of the proboscis, which, he states, is attached to the " walls of the general cavity." The complex struc- ture of the anterior region is not precisely detailed, and the same remark is applicable, as in the case of M. Marion, to his definition of the granular basal apparatus of the central stylet, which is held to be brownish. He, however, has evidently more acquaintance than his colleague with the muscular cavity (e in our figures) behind the floor of the anterior chamber, though his description is somewhat obscure. Three marginal stylet-sacs are mentioned as characteristic of the species. The dark layer above the styliferous apparatus would have been whitish by reflected light. He agrees with M. Marion in calling the reservoir a poison-sac, but is not definite enough in his account of the termination of its duct (which opens into the chamber s). The physiological observations on the ejection of the proboscis have been anticipated. 1 c Proceed. Roy. Soc./ vol. xxi, No. 142., received January, 1873 ; also in e Annals Nat. Hist./ vol. xi, 4th ser., No. 64, April, 1873, &c. 3 < Trans. Hoy. Soc. Edinb./ vol. xxv, p. 305, 1869. 3 < Ann. Nat. Hist./ vol. ii, 4th series, No. 65, p. 398, May, 1873 (from the < Comptes Eendus/ April 14th, 1873). ERRATUM. Delete the first synonym (date 1776) on p. 156, and the allusions thereto on pp. 10 and 158. PLATE XL Fig. 1. Transverse section of the cephalic ganglia of Amphiporus lactifloreus, in the line of the commissures, the superior of which, from the flattening of the preparation, is shown very plainly, a, proboscis ; d, circular muscular fibres of the body- wall ; k, muscular and cellular stroma of the region, x 90 diam. 2. Section through the body of the same animal some distance behind the ganglia. The sheath for the proboscis now separates the latter from the oesophagus, which has attained considerable size. The lateral nerve-trunks have nearly reached their proper position, viz. to the inner side of the internal muscular layer of the body-wall ; s, granular masses (from the digestive cavity proper) at the sides of the oesophagus. X 55 diam. 3. Section of the same specimen behind the foregoing and towards the posterior end of the oesophageal apparatus, u, ova pressed forward by the contraction of the textures. 4. Transverse section of the anterior region of the proboscis of Amphiporus pulcher. a, central cavity ; 5, the papillary glandular layer ; c, internal circular muscular coat ; d, inner longitudinal layer; e, reticulated or beaded layer ;/, external longitudinal muscular layer; g, external (elastic) layer; h, basement-layer. X 55 diam. 5. Transverse section of the stylet-region of the proboscis of A. lactifloreus, in the line of the marginal sacs. The circumference of the preparation is somewhat distorted from pressure. X 350 diam. 6. Transverse section of the same region in another specimen, in which the knife has pressed aside the basal apparatus of the central stylet (X), and in which the ejaculatory duct (ju) has been cut obliquely. In this and the preceding preparations the peculiar arrangement of the muscular fibres of the region is represented. X 210 diam. 7. Longitudinal section of the anterior region of the proboscis of Amphiporus lactifloreus. X 90 diam. 8. Longitudinal section of the same region of the proboscis. X 350 diam. 9. Transverse section of the same part of the proboscis. e, the ends of the longitudinal bands of the reticulated layer, which have assumed a finely granular aspect in the pre- paration. X 350 diam. 10. Glandular papillae in the anterior region of the proboscis of A. lactifloreus, seen in the ordinary condition of the organ under pressure. X 210 diam. 11. Central stylet and basal apparatus of Nemertes Neesii. X 350 diam. 12. Central stylet of N Neesii. X 700 diam. 13. Developing or recently repaired central stylet-apparatus of Tetrastemma Candida. X 700 diam. 14. Stylet from a marginal sac of the same animal. X 700 diam. 15. Central stylet and a portion of the basal apparatus in a large Nemertes gracilis. X 350 diam. 16. Extremity of the posterior region (c) of the proboscis of A. lactifloreus distended with fluid. a, a group of the peculiar moving granules. X 90 diam. 17. Posterior end of a young example of Tetrastemma dorsalis, showing the usual hernia of the proboscis under pressure. X 350 diam. PL- X! / *. 15 o pa. I- 5. " is^ ■ " ' r i:l (I //. 10. ^ 3 ! p* ~ ~ - : ■ ■ mg PLATE XII. ElG. 1. Structure of the stylet-region in a large Ampkiporus lactifioreus. The specimen had two marginal sacs on one side. X 350 diam. 2. Structure of the stylet- and reservoir-regions in the same form. Considerably magnified. 3. Abnormal stylet-region in the same species, a, perfect stylet-sac of the left side ; b, shriveled sac of the right side. X 210 diam. 4. Termination of the posterior chamber of the proboscis (c) of A. lactifioreus, with muscular ribands. X 210 diam. 5. The central (a) and marginal stylets (6) from a young J. lactifioreus, on the first appearance of the former. X 700 diam. 6. Structure of the stylet-region of the proboscis of Amphiporm pulcker. X 90 diam. 7. Central stylet-apparatus of the same species, a, central stylet; b % reserve-stylet in situ. X 210 diam. 8. Structure of the stylet-region in Tetrastemma melanocep/iala, X 90 diam. 9. Structure of the stylet-region in Tetrastemma flavida, with the reservoir somewhat contracted. X 210 diam. 10. Extremity of the posterior chamber of the proboscis of Tetrastemma dorsalis, apparently after rupture of the muscular ribands from the sheath of the organ. X 350 diam. 11. Structure of the stylet-region of the proboscis in Nemertes gracilis. X 210 diam. 12. Structure of the stylet-region of the proboscis of Nemertes Neesii. X 210 diam. 13. Portion of the posterior chamber of the proboscis of the same species, showing the charac- teristic plaits of the mucous surface. X 90 diam. 14. Structure of the stylet-region of the proboscis of Nemertes carcinophila. X 700 diam. PL. XII ■-. - -\ NfaiUru 'Bros. imp. PLATE XIII. Fig. 1. Structure of the stylet-region of the proboscis of Prosorhochmus Claparedii. Degeneration of the marginal sacs has ensued from long confinement. X 90 diam. 2. Aspect of the developing proboscis (a) of Tetrastemma melanocephala, about the fifth day after the removal of the original organ. X 55 diam. 3. Structure of the stylet-region of a developing proboscis of the same species. /, canal, which by-and-by is occupied by the central stylet. The organ is contracted. X 350 diam. 4. Central stylet and basal apparatus with radiating fibres in Tetrastemma vermicula. X 350 diam. 5. Stylet- region of the proboscis of T. Candida, with the ejaculatory duct pressed to the left side. The marginal stylet-sacs are out of focus. X 210 diam. 6. Central stylet and basal apparatus of a small specimen of the same species. X 420 diam. 7. Structure of the stylet-region in Tetrastemma dorsalis, somewhat contracted, with the floor of the anterior chamber pouted forward, and the reservoir shortened in its antero- posterior diameter. X 210 diam. 8. Stylets of the same species, a, central stylet; b, stylet from a marginal sac. X 700 diam. c, central stylet and its basal granular apparatus. X 420 diam. 9. Stylets of Tetrastemma flavida. a, central stylet; b, stylet from a marginal sac. X 700 diam. c, central stylet and its basal apparatus. X 420 diam. 10. Superficial structure of the stylet- and reservoir-regions of A. lactijioreus. Considerably magnified. 11. Isolated marginal stylet-sac of the same species, a, fibres which probably act as constrictors of the aperture of the duct. The laminated arrangement of the calcareous layers of the stylets is indicated in this figure. X 350 diam. 12. Stylet-region of the proboscis of a young animal of the same species, illustrating the first appearance of the stylets and the development of the parts. The organ is drawn as it bulged from a wound in the body- wall of the specimen. X 700 diam. 13. Stylet-region of a young A. lactijioreus, some weeks older than that represented in the pre- vious figure. X 350 diam. 14. Proboscis of an adult of the same species, gently but completely extruded under chloroform, so as to render the central stylet prominent. X 55 diam. 15. Transverse section of the contracted reservoir-region of the proboscis of the same species, showing the complex spiral arrangement of the fibres. The organ is cut towards its posterior end. X 55 diam. 16. Transverse section of the posterior chamber of the proboscis in a large example of the same species. X 90 diam. 17. Structure of the stylet-region in a developing proboscis of Nemertes gracilis. X 350 diam. 18. Central stylet and its basal apparatus in the same species, turned round so as to demon- strate the curve of both. X 100 diam. 19. Proboscis of Amphiporus pulcher treated as in fig. 14. X 55 diam. 20. Fragment of the oesophageal region of the digestive tract from a living A. lactijioreus. a, inner edge of ciliated fold ; b } sulcus between two folds. X 350 diam. PL. XIII i >■ r : ■ i PLATE XIV. Fig. 1. The anatomy of Tetrastemma Candida, chiefly with respect to the digestive and proboscidian systems. Considerably magnified. h°, abnormality of the right ganglion. 2. Structure of the head of a young Tetrastemma melanocephala, showing the ganglia and the relation of the pigment-patch to the eyes. Considerably magnified. 3. Digitate or lobate arrangement of the digestive canal of Nemertes gracilis. X 24 diam. 4. Head and anterior portion of Nemertes carcinophila. f, powerful transverse fibres which retain the posterior part of the oesophagus in situ. X 180 diam. 5. Superficial structure of the reservoir in Nemertes Neesii, showing the elaborate interlacing of the fibres. X 210 diam. 6. Stylet from a marginal sac of Tetrastemma Candida (same animal as in fig. 6, Plate XIII). X 700 diam. 7. Stylet from the central apparatus of the same specimen. X 700 diam. 8. Stylet from a marginal sac of Tetrastemma melanocephala. X 700 diam. 9. Stylet from the central apparatus of the same specimen. X 700 diam. 10. Marginal stylet of Tetrastemma Robertianoe. a X 350 diameters, b X 700 diam. 11. View of the under surface of the snout of Amphiporus pulcher. The mouth is indicated at w, the cephalic furrows and their branches at m", and the situation of the ganglia at i. Enlarged under a lens. 12. Transverse section of the wall of the oesophagus of A. lactifloreus, after mounting in chloride of calcium. X 210 diam. 13. Compound cells from the wall of the digestive cavity of Tetrastemma dorsalis. X 350 diam. 14. Cephalic ganglia of Tetrastemma flavida. X 210 diam. 15. Eye of Amphiporus pulcher from a dead and slightly injured specimen. X 210 diam. 16. Portion of a sperm-sac from Tetrastemma flavida, exhibiting a streaky and granular aspect from the varying nature of the contents. X 350 diam. 17. Granules from a developing sperm-sac of T dorsalis. X 400 diam. 18. Spermatozoa of Amphiporus lactiflor ens. X 800 diam. PL. XIV- • ■ ' %§v w V' • ' 11 ■ r- 1 II Vvl I # PLATE XV. Fig. 1. Transverse section somewhat behind that shown in Plate XI, fig. 1. The instrument has passed obliquely across the body so as to cut the ganglia at different distances from the front. On the right only the tip of the superior lobe remains, while the commencement of the great nerve-trunk — in full bulk — is cut beneath. X 90 diam. 2. Snout and anterior region of A. pulcher. g,g, glandular masses. X 55 diam. 3. Arrangement of the circulatory and nervous systems in A. lactifloreus (a small specimen). X about 40 diam. 4. Portion of the head of the same species considerably flattened. X 210 diam. 5. Head of Nernertes Neesii. X about 60 diam. 6. Nerve-cells from a cephalic ganglion of A. lactifloreus. X 400 diam. PL. XV. PLATE XVI. Fig. 1. Anterior end of Tetrastemma dorsalis. a, proboscis, whose fibres have temporarily assumed a spiral aspect from twisting, b, tube connected with the cephalic sac of the right side. Considerably magnified. 2. Longitudinal section of the body-wall of A. lactifloreus, in a somewhat shriveled condition. /,/, ovisacs from which the contents have fallen. Other letters as usual. X 90 diam. 3. Nervous plexus from the lateral trunk (n) in A.pdcher. X 210 diam. 4. Transverse section of the anterior part of the stylet-region proper, showing the divergent arrangement of the oblique fibres and the position of the longitudinal series. X 210 diam. 5. Three sperm-sacs (ef) with a portion of the body-wall of A. lactifloreus. X 90 diam. 6. Spermatozoa of Tetrastemma vermicula. X 1000 diam. 7. Spermatozoa of Tetrastemma dorsalis. X 400 diam. This drawing was made many years ago, and probably represents imperfectly developed bodies. 8. Unimpregnated ovum of A. lactifloreus. a, outer coat; b 9 inner coat; c, vitellus ; d, " micropyle," or cicatrix-like arrangement. X 90 diam. 9. The same ovum some hours after impregnation. The vitellus (c) is now divided into two portions. X 90 diam. 10. The same ovum a few hours later. The vitellus is in four portions. X 90 diam. 11. Ovum of the same species in the mulberry-stage. X 90 diam. 12. Ovum just before the extrusion of the embryo. X 90 diam. 13. Arrangement of the ova in the ovisacs of Tetrastemma vermicula. a, proboscis ; o, probos- cidian sheath. X 24 diam. 14. Ovum of the same species. X 90 diam. 15. Ovum of Nemertes gracilis after impregnation, a, outer coat; b, inner coat; c, vitellus. X 90 diam. 16. The inner coat and vitellus of an ovum (of N. gracilis) at the same stage of development, with the relations of the spermatozoa. X 210 diam. 17. Ovum of N. Neesii. X 55 diam. 18. Portion of the mucous sheath with the ova of Nemertes carcinophila. X 24 diam. 19. Ovum of the same species immediately after deposition. X 350 diam. 20. Another ovum, about the tenth day, showing the ciliated embryo revolving therein. X 350 diam. PL. XVI. -^ 12. "b.....i: i 1:1 ! V ; 18. ; | . .' ■ ! ' : : • ' '■ s : I 15. T, 14-. 20. 19. X 10. H ■ VH. •■„?-' i PLATE XVII. Fig. 1. A young specimen of A. ladifloreus on extrusion from the egg. Somewhat compressed. X 55 diam. 2. Another specimen eight days older than the preceding, b, stylet-region ; c, point where the posterior chamber of the proboscis becomes lost, after curving forward. x 90 diam. 3. Outline of a young specimen of Tetrastemma dorsalis shortly after extrusion from the egg. X 350 diam. 4. The same compressed, so as to exhibit its cellulo-granular structure. X 350 diam. 5. Young specimen of T. dorsalis, about a week older than the preceding, a, cutaneous textures; b, cells and granules of the alimentary tract; c, stylet-region. X 210 diam. 6. A specimen eight days older than the foregoing, showing a considerable advancement in all the organs. X 210 diam. 7. A young example of N. carcinophila extruded from the body of the adult under pressure. It has the same appearance when originating in a free ovum. X 350 diam. 8. Spermatozoa of Nemer tes gracilis. X 700 diam. 9. Spermatozoa of iV". carcinophila. X 950 diam. 10. Spermatozoa of Am/phiporus pulcher. X 700 diam. 11. Magnified view of the ganglionic region of a large A. ladifloreus y in which a parasitic ovum (y) lay imbedded in a granular lobulated mass (y). 12. Parasitic ovum immediately after removal, a, opaque mass of cells and granules ; b, ventral disc; c, oral disc; d, capsule, to which some shreds of the surrounding tissue are adhering. Considerably magnified. 13. The same ovum some hours afterwards, showing slight contraction of the discs. 14. Parasite extruded from the capsule, a, opaque cellular and granular mass; b } ventral disc ; c, oral disc ; d, oesophageal bulb ; e 9 alimentary caeca ; /and g, large circular granular bodies. 15. Streaked arrangement of the cutis from the dorsum of Linens gesscrensis. X 210 diam. 16. View of the cutis of the same species (at a pale portion) as a transparent object. X 210 diam. 17. Portion of the skin of a living Carinella annulata. X 350 diam. 18. Pigment-cells from the anterior dorsal region of Linens gesserensis. X 350 diam. 19. Papillae on the snout of the same species. X 210 diam. 20. Tip of the snout in the same species, with the proboscis partly extruded. X 210 diam. 21. Posterior extremity and styliform process of Micrura fasciolata. a, central cavity, containing fluid; z, anus. X 210 diam. 22. Posterior extremity of a young example of Z. gesserensis, showing the anal papilla. X 210 diam. 23. Corpuscles of the extruded fluid (page 114) from Borlasia fflizabethce. Highly magnified. 24. Anterior ^extremity of Carinella annulata. a, aperture in snout for proboscis ; b, cephalic furrows ; c, cephalic blood-vessel ; m, cephalic sac ; w, mouth. Magnified. 25. Spermatozoa of Amphiporus bioculatus. X 700 diam. 26. Spermatozoa of Tetrastemma Robertiance. X 700 diam. PL. XVI {) 6 4 >^ r 13. 12. 19. // \ U\ \\\ 24. 21. '""-'■!■'/ 10. n't] / S 5 ^ h i 17. <**, ',-: '< 16. ISM w MHirteni IBros PLATE XVIII. Fig, 1. Dorsal view of the head of Lineus marinus after long confinement. The blanching of the cutaneous tissues renders the eyes conspicuous. Magnified under a lens. 2. Ventral view of the same specimen exhibiting the mouth (w). Similarly magnified. 3. Profile of the same head, showing a cephalic fissure with its reddish coloration posteriorly. 4. Transverse section of the body- wall of Lineus gesserensis. X 350 diam. 5. Transverse section of the body-wall of Lineus marinus at a somewhat narrow portion. d, external cuticular layer ; d", pigmentary layer divided into two strata by a definite black band (2) ; 3, curious translucent stratum cut into regular spaces. Other letters as usual. X £10 diam. 6. Longitudinal section of the same tissues. 4, 4, sections of the transverse connecting trunks between the lateral and dorsal vessels ; 5, granular stroma within the inner longitudinal muscular coat, supporting the former and various other tissues. X 90 diam. 7. Transverse section just behind the tip of the snout of L. gesserensis. The grouping of the pigment (3) readily enables the observer to distinguish the dorsal from the ventral surface ; 2, powerful series of fibres arching over the channel for the extrusion of the proboscis, and radiating into the surrounding stroma (k), X 55 diam. 8. Transverse section somewhat behind the preceding, and through the anterior part of the cephalic fissures. The channel for the proboscis has become more central in position. The superior pigmentary belt (3) is somewhat narrower, and an inferior (4) has now appeared. The central channel has a layer of longitudinal muscular fibres internally, and a powerful series of oblique and circular fibres (2, 2) form a very efficient exterior invest- ment. X 55 diam. 9. Transverse section of the cephalic ganglia of a smaller specimen than the preceding. X 55 diam. 10. Horizontal section of the snout of the same species through the ganglia, exhibiting the relations of the latter and the reticulations of the cutaneous tissues in front of them. X 90 diam. 11. Transverse section of a specimen of L. gesserensis (after spawning) a little in front of the tip of the tail. X 90 diam. 12. Elements from the glandular papillae of the proboscis of the same species, after their escape into the water. X 700 cliam. 13. Elements from the proboscis of Micrara faseiolata. Similarly magnified. 14. Portion of the inner surface of the proboscis of L. gesserensis, showing the glandular papillae. Slightly compressed. X 700 diam. 15. Snout of Cephalothrix linearis with the proboscis slightly everted, so as to exhibit the acicular papillae. X 350 diam. 16. Fragment of the wall of the proper digestive chamber of L gesserensis. The cilia mark the inner surface. X 350 diam. 17. Parasitic ciliated animal from the tissues of the same species. The letters a, b, c, and d correspond with the groups of segments described in the text. X 350 diam. 18. The foregoing parasite at an earlier stage of development. X 350 diam. 19. The last-mentioned specimen subjected to slight pressure, so as to exhibit the segments. X 350 diam. ,1 PL, X.vlll fit : I ' - : ; - ' 13. 19 17 18 ■ ; . i iPS^Ii 14. 3 12. 16. ■ . ; . ■ , '■'■•>;■ - : -- " _. :■_■: PLATE XIX. Fig. 1 Enlarged view of the anterior region of Lineus gesserensis, as a transparent object. 2. Anterior portion of Lineus sanguineus, g, peculiar incurvation of the wall of the ali- mentary canal, marking the boundary between the oesophageal and the succeeding division of the digestive apparatus. X 90 diam. 3. Anterior portion of Lineus lacteus. X 90 diam. 4. Portion of the middle region of L. gesserensis, representing the arrangement of the vessels in the living animal. Considerably enlarged. 5. Arrangement of the vessels at the posterior extremity of the same species. Similarly magnified. 6. Posterior portion of a specimen of the same species having an unusually distinct anus (probably from partial repair after injury). a, mass of granular and cellular debris revolving in the direction of the arrow by aid of the cilia of the digestive cavity ; b, anus. X 210 diam. 7. Transverse section of the proboscis of Borlasia Mizabethce. X 210 diam. 8. Transverse section of the proboscis of Micrura fusca. X 350 diam. 9. Highly magnified view of the anterior end of Cephalothrix linearis, 6, b, bridles of the sheath for the proboscis. 10. Gregariniform parasite from the digestive canal of Lineus lacteus. X 350 diam. 11. Outline of one of the same parasites after prolonged immersion in water. - Mmtern Bros. imp. PLATE XX. Fig. 1. Transverse section of the oesophageal region of Lineus gesserensis after the channel has attained full development. X 55 diam. 2. Transverse section of the oesophageal region of a large specimen of the same species in which a favourable view of the vascular meshes (u) around the cavity is obtained, v, one of the larger spaces on each side of the sheath for the proboscis. X 55 diam. 3. Transverse section of a fine specimen of L. gesserensis some time after spawning, and when the animal has regained its plump condition. The shriveled traces of the repro- ductive organs are seen at ov. A doubling of the proboscis in its sheath has occurred. X 40 diam. 4. Transverse section of the proboscis of Micrura fusca. a, external coat ; b, great longi- tudinal muscular layer ; c, belt of circular muscular fibres ; d, basement-layer - e, in- complete series of longitudinal fibres which do not occur in the common species; /, glandular mucous coat ; g, peculiar lozenge-shaped portion of longitudinal fibres, formed by the splitting and crossing of two bands from the circular muscular coat ; /, separate segment at the other pole of the circle. X 90 diam. 5. Transverse section of the proboscis of Meclcelia asulcata. a, external spiral coat; b, longi- tudinal layer ; c, central cavity surrounded by the glandular coat ; d, cross of fibres at the poles. X 210 diam. 6. Transverse section of the proboscis of Carinella annulatci* X 90 diam. 7. Gland-cells from the wall of the digestive cavity of Amphiporus lactifloreus. X 400 diam. 8. One of the same slightly compressed glands. X 700 diam. 9. Contents of the former, with oil-globules. X 700 diam* 10. Pseudo-navicellee extruded with the former parasites from the digestive canal of Lineus sanguineus. X 350 diam. 11. Portion of a gelatinous cord containing ova from the digestive canal of L. gesserensis. X 180 diam. 12. Ovum from the same. X 350 diam. 13. Transverse section of the body- wall in the region of the lateral nerve of a Lineus from Fetlar, showing the intricate arrangement of radiating fibres which pass through the cir- cular coat and divide the external longitudinal muscular layer into endless fasciculi. X 90 diam. . PL. XX / / ■xr .] 7 o 12. ^ - 13. . , / 2 :' fee.?. Tnxp PLATE XXL Fig. 1. Transverse section of a specimen of Linens gesserensis in which the ova are well developed. The shrunken condition of the walls of the digestive cavity (/), with the numerous gregariniform parasites, is in strong contrast with the state of the animal after spawn- ing. The specimen had been in spirit a considerable time before dissection. X 55 diam. 2. Transverse section of Cephalothrix linearis. The proboscis is coiled in its sheath. X 90 diam. 3. Transverse section of one of the Lineidce from St. Magnus Bay, Shetland, in which the sheath for the proboscis is surrounded by the internal longitudinal muscular coat. X 28 diam. 4. Transverse section of Borlasia Elizabeths after contraction in spirit. The enormous muscular mass forming the body-wall is well shown in this preparation. X 24 diam. 5. Transverse section of the proboscis of Lineus marinus. X 55 diam. 6. Transverse section of a lateral nerve-trunk (n) in Lineus gesserensis. n\ fibro-granular matrix, in which the nerve lies in its own proper sheath ; e, external longitudinal muscular layer of the body-wall ; e, circular muscular layer. X 700 diam. 7. Cellular elements of the wall of the digestive chamber of the same species. X 700 diam. 8. Cells from the digestive cavity of a young Cephalothricc linearis. X 700 diam. 9. Head and proboscis of a remarkable variety of Carinella brought from Shetland by Mr. Gwyn Jeffreys. b, frilled arrangement, apparently homologous with the superior lip of the cephalic fissure ; w, prolapse of textures from mouth. Magnified under a lens. 10. Spermatozoa of Lineus gesserensis. X 700 diam. 11. Spermatozoa of Lineus sanguineus. X 800 diam. 12. Spermatozoa of Lineus marinus, from a fragmentary specimen. X 900 diam. 13. Spermatozoa of Cephalothrios linearis. X 900 diam. PL- XXI \ ; I, ii / 1 I _.-e ,_" ') ',\M ■ :| H ; PLATE XXII. Fig. 1. Transverse section of the cephalic ganglia of Linens gesserensis. The pale central portions are caused by the imperfect penetration of the fluid in mounting. X 210 diam. 2. Transverse section of the curious variety of Carinella from Balta. d, external layer of cutis ; d\ basement-layer; e, longitudinal muscular layer; [e a, dorsal subdivisions of the latter coat in the central line ; e', circular muscular coat ; j, section of the oesophageal region of the digestive tract; j a, distinct band of muscular fibres enclosing the latter; n } lateral nerve; o, sheath for proboscis; r y vascular spaces. X 55 diam. 3. Transverse section of the postganglionic region of Lineus lacteus, showing the long vascular lacunae (s, s) in front of the oesophageal region. The slice of the proboscis has fallen out of its sheath (o). X 90 diam. 4. Anterior 'end of a contracted specimen of L. gesserensis, turned round so as to exhibit the marked separation between the oesophageal region and the digestive cavity proper. X 90 diam. 5. Adventitious granular mass {a) in a longitudinal section of the dermal tissues of Lineus marinus. b, b, spaces from which similar structures have fallen. Other letters as in pre- vious figures. X 210 diam. 6. Aggregations of fatty granules from the discarded coating of the embryo of Lineus gesserensis. X 210 diam. 7. Anterior end of a fragment of Lineus sanguineus, about three weeks after rupture, a, terminal aperture; d, cutaneous layers. X about 40 diam. 8. Posterior end of the same fragment, similarly magnified, z, anus. 9. Anterior portion of a fragment in a more advanced condition, a, developing proboscis ; h, indication of ganglia. 10. Anterior region of a complete, or nearly complete, animal developed from a fragment; j, oesophageal division of the alimentary canal; m % cephalic pit and sac ; w, mouth. 11. View of a similar specimen; the regenerated anterior portion, consisting of the head and the oesophageal region of the digestive chamber, is recognized by its pallor ; b, cephalic fissure. Magnified under a lens. PL. XXI : H _^ \ \ \ i ( YO ■ ea, o ea. La PLATE XXIII. Fig. 1. Pale oily region with germinal vesicle (a) and germinal dot (b), in an ovum removed from the body of the female Lineus gesserensis. X 350 diam. 2. Flask containing two ova from the mucous cord of the same species after deposition. One is simply outlined, but the other is shaded— to indicate the natural opacity, x 55 diam. 3. Flask on the second day, showing the yolk divided into four portions. X 55 diam. 4. Ovum some hours older and somewhat compressed, exhibiting the further subdivision of the yolk. X 55 diam. 5. Flask having its single ovum in the mulberry-stage, x 55 diam. 6. Flask containing three ova in the same condition. X 55 diam. 7. Flask having a ciliated embryo (about the 12th or 13th day); it remains in this condition some weeks, x 55 diam. 8. Flask enclosing two young animals, somewhat compressed. a, embryo forced from its ciliated cellulo- granular fatty coating, the bulk of which lies at c ; b, embryo still within the ciliated coating. X 55 diam. 9. A young specimen of L. gesserensis immediately after leaving the flask; b, opening of the right cephalic sac. X 90 diam. 10. Magnified view of a young example of the same species after it has attained a considerable degree of advancement. It still possesses only two eyes. 11. Flask from the mucous cord of Lineus marinus* The contained embryos are nearly disin- tegrated from decomposition. X 55 diam. 12. Ovum of Cephalothrix linearis immediately after deposition. X 350 diam. 13. Embryo of the same species shortly after extrusion from the egg. X 350 diam. 14. A young specimen two days older than the preceding, a, mouth ; b, granules of digestive cavity. X 210 diam. 15. An example about three days older than the last (fig. 14). X 210 diam. 16. A young specimen of Cephalothrizc linearis after shedding the long anterior whip of cilia, but having the lateral tufts (c) and eyes, a, mouth ; b, granules of digestive cavity. X 210 diam. 17. Transverse section of the proboscis of Cerebratulus angulatus, O. F. Muller. g a, the inner wedge of longitudinal fibres described in the text ; g b, the outer band of longitudinal fibres. The other letters as usual. X 40 diam. 18. Stylet-region of Ampliiporus Jiastatus, somewhat contracted. It has the same letters as other figures of the Enopla. X 55 diam. 19. Stylet-region of Ampliiporus bioculatus. X 55 diam. 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