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WA OR None ect a co | png tenet eat ccercrsiase are ia noe , fastens an Bre ap? r\ tte gAbdaunr? “uae whtaa 4 4 Een Besa v- AVA, | a nae sett pe 1 fi Onan ae HAT ra ry n \ i: ay 0 Prtan Panes aint aiia Meace gee Oma Ae am cy 4uaN =i IO iaey Vainio) Mae. ¢ aay aaah aN TAZA NAA. acne Bia ee on AN da reER HR TALE ve Poel LL Pe. 0 +g ae, lang Pagns oases saan a Bi me ogg A Ie} Beaks A pe pyamnaey Bohs aie 7 pseate PABA lank the *Bagnenny) sate Sica’ lab cla Wee ery MURR Aah aah 2 he pheeniRaeact Meer ae} 7 a. 4,7 4 Wa agprm a A Au WA! sR RRNA AR Ws a ee : \\ ¥ . a7 wont Reset Ly 1s sl ie wren. ,~PPAARNG ‘f ‘A iA BoM on Lan aA AA Musedoarcnrit( Mh eantttlamaacting. yo UmAR.S cotoa0 “ih escanentcarnans aanaeeeey ARAL? WANN nan Whit tes S.A. ae rk On Shalini, YN ayy SAA A ip fenton ah) i wy ; a hy LT I Die Aaa art eins Cab SEP biliallal 1) Rew LPP Pre rio | | toca AAte a mtd a nak Phy Ty Penge earns haa” ry: ~ fring nanee Paap yr belay Va ae. mag: “e The Rae Ge ie Vie -RAR “AAR N - wy . we poaeti eM NtaS ine ms, A oy Ap a bite rs Cabhippi his ww" penta a _ ANDSS n*® Ing ponte, ; ann ne \ ‘ TARR aaa antaarAnada *! Nee anparre, Hib, sib ts Mpa Hai WA aaragin AKL Sap Van ar AU RDRARe {ey a” - VE iil YN gh learn faanas””. pall | WY lt AAEFPT AP i Mk ono ana a2Pnaas > 1 Gn iS oF ea RAE OL PEE eee ON conti ey li yah a ‘lp es a [Novemser, 1891. | THE Pa of. 29 SCIENTIFIC TRANSACTIONS OF THE BOY Mite DUS LING SOC Tie VOLUME IV. (SERIES II.) XII. A REVISION OF THE BRITISH ACTINIA. PART II.: THE ZOANTHEA. By ALFRED C. HADDON, M.A. (Cantab.), M.R.I.A., Professor of Zoology, Royal College of Science, Dublin; and MISS ALICE M. SHACKLETON, B.A. Plates LVIII., LIX., LX. Msp ie a DUBLIN: PUBLISHED BY THE ROYAL DUBLIN SOCIETY. LONDON: WILLIAMS AND NORGATE. PRINTED AT THE UNIVERSITY PRESS, BY PONSONBY AND WELDRICK, PRINTERS TO THE SOCIETY. 1891. Price Three Shillings and Siapence. [ \. JI Prtar ‘4 J IN _ [Novemser, 1891. } > THE SCIENTIFIC TRANSACTIONS OF THE RO Se PUISLEN SOC THI VOLUME IV. (SERIES IL.) XII. REVISION OF THE BRITISH ACTINIA. Ve PART II.: THE ZOANTHE. By ALFRED C. HADDON, M.A. (Cantab.), M.R.I.A., Professor of Zoology, Royal College of Science, Dublin ; and MISS ALICE M. SHACKLETON, B.A. Plates IOVIU bse, IUDon! IED, ——_———— oe . ™. unsoman Instityge Ss Tae eg | onal Musev® 7” tial Muse DUBLIN: PUBLISHED BY THE ROYAL DUBLIN SOCIETY. LONDON: WILLIAMS AND NORGATE. PRINTED AT THE UNIVERSITY PRESS, BY PONSONBY AND WELDRICK, PRINTERS TO THE SOCIETY. 1891. | 609 ] XII. A REVISION OF THE BRITISH ACTINIA. PART II.: THE ZOANTHEA. By ALFRED C. HADDON, M.A. (Cantab.), M.R.I.A., Professor of Zoology, Royal College of Science, Dublin; and MISS ALICE M. SHACKLETON, B.A. Puarzs LVIII., LIX., LX. [Read Frsrvary 18, 1891. ] CONTENTS. PAGE Introduction, . F : : . 609 General account of the Anatouy of a Fea, : : ; . 612 Classification of the Group, . é : : : j . 626 Systematic Account of the British Zeaien, : : ; ; . 634 Bibliography, . 3 : 5 4 , : ; j : . 663 Index, f ; : : ¢ P , 5 ; 4 ‘ . 671 INTRODUCTION. Tue first part of this Revision dealt with a new sub-family of the Sagartide, the Chondractinine, which included the genera Chondractinia, Hormathia, Chito- nactis, Actinauge, and Paraphellia. A few notes were made on the genus Sagartia ; and details are given of British representatives of Gephyra dohrnit. 'The British members of the families Edwardside and Halcampidzx were described; and the nature of Gonactinia prolifera was discussed. An account was also given of the arrangement of the mesenteries in the Zoanthee. The Paper concluded with a summary of the development of the mesenteries of Actinia; and certain general considerations were advanced on the phylogenetic value of the mesenteries. Unavoidable circumstances caused this first part of the Revision to be heteroge- neous in character, and unsatisfactory in many details. The present instalment of the Revision is confined to a very distinct group of the Actiniz. Although there has been considerable confusion within the group, the TRANS. ROY. DUB. SOC., N.S. VOL. IV., PART XII. 48 610 Happon anp SHacxteron—A Revision of the British Actinic. Zoanthez themselves have, since the time of de Blainville, been recognized as a well-marked division of the Actiniz. With the exception of the genus Sphenopus, and certain free varieties of the genus Hpizoanthus, all the members of this group are permanently fixed, and with very few exceptions form colonies, the individuals of which are united by the adhering base or ccenenchyme. The ccenenchyme extends laterally, and from it new polyps arise, which remain permanently connected with the colony. The ccenenchyme may be band-like or form broad encrusting sheets; usually it is thin, but in the genus Palythoa it is so thick that the polyps are more or less immersed within it. The polyps may be placed at considerable intervals from each other, or they may be crowded together, the latter condition being usually due to gemmation from the base of the polyps rather than from the coenenchyme. It is characteristic of the group for the body-wall of the polyp and coenenchyme to be incrusted with foreign particles—grains of sand, spicules, foraminifera, and such like. Some genera, such as Palythoa and Sphenopus, are always densely incrusted ; the incrustations in Parazoanthus vary according to the species from a considerable amount to very few; finally, the genera Zoanthus and Mammillifera are unincrusted. The Zoantheze have the same body-regions as other Actiniz, with the excep- tion of the basal disc, which must necessarily be absent in the colonial forms, and of a physa in the free forms. In all the column is divisible into scapus and capitulum ; the former is usually rigid. In nearly all preserved specimens the capitulum is retracted, and this appears to be generally the case when living, for these forms do not fully expand so frequently as most other sea-anemones. The capitulum is usually thrown into triangular ridges. The tentacles are bicyclic, and may be very short or moderately long. When fully expanded, the oral disc may be flat or projecting. The mouth is always linear. Only one cesophageal groove is present. The colours are usually various shades of yellow, buff, and brown, due to the sand incrustations; some have varied colours—pink, green, violet, and so forth— but it is very rare for the colours to be so vivid as is customary among other Actiniz. Reproduction takes place by means of ova, by basal and ccenenchymatous gemmation, and by fission. The foregoing are all the characters which are available for the field naturalist, and, until quite recently, were the only ones on which the definition of species and their systematic arrangement were based. These purely external characters are more than usually unsatisfactory for diagnostic purposes; hence Happon anp SuackLeTon—A Revision of the British Actinic. 611 the not unnatural confusion into which the group has fallen, and from which it has, to a certain extent, been extricated through the labours of Erdmann and M*Murrich. In no group is it more necessary to combine anatomical and microscopical examination with the methods of the older zoologists—for the species of Zoantheze can only be established after sections have been cut and studied. The identification of new material with recognized species requires the utmost circumspection. It is impossible to determine the genus to which many previously described species belong until the types have been re-discovered, and then submitted to an anatomical investigation. A complete monograph of the group is at present an impossibility. We have, however, ventured as far as we safely could in this direction. We have investigated the anatomy of eleven species belonging to five genera of Zoanthez from Torres Straits, besides several other forms, at the same time that we were occupied upon the British representatives. Our Paper on the Torres Straits specimens is published simultaneously with this one, and in the same Journal ; and we would ask those who are interested in this group to study both Papers together, for the two are, to a certain extent, complementary to each other. Methods.—All the specimens examined by us were preserved in alcohol, and when a sufficient quantity of strong alcohol is used this answers perfectly well. We stained the objects whole in borax carmine, imbedded them in paraffin, and cut them with a ‘‘rocking” microtome. In a few cases we stained the sections after they were fixed on the slides. The unincrusted genera are very easy to cut, and so are some of the incrusted forms, especially some of the species of Parazoanthus. Those wishing to study the anatomy of the group cannot do better than commence with P. axinelle, which is very easily cut by the ordinary paraffin method. It was perfectly unnecessary for von Koch to employ his ‘‘ Schliff-methode” (Morph. Jahrb. vi., 1880, p. 359) when investigating this species. We mention this solely to prevent others from taking superfluous trouble. The different species of the genus EKpizoanthus are, as a rule, difficult to sectionize, on account of the incrustations. ZL. paguriphilus is, however, practically free from them ; owing to the great thickness of the mesoglcea in this species, celloidin is a better imbedding material than paraffin, as heat has to be employed in the latter method. Asarule, the incrustations in Zoanthez from coral seas are calcareous, and admit of being readily dissolved away. We use nitric acid for this purpose. The use which we have made of the Papers of Erdmann and M*Murrich will emphasize the indebtedness of students of the Zoanthez to those in- vestigators. References to other workers will be duly acknowledged where we 482 612 Happon AnD SuackLteton—A Revision of the British Actinie. utilize their results. The laborious monograph of Andres has been in constant requisition. It is now our pleasing duty to acknowledge the assistance of many friends. The Rey. Canon. A. M. Norman and Professor W. C. M‘Intosh have generously placed the whole of their collections at our service; and it is due to the considerable number of foreign (Mediterranean and North Atlantic) specimens belonging to the former that we have been enabled to determine several non-British species. The Director of the Marine Biological Laboratory at Plymouth, and Mr. G. Y. Dixon have also supplied us with specimens, as have also our foreign colleagues, Drs. D. C. Danielssen and J. Playfair M*Murrich. Finally, we have to thank Dr. E. Perceval Wright for the loan of books and for ready assistance in the solution of taxonomic and synonymic difficulties. GENERAL ACCOUNT OF THE ANATOMY OF THE ZOANTHE. The main external characters of the Zoanthez have already been given in the Introduction ; and before giving a detailed account of the anatomy of the group it will be necessary to say a few words as to the anatomy of these Actinie. As in other Actinozoa, the body-wall is composed of three layers: the ectoderm, the mesogloea, and the endoderm. There is now no need to adduce arguments in favour of the employment of the second of these terms. The mouth leads into a rather short cesophagus or stomatodeum, the walls of which are often thrown into folds; at one end a distinct and sometimes a very deep groove is present, for which one of us has suggested the name of “sulcus,” or sulcar groove. Projecting into the cavity, or ccelenteron of the polyp, from its body-wall, area number of soft plates which are known as mesenteries; sometimes these are called “‘sarcosepta,” and occasionally they are erroneously spoken of as “septa.” The employment of the latter term cannot be too strongly deprecated as leading to confusion with the septa, or calcareous radial partitions of the Madre- poraria. The mesenteries of the Zoanthes fall under two categories— (1) The large mesenteries which extend from the body-wall to the stomato- dzum, and which alone bear mesenterial filaments and gonads. These are the “perfect mesenteries” or ‘‘ macrosepta” of authors. (2) The small mesenteries which extend only slightly from the body-wall into the ccelenteron, and which are sterile, and do not bear mesenterial filaments. These are the “‘ imperfect mesenteries” or ‘‘ microsepta.” As in most Actiniz a pair of mesenteries occurs at each end of the cesophagus ; these are usually spoken of as the “directives,” or “ directive mesenteries,”’ Happon anp SHACKLETON—A Revision of the British Actinic. 613 The mesenteries which yield such a valuable aid to classification in the Actiniz generally are arranged in this group in a very uniform manner. In the first part of this revision (1889, p. 343), a short account is given of the history of the elucidation of the arrangement of the mesenteries in the Zoanthee. Since this was written the second part of Hertwig’s ‘‘ Challenger” Report has been published, without, however, adding anything to Erdmann’s account. M°Murrich has also written two valuable Papers (1889 and 1889 a), but no new type of mesen- teric arrangement has been described beyond those first pointed out by Hertwig (1882), and properly described by Erdmann. It is necessary to have a recognized system of terminology in order to deseuihe the arrangement of the mesenteries in the Actiniz; and it is advisable to have such a terminology as is applicable to the whole of the Actinozoa. One of us has already (1889) proposed the adoption of certain terms, and the abolition of others which have not a precise meaning—as, for example, such words as ‘“ dorsal” and “ventral,” these latter were replaced by ‘ sulcular” and “ sulcar,” respectively. When only one axial cesophageal groove is present, it is usually (? always) the sulcar. In the same Paper attention was called to the value of the order of the appearance of the mesenteries in young Actiniz, as suggesting the affinities of different groups of sea-anemones. ‘The following diagram illustrates the pro- posed method of naming the mesenteries and chambers at a stage when twelve mesenteries have made their appearance :— Gtnotunwarsvesece suena rae Sulcular directives. (LSS : Sulcular endocele...........-- Sulcular exoccele............-------5, Ne eas Sleulasenlealan laterals Suleulo-lateral endoccele........-f_ > WM & Denies Sulco-sulcular lateral. Materaltexocozlessereitejectaciieene ‘i Sulculo-sulcar lateral. Sulco-lateral endocele.......__.... ulco-sulcar lateral. Sulcar exoccele..,......+.++s-n-- Shae get Tees Sulcarendoccele sr. «skies sisceson es WF NCSL ES Aes Sulcar directives. Examples.—Edwardsia has a pair of sulcular and a pair of sulear directives; a -sulculo-sulcular lateral mesentery, and a sulculo-sulcar lateral mesentery on each side, all of which are perfect. The larval form of Zoanthus has a pair of sulcular imperfect directives and a pair of sulear perfect directives; a sulculo-sulcular lateral perfect mesentery, a sulco-sulcular lateral imperfect mesentery, a sulculo-sulcar lateral perfect mesen- tery, and a sulco-sulcar lateral imperfect mesentery on each side. 614 Happon AND SHAacKLETON—A Revision of the British Actinic. The larval form of Epizoanthus agrees with Zoanthus, except that the sulco- sulear lateral mesenteries are perfect. In the Zoantheze new mesenteries appear in the sulcar exocceles in such a way that the mesenteries nearest the sulcus are the youngest, and those furthest from it the eldest. In the Sagartidz the new mesenteries appear in pairs in all the exocceles. The mesenterial filaments, the gonads, the mesenteric canals, and the ccenen- chyme will be dealt with later on. We will now proceed to describe the structure of the Zoanthee in greater detail in the following order :— Body-wall—ectoderm, incrustations; mesogloea, cell-enclosures, endodermal bays, ectodermal bays ; endoderm, diffuse endodermal muscle, sphincter muscle ; capitulum. Tentacles and Dise. Esophagus. Mesenteries.—Imperfect mesenteries, perfect mesenteries, reflected ectoderm and mesenterial filaments, mesoglcea, canals, endoderm, muscles, gonads. Canenchyme. Development. Parasites. Body-wall.—Ectoderm.—The ectoderm is very liable to be rubbed off in the incrusted genera; where present it generally appears as a continuous layer of narrow columnar cells. In the unincrusted genera, in Gemmaria macmurrichi and in Lpizoanthus paguriphilus, the ectoderm is traversed by strands of mesogleea, which unite to form a layer peripheral to the ectoderm, and which, in some species break up the ectoderm into more or less cubical blocks (PI. u1x., fig. 6). External to the ectoderm there is always a cuticular layer which may be very thin, and stains of a darker colour (Parazoanthus divoni, Pl. u1x., fig. 9), or it may be thick, in which case it rarely stains, and is often impregnated with dirt (Lpizoanthus wright, Pl. urx., fig. 3). As the cuticle is an ectodermal secretion in forms with a continuous ectoderm, and, as the peripheral layer of mesogloea must also be of ectodermal origin, and is, as a matter of fact, often indistinguishable from the cuticle, we do not consider it of any importance to discriminate between them in the forms with discontinuous ectoderm. The above-mentioned layer of mesoglcea, peripheral to the ectoderm, is that which is called the subcuticle by Andres (1877, p. 222). The ectoderm usually contains nematocysts, which M*Murrich and others have failed to observe. As a rule these do not stain readily. In some species they are clear; in others—e. gy. L. norvegicus (Pl. 11x., fig. 5), where they are, by-the-by, Happon anp SHAcKLETON—A Revision of the British Actinic. 615 unusually numerous—they contain pigment granules. In LZ. paguriphilus they are very dark; often they have a yellowish colour, and are somewhat opaque. Zooxanthelle are present in the ectoderm of the three species of Isaurus which have been microscopically examined, and in many other species of the Brachy- cneminz, but apparently not in all. We have not found them in any of the Macrocnemine. Incrustations.—The incrustations which form such a characteristic feature of this group of Actiniz are absent in the genera Zoanthus and Isaurus, though very rarely a stray spicule, or grain of sand, may be entangled in the cuticlar layer of these genera. With regard to the other genera, according to our experience, it appears that certain species have a proclivity for a particular kind of incrustation. The character of the incrustation must be conditioned by the precise habitat, 7.e. whether sand-grains are calcareous or siliceous, or, again, whether the bottom is sandy or stony ; if sponges are abundant on a rocky bottom (as, for example, in Albany Pass, Torres Straits), the forms will probably largely make use of sponge-spicules, as in Parazoantha douglast. The best example we have of apparent selection is in the case of Epizoanthus inerustatus ; of this species we have cut specimens from Norway, Shetland, West of Ireland, and N. E. America (£. americanus, Verrill), and in all cases we find the incrustations to be composed almost entirely of grains of sand. In the single specimen we have been able to examine, of £. macintoshi, from Shetland, the incrustations are almost entirely Foraminifera. In Norman’s type specimens of Parazoantha anguicoma, from Shetland, the incrustations include grains of sand, Foraminifera, and sponge spicules; this holds good for the same species from the West of Ireland, as well as for the other species (P. divont) from the same district. The amount of incrustation also varies—for example, the species of Epizoanthus are usually thickly incrusted, but in Lpizoanthus paguriphilus the incrustations are very few in number. In Parazoanthus dichroicus there are very numerous incrus- tations, but in P. axinelle they are sparse, and in P. dixoni there are still fewer. Mesoglaa.—The mesogleeal ground substance is always homogeneous; it is penetrated by numerous minute cells, which are sometimes star-shaped, but more frequently produced at each end into a long fibril which extends in a radial direc- tion. Some of these fibrils are undoubtedly connected with the ectoderm, and others with the endoderm (PI. txtv., fig. 1)*; it is impossible to determine whether some may not stretch right across the mesoglea. We have not been able to satisfy ourselves of their presence in every case (ex. H. wrightit). * Plates nxr. to uxry. will be found in the Memoir of these Transactions immediately succeeding this one, viz. that on the Zoanthez of Torres Straits. They are frequently referred to in the present account of the anatomy of the group. 616 Happon anp SHackLteron—A Revision of the British Actinie. Cell enclosures. —Large ectodermal canals, penetrating the mesoglea, are very characteristic of the genus Zoanthus; they also occur in Parazoanthus. In Z. coppingert there are numerous large anastomosing canals which arise from the ectoderm (PI. txu., fig. 1), and have a general radial direction; many of the canals pass into the mesenteries. In Isaurus the canals are relatively much smaller than in Zoanthus, and are more broken up than in Z. coppingeri, and undoubtedly have an endodermal as well as an ectodermal origin (Pl. txut., figs. 5 and 6). The chief feature of the canal system in Parazoanthus is the presence of an encircling sinus, which lies just beneath the endoderm, and extends throughout the whole body-wall. This sinus is not everywhere continuous, but is frequently crossed by bars of mesogloea (PI. L1x., fig. 8). It is connected with the ectoderm by radial, occasionally branched canals. In P. anguwicoma and P. divoni, and in some other species, very fine canals connect the sinus with the endoderm (PI. irx., fig. 9). Although the encircling sinus may have connexions with the endoderm, these are very delicate, and the sinus itself is undoubtedly of ectodermal origin. The encircling sinus is the same as the ‘‘ ring-canal” described by Erdmann in his ‘sp. 8 Palythoa sp.” (1885, p. 469). [This is the Palythoa anguicoma of Hertwig, which we believe to be another species, for which we would suggest the name Parazoanthus hertwigi.| Nematocysts are present in the canals of many of the species of Zoanthus and Parazoanthus; possibly they are of universal occurrence in the canals. In Gemmaria macmurrichi a somewhat similar encircling sinus is present, but it is very largely broken up by the mesoglcea into a number of vertical canals which appear in transverse section as a series of lacunz, each one lying immediately below the union of a mesentery with the body-wall (Pl. uxim., fig. 7). These vertical canals are often connected by finer ones. Lacune are found in all the genera of the Zoantheze except Epizoanthus and Sphenopus. In Zoanthus it appears that the canals are more or less broken up to form the lacunze, least so in Z. coppingert and Z. dane (as identified by Hertwig), and most so in Z. jukesi (Pl. uxi1., fig. 2), in which species continuous canals are rare; the same also obtains in Jsaurus asymmetricus. In Palythoa there are no continuous canals; but lacune are present, as these are so similar to those which we know to be of ectodermal origin in other species; and as nematocysts are present, we believe that these lacune are of ectodermal origin (PI. Lxu1., figs. 8 and 9). Small groups of cells, irregularly scattered in the mesogloea, are especially characteristic of the genus Epizoanthus ; they may be very numerous, as in F. pagu- riphilus (Pl. urx., fig. 6), and in some of the species described by Erdmann, but in other species, /. incrustatus, E. couchii, and £. wrightii, they are very rare. They Happon anp SHackLETON—A Revision of the British Actinic. 617 are abundant in the Parazoanthus dichroicus, and are also common in P. anguicoma, and P. douglast. They occur also in Gemmaria macmurrichi, Palythoa howesii, and P. kochit. We have no proof that these small and isolated groups of cells, which have been aptly termed ‘cell-islets” (‘‘ Zellinseln”) by Erdmann, are connected in any way with the canals or the lacune, and, like that investigator, we do not know their origin. We regard these islets as simply groups of ordinary meso- gleeal cells. Endodermal and ectodermal bays.—We may here refer to the endodermal bays described for Zsaurus [‘* Mammillifera”’| tuberculatus by M*Murrich (1889, p. 118) ; he says: ‘In some of my sections deep bays can be seen running from the endoderm into the mesoglea, and from their ends and sides numerous canaliculi can be seen branching out. These bays can be found in various states of enclosure by the mesoglea, the cells which they contain being in some cases continuous with the general endoderm, in other cases almost separated from it, and finally quite so. So, too, with the ectoderm.” We have found similar deep endodermal bays in Jsaurus asymmetricus (Pl. ixtv., fig. 9), but in no case were the bays quite separate from the general endoderm. In our species the ectodermal bays (Pl. Lx11., fig. 4) differ considerably from those of M*Murrich’s species; the latter we have been able to examine through the courtesy of our friend, and as he has not figured one of these bays we add one for comparison (Pl. Lxi., fig. 3). Endoderm.—The endoderm of the body-wall presents few features worthy of remark. In J. asymmetricus we have found nematocysts smaller than those which occur in the ectoderm. Zooxanthelle are present in the three species of Zoanthus from Torres Straits, and appear to be characteristic of this genus as well as Isaurus. They are also extremely numerous in G. mutuki, and are present in Palythoa howesii and P. kochii. In Parazoanthus dixoni the endoderm is thickened into ridges between the mesenteries, but in most cases it is of uniform thickness. Diffuse endodermal muscle—The base of the endoderm forms a feeble but complete muscular sheath; as the fibres run in a horizontal direction, the muscle is scarcely to be seen in transverse sections; in vertical sections (PI. urx., figs. 9 and 12) they are readily seen. Sphineter muscle—The diffuse endodermal muscle of the general body-wall becomes converted in the capitular region into a sphincter muscle, which in contrac- tion causes the introversion of the corona and capitulum. The genus Parazoanthus is unique amongst the Zoanthes in possessing an endodermal sphincter. This fact was first discovered by Erdmann (1885, p. 468), who made this a primary character in the definition of his interpretation of the genus Palythoa, of which he took P. azinelle as the type. As we shall subsequently explain, Erdmann’s genus Palythoa cannot stand; so we have erected the new genus of Parazoanthus in its TRANS. ROY. DUB. SOC. N.S, VOL. IV., PART XII. 4T 618 Happon anp Suackteron—A Revision of the British Actime. stead. The infoldings of the endodermal sphincter, especially in its upper portion, are frequently so cut across by the razor in sections as to appear isolated, and thus the muscle might be supposed to be partly mesoglceal in character (Pl. ux., fig. 8). It is possible that this may actually occur to a very slight extent. In either case the distinction between Zoanthez with an endodermal and a mesoglceal sphincter is not so fundamental as might appear at first sight. All other Zoantheze have a mesogloeal sphincter. In Sphenopus the sphincter is extremely long, as Erdmann has previously remarked; Zoanthus alone has a double sphincter (Pl. ix1v., figs. 3 and 5). Capitulum.—The capitulum, as all authors have described, is thrown into ridges; these have a certain amount of specific value, but too much reliance should not be placed upon this character. In all species the ectoderm retains its character as a continuous epithelium. In Z. coppingert the ridges are crowded with nematocysts, but we do not find this of common occurrence. Tentacles.—The ectoderm of the tentacles contains numerous sausage-shaped nematocysts. The deeper layer of the ectoderm usually exhibits a well-marked nervous layer, the nerve-cells of which are shown in PI. ux1v., fig. 2. There is a diffuse ectodermal muscular sheath, the fibres of which have a longitudinal direction. The mesogloea is usually thin. The endoderm is relatively thick; and in Z. coppingert, Z. jukestt, and Z. macgillivrayt zooxanthellee are here especially abundant, but in J. asymmetricus and in Palythoa howesii and P. kochii, although they are present in the endoderm of the body-wall, few, if any, are to be found in this region. In Z. coppingeri numerous nematocysts of oval shape, similar to those found in the ectoderm of the body-wall, are present in the endoderm of the tentacles (Pl. txrv., fig. 2). And in some of our specimens of &. couch similar nematocysts are to be found in the ectoderm of the tentacles. A diffuse endodermal muscular layer consisting of fibres which run in a circular or horizontal direction, and which may be regarded as an extension of the muscular layer of the body-wall, is found in the tentacles of all our species. Dise.—The structure of the dise is usually similar to that of the tentacles. As in the latter, there are no incrustations. sophagus.—The ectoderm of the cesophagus is usually more or less folded ; but as the degree of folding is variable in different individuals of the same species, and probably also in the same individual in different conditions of contraction, this character is of little value for systematic purposes. The same may be said of the nature and extent of the groove. wall is incrusted ; the ectoderm is usually continuous, but may be discontinuous ; cell-islets in the mesoglea. Dicecious. Polyps connected by ecenenchyme, which may be band-like, incrusting, or greatly reduced as in the free forms. The genus Epizoanthus was established by Gray in 1867 for incrusted Zoanthee : ‘“‘ TT, coral attached ; cells arising from a foliaceous expanded base. ... The base expanded foliaceous (parasitic on shells); the cells cylindrical, simple, separate from each other from the base ; tentacles numerous” (p. 237). Z. papillosus, Johnst., is his type. Verrill adopted Gray’s genus. At first Hertwig (1882) agreed with Verrill in using this term to denote incrusted forms which rose above their ceenenchyme. After Erdmann’s investigations, he (1888) restricted the genus to macrocnemic Zoanthez, with ‘Integument incrusted, coenenchyme (mostly ?) lamellar ; sphincter simple, mesoglceal; mesenteries arranged on the macrotype ; colonies (mainly ?) parasitic” (p. 87). We have studied the type species of this genus, and find that it does conform to Krdmann’s and Hertwig’s definition of the genus. We may add that all observers have agreed in relegating to this genus all those incrusted Zoantheze which form carcineecia. ° In 1858 Gray erected the genus Sidisia for free Zoanthez, ‘‘ which may be characterized by the emission of buds on the surface of the cylindrical body ” (p. 582), S. barleei being the sole species. He considered that this species ‘‘evidently belongs to quite a different group” from Dysidea papillosa, Johust., which Mr. Barlee (im Mét.) informed Gray ‘‘ was a Zoanthus, allied to the genus Mammillifera of Lesueur,” an opinion which Gray adopted. Our investigations prove that S. barleec is only a variety of L. cncrustatus (= LE. papillosus). We do not propose to keep the name Sidisia for the genus, although it has priority, and for this reason: it was solely erected for a species which is only Happon anp SHackLteton—A Revision of the British Actinic. 635 a variety of an older form; and the name has only been occasionally retained for this variety of that particular species, whilst Epizoanthus has been universally adopted for the more typical forms of this genus. Both names were originated by Gray, and we have therefore less hesitation in keeping to the latter. Erdmann examined some free Zoanthez which were dredged by ‘‘ H. M. 8. ‘ Triton,’ 640 Fuss” (1885, p. 481). Without paying any attention to the litera- ture of the subject, he relegated these to a new genus, which he did not name. Very likely it is the Shetland species. Danielssen (1890) described specimens which he referred to Erdmann’s new genus, which he named Mardcell; and he called his new species J. erdmanni (p. 117). Through the courtesy of Dr. Danielssen we have been able to examine this form, and have cut sections of it. We are perfectly satisfied as to its specific distinction from the free variety of E. ierustatus. The imperfect mesenteries of Z. erdmanni are much more developed than in £. merustatus ; and there is almost invariably a well-marked lacuna in the mesogloea at the base of the insertion of each mesentery. In every respect it is an Epizoanthus, the sphincter being mesoglceal instead of endodermal, as Danielssen states, and the arrangement of the mesenteries is macrocnemic, though Danielssen’s figures do not show this. BRITISH SPECIES OF THE GENUS EPIZOANTHUS. E. incrustatus, Diib. & Kor., 1847. EB. paguriphilus, Verr., 1882. BE. couchii, Johnst., 1838. E. macintoshi, n. sp. (E. rubricornis, Holdsw., 1861.) E. wrightii, n. sp. SYNOPSIS OF BRITISH SPECIES OF EPIZOANTHUS. One polyp ventral, remainder marginal, . . . . paguriphilus. Forming carcinecia, . Polyps on upper surface only, Polyps radiating in one plane from a common f &. ¢nerustatus. point; diameter to height of polyp as 1 to 2, Free Colonies, dae A ie hs Polyps radiating in all directions from a common point; diameter to height of polypaslto4, . CE incor) a. Coenenchyme usually band-like, . . - - + +) #. couchii. Diameter to height of polyp as 1 to 4, . | (S. W. Ireland.) es ef Sas Ito:3;.. (S. W. England.) Inerusting Colonies, . Cenenchyme probably band-like; diameter of if cone polyp nearly as great as height, . Slane b. Conenchyme irregular; diameter of polyp greater i5). CORTE, than height, : The above relative proportions of diameter to height refers solely to contracted spirit specimens. 4X2 636 Happon anp SHacktetoN—A Revision of the British Actinic. Epizoanthus incrustatus (Diib. and Kor.). (COR rysandigs carer, eee Tell, wei, sales Rell done, ante, Ils) Spongia suberia : Johnston, 1834, Loudon’s Mag. Nat. Hist., vm., p. 431, fig. 60. Dysidea (?) papillosa : Johnston, 1842, Hist. Brit. Sponges, pp. 190, 251 (in part), fig. 18 (not pl. xvi., figs. 6, 7), Gray, 1858, Proc. Zool. Soce., p. 531. Mammillifera incrustata : Diiben and Koren, 1847, Forhandl. Skand. Naturf. Méde, p. 268 (cf. transl. in Isis, 1848, p. 586). Sars, 1851, Reise i Lofot. og Finm., Nyt Mag. Naturvid., vr. (2), p. 142. Danielssen, 1859, Nyt Mag. Naturvid., x1. (1861), p. 45. Sidisia barleet : Gray, 1858, Proc. Zool. Soc., xxv1., p. 532, pl. x., fig. 8. Gray, 1867, Proc. Zool. Soc., p. 287. Norman, 1868, Rep. Brit. Assoc. Ady. Sci., p. 319. Zoanthus couchti : (Not of Couch). Landsborough (in part), 1852, Brit. Zooph., p. 225. Holdsworth (in part), 1858, Proc. Zool. Soc., p. 557, pl. x., fig. 3; and 1859, Ann. Mag. Nat. Hist., (3), 1v., p. 152. Var. diffusa, Gosse, 1860, Brit. Sea Anemones, p. 298, pl. rx., fig. 10; and var. liter, p. 298, pl. m., fig. 9. Var. M. incrustata, Alder, Trans. Tyneside Nat. Field Club, v. Zoanthus incrustatus : Sars, 1860, Forhandl. Vidensk., Christiania, p. 141; also Forhandl. Skand. Naturf. Méde. Kjob., viz., p. 691. Norman, 1868, Rep. Brit. Assoc. Adv. Sci., p. 819. Eipizoanthus americanus : Verrill, 1864, Mem. Boston Soc. Nat. Hist., 1, pp. 34, 45 (addenda); 1866, Proc. Boston Soc. Nat. Hist., x., p. 385 (Gemmaria americana, Verrill, Am. Nat., u., p. 9, fig. 42) ; 1871, Am. Jour. Sci., m, p. 361. Dana, 1872, Corals and Coral Islands (2nd ed.), p. 62, figs. 1, 2. Verrill, 1878, U.S. Fish. Com. Rep., pp. 446, 510, pl. xxxvuz., figs. 286, 287; 1874, Am. Jour. Sci., va., p. 413; ibid. (8), xxm., 1882, p. 316. Smith and Harger, 1874, Trans. Connect. Acad., ut., pp. 9, 10, 11, 55, pl. vm., fig. 2. Verrill, 1883, Bull. Mus. Comp. Zool., x1., 1883-1885, p. 60, pl. vm., figs. 1, 6; 1885, U.S. Fish. Com. Rep. (1888), p. 534. Epizoanthus papillosus : Gray, 1867, Proc. Zool. Soc., 1867, p, 237. Ridley, 1886, Proc. Roy. Irish Acad. (2), rVv., No. 5, Sci., p. 617. Palythoa arenacea : Carus, 1884 (not of D. Ch.), Prod. Faunz Medit., p. 75. Polythoa arenacea : Andres, 1884 (not of D. Ch.), Le Attinie, p. 308. Pennington, 1885, Brit. Zooph., p. 182. Epizoanthus cancrisocius : Hertwig (not of Studer), 1888, Zool. Voy. ‘‘ Challenger,” Rep. Actiniaria, Suppl. uxxmt. p. 41, pl. 1, fig. 15. Polythoa incrustata : Bourne, 1890, Journ. Marine Biol. Assoc., 1., p. 319, Happon ann SHackLeton—A Revision of the British Actinic. 637 Form.—Thickly incrusted forms, of which the well-grown polyps are twice as high as broad. Two well-marked varieties:—A. Incrusting form, ccenenchyme ' forming carcineecia by replacement of a gasteropod shell; the two primary polyps at each end of the shell, usually forming a well-marked posterior marginal row of polyps; other polyps scattered on dorsal surface ; maximum number about 10-12, varying much in height; no polyps on the under surface of the carcineecium. B. Free form, primarily consisting of two individuals base to base, each of which may divide more or less regularly, or one only may divide. Colour.—Sandy. Dimensions—Polyps, 3-9 mm. in height; 1:5—4°5 mm. in average diameter. Colonies, greatest length, 22-35mm.; greatest breadth, 13-20 mm. Locality.—Shetlands; W. and 8S. W. Ireland; N. E. England; Lerwick (Barlee); 30 miles E. and N. of Brassey I., 70-80 faths. (Barlee); Haaf, Shetland, 1863 (A. M. N.); 5-8 miles E. of Balta, Shetland, 40-50 faths., July 20-23, 1867 (A. M. N.), ‘‘commensal with Pagurus levis” (Pl. tvut., figs. 1-13); also in St. Magnus Bay (A. M. N.); 40 miles 8. W. of Cape Clear, Co. Cork, 80-90 faths., 1885, commensal with Hupagurus excavatus and Spiropagurus levis (A. C. H.); Nymph Bank, Co. Cork, 50 faths., 1886 (A. C. H.); Clew Bay, 1890; 338-40 faths. off Aran, Co. Galway, 1891 (A. C. H.), (PI. tvut., figs. 14-22); 33-36, Donegal Bay, 1891 (A. C. H.); Scarborough (Bean, f. Johnston); Northumberland, ‘‘ deep water” (Alder); 48° 59’ 42” N., 10° 7 27” W., 90 faths., 1889 (G. C. Bourne), associated with £. meticulosus ; Plymouth Sound (specimens in Mus. of Marine Biol. Assoc. Laboratory). The geographical distribution of this species is North Atlantic, extending from the east coast of N. America to N. W. Europe. The synonymy of this species is much involved, but we think the foregoing list is sufficiently complete. We agree with Norman in rejecting Johnston’s specific name, as he considered it to be a sponge; and some years later (Hist. Brit. Zooph., 2nd ed., 1847, p. 202) he quotes Couch’s description of Z. couchi’, and has ‘‘the pleasure of naming this the only European Zoanthus after its discoverer.” It is therefore clear that he did not regard his own form as a Zoanthean. We are thus obliged to adopt the specific name given to this species by Diiben and Koren. Holdsworth, Gosse, and others have regarded this as a variety of LZ. couchii: we think that it will be admitted from our anatomical studies that this is not the case ; neither can it be associated with L. arenaceus, D. Ch. Owing to the kindness of Canon Norman we have been enabled to study some authentic Norwegian specimens of this species, and find them to be identical with the Shetland and Irish forms. Dr. Gray had no hesitation in referring some specimens from the coast of Massachusetts, collected in forty-fathom water (Proc. Zool. Soc., 1867, p. 237), to 638 Happon anp SHAcKLETON—A Revision of the British Actinic. this species. Verrill, however, erected a new species for the forms dredged off the east coast of N. America. Thanks again to Canon Norman’s courtesy we have examined some of Professor Verrill’s specimens, and we must confess to not being able to distinguish them specifically from the European examples. It is difficult to understand why Professor Hertwig ignored these two specific names and adopted for his specimen (Challenger Sta., 49, off Nova Scotia, 85 faths.) the name of a form from the Pacific Ocean. Verrill (1885) says it (incrusting variety) ranges from ‘‘ 49-906 fathoms; abundant.” The synonymy has also been complicated on account of the occasional free habit. This variety was first named Sidisia barleei by Gray. Gosse, Holdsworth, and others have regarded it simply as a variety of the typically incrusting Z. couchii. Verrill, too, recognises a free and an incrusting variety of FH. americanus, and also for his L. abyssorum; of this latter he says: ‘ This species generally forms the carcinzecia of Parapagurus pilosimanus, but sometimes consists of two or three large obeonic polyps arising from a grain of sand” . (2. ¢. 1885, p. 535). Norman, however, in referring to this variety, says (1868, p. 319): “ Taken abundantly in company with Zoanthus inerustatus, of which I was at one time inclined to consider it a variety ; but more careful examination and dissection has convinced me that there are certain distinctions between the two, besides the fact of Sidisia being a free-living, unattached form. Whether these distinctions are specific or sexual, a careful examination of the living animal must hereafter determine.” We have compared microscopically the two varieties, and find them to be essentially similar. Incrusting Form.—Ceenenchyme incrusting gasteropod shells inhabited by hermit-crabs, the shells being rapidly absorbed and replaced by the ccenenchyme which thus forms the carcinecium. In old specimens the polyps appear to be irregularly arranged ; but on an examination of younger specimens, three series of polyps can be distinguished. In the youngest example we have seen (Pl. Lvm., fig. 14) there is only a single polyp, which is situated at the apex of a small gasteropod shell, the shell itself being entirely coated by the ccenenchyme. The second polyp arises at the oral axis, or hilum, of the shell (fig. 15), A third one usually makes its appearance above the mouth of the shell. We have seen several cases in which the apical polyp is in the act of fission (Pl. tym, fig. 12). These three polyps form the first series. The second series forms a marginal row which corresponds to the aboral varex of such a shell as Ranella. The third series forms an irregular row between the two former. In no specimen of the very large number we have examined is there a polyp on the under surface of the carcinecium. The polyps bend slightly towards the oral or anterior aspect of the carcinecium. In a contracted state the capitulum forms a Happon AND SHACKLETON—A Revision of the British Actinic. 639 flattened disc-like termination to the polyp, on which indistinct radii, usually about 18 or 20 in number, can usually be discerned. The disc-like termination is sensibly of greater diameter than the column of the polyp. Free Form.—The earliest stage we have seen consists of two polyps base to base. These may divide by fission more or less symmetrically (Pl. tvmt., figs. 5-11), or one polyp may divide repeatedly, and the other not at all (Pl. ivmt., fig. 2-4). The variations are so great that it would be impossible to attempt to describe them all; and we would here point out that the two species of Epizoanthus we have examined which have free forms (viz. H. incrustatus, E. erdmanni) vary in such a similar manner that the variations appear to have no taxonomic value; the same also holds good for £. abyssorum, Verr. We have seen specimens of similar varieties of other species which have not as yet been identified ; one which comes from Naples will, we believe, be found to be a free variety of £. arenaceus. The size of the polyps and the character of the incrustations seem to be the only external features which distinguish the free forms of these species from each other, and these are obviously insufficient. It is worthy of notice that the capitulum of the free varieties is usually less flattened than that of the incrusting forms. The size which the polyps may attain apparently varies with the locality ; for example, the largest of the Shetland specimens are 9 mm. in height, by 4:5 mm. in diameter; the largest colony from Balta measuring 30 x 20 mm.; that from Haaf being 35 x 20mm. In the free variety the fully grown polyps average 6-7 mm. high, and 38—3°5 mm. across; the larger colonies being 22-23 mm. long by 8-11 mm. broad. From the 8. W. of Ireland, the polyps range up to 7-5 mm. high by 3°5 in diameter, the carcinecia being 24x 15mm. The W. of Ireland specimens from off Aran and from Donegal Bay run a good deal smaller: the polyps average 3-6 mm. in height and 1-5-3 mm. in diameter; most of the colonies are quite small, the largest being 22 x 13 mm. The nature of the incrustations also gives them a black-gray colour. The difference in size and colour between these and more normal specimens is so marked as to constitute a distinct variety. Verrill’s original description (1866, p. 34) of this species (his Epczoanthus americanus, n. sp.) is as follows:—‘ This species, which is parasitic on shells, has an incrusting base, smooth and uniform on the lower side of the shell, but giving rise to from fifteen to twenty polyps on the upper side, which diverge in all directions. Polyps variable in height and size, those of the upper central portion generally half an inch in height (13 mm.) and one-eighth (8-25 mm.) in diameter ; while those around the margin of the base are not more than half so large, and much crowded. Base spreading over and completely investing dead shells of Natica, Buccinum, &c., both externally and internally. The substance of the 640 Happon anp SHACKLETON—A Revision of the British Actinie. shell in every case has been entirely removed, but the form in all parts is perfectly preserved by the membranes of the polyps, while the cavity is inhabited by a species of hermit crab (Hupagurus pubescens). Column pillar-like, smallest in the middle, increasing gradually below, but enlarging rapidly at the summit. Walls thin, covered by a layer of closely adhering fine sand. When contracted, the summit is slightly concave; and in the medium-sized polyps has seventeen, in the largest twenty-four sulcations, radiating from the centre, which is seldom completely closed. ‘Tentacles, forty-eight or more, short, conical. The localities at which this species had been obtained up to that time are given by Verrill in 1882, p. 316. The free or type-form (of Z americanus, Verr.) occurred at 28 stations, 28 to 487 fathoms, whereas the incrusting variety “(= Zoanthus norvegicus, Kor. & Dan.)” occurred at 11 stations, 69-160 fathoms. The former is by far the most abundant numerically. Later (1885), he gives the bathymetrical range of the free form as ‘‘26—547 fathoms; generally diffused and very abundant” (p. 5384); and of the incrusting variety, ‘‘49—906 fathoms ; abundant” (p. 535). Smith and Harger (1874) report this species from off the coasts of New Jersey to the Gulf of St. Lawrence; the specimens with incrusted shells inhabited by Eupagurus pubescens came from 60-65 fathoms; while those from 480 fathoms were on stones and on hydroid stems. The figure, which is of a magnified polyp, is of no real value. In Verrill’s last Paper (1885, p. 60), he says it is mostly commensal with Lupagurus politus, Smith, and L. kréyeri, very common; those on grains of sand (free variety) were even more abundant. Some occurred incrusting sponges, shells, hydroids, tunicates, gorgonia, Paramuricea grandis, pebbles, &c. The original specimens off New Jersey, 30 fathoms, were commensal with L. pubescens. We think it possible that more than one species has been identified by our American colleague as £. americanus. Body-wall (Pl. u1x., fig. 2).—The incrustations in this species are numerous, and consist for the most part of coarse grains of sand, so that it is difficult to make out the structure of the body-wall from our sections. The ectoderm is continuous, and is covered by a cuticle, to which diatoms and dark granules are attached. Nematocysts, containing similar granules, are usually abundant in the ectoderm. The incrustations are embedded in the mesogloea throughout its entire thickness, often protruding into the ccelenteron. Single cells are oc- casionally found enclosed in the mesogloea; and lacunee are sometimes found near the union of the mesenteries with the body-wall; but the mesoglcea is for the most part devoid of cell enclosures. The usual endodermal muscular layer is present, being especially well-developed in the upper part of the column. The endoderm is formed by a thin layer of columnar cells of uniform height. Happon AND SHAcKLETON—A Revision of the British Actinic. 641 Sphincter muscle.—The mesogleeal sphincter muscle is short, and consists of well-defined cavities. Disc and Tentacles.—The dise and tentacles present the usual structure. The - muscular layers appear to be feebly developed. Gsophagus.—The shape of the cesophagus in cross-section varies in our speci- mens. Sometimes it is almost circular (Pl. Lx., fig. 1), the groove forming a very slight depression; in other specimens the groove is fairly-well marked. The ectoderm is almost smooth, being but very slightly folded. Mesenteries.—The arrangement of the mesenteries is macrocnemic. The imperfect mesenteries are very slightly developed, extending into the ccelenteron but little beyond the endoderm. The ectoderm of the cesophagus is reflected, and forming a series of folds along each mesentery, is continued downwards in the usual manner to form the mesenterial filaments. he mesogloea of the mesenteries is shghtly developed. The muscle-fibres form simple layers, there being no mesogleeal plaitings. The endoderm of the mesenteries is thin, resembling that of the body-wall. Gonads.—There were no gonads in the specimens examined by us. Var. barleei.—The specimens we have cut of the free variety agree very closely in their anatomy with the above account; but the sphincter muscle appears to be longer and more powerful. Epizoanthus paguriphilus. (Pl. tvin., figs. 23-25; Pl. uix., fig. 6; Pl. ix., fig. 5.) Epizoanthus paguriphilus : Verrill, 1882, Am. Journ. Sci. (8), xxm., pp. 137, 316; 1883, Bull. Mus. Comp. Zool., Cambridge, Mass., x1. (1883-85), p. 61, pl. vim., fig. 5; 1884, Am. Fish. Com. Rep. for 1882, p. 658; 1885, Am. Fish. Com. Rep. for 1883, p. 585, pl. vut., fig. 28. Bourne, 1890, Journ. Marine Biol. Assoc., 1., p. 318. Zoanthus (Corticanthus) paguriphilus : Andres, 1884, Le Attinie, p. 326. Form.—Colonies always forming carcinecia; slightly incrusted; mesogloea very thick; one polyp on ventral surface, the remainder forming a radiating single row, the ‘‘ posterior polyp” of which is the smallest. Colour.—Brownish in spirit specimens, but bluish-gray in colour where the thin incrustation is rubbed away. Dimensions.— Average diameter of coenenchyme, 55mm.; average height of polyps, 20-25 mm.: average width of polyps, 12-16 mm. ; average thickness of polyps, 8—10 mm. TRANS, ROY. DUB. SOC., N.S. VOL. IV., PART XII, 4Y 642 Happon and SHACKLETON—A Revision of the British Actinic. Locality.—W. and 8. W. Ireland :—50° 29’ 26” N., 11° 4’ W., 400 faths., July 11, 1889 (G. C. Bourne): 500 faths., 54 miles off Achill Head, Co. Mayo, July 10, 1890 (A. C. H.), (Pl. tvut., fig. 25). The specimens figured on PI. Lvm., figs. 23, 24, are in the British Museum; they came from 71 miles W. by S. of the Fastnet, 315 faths., and possibly also from deeper water (ef. Ann. Mag. Nat. Hist. (6), 1v., 1889, pp. 411, 480). . The geographical distribution of this species is North Atlantic, extending from the N. KE. coast of America to N. W. Europe, in deep water. This is the largest and most striking of the species of British Zoanthez, and is quite a recent addition to our fauna. The polyps are in two positions, one central and inferior, the remainder marginal, divergent, and uniserial. The ccenenchyme entirely surrounds the shell on which it grows, save for the orifice through which the commensal hermit- crab emerges. ‘The orifice is ventrally situated, and is about 5 mm. distant from the anterior border of the carcineecium, and is from about 15-20 mm. in diameter. Immediately behind the orifice is a polyp, which in spirit-specimens does not rise above the general surface of the ccenenchyme, and is less than 10mm. in diameter. The marginal polyps are prominent, and elliptical im section. At the posterior end of the carcineecium one polyp can readily be distinguished as being markedly smaller (15mm. in height) than the other marginal polyps; this we term the ‘ posterior polyp.” There are in the three specimens which we have examined four well-grown polyps to the left of the posterior polyp, and four, five, and six, respectively, on the right side of the carcinecium. There is a space of 20mm. between the right and left polyps on the anterior convex border of the carcinzecium. Under-surface of the carcinzecium flat; upper surface irregularly convex, with the greatest prominence towards the right. A young specimen, which one of us dredged off the W. of Ireland, and which is drawn of the natural size in Pl. tv, fig. 25, shows that the order of the appearance of the polyps is probably as follows:—(1) the ventral polyp; (2) the posterior polyp; (8) the right and left anterior polyps; (4) the succeeding lateral polyps, of which the most posterior are the youngest. After four pairs of marginal polyps have appeared the further production of polyps appears to be confined to the right side. This species is always commensal with Lupagurus pilosimanus. Verrill first described this species in 1882 in the following terms :——‘“ Polyps few and very large, stout, with broad, swollen bases, arising from a very thick, smooth, lubricous, gray or mud-coloured, translucent coenenchyme, which at first invests small univalve shells, occupied by Parapagurus pilosimanus, but finally grows far larger than the shell, and eventually absorbs it. Dise broad, larger Happon anp SHackiteton—A Revision of the British Actinic. 643 than column; tentacles numerous, rather long, light orange. Breadth of colony, 2 to 3 inches; height of polyps in expansion, 1 inch or more; diameter, °6 to ‘7 of an inch” (p. 137). He further adds :——“‘ Hitherto it has not been found elsewhere than upon the back of this particular species of crab, which, likewise, has not been found without its polyp. Of these associated creatures we took about 400 couples, at station 947, in 312 fathoms, at one haul. It had previously only been known by a few specimens taken by the Gloucester halibut fishermen, in deep water, off Nova Scotia, and by ourselves in 1880.” On p. 816 of same journal (Am. Jour. Sci. (3), xxi.) he adds :—“ [Station 947, S. by W.3 W, 89 miles off Martha’s Vineyard, sand, mud, Aug. 9, 1881; temperature 44° Fr. U.S. Fish. Com. Rep. for 1882-1884, p. 643].” “ Epizoanthus paguriphila, Verrill, sp. noy., 252-458 faths.’—and gives a list of the stations at which it was obtained. In the Bulletin Mus. Comp. Zool. Cambridge, Mass., Verrill gives the colour as translucent bluish or purplish-gray, or grayish-brown. In fresh specimens the tentacles are pale-orange or salmon, with lighter tips, and polyps more or less of a salmon-colour. ‘The diameter of ordinary specimens, 60-70 mm.; vertical thickness, 25-30 mm.; length of polyps, 15-20 mm.; diameter in middle, 10-12 mm.; and at base, 12-18mm. Some specimens considerably larger than this were obtained. ‘There are seven to twelve polyps. Body-wall (Pl. rx, fig. 6).—The ectoderm is not continuous, but is penetrated by strands of mesoglcea, which unite (as in Z. coppingeri and other species of Zoanthus and of Isaurus, and also in G@. macmurrichi, to form a peripheral layer of mesoglea. This peripheral layer of mesoglea is not distinguishable from the cuticle which covers the body. A more deeply stained outer layer may often be seen, but it appears to be simply due to the shrinking of the edge of mesogloea under the action of heat. The columnar cells of the ectoderm are closely packed, and stain deeply. They often contain dark pigment granules. Nematocysts filled with similar pigment-granules are frequently found amongst them. The few foreign particles (chiefly foraminifera and grains of sand) which incrust this species are generally found partly embedded in the ectoderm and partly in the adjacent mesoglea. The mesoglcea is remarkably thick, being relatively much thicker than in any other species of Zoanthean examined by us. In section the mesoglcea appears to enclose numerous “ cell- islets.” Some of these, however, are much elongated, and might possibly be regarded as forming parts of canals. We have not been able, however, to trace any distinct canals arising from either ectoderm or endoderm ; and it seems more probable that all these cell enclosures are completely surrounded by mesogloea. The usual spindle-shaped cells drawn out into long fibres can be discerned running through the mesoglea. The endodermal muscular layer is not very well 4Y2 644 Happon anp SHackLteton—A Revision of the British Actinie. developed; the fibres are supported on slight, rounded plaitings of mesoglcea. The endoderm consists of a single layer of columnar cells, the peripheral portion of the cells being of a deep brown colour owing to the presence of pigment- granules. Sphincter muscle—The single mesoglceal sphincter is not a very powerful one. No cavities are visible, the fibres being completely embedded in the substance of the mesogloea. Tentacles—The ectoderm of the tentacles is thrown into transverse folds. Numerous pigment-granules are to be found amongst the usual small nematocysts, and the nuclei in the peripheral portion. The muscular layer is not well developed. The mesoglcea forms an extremely thin layer. The endoderm is also pigmented. Dise.—The disc is very similar in structure to the tentacles. sophagus.—The ectoderm of the cesophagus is thrown into numerous folds. There is a well-marked groove. The mesogloea forms a thin layer, except in the region of the groove where it is somewhat thicker. It contains a few cell-islets. Mesenteries—The mesenteries have the usual macrocnemic arrangement. The reflected ectoderm of the cesophagus is attached to them in the lower part of the esophageal region and lower down forms the filaments as in other Zoanthee. The mesogloea is well developed in the cesophageal region, and here, on one side of each mesentery, plaitings which support the longitudinal fibres can be distinctly seen. Plaitings on both sides of the mesentery nearer to the body- wall which support the parieto-basilar fibres are exceedingly slight. The mesoglea is much thinner in the lower part of the body. The endoderm is very similar to that which lines the body-wall. Gonads.—'The sexes are distinct. Male gonads are present in our sections; they are very numerous, and closely packed together, almost entirely filling up the body-cavity below the cesophagus (PI. xx., fig. 5). Epizoanthus couchii (Johnston). (PI. tv, figs. 26-28; Pl. uix., fig. 4; Pl. ux., fig. 3.) Zoanthus couchtt : Johnston, 1838, in Couch, Cornish Fauna, m., p. 78, pl. xv., fig. 8 (not of Thompson, 1843, Br. Assoc. Rep., p. 284; nor of Thompson, 1844, Ann. Mag. Nat. Hist., xm, p. 440; nor of Landsborough, 1845, cbid., xv., p. 827; all of which are Sarcodictyon catena, cf. Johnston, 1847, l.c., p. 180). Forbes, 1844, Ann. Mag. Nat. Hist., xrv., p. 415. Johnston, 1847, Brit. Zooph., ed. 2, p. 202, pl. xxv., fig. 9. Landsborough, 1852 (in part), Brit. Zooph., p. 225. Thompson, 1856, Nat. Hist. Ireland, r1v., p. 462; Holdsworth, 1858 (in part), Proc. Zool. Soc., p. 557, pl. x., figs. 4-7. Wright and Greene, 1858, Brit. Assoc. Rep., p.180. Gosse, 1860, var. lincaris, Brit. Sea Anem., p. 297, pl. x., fig. 5. Hincks, 1861, Ann. Mag. Nat. Hist. (3), vim, p. 868. Hapvon anp SuHackLeton—A Revision of the British Actinie. 645 (Dysidea (?) papillosa : Johnston, 1844, Hist. Brit. Sponges (in part), pp. 190, 251, pl. xvz., figs. 6, 7. Carolia couchit : Gray, 1867, Proc. Zool. Soc., p. 239. Palythoa couchtt: Fischer, 1874, Nouv. Arch. Mus., Paris, pp. 285, 289; 1874, Comptes rendus, Lxxrx., p. 1209 (trans. 1875, Ann. Mag. Nat. Hist. (4), xv., p. 874); 1875, Actes Soc. linn. Bordeaux, xxx., p. 8. Polythoa arenacea: (Not of D. Ch.) Andres, 1884, var. couchit, Le Attinie, p. 808 ; Pennington, 1885, var. linearis, Brit. Zooph. (in part), p. 182. Palythoa arenacea: (Not of D. Ch.) Carus, 1884, Prod. Faunw Medit., p. 75. Form.—Column cylindrical, rising to about three or four times its diameter. Margin cut into 12 or 14 (generally the latter number) large, fleshy, triangular teeth, which are connected by a thin web of transparent membrane. In a state of semicontraction these teeth form strongly marked, converging ridges on the flat summit of the column. Incrustations of fine sand. When the column is much distended, the grains of sand become considerably separated, and the visceral cavity can be seen through the transparent and smooth integuments. Disc, generally flat or slightly concave, but protusile in a conical form; radii distinct. Tentacles 28 (or 24), bicyclic, those of the inner row correspond to the marginal teeth; they are subequal, they taper gradually, are bluntly pointed, and about equal in length to the diameter of the column. Ccenenchyme, narrow, irregularly creeping, soft, invested with sand like the column. Colour.—Column and ccenenchyme pale brown; disc pellucid, reddish-gray, dusted with excessively minute white specks; tentacles translucent, nearly colourless, opaque white tip; lip opaque white. Dimensions.—‘‘ One-eighth of an inch [8 mm.] in diameter, and about thrice that height [9 mm.] in extension. In contraction the button is usually about aline [2 mm.] in height. Myr. Holdsworth has obtained specimens much larger than these.” Habitat.— var. linearis—The condition above described, in which the root- band creeps in a narrow ribbon over stones and shells. Cornwall and Devon.” The foregoing description is taken from Gosse, and refers to the specimens he had seen alive; perhaps he has incorporated older observations in it. We have not been able to see any specimens of this species from the recorded localities, although we have made numerous efforts to do so. Our generous friend Canon Norman put some Zoanthez from the Channel Islands at our disposal, which bear a very strong superficial resemblance to ZL. couchii, as defined 646 Happon anp SHackLeron—A Revision of the British Actinie. above; unfortunately they had been dried at some time or other, although they were in spirit when we had them, and though we made sections of them we could not make any satisfactory observations. In order to facilitate the work of future observers we abstract all the additional information about this species, which is valuable from a descriptive point of view. Johnston (1847) defines the genus and species as follows:—‘“ Zoanthus : polypes distant, united by a creeping, root-like, fleshy band. Z. couchii: body cylindrical; tentacula in several circles.” In quoting from Couch he adds the following details :—‘‘It is a very small species ... of a light sandy or opaque red colour, and its surface is minutely glandular [this is an error of observation, and probably refers to the grains of quartz]. In its contracted state it is sub- conoidal, resembling both in shape and size a split pea. When semi-expanded it elevates itself to about twice its former height, and becomes contracted about its middle into an hour-glass form. When fully expanded the tentacula become distended and elongated to about the length of the transverse diameter of the body; and they are generally darker at their extremities than towards the base.” - Holdsworth (1858) obtained some specimens from 10-12 fathoms off Torbay. ““Qne group of six polypes on the inside of a valve of Cardium rusticum is arranged in a linear series; ... others are scattered over the surface of a flat stone, and have no perceptible connexion with one another, except in a few instances when two or three of them are united. ... The body forms a cylinder from 2 to 4 lines [about 4°5—9 mm.], by about half that in breadth, and is clothed with a dense coating of fine sand, which at the upper extremity is divided into 14 deeply- cut, marginal teeth; these cover the top of the column when the animal is closed. The tentacula are moderate in length, slightly tapering, smooth. ... They are arranged in two rows containing 14 each, of which the inner series are rather the longer, and are placed opposite the angular prolongations of the column, those of the outer row alternating with them.... The general colour of the disc and tentacula is a pale transparent brown, becoming opaque white around the mouth and at the tips of the arms, and all the intermediate parts are finely speckled with the same tint.” The following year (1859) he obtained some much larger specimens from Torbay. Hincks (1861) says, ‘‘ Not uncommon: Salcombe Bay [Devonshire], on slate, stone, &e. (in about 12-15 fathoms).” : The following is a description of an Epizoanthus dredged by one of us in the S. W. of Ireland, and which we refer with some hesitation to this species. If E. rubricornis should prove to be a different species from L. couch, our form will probably be found to be the same as the former, although the tentacles are of a different colour, and the habit of growth is different. Happon anp SHackteron—A Revision of the British Actinic. 647 Form.—The column is elongated, tapering from above downwards; the body- wall is well incrusted, but when the sand is rubbed off, the body-wall is thin and translucent. The capitulum has about 14 ridges; these may be present or absent in preserved specimens; in the latter case their absence appears to be due to their being rubbed when in the dredge. Tentacles bicyclic, about 14 in number in each cyle, the inner being slightly the longer and more curved. Mouth linear, on a slight cone. Coenenchyme, thin, either band-like, or forming small expansions. Colowr.—Sandy, sometimes dull, tawny-orange when alive; disc translucent buff, lips white, pale radii; tentacles translucent buff, opaque-white spot at tip. Dimensions.—Usually about 10-14 mm. in height, and 2-3 mm. in diameter at the top of the contracted specimens, occasionally reaching a height of 18—20 mm., with a diameter of 4°5—5 mm. Habitat.—S. W. Ireland; about 30 miles off Cape Clear (PI. tv, figs. 27, 28), 80 fathoms; 40 fathoms off Glandore, Co. Cork ; Berehaven, Bantry Bay, 10 fathoms (A. C. H.), (Pl. tvut., fig. 26), [Proc. Roy. Irish Acad. (2), iv., Sci., 1886, in which Report Mr. 8. O. Ridley identified this form as Pal, iblon arenacea(?), D. Ch., p. 617]. The Rev. Canon Norman has sent us specimens of an Si feantive from Birterbuy Bay, Co. Galway. They were unfortunately too badly preserved for us to be able to study them minutely, but at all events the sphincter muscle closely resembles that of our specimens from 8. W. of Ireland, and externally they agreed fairly well with the English specimens of this species. Some very similar Channel Island specimens (identified as ‘‘ Z.” couchii), which he gave us at the same time, probably belong to this species. Fischer’s (1874) description is as follows :—‘ The base of the colony is clothed with a layer of agglutinated sand, extending more or less ; the polyps, irregularly disposed, have their column protected by a coating of sand; this is cylindrical and elongated when completely extended ; colour cindery-gray ; the superior border has 14 to 15 teeth. The tentacles, disposed in two rows, are short, whitish, and to the number of 28-30. The disc is whitish; the mouth small, transverse.” The specimens came from “ Arcachon, from 20-45 brasses. The colonies were fixed on to the shell of Chenopus pes-pelicant, which gives lodging to a Sipunculus. Alder has identified it at Guernsey. M. Sauvage has obtained it at Boulogne on Pecten maximus, dredged in the channel” (p. 235). In his “‘bathymetrical distri- bution ” he records this species on the oceanic coasts of France, from the Nullipore zone (28-72 metres), p. 239. The other Papers are merely abstracts. To sum up the history of this species we may put the present state of our knowledge in this form. Johnston quotes Couch’s description of the Cornish type specimens. Gosse, Holdsworth, and Hincks obtained Devonshire specimens which are probably the same as the former. Forbes identifies it as having been dredged 648 Happon anp Suackteton—A Revision of the British Actinic. by Mac Andrew in Loch Fine, W. Scotland, in 1844. Thompson records it as having been dredged by himself and Hyndman in 1835 and 1846, 15—20 fathoms, from Strangford Lough (N.K. Ireland). Wright and Greene copy this. It may or may not be this species. We now describe specimens from 8. W. Ireland which may possibly be this species: Fischer identifies it from the N. and W. coasts of France. Andres and Pennington merely quote Gosse. Body-watl (Pl. u1x., fig. 4).—The body-wall is extremely thin in this species. The ectoderm, where present, is continuous, and is covered by a thin cuticle. It contains occasional nematocysts. Incrustations, which consist chiefly of grains of sand, are fairly numerous. Cell-enclosures are very rare. The endoderm is very thin, and of uniform thickness. The muscular layer is rather feebly developed. Sphincter muscle.—The single mesogleeal sphincter is well developed, although it is not so powerful as in the free variety of H. merustatus. It consists of elongated cavities which are well filled with muscle-fibres, the cavities form- ing for the most part a single row (PI. xx., fig. 3). Dise and Tentacles.—The structure of the disc and tentacles is for the most part as in other species of Zoantheze ; but oval nematocysts, similar to those which are found in the ectoderm of the body-wall and of the cesophagus, are present in the ectoderm of the tentacles of more than one of the specimens which we have cut. We have not, however, found them in all our specimens. Gsophagus.—The ectoderm of the cesophagus is thrown into folds which appear to be deeper as a rule in the short than in the longer specimens. ‘There is a well- marked groove. Nematocysts are generally to be found in this region; but in one or two specimens we have not been able to find them. In some cases they are very abundant. Sometimes they appear to contain black pigment-granules. In other cases they are quite clear, containing a distinct, coiled thread. Mesenteries.—The mesenteries present the usual macrocnemic arrangement. The imperfect mesenteries are fairly well-developed. The longitudinal muscles are borne upon mesoglceal plaitings which are frequently well-marked, but in some of our specimens they are much slighter than in others. Nematocysts are very abundant in the ectoderm, which forms the mesenterial filaments in the usual manner. Gonads.—We found no gonads in any of our specimens. Happon and SHAcKLETON—A Revision of the British Actinic. 649 [Epizoanthus arenaceus (D. Ch.), (not British, Mediterranean). (Polythoa (str. s.) arenacea. Andres, 1884, p. 308. Type var. Palythoa arenacea, Carus, 1884. 105 ()5)) Ql prix ones) ix.,) fio. 4s) Form.—Column cylindrical. Body-wall, thick and opaque, sometimes transversely wrinkled, about 15 capitular ridges and 30 tentacles; ccenenchyme incrusting, with a tendency to form linear bands. Colour.—Dirty sand (in spirit). Dimensions.—Height, 7-12 mm.; diam., 3°5—4'5 mm. The above description is taken from specimens identified at the Naples Zoological Station. It will be seen that H. arenaceus differs from FE. couchit, chiefly in the great thickness of its body-wall, which gives it a very characteristic appearance (PI. trx., fig. 7). Our specimens were not well preserved, and we have therefore some difficulty in determining satisfactorily anatomical characters. The mesoglceal sphincter muscle differs from that of Z. couchw in the appearance of its cavities, the muscle-fibres being arranged in a single row round the mesoglea, leaving an empty space in the centre of the cavity (Pl. ux., fig. 4). The thickness of the body-wall can be well seen in transverse sections. Nematocysts are present in the ectoderm of the cesophagus, and in the mesenterial filaments. ] Epizoa th macintoshi, n. sp. (ELS GVAIIo tox 2 Orr eerix, pio be) Form.—Short, very stout, rigid column, incrusted with foraminifera which give it a very characteristic, white, granular appearance. Upper surface of contracted column with 18 radial ridges. Ccenenchyme apparently linear, of same nature as the wall of the column. Colour.—Grayish white. Dimensions.—(In spirit) one polyp, 7mm. high by 6mm. in diameter; the other, 5mm. high by 4:5 mm. in diameter. Locality.—Shetlands (1871). A small colony of three specimens of this species was kindly handed over to us by Dr. W. C. M‘Intosh, F.R.S., Professor of Zoology at St. Andrews. One of these we devoted to the microtome; the remaining specimens are in Prof. M‘Intosh’s collection. We are pleased to be able to associate such a well-marked species with the distinguished Scottish Zoologist who has placed his collection of Actiniz at our disposal. TRANS. ROY. DUB. SOC., N.S. VOL, IV., PART XII. 4Z 650 Happon anp Suackteron—A Revision of the British Actinic. Body-wall (Pl. wrx., fig. 1).—-The ectoderm is much broken, owing to the incrustations. Where present it is continuous, and is covered by a thin cuticle. Thread cells, containing a few, almost black, pigment-granules, are occasionally to be met with amongst the columnar cells of the ectoderm. The mesoglea is thinner relatively to the diameter of the column than in most species of Zoanthese. The incrustations consist almost exclusively of foraminifera, which are frequently so large that a single specimen extends right across the body-wall, and is partly embedded in the ectoderm and partly in the endcderm, as well as in the mesoglcea. There are hardly any cell-enclosures in the mesoglea. Single cells only are occasionally to be seen enclosed. The endodermal muscular layer appears to be fairly well developed. The endoderm is formed by a thin layer of columnar cells of uniform height. Sphincter muscle-—The single mesogloeal sphincter is thick, extending right across the wall of the capitulum. The cavities in the mesoglea are large. ; Dise and Tentacles.—The nuclei of the ectoderm are diffused, and do not form a central band. The muscular layers are well developed. Gsophagus.—The ectoderm of the cesophagus appears to be quite smooth, not being thrown into folds. The groove is well marked, and there is a slight thicken- ing of the mesoglcea in this region. Mesenterves.—The arrangement of the mesenteries is macrocnemic. Owing to the presence of a parasitic crustacean in the single specimen we have cut it is difficult to determine the details regarding the mesenteries. The imperfect mesenteries extend but a short way into the body-cavity. The mesoglea is well developed, and is thrown on one side of each mesentery into distinct plaitings, which support the longitudinal muscle-fibres. The parieto-basal muscles are less well developed, and appear to extend but a short way from the body-wall. Gonads._—-We found no gonads. Parasitie Crustacean.—It is impossible to determine the nature of the crustacean infesting our specimen, or to say whether it is a fully developed or a larval form. [Epizoanthus norvegicus (Kor. & Dan.). (Not British, Norway.) (Pl. u1x., fig. 5.) Form.—Rather more clavate than £. macintoshi ; ecoenenchyme forming expan- sions, in which the polyps, in the specimens we have examined, appear to have a tendency to form linear series. Colour.—Sandy brown (in spirit). Dimensions.——Height, 6-12 mm.; diam., about 6 mm. Happon anp SHACKLETON—A Revision of the British Actinic. 651 We are again indebted to our friend Canon Norman for specimens (identified by Danielssen) of this species. Outwardly it differs from £. macintoshi in the rather more clavate form mentioned above, and in the darker and more brownish colour. Our specimens of either species are not sufficiently numerous to lay much stress on the difference in the ccenenchyme, which in many species varies much according to the nature of the body to which the polyps are attached. Anatomically the two species can be readily distinguished. The ectoderm of the body-wall in Z. norvegicus is very thick, and is crowded with nematocysts (Pl. urx., fig. 5). In Ei. macintoshi the ectoderm is very thin relatively to the diameter of the column, and contains very few nematocysts (Pl. uix., fig. 1). The incrustations in £. norvegicus are various, consisting of spicules, grains of sand, and foraminifera. In E. macintosh they consist almost exclusively of foraminifera. The endoderm also in EL. norvegicus is much thicker than in L. macintoshi. The imperfect mesenteries in E. norvegicus are remarkably well developed. In £. macintoshi they are feebly developed, extending a very short way into the body-cavity.] Epizoanthus wrightii, n. sp. (Pl. tviu., figs. 30-33; Pl. u1x., fig. 3; Pl. ux., fig. 2.) Form.—Column somewhat thick-set, body-wall incrusted but not particularly rigid, 16 capitular ridges, mouth a narrow slit, with one cesophageal groove; tentacles 32 in number, bicyclic, transversely corrugated when not fully extended. Ceenenchyme broad, flat, irregular. Polyps arise from the ccenenchyme ; craspeda ejected from the mouth when irritated. Colour.—Dirty pellucid-white or orange-pink ; in both the disc is speckled with opaque white ; tentacles with an opaque white tip; craspeda, white or orange-pink, according to the colour of the polyp. Dimensions.—Height, 13 mm.; diameter of column, 8°5 mm.; diameter of disc, 13 mm. ; length of tentacles, 13mm. Average height of expanded spirit specimens, 4 mm.; average diameter of column, 3 mm. In the contracted specimens the height and diameter are about equal, or the latter may even be the greater. Habitat.——Dalkey Sound, Dublin Bay; between tides; spreading over incrus- tations on the granite rocks but never actually attached to the granite itself, We are indebted to the brothers Dixon, for these specimens, and the above description is mainly taken from an account recently published by them (‘“ Notes on the Marine Invertebrate Fauna of Dublin,” Proc. Roy. Irish Acad., ser. ur, vol. ii., p. 29, 1891). They very kindly placed all their specimens at our disposal. We have the pleasure of dedicating this species to our friend Dr. E. Perceval 4Z2 652 HAppoNn AND SHACKLETON—A Revision of the British Actinie. ~- Wright, who is so well-known as a student of the Actinozoa, and who is always ~ so ready to help his scientific colleagues. Body-wall (Pl. urtx., fig. 3).—The ectoderm, where present, is continuous. It consists of numerous granular and deeply staining columnar cells, with occasional nematocysts scattered amongst them. It is protected by a thick cuticle, which does not stain but is of a dark brown colour owing to the presence of dark brown granules and of various foreign bodies. Incrustations chiefly consisting of coarse grains of sand, with a few foraminifera, are embedded in the mesogloea, which contains very few cell-islets or other enclosures. The endo- derm is formed by a rather thin layer of ordinary columnar cells. The endoder- mal muscular layer appears to be but slightly developed. Sphineter muscle——The single mesoglcoeal sphincter consists of several rows of simple cavities at the distal end. Proximally it is reduced to a single row of very small cavities (Pl. ux., fig. 2). Dise and Tentacles.—There is little worthy of note in the structure of the dise or tentacles. Both ectodermal and endodermal muscular layers are well developed. _ sophagus.—The ectoderm of the cesophagus is thrown into well-marked folds ; there is a distinct groove, but little if any thickening of the mesoglcea in this region. Mesenteries.—The mesenteries have the usual macrocnemic arrangement. The imperfect mesenteries are distinct, although they extend but a short way into the body-cavity. The reflected ectoderm forms the mesenterial filaments in the usual way. The mesoglea is not very well developed; both parieto-basilar and longitudinal muscles form almost simple layers. The endoderm is thinner than that of the body-wall, and contains in addition to the ordinary columnar cells, small oval cells which stain a very deep carmine. Gonads.—No gonads were present in the specimens examined by us. PROBABLY BELONGING TO THIS GENUS. Zoanthus rubricornis, Holdsworth. Zoanthus rubricornis : Holdsworth, 1861, Proc. Zool. Soc.: and Ann. Mag. Nat. Hist. (3), vit., p. 484, woodcut. Hincks, 1861, loc. cit. (8), vi., p. 364. Polythoa (Endeithoa) rubricornis : Andres, 1884, Le Attinie, p. 316. Form.—An unattached group of ten polyps, each gradually tapering from above downward, incrusted with sand; marginal serrations not nearly so conspicuous as in EF. couchit, Happon anp SHackLteTon—A Revision of the British Actinic. 653 Colour.—Tentacles a distinct red. Dimensions.—Largest polyp, 25 mm. in height, and about 5—6 mm. diameter at the top when contracted. (Judging from the figure, 20 mm. is the average height, and 5 mm. the eapitular diameter.) Habitat—Plymouth Sound. This species has apparently never been met with since its discovery; and we are unable to do more than recast Holdsworth’s description. We have no doubt that this species is an Epizoanthus; and it very closely resembles in outward appearance the specimens of L. couchii, which one of us has dredged off S. W. Treland, the habit of growth being the most distinguishing feature, and upon this we do not place any reliance. Should this species be found to be distinct from £. couchiti we expect that our Irish specimens would have to follow the former. PARAZOANTHUS, n. g. Macrocnemic Zoanthez, with a diffuse endodermal sphincter muscle. The body-wall is incrusted. The ectoderm is continuous. Encircling sinus as well as ectodermal canals, lacune, and cell-islets in the mesoglea. Dicecious. Polyps connected by thin ccenenchyme. This is a very well marked genus anatomically ; but it is often impossible to distinguish between certain species of this genus and those of Epizoanthus on external examination only. We have taken for our type P. azinelle (Schmidt), as this form is so readily obtainable, and, thanks to the Naples Zoological Station, is to be found in most museums. Another advantage is that it is one of the easiest of the incrusted Zoantheze to study microscopically. Erdmann was the first to separate the macrocnemic Zoanthee, with a diffuse endodermal sphincter, from those with a mesoglceal muscle. - He rightly retained the genus Epizoanthus for the latter, but wrongly referred the former to Palythoa, of which he also took P. awinelle as the type. We have elsewhere (1891) entered into a detailed discussion of our reasons for restoring Palythoa to its type species P. mammillosa (HK. & S.), and we consequently have to erect the new genus defined above. BRITISH SPECIES OF THE GENUS PARAZOANTHUS. P. anguicoma (Norman), 1868. P, dixoni, n. sp. 654 Happon anp SHackiEron—A Revision of the British Actinic. SYNOPSIS OF BRITISH SPECIES OF PARAZOANTHUS. (EXTERNAL CHARACTERS.) Cenenchyme thin, band-like, or inconsiderable; capitular ridges about 18, prominent, granulated, 5 é % 3 : ‘ ; P. anguicoma. Ceenenchyme thick, soft, expanded; capitular ridges about 21; not so prominent as in former, : : : ; : ; : 3 P. dizoni. (ANATOMICAL CHARACTERS.) Mesenteries project only a short distance from the body-wall into the ccelenteron ; endoderm of moderate thickness, uniform ; incrustations numerous, 3 P. anguicoma, Mesenteries project a considerable distance from the body-wall into the ccelen- teron ; endoderm forming very thick ridges between every two mesenteries ; incrustations few, . ; ; i : 5 ; | P. dixoni. The following species is inserted for comparison with the above :— Conenchyme thin, band-like or irregular expansions; capitular ridges 138-15, not very prominent, . ° ¢ . : : 6 : P. axinelle Mesenteries much as in P. anguicoma ; endoderm very thin and uniform; incrus- | (Mediterranean). tations not very numerous, chiefly spicular, Parazoanthus axinelle (Schmidt). Type species.—(Not British.) (PY Li, fe. 8s ohx oss sa) Palythoa axinelle : Schmidt, 1862, Spongien des Adriatischen Meeres, p. 61, pl. v1., figs. 2, 8. Gray, 1867, Proc. Zool. Soc., p. 238. Heller, 1868, Ber. k. zool., bot., Gesellsch., Wien, p. 21. Jourdan, 1880, Ann. des. Sci. Nat. (6), x., p. 43. Miller, 1883, Morphologie Palythoa u. Zoanthus, p. 8. Carus, 1884, Prod. Faune Medit., p. 76. Zoanthus avinella : Koch, 1880, Morph. Jahrb., vz., p. 859, pl. xv1., figs. 1-6. = Polythoa (str. 8.) avinelle : Andres, 1884, Le Attinie, p. 311, pl. x., fig. 7. Form.—Polyps obconical, coated with foreign particles; capitular ridges, 13-15, not very distinct. Tentacles, 26-380; pointed with a very slight Happon anp SHackLeton—A Revision of the British Actinic. 655 terminal swelling, perforated. Coenenchyme hand-like, linear, adhering to sponges ; polyps usually in linear groups of three or four, sometimes solitary. Colowr.—Y ellowish. Dimensions.—Height, 7 mm.; diameter, 3 mm.; tentacles, 5-10 mm. Habitat—On various sponges, also on corallines and stones. Adriatic, Marseilles, Naples. The foregoing description is compiled from the accounts given by Andres and Carus. In the specimens we have examined, as sent out by the Naples Zoological Station, we find that there is a considerable variation in, the size of the polyps, some attaining a height of 13 mm., and the ccenenchyme forms an irregular expansion on which the polyps are very crowded. The following anatomical account is based upon these specimens. We leave it for others to determine whether more than one species is commonly identified as P. azinelle. Koch’s specimens appear to be the same as ours, so far as his description and figures go. The Adriatic specimens require re-investigation. Body-wall (Pl. urx., fig. 8).—The body-wall is covered with a delicate cuticle, beneath which lies a rather thin layer of continuous ectoderm. Numerous oval nematocysts, which do not stain, are generally to be found among the granular and deeply staining columnar cells of the ectoderm. Incrustations, consisting for the most part of sponge spicules, are scattered, sometimes thickly, sometimes more sparingly, through the mesogloea. Beneath these incrustations, separated from the endoderm by a thin layer of mesogloea, lies an encircling sinus, containing deeply staining nuclei and cell contents, as well as numerous nematocysts similar to those which are found in the ectoderm. The sinus is frequently interrupted by bars of mesoglcea of variable thickness, so that in cross section it often appears to consist of a circular series of rather narrow lacune. Canals frequently branch off from the sinus, and in many cases their connexion with the ectoderm can be distinctly seen. Single isolated cells are occasionally found enclosed in the mesogloea. The endoderm forms a very thin and almost uniform layer. Sphincter muscle-——The sphincter muscle is, as described by Erdmann, diffuse and endodermal. Dise and Tentacles——There is nothing worthy of special note in the structure of the disc and tentacles. Csophagus.—The groove is well marked, and the mesoglcea is considerably thickened in this region (Pl. ux., fig. 6). Mesenteries—The arrangement of the mesenteries is macrocnemic. The imperfect mesenteries are well developed, often reaching nearly half way from the body-wall to the cesophagus. ‘I'he longitudinal muscles are well developed in the upper part of the mesenteries, close to the disc, the fibres being supported in this 656 Happon anp SHackLteton—A Revision of the British Actinic. region by well developed mesoglceal plaitings. Lower down the plaitings disappear, the muscles forming an almost simple layer. Close to the disc a bundle of transverse fibres are seen on the opposite side of each mesentery to that which bears the longitudinal fibres. These seem to be the prolongations of the endodermal muscles of the disc and tentacles. The reflection of the ectoderm of the cesophagus, and its connexion with the filaments, can be well seen in this species (Pl. ux., fig. 6). The mesoglea and the endoderm appear to be involved to some extent in the reflection also. The endoderm of the mesenteries forms, for the most part, a very thin layer, but it is much thickened in the region of the filaments (Pl. Lx., fig. 7), the mesenteries in this region resembling those of Z. macgillivrayi (Pl. uxiv., fig. 8), but the thickening is not so marked as in that species, nor do we find here either zooxanthelle or nematocysts. Gonads.——In one of our specimens male gonads are present. They are surrounded by a thickened layer of endoderm (PI. Lx., fig. 7). Parazoanthus anguicomus (Norm.). (Pl. tvmt., figs. 34—86; PI. xix., figs. 11, 12.) Zoanthus sulcatus ? : Bowerbank, 1867, Proc. Zool. Soc., p. 351. Zoanthus anguicoma : Norman, 1868, ‘‘ Shetland Report,’’ Rep. Brit. Assoc., p. 819. Polythoa (Teniothoa) anguicoma : Andres, 1884, Le Attinie, p. 817. Palythoa, sp. : Ridley, 1886, Proc. Roy. Irish Acad. (2), 1v., Sci., p. 617. Palythoa anguicoma : Hertwig, 1888, Suppl. ‘‘ Challenger” Rep., Actiniaria, p. 46, pl. 1, fig. 7. Is probably not P. anguicoma, but an allied species, P. hertwigi, n. n. Form.—Body rigid, rough; in some specimens the column has an almost warty appearance ; capitular region swollen when contracted; radial ridges about 18 in number, prominent, rough. Tentacles in two cyles, of about 17 in each, very long and extensile, more than equal to diameter of disc when fully expanded; gradually attenuating to very slender points. Ccenenchyme incrusted, thin, either band-like, creeping on sponges and other objects, or forming broader expansions. The ccenenchyme is never well developed, and sometimes the polyps are isolated or in small groups. The smaller specimens, when contracted, have a button-like appearance. Colowr.-—Pinkish-white (Norman); sand colour in preserved specimens. Happon anp SHackteTon—A Revision of the British Actinic. 657 Dimensions ——“ Column, 8-5 times as high as broad” (Norman). Height of column, when fairly extended (in spirit), 13 mm.; diameter of withdrawn eapitulum, 3-4mm. In the ‘“ button” condition the height is much less, about 4—5 mm., or even less. Some West of Ireland specimens have, in spirits, a height of 15 mm., diameter of capitulum 5—6 mm., diameter of middle of column 3—4 mm. Locality.—Shetlands, W. and 8.W. Ireland. The exact localities for this species are as follows:—‘‘Living on sponges, Phakellia ventilabrum and P. robusta, Normania crassa, Oceanapia jeffreysii, &e., in very deep water, 110-170 faths., 20-25 miles N.N.W. off Burrafirth Lighthouse” (A.M.N.), (Pl. tvut., fig. 34); St. Magnus Bay, Shetland, 1867; ‘‘ Porcupine, 1869, St. 8, 100-159 faths.” [off Galway Bay, W. Ireland]. The foregoing are in Canon Norman’s collection. 80 faths., 40 miles S.W. of Cape Clear, Co. Cork, 1885 (A.C.H.), (Pl. tvut., fig. 36); 80 faths., off the Skelligs, Co. Kerry, July 18, 1886 (A.C.H.), (Pl. tv, fig. 35); 126 faths., off Achill, Co. Mayo, 1890 (A.C.H.), This species is subject to considerable variation in general appearance, so much so that we at one time thought that the forms we had under review might belong to two species. This is the ‘‘squat button-like form” of Ridley (J.c.). There can be no doubt that this is the “‘ Zoanthus sulcatus ?—dispersed in patches on the surface of Desmacidon jeffreysi’, from Shetland,” of Bowerbank. Hertwig (1888, Suppl. ‘Chall.” Rept. Actiniaria, pp. 446-48) doubtfully refers a colony of ‘‘Palythoa” to this species from Inaccessible Island, Tristan d’Acunha (S. Atlantic), 60-90 faths. From Erdmann’s anatomical investigations of these specimens it is certain that they belong to the genus Parazoanthus. The species is certainly very close to P. anguicoma; but we consider that the slight differences in the external characters, together with the ‘considerable hollow expansion” of the encircling sinus (‘‘ring-canal”) invariably opposite the insertion of the mesenteries, are sufficient to separate the two species, and for the latter we would propose the name of Parazoanthus hertwigi. Body-wall (Pl. u1x., figs. 11, 12).—The ectoderm, where present, is continuous, and is covered by a thin cuticle. It forms a layer of variable thickness, and consists of columnar cells containing deeply staining granules, and of oval nematocysts which do not readily stain. Incrustations, consisting of sand spicules, foraminifera, &c., are fairly numerous, and are embedded both in the ectoderm and in the mesogleea. There is a well-developed encircling sinus, which lies beneath the incrustations. It is of variable thickness, and is frequently crossed by strands of mesoglea; but these strands are not at all so thick as those in P. axinelle, and the sinus in consequence presents a much less broken appearance than in that species. Branching and anastomosing canals, very similar to those which we describe for Z. coppingeri (1891), connect the encircling sinus with the ectoderm. Nematocysts are frequently to be found in the encircling sinus. TRANS. ROY. DUB. SOC., N.S. VOL. IV., PART XII. ; 5A 658 Happon anp SuHackteron—A Revision of the British Actinic. Cell-islets and lucunz are also often enclosed in the mesoglea. ‘The endoderm forms a thin layer of almost uniform thickness. The diffuse endodermal muscular layer is well developed. Sphincter muscle—The sphincter muscle is diffuse and endodermal, as in other species belonging to this genus. The mesoglceal plaitings are deep and well developed, but they branch very slightly. Dise and Tentacles.—There is little worthy of special note in the structure of the disc and tentacles. The ectodermal muscles are exceedingly well developed. Csophagus.—The ectoderm of the cesophagus is generally thrown into folds, but these are in some cases very slight. There is generally a well-marked groove, the mesogloea being here somewhat thickened. Occasionally cell-islets are to be found in this region. Mesenteries.—The arrangement of the muscle is macrocnemic. The imperfect mesenteries generally extend well into the ccelenteron. The longitudinal muscles vary considerably in the degree to which they are developed, not only in individuals, but in different parts of the same individual. In some cases they form an almost simple layer, whilst in others they are supported on well- developed plaitings of the mesoglea. The filaments are formed by the con- tinuation of the ectoderm in the usual manner. Immediately below the cesophagus, the perfect mesenteries, bearing the filaments, extend but a short distance into the ecelenteron, leaving considerable empty space in the centre. Lower down they again increase in size, and near the base of the polyp they contain sinuses which appear to be of the same origin as the ectodermal enclosures of the body-wall. Gonads.—There were no gonads in the specimens of this species which were examined by us. Parazoanthus* dixoni, n. sp. (Pl. tvi1., figs. 37, 38; Pl. irm., figs. 9, 10; Pl. ux., figs. 8, 9.) Form.—Body long, cylindrical, or quite short, smooth, or slightly roughened, very few incrustations. Polyps crowded, springing irregularly in all directions from an expanded, soft, thick coenenchyme. Buds often arise from close to the bases of the older polyps. Scarcely any diminution in the length of the contracted polyps is noticeable as compared with the expanded specimens. The upper end of the contracted specimens is swollen, and has about 21 inconspicuous * We name this species in honour of our friends the brothers G. Y. and A. F. Dixon, who have done much valuable work in connexion with the Irish Actinie. Happon AND SHACKLETON—A Revision of the British Actinic. 659 radial ridges. Disc with distinct radii; mouth ellipsoidal, lips prominent. Tentacles in two cycles of about 21 in each; length about the diameter of the dise. Colour—Creamy white; polyps with a slight pinkish tinge. Dimensions.—(In spirit). A. The larger specimens: height of column, 20mm. ; diameter, 4-5 mm. ; diameter of dise and tentacles, 10 mm.; the ccenenchyme of one colony measured 60mm. by 30 mm. (Pl. tv, fig. 37). B. Medium specimens: height of column, 16 mm.; diameter, 3mm.; average diameter of disc and tentacles, 9mm. C. Small variety: average height of column, 5mm.; diameter, 4 mm. (Pl. tvmt., fig. 38). Locality.— West of Ireland (56-8 miles W. of the Great Skellig, Co. Kerry, 70-80 faths., July 13, 1886. A.C. H.). This species was also obtained by the “‘ Porcupine” in 1869. (No locality. Norman collection). Body-wall (Pl. u1x., figs. 9, 10).—The ectoderm is continuous, and is covered by a thin cuticle. It forms a thick layer, consisting of very granular columnar cells, which stain deeply, and of numerous nematocysts which do not stain. The nematocysts in this species are scattered throughout the ectoderm in a fairly uniform manner. Incrustations consisting of spicules, grains of sand, and foraminifera may be found scattered at intervals through the mesogloea, but in our specimens of the larger variety these are very rare. Beneath the incrustations lies a well-developed encircling sinus. It is frequently broken by strands of mesoglcea, and is connected with the peripheral ectoderm by numerous branching and anastomosing canals, very similar to those we find in P. anguicoma. ‘he encircling sinus is connected with the endoderm by the fibrils or canalaculi of the mesoglcea, which are numerous and very distinct in our sections. The endoderm is not of uniform thickness as in P. anguicoma, but becomes very thick in the centre of each endoceele and ectocele, thus forming a longitudinal ridge between every two mesenteries. The diffuse endodermal muscular layer is well developed. Sphincter muscle (Pl. ux., fig. 8)—The diffuse endodermal sphincter is well developed, but very simple in character, the mesoglcea being raised into distinct but unbranched plaitings. In some sections some of these plaits appear to unite so as to enclose part of the muscle entirely in the mesoglea, but we are uncertain whether this appearance is not due to the direction in which the sections are cut. Dise and Tentacles.—-There is little worthy of note in the structure of the disc and tentacles. The ectodermal muscular layer is well developed. Gsophagus.—The ectoderm of the cesophagus is thrown into deep folds, into which the mesoglea also enters. There is a deep, well-marked groove, and the mesogloea is here very much thickened. Mesenteries—The arrangement of the mesenteries is macrocnemic. The imperfect mesenteries are well developed, and extend into the body-cavity nearly half-way between the body-wall and the cesophagus. The ectoderm of the 5 AQ 660 Happon anp Suackiteron—A Revision of the British Actinic. cesophagus is connected with the filaments in the usual manner. The mesoglea of the mesenteries is well developed in all our specimens, and is thickened as well as raised into distinct plaitings on that side of each mesentery which bears the longi- tudinal muscle fibres (PI. tx., fig. 9). The parieto-basal muscles are not so well de- veloped as the longitudinal ones; and they extend along each side of the mesenteries, but a short way into the ccelenteron ; there is therefore no difficulty in distinguishing between the two sets of muscles; and the pairing of the mesenteries can be very distinctly seen in this species. The endoderm of the mesenteries is thinner than that of the body-wall. The perfect mesenteries, from the termination of the cesophagus downward, extend far into the ecelenteron, which is, in consequence, almost filled up by the mesenteries and their filaments. Transverse sections of P. dixoni, taken just below the cesophagus, present in consequence a very different appearance from those of P. anguicoma taken from the same region. In our specimens of the small variety we find well-marked sinuses in the mesoglcea of the mesenteries, extending from the coenenchyme a short distance upward into the ceelenteron, disappearing at about the lower termination of the mesenterial filaments. These sinuses are very similar in appearance to the ectodermal sinuses of Z. coppingeri, but we are unable to find in them any connexion with the ectodermal canals of the body-wall, whilst in several places they appear to be distinctly connected with the endoderm. We do not find these sinuses in the mesenteries of any of those specimens of the larger variety of P. dizoni which we have cut. Gonads.—We have found no gonads in our specimens of this species. OF UNCERTAIN POSITION. Zoanthus sulcatus, Gosse. Zoanthus sulcatus : Gosse, 1860, Brit. Sea Anemones, p. 808, pl. 1x., fig. 7; pl. xm, fig. 2. Hincks, 1861, Ann. Mag. Nat. Hist. (3), vir., p. 864. Gemmaria (?) sulcata : Gray, 1867, Proc. Zool. Soc., p. 288. Palythoa sulcata : Fischer, 1874, Nouv. Arch. Mus. Paris, pp. 286, 289 ; 1874, Comptes rendus, txxix., p. 1207 (trans. Ann. Mag. Nat. Hist. (4), xv., p. 874); 1875, Actes Soc. linn. Bordeaux, xxx., p. 8; 1887, Arch. Zool. exp. gén. (2), v., pp. 485, 487. Jourdan, 1890, Bull. Soc. Zool., xv., p. 175. Polythoa (Te@niothoa) sulcata : Andres, 1884, Le Attinie, p. 817. Pennington, 1885, Brit. Zooph., p. 183. Form.—Column generally cylindrical, but versatile; upper third of extended column free from sand, and indented with twenty-two longitudinal sulci; lower portion sparsely incrusted with very fine sand. Disc saucer-shaped. Tentacles, Happon anp SuackLteton—A Revision of the British Actinie. 661 42, in two rows, the inner row corresponding in position to the marginal teeth, the outer intermediate ; sub-equal, conical, pointed, usually radiating horizontally. Coenenchyme band-like, often bearing three polyps abreast, loosely invested with coarse sand. Colowr.—Column dull uniform olive, each intersuleus having a blackish spot near its summit; each tooth is silvery white. Disc olive-yellow; tentacles colourless, transparent, with yellow-brown pigment granules. Dimensions.—Column about 3 mm. high, and about 2 mm. wide. Locality — Torbay, on rock, between tidemarks. Hincks (/.¢., p. 864) says:—‘‘ Mr. Gosse mentions a single colony of this pretty but very minute species as having occurred to him at Broadsands, near Brickham, on sandstone rock. On the opposite side of Torbay, however, and very close to Torquay, I have found it abundantly in the small basins hollowed out in the limestone. The Zoanthus forms little colonies on the floor of these miniature pools; but they may readily be passed over as tufts of some minute weed.” Mr. G. Y. Dixon informs us that he has carefully hunted over the rock where Gosse obtained his original specimens, without being able to re-discover this species. Fischer (1874, p. 236) describes this species as follows :—‘ Column covered in its superior half with very fine and agglutinated sand, uniformly brownish or olive, with 22 rays or ridges, on which one sees grains of sand arranged in ver- tical lines. The superior border of the column is indicated by a dentate border ; the teeth are 11 in number, and their colour is white. The disc of the same colour as the column appears rayed. The tentacles to the number of 22 are arranged in two rows; the 11 tentacles of the imner row are longer than the marginal by a third or a fourth. They are conical, transparent, ornamented with some brown spots; their extremities have an opaque white colour. The yellow mouth is not prominent.” ‘‘T have found this species at the landing place of Arcachon, at the limit of low tide ; it forms very numerous colonies, which have an appearance of the perforating sponges (Cliona), but their colour is more pronounced. The colony is fixed upon an expansion thickened by sand and other adherent matter. This is perforated by circular holes for the emission of the Zoanthez, which sink in and disappear when they are disturbed. M. Lafont has met with this species at Guéthary, on rocks. ‘The figure given by Mr. Gosse is very bad. . . . The small size, the colour, the habitat of this species, readily distinguish it from the preceding [£. couchii’}. When it is extended it measures 4 mm. in diameter.” — It occurs between tides (littoral zone), p. 239. The other Papers are merely abstracts. Later (1887), Fischer gives the following French localities :—‘ Le Croisic, Piriac (Région armoricaine); Arcachon, Guéthary, (Région aquitanique); Zone littorale,” p. 435. 662 Happon anp SHAackLeEtToN—A Revision of the British Actinic. Jourdan has recently (1890, p. 175) identified a form dredged by the Prince of Monaco (? either from the Bay of Biscay or off the Azores) as ‘‘ Palythoa sulcata Gosse.” Zoanthus alderi, Gosse. Zoanthus alderi : Gosse, 1860, Brit. Sea Anemones, p. 305, pl. 1., fig. 8; pl. xu., fig. 5. Gray, 1867, Proc. Zool. Soc., p. 284. Pennington, 1885, Brit. Zooph., p. 188. Alder, Trans. Tyneside Nat. Field Club, v. Zoanthus (Rhyzanthus) alderi : Andres, 1884, Le Attinie, p. 328. Form.—“ Polyp inversely conical, the summit being two or more times as broad as the base ; summit (in the button state) swelling, flat, depressed in the centre, with many (about twenty ?) radiating strie, indicating the marginal teeth. Surface smooth, without any investment of sand, but marked throughout with close-set, transverse, or annular wrinkles. Ccoenenchyme narrow, smooth, irregularly branching, free from sand.” Colour.-—Opaque, milk-white. Dimensions Height of column about two lines (4 mm.); greatest diameter about half a line (1 mm.). Habitat.—Northumberland ; under-surface of a stone, at extreme low water, near the ‘‘ Bear’s Rock,” Cullercoats (Alder). This species has not been met with since its first discovery by J. Alder in 1857. Gosse says: ‘‘ There were about a dozen polyps in the colony, all of the same size, which seems to be good evidence that they had attained adult dimensions.” Alder adds that he has “searched for it several times without success.” We cannot help regarding this as an immature form. No representative of the genus Zoantha, as determined by anatomical investi- gation, is known to occur in the extra-tropical portion of the North Atlantic. Until the anatomy of “ Z. rubricornis,” “ Z. sulcatus,’ and “ Z. aldert” is investigated it will be impossible to tell the genus, let alone the species. The same criticism applies to the identification of nearly all the Zoanthez. 1767. 1786. 1798. 1801. 1802. 1816. 1817. 1817. 1821. 1828. Happon anp SHACKLETON—A Revision of the British Actinic. 663 BIBLIOGRAPHY OF THE ZOANTHEZ:. Etuis, J.: An account of the Actinia sociata, &e. (Phil. Trans. Roy. Soc., nvm., pt. i. (1768), p. 428, pl. xix.) Euis, J., anD SonanpDer, D.: The Natural History of many curious and uncommon Zoophytes. London, pls. Cuvier, G. C. L. D.: Tableau élémentaire de |’ Histoire naturelle des Animaux. (Ann. 6, Journ. de Phys., xivz., pp. 370-384.) Lamarck, J. B.: Systéme des Animaux sans Vertébres. Paris. Boso, L.: Histoire naturelle des Vers. Suites 4 Buffon. Castel, Paris. Lamovrovx, J. V. F.: Histoire générale des Polypiers coralligénes flexibles. Caen. Cuvier, G. C. L. D.: Réegne animale, rv. Lesvevr, C. A.: Observations on several species of the Genus Actinia. Illustrated by figures. (Journ. Acad. Nat. Sci. Philadelphia, 1., pp. 149, 169, pls. vii., viii.) Lamourovx, J. V. F.: Exposition méthodique des genres de l’ordre des polypiers avec leur description et celle des principales espéces figurées dans 84 planches ; les 63 premiéres appartenant a’ Vhistoire naturelle des Zoophytes d’ Ellis et Solander. Paris. Gray, J. E.: Spicilegia Zoologica, pls. 664 1830. 1832. 1833. 1834. 1834. 1834. 1836. 1838. 1842. 1843. 1844. 1844. 1845. Happon anp SuHackteton—A Revision of the British Actinie. Lesson, R. P.: Zoologie. Voyage autour du monde sur la corvette de §. M. la Coquille, pendant les années 1822-1825, par L. J. Duperrey. Paris, 1828, pls. Detie Caras, §.: Istituzioni d’ Anatomia comparata. Napoli, pls., (edition 2, 1836). Quoy et GamarD: : Zoologie du Voyage de la corvette l’Astrolabe, pendant les années 1826-1829, by G. Dumont d’Urville. Paris, 1830, pls. Eurensere, C. G.: Beitrige zur physiologischen Kenntniss der Korallenthiere im Allgemeinen und besonders des Rothen Meeres nebst einem Versuche zur physiologischen Systematik derselben. (Abhandl. d. Konig. Akad. d. Wissensch., Berlin, 1832, p. 225.) [Published in 1834, and also as a separate volume, Die Korallthiere des Rothen Meeres. | JOHNSTON, G.: Illustrations in British Zoology. Spongia suberia. (Loudon’s Mag. Nat. Hist., vi., p. 491, fig. 60). Buavitte, H. M. ve: Manuel d’ Actinologie ou de Zoophytologie, with Atlas. Paris. Lamarck, J. B.: Histoire des Animaux sans Vertébres. [Deshayes and Milne Edwards’ revised and augmented edition. | Coucn, J.: A Cornish Fauna, being a Compendium of the Natural History of the County. London. JOHNSTON, G.: History of British Sponges and Lithophytes, pls. and woodcuts. Edinburgh. Tompson, W.: Report on the Fauna of Ireland, div. Invertebrata. (Brit. Assoc. Rep., p. 245.) TuHomeson, W. : Additions to the Fauna of Ireland. (Anno. Mag. Nat. Hist., xm., p. 480.) Forsss, H.: Notice of some additions to the British Fauna discovered by Robert Mac Andrew, Hsq., during the year 1844. (Ann. Mag. Nat. Hist., xrv., p. 415.) Lanpssorouan, D. : Notice of some Rarities found on the West Coast of Scotland. (Ann. Mag. Nat, Hist. (1), Xv., p. 327.) 1846. 1847. 1847. 1848. 1851. 1851. 1856. 1856. 1857. 1858. 1858. 1858. 1858. 1859. HAppon AND SHACKLETON—A Revision of the British Actinic. 665 Dana, J. D.: Report on Zoophytes, U. 8. Explor. Exped., 1838-1842, with Atlas. JOHNSTON, G.: A History of British Zoophytes, vol. i, vol. ii, pls., 2nd edit. [The one which is always used.] Dusen, M. W., anp Koren, J.: Om. nogle norske Actinier. (Forhandl. Skan. Naturf. Méde, p. 266.) Dtsern, M. W., anv Koren, J.: Ueber einige norwegische Actinien. Isis, p. 586. Sars, M.: Beretning om en i Sommeren 1849, foretagen zoologisk Reise i Lofoten og Finmarken. (Nyt Mag. Naturvid., vi. (2), p. 122.) Le Contr, J. L.: Zoological Notes. New species of .... Zoantha. (Proc. Acad. Nat. Sci. Philadelphia, v., p. 320.) Tompson, W.: The Natural History of Ireland. (London, 1849-1856, vol. iv., 1856.) SrEENsTRUP, J.J. S.: Kongelige Danske Videnskab. Selskabs. Forhandl. Minne-Eipwarps, H.: Histoire naturelle des Coralliaires, ou Polypes proprement dits, 1., with atlas. Paris. Gray, J. H.: On the Dysidea papillosa of Dr. Johnston. (Proc. Zool. Soc., 1858, p. 581, pl. x., fig. 8, of separate vol., ‘‘ Radiata ’’). [Sidisia barleet, g. and sp. un. | Hoxtpsworts, K. W. H.: On Zoanthus couchit, Johnston. (Proc. Zool. Soc., 1858, p. 557, pl. x., figs. 8-7.) Waicut, E. P., anp Greens, J. R.: Report on the Marine Fauna of the South and West Coasts of Ireland. (Brit. Assoc. Rep., p. 176.) Gray, J. E.: Note on Dysidea papillosa, Johnston. (Ann. Mag. Nat. Hist. (8), m., p. 489.) Danretssen, D. C.: Beretning om en zoologisk Reise foretagen i Sommeren 1857. (Nyt Mag. Naturvid., x1 (1861), p. 1.) TRANS. ROY. DUB. SOC., N.S. VOL. IV., PART XII. 5B 666 Happon anp SHackteton—A Revision of the British Actinie. 1859. Hotpswortu, EK. W. H.: On Zoanthus couchii, Johnston. (Ann. Mag. Nat. Hist. (8), 1v., p. 152.) 1860. Sars, M.: Oplysninger om nogle Coelenterater fra Norges Kyster. (Forhandl. Skand. Naturf. Mode. Kjébenhavyn, vin, p. 690.) Om nogle nye eller lidet bekjendte norske Celenterater. (Forhandl. Vidensk. Selsk. Christ.) 1860. Gossz, P. H.: Actinologia Britannica: A History of the British Sea Anemones and Corals. London. [Part x1., pp. 821-852, which contains the Zoanthe, was published in Noy., 1859.] 1860. Ducuassaine, P., et Micurnortt, J. : Mémoire sur les Coralliaires des Antilles. (Mem. Reale Accad. Sci., Turin (2), xx. (1861), p: 279, pls.) 1861. Honpswortn, E. W. H.: On an Undescribed species of British Zoanthus. (Proc. Zool. Soc., 1861, p. 99; also in Ann. Mag. Nat. Hist. (3), vi, p. 484, fig.) [2Z. rubricornis, n. sp. | 1861. Hincxs, T.: Catalogue of the Zoophytes of South Devon and South Cornwall. (Ann, Mag. Nat. Hist. (8) vul., p. 364.) 1862. Auprr, J.: Supplement to a Catalogue of the Zoophytes of Northumberland and Durham. Trans. Tyneside Nat. Field Club, v., pt. iii.) [Vol. v. runs from 1861-1863. | 1862. Scumipr, O.: Spongien des Adriatischen Meeres. Leipzig, pls. 1864. Verrim, A. H.: Revision of the Polypi of the Eastern Coast of the United States. (Mem. Boston Soc. Nat. Hist., 1. (read 1862, published 1864), p. 1, pls.) 1866. Verrit, A. E.: On the Polyps and Echinoderms of New England. (Proc. Boston Soc. Nat. Hist., x., p. 333.) 1866. Ducuassaine, P., ev Micuenorrt, J.: Supplément au Mémoire sur les Coralliaires des Antilles. (Mem. Reale Accad. Sci., Turin (2) xx, p. 97, pls.) 1867. Bowrrpang, J. S.: Additional Observations on Hyalonema mirabile. (Proc. Zool. Soc., p. 350.) 1867. 1868. 1868. 1869. 1872. 1873. 1874. 1874. 1874. 1875. 1875. 1877. Happon anp SHackieron—A Revision of the British Actinic. 667 Gray, J. E.: Notes on the Zoanthinw, with Descriptions of some New Genera. (Proc. Zool. Soc., 1867, p. 288, woodeut.) [Brit. sp. referred to—Zoanthus aldert ; Sidisia barleet ; Kpizoanthus, n.g.; E. papillosus; Gemmaria (?) sulcate; Carolia, n. g.; C. couchit. | Hetwer, C.: Die Zoophyten und Echinodermen des Adriatischen Meeres. (Ber. k. zool. bot. Gesellsch., Wien.) Norman, A. M.: Last Report on Dredging among the Shetland Isles. (Brit. Assoc. Rep., p. 232.) Verriut, A. E.: Notes on Radiata. Review of the Corals and Polyps of the West Coast of America. (Trans. Connect. Acad., 1., 1867-1871, p. 877 (p. 495, Mar., 1869).) Dana, J. D.: Corals and Coral Islands. Verrint, A. E.: Report upon the Invertebrate Animals of Vineyard Sound and the Adjacent Waters, with an Account of the Physical Characters of the Region. 1v., 5, Fauna of the Muddy Bottoms off the open Coast. (Report of the United States Commissioner of Fish and Fisheries, 1873, pp. 295-747, pls. 1. to xxxvim.) Fisouer, P. : Sur les Actinies des cétes océaniques de France. (Comptes rendus, uxxxix., p. 1207; translated in Ann. Mag. Nat. Hist. (4), xv., 1875, p. 373.) Fiscuer, P.: Recherches sur les Actinies des cétes océaniques de France. (Nouy. Arch. du Muséum, Paris, x., p. 193.) [The title page of the vol. gives 1874, but Dr. Fischer (1887) and other authors give the date as 1875.] Suits, S. J., anp Harcmr, O.: Report on the Dredgings in the Region of St. George’s Banks in 1872. (Trans. Connect. Acad., m., p. 1, pls.) Martens, EH. von: Ueber Palythoa. (Sitzungesber. Gesell. Naturf. Freunde. Berlin, p. 21.) Fiscuer, P. : Anthozoaires du département de la Gironde et des cétes du sud-ouest dela France. (Actes Soc. linn. Bordeaux, xxx., p. 183.) Anpres, A.: On a New Genus and Species of Zoanthina malacodermata- [Panceria spongiosa, sp. n.] (Quart. Journ. Mier. Sci. (N. 8.), 1877, p. 221 pl. xv.) 5B2 668 1877. 1878. 1880. 1880. 1882: 1882. 1882. 1883. 1883. 1884. 1884. 1884. Happon AnD SHAcKLETON—A Revision of the British Actinic. Kuunzincer, C. R.: Die Korallthiere des Rothen Meeres, 1. Aleyonarien und Malacodermen. Berlin. Stuper, T.: Zweite abtheilung der Anthozoa polyactinia, welche wihrend der Reise 8. M. 8. Corvette Gazelle um die Hrde gesammelt werden. (Monatsber. Konig]. preuss. Akad. Wissensch. Berlin, p. 524, pl.) Koon, G. von: Notizen titber Korallen. (Morph. Jahrb., v1., p. 355, pl. xvi.) JourpaN, H.: Recherches zoologiques et histologiques sur les Zoanthaires du Golfe de Marseille. (Ann. des Sci. Nat. (6), x., p. 1.) Verriny, A. H.: Notice of the remarkable Marine Fauna occupying the outer banks of the Southern Coast of New England, No. 3. (Am. Journ. Sci. (8), xxu., p. 185; ibid., No. 5, p. 309.) Herrwie, R.: Report on the Actiniaria dredged by H. M. §. ‘Challenger’ during the years 1878-1876. (The Zoology of the Voyage of H. M.S. ‘‘ Challenger,” pt. xv., 1882, pls. Supplement, 1888, pls.) Marion, A. F.: Actiniaires atlantiques des dragages de l’aviso le Travailleur. (Compt. rend., xciv., p. 458; translated in Ann. Mag. Nat. Hist. (5), m., p. 334.) Verriuu, A. H.: Report on Anthozoa and on some additional Species dredged by the ‘“‘ Blake,” in 1877-1879, and by U. S. Fish Commission Steamer ‘“ Fish Hawk” in 1880-1882. (Bull. Mus. Comp. Zool. Cambridge, Mass., x1., 1883-1885.) Miter, G.: Zur Morphologie der Scheidewiinde bei einigen Palythoa und Zoanthus. Marburg. [Disser- tation for Doctor’s degree privately printed. ] Carus, J. V.: Prodromus Faune Mediterranee. Stuttgart. Awnpres, A.: Le Attinie. (Fauna u. Flora d. Golfes v. Neapel, rx. Leipzig.) [Published in the Atti. R. Acead. dei Lincei, Rome (8a), xrv., 1883.] Verrii, A, H.: Notice of the remarkable Marine Fauna occupying the outer banks off the Southern Coast of New England, and of some additions to the Fauna of Vineyard Sound. (Am. Fish, Com. Rep. for 1882, p. 641.) [Partial reprint of Verrill, 1882.] 1885. 1885. 1885. 1886. 1886. 1887. 1888. 1889. 1889. 1889. Happon AND SHACKLETON—A Revision of the British Actinic. 669 Verritt, A. H.: Results of the Explorations made by the steamer ‘‘ Albatross ”’ off the Northern Coast of the United States in 1883. (U.S. Fish. Commission Report for 1883, p. 503, pls.) Pennineton, A. S.: British Zoophytes : an Introduction to the Hydroida, Actinozoa, and Polyzoa found in Great Britain, Ireland, and the Channel Islands ; with plates. London. Erpmann, A.: Ueber einige neue Zoantheen. Hin Beitrag zur anatomischen und systematischen Kenntniss der Actinien. (Jenaische Zeitschr. Naturwiss., xrx., p. 480, pls.) Kocu, W.: Neue Anthozoen aus dem Golf von Guinea. Marburg, 36 pp., 5 pls. Rotey, 8. O.: Zoanthide—First Report on the Marine Fauna of the South-West of Ireland. (Proc. Roy. Trish Acad. (2), 1v., Sci., p. 599.) Fiscuer, P.: Contribution 4 l’Actinologie frangaise. (Arch. Zool. exp. et. gén, (2), v., p. 881.) Herrwie, R.: Supplementary Report. (See 1882.) Happon, A. C.: A Revision of the British Actiniz, pt.1. (Trans. Roy. Dubl. Soe. (2), 1v., p. 297, pls.) Fiscumr, P.: Nouvelle contribution 4 l’Actinologie frangaise: 1° partie, Actinies d’Arcachon; 2° partie, Actinies de Guéthray. (Actes. Soc. linn. Bordeaux, xum., p. 252.) M*Mourricu, J. Puayrarr: A Contribution to the Actinology of the Bermudas. (Proc. Acad. Nat. Sci., Philadelphia, p. 102, pls. vi., vit.) 1889 4. M*Murricu, J. Puayrair : 1890. 1890. The Actiniaria of the Bahama Islands, W.I. (Journal of Morphology, m., p. 1, pls. 1.-1v.) [The latter Paper was. written before the former, though it was published slightly subsequently to it.] Dantetssen, D. C.: Actinide. (The Norwegian North Atlantic Expedition, 1876-1878. Zoology. pls.) Bourne, G. C.: Report of a Trawling Cruise in H. M. 8. “Research” off the South-West of Ireland. (Journal Marine Biological Association (Plymouth), 1., p. 806.) 670 Happon anp SHAackLeToN—A Revision of the British Actinic. 1890. Jourpan, E.: Note préliminaire sur les Zoanthaires provenant des Campagnes du Yacht 1’ Hirondelle, 1886- 1888. (Bull. Soc. Zool. Paris, xv. p. 174.) 1890. Breneprn, EH. Van: Les Anthozoaires pélagiques recueillis par M. le Prof. Hensen dans son Expéd. du Plankton. 1. Une Larve voisine de la Larve de Semper. (Bull. Acad. roy. Belgique (3), xx., p- 55, pl.) 1891. M*Murricu, J. Puayram: Contributions on the Morphology of the Actinozoa. m. The Phylogeny of the Actinozoa. (Journal of Morphology, v., pp. 125-164, pl. rx.) 1891. Happon, A. C., anp Smackueton, A. M.: Actinie.—I. Zoanthee. Reports on the Zoological Collections made in Torres Straits by A. C. Haddon, 1888-1889. (Trans. Roy. Dubl. Soc., vol. 1v., ser. ii., pt. xi.) Happon anp SHAckLeton—A Revision of the British Actinic. 671 INDEX OF GENERA AND SPECIES. CAROLIA = EPIZOANTHUS, 634. couchii, 645. CORTICIFERA = PALYTHOA. lutea, 631. DYSIDEA = EPIZOANTHUS, 634. papillosa, 634, 636, 645. ENDEITHOA (? genus). rubricornis, 652. EPIZOANTHUS, 632, 634. abyssorum, 633, 638, 639. americanus, 615, 632, 636, 638, 639, 640. arenaceus, 619, 632, 637, 639, 649. cancrisocius, 632, 638, 636. couchii, 616, 618, 619, 632, 635, 637, 644, 645, 646, 647, 649, 653, 661. var. linearis, 645. elongatus, 633. erdmanni, 628, 633, 635, 639. eupaguri, 633. incrustatus, 615, 616, 618, 619, 622, 627, 632, 634, 635, 636, 639, 648. macintoshi, 615, 625, 633, 635, 649, 650, 651. norvegicus, 614, 632, 650, 651. paguriphilus, 611, 614, 615, 616, 620, 622, 6338, 635, 641, 643. papillosus, 632, 634, 636. parasiticus, 633. stellaris, 633. thalamophilus, 633. wrightii, 614, 615, 616, 633, 635, 651. GEMMARIA, 630. isolata, 621, 627, 630. macmurrichi, 614, 616, 617, 630, 643. mutuki, 617, 630. philippinensis, 630. rusei, 621, 626, 627, 630. sulcata, 660 (? genus). ISAURUS, 630. asymmetricus, 616, 617, 618, 621, 622, 623, 630. cliftoni, 630. spongiosus, 630. tuberculatus, 617, 621, 623, 626, 630. MAMMILLIFERA, 630, 684. auricula, 626, 630. conferta, 629 (= Zoanthus confertus). incrustata, 636 (= Epizoanthus incrustatus). nymphea, 630. tuberculata, 617, 621, 628 (= Isaurus tuber- culatus). MARDCLL = EPIZOANTHUS. erdmanni, 623, 635. PALYTHOA, 631, 6384. ageregata, 631. anguicoma, 656 (Parazoanthus). arenacea, 636, 645, 649 (= Epizoanthus arenaceus). argus, 631. axinelle, 617, 654 (Parazoanthus). calcaria, 631. caribeorum, 631. cinerea, 631. 672 PALYTHOA—(continued). ceesia, 631. coesia ?, 619, 631. couchii, 645 (Epizoanthus). flava, 631. flavo-viridis, 631. glareola, 631. glutinosa, 631. howesii, 617, 618, 622, 628, 625, 631. kochii, 617, 618, 622, 623, 631. lutea, 631. mammillosa, 626, 631, 653. ocellata, 631. sulcata, 660 (? genus). tuberculosa, 631. sp-, 656. PARAZOANTHUS, 633, 653. anguicoma, 615, 616, 617, 619, 621, 622, 633, 653, 654, 656, 657, 659, 660. axinelle, 611, 615, 617, 620, 622, 627, 683, 658, 654, 655, 657. dichroicus, 615, 617, 619, 622, 625, 633. dixoni, 614, 615, 616, 617, 619, 620, 621, 622, 633, 653, 654, 658. douglasi, 615, 617, 619, 624, 625, 633. hertwigi, 616, 633, 657. sp., 638. POLYTHOA = PALYTHOA (pars), and PARA- ZOANTHUS (pars), 634. anguicoma, 656 (Parazoanthus). arenacea, 636, 645, 649 (= Epizoanthus arenaceus). axinelle, 654 (Parazoanthus). incrustata, 636. rubricornis, 652 (? genus). sulcata, 660 (? genus). HAppon AND SHACKLETON—A Revision of the British Actinic, RHYZANTHUS (? genus). alderi, 662. SIDISIA = EPIZOANTHUS, 634. barleei, 632, 634, 636, 638. SPHENOPUS, 632. arenaceus, 632. marsupialis, 626, 632; var. bursiformis, 632. pedunculatus, 632. SPONGIA = EPIZOANTHUS, 634. suberia, 636. TASNIOTHOA (? genus). sulcata, 660. ZOANTHUS, 629, 634. alderi, 662 (? genus). anguicoma, 656 (Parazoanthus). axinelle, 654 (Parazoanthus). coppingeri, 616, 618, 621, 622, 6238, 629, 643, 657, 660. confertus, 629. couchii, 636, 637, zoanthus). dane (?), 616, 620, 623, 629. danai, 629. flos-marinus, 621, 622, 629. incrustatus, 636, 638 (Epizoanthus). jukesii, 616, 618, 620, 621, 623, 629. macgillivrayi, 618, 620, 621, 622, 628, 625, 629, 656. paguriphilus, 641 (Epizoanthus). rubricornis, 652 (? genus). sociatus, 621, 626, 629. sulcatus, 656, 657, 660 (? genus). sp., 623, 629. 638, 644, 646 (Epi- EXPLANATION OF PLATE LVI. TRANS. ROY. DUB. SOC., N.S. Je JAN IP ID) Ib) WAIL IE, Fig. 1-22. Hpizoanthus incrustatus (Diib. & Kor.), (p. 636). I-11. Free variety from Shetland; Mus. Normani—1, simple form, with two polyps ; 2-4, 5-8, 9-11, three varietal series. 12-138. Typical incrusting forms from Shetland; Mus. Normani. 14-21. Incrusting forms from Galway Bay. These are rather smaller and darker than the more usual forms. This series, starting from a single polyp, illustrates the manner in which new polyps arise. 22. Antero-posterior section of a carcinecium, to show the position of the polyps and the absence of a ventral polyp. All the above are drawn from spirit specimens, and are natural size. 23-25. Hpizxoanthus paguriphilus, Verr. (p. 641). 23-24. Upper and under surface of two different specimens from off S.-W. Ireland; half natural size. 25. Young specimen from W. of Ireland; natural size; p.p. posterior polyp. 26-28. Epizoanthus couchit (Johnst.), (p. 644). 26. Living specimen from Berehaven; drawn by A. C. H. 27-28. Spirit specimens from §.-W. Ireland; all natural size. 29. Epizoanthus macintoshi, nu. sp. (p. 649). Spirit specimen from Shetland; natural size. 30-33. Epizoanthus wrightii, n. sp. (p. 651). 30-82. Living specimens from Dublin Bay; drawn by Mr. G. Y. Dixon; not to scale. 32 showing larvee swimming inside the tentacles. 83. Spirit specimen ; natural size. 84-86. Parazoanthus anguicoma (Norm.), (p. 656). 34. Some of the original type specimens, consisting of one isolated example, and a group of four polyps on a sponge, from Shetland (the specimen has unfortunately dried up); Mus. Normani. 85. Ordinary forms from §.-W. Ireland, on the tube of a Serpula. 86. Button-like variety, on the tube of a Hyalonecia; both natural size, from spirit specimens. 37-38. Parazsoanthus dixont, nu. sp. (p. 658). 37. Group of living specimens from §.-W. Ireland; tall variety ; drawn by A. C. H. 88. Short variety ; spirit specimens all natural size. [All the above specimens are in the British Museum, excepting Nos. 1-18 and 34. No. 29 was presented by Prof. W. C. M‘Intosh, and No. 83 by Mr. G. Y. Dixon. |] Trans. R.Dub.S.N.S. Vol IV. Plate LYVIIL. MP Parker delet hth. West, Newman imp. EXPLANATION OF PLATE LIX. ‘TRANS. ROY. DUB. sod., N.S. VOL. IV., PART XII. Fig. 10. nL 12. Pa AS exe LETTERING ADOPTED IN THE FIGURES. CU Ae ee CULICLE: q tej oo. 6 dillynil, ect. . . . . ectoderm. imer.,. . . » inerustation. ect. can.,. . . ectodermal canal. My . + « « mesogloea. enc. sin.,. . . encircling sinus. mes... . . . mesentery. end... . . . endoderm. nem.,. . . . nematocyst. end. can., . . endodermal canal. p.b.m.,. . . parieto-basilar muscle. Epizxoanthus macintoshi, n. sp. (p. 649). Transverse section through the body-wall, a Epizoanthus incrustatus (Diib. & Kor.), (p. 636). Transverse section through the body-wall, 2 : Episoanthus wrightii, n. sp. (p. 651). Transverse section through the body-wall, = Epizoanthus couchii (Johnst.), (p. 644). Transverse section through the body-wall, = Epizoanthus norvegicus (Kor. & Dan.), (p. 650). Transverse section through the body-wall, es Epizoanthus paguriphilus, Verr. (p. 641). Transverse section through the body-wall, a Epizoanthus arenaceus (D. Ch.), (p. 649). Transverse section through the body-wall, = Parazoanthus axinelle (Schmidt), (p. 654). Transverse section through the body-wall, = Parazoanthus dixoni, n. sp. (p. 658). Vertical section through the body-wall, = Parazoanthus dixont. Transverse section through the body-wall, = 2 ’ B . Parazoanthus anguicoma (Norm.), (p. 656). Transverse section through the body-wall Parazoanthus anguicoma. Vertical section through the body-wall, = * These letters of magnification refer in all cases to Zeiss’ system. _ Trans. R.Dub.S.,N.S.,VolL.IV. Plate LIX. a * aC ~ NS eat ANT OM ON a a p West, Newman imp. AMS .del.ad nat. MP. Parker chr. hth. EXPLANATION OF PLATE LX. PLATE LX. LETTERING ADOPTED IN THE FIGURES. Win “a 5 9 6 Countaley mem., . . . Nematocyst. eot.. . . . . ectoderm. @s., . . . . cesophagus. enc. sin. . . encircling sinus. @s.7., . . . esophageal ridge. -end., . . . . endoderm. p.b.m., . . parieto-basilar muscle. end. sph. m., . endodermal sphincter muscle. rect, . . . reflected ectoderm. incr... . . . inorustation. r.end., . . . reflected endoderm. m., . . . . mesogloea. rm. . . . retractor muscle. m.cn. mes., . Mmacrocnemic mesentery (the sulco- s.d., - + + sulear directive mesenteries. sulcar lateral mesentery). sl.d., . . . sulcular directive mesenteries. m. f., . . . mesenterial filament. 8.gr., . . . sulcar groove. m. sph.m., . . mesogleeal sphincter muscle. sp... . . sperm-cell (testis). Epizoanthus incrustatus (Diib. & Kor.), p. 636). Transverse section through the cesophageal region of the column, foe, a* 10 % : 2 Epizoanthus wrightii, n. sp. (p. 651). Vertical section through the sphincter muscle, Re Epizoanthus couchti (Johnst.), (p. 644). Vertical section through the sphincter muscle, = Enizoanthus arenaceus (D. Ch.), (p. 649). Vertical section through the sphincter muscle, 2 : Epizoanthus paguriphilus, Verr. (p. 641). Transverse section through a fertile mesentery, — : a Paraxoanthus axinelle (Schmidt), (p. 654). Transverse section through the cesophageal region of the column, 4 a® 10 é : : 2 Paraxoanthus axinelle. Transverse section through a fertile mesentery, RB ae P ‘ j 2 Parazoanthus dizont, n. sp. (p. 658). Vertical section through the sphincter muscle, B: 2 Parazoanthus dizont. Transverse section through a perfect and an imperfect mesentery, R * These letters of magnification refer in all cases to Zeiss’ system. SieeeaeDubsS oN S.ValllVv: PlatesaXe del at, By as) Sea reeene ea oe West Nevanan imp. TRANSACTIONS (NEW SERIES). VOLUME I. Parts 1-25.—November, 1877, to September, 1883. (Part 25 contains Title-page to Volume.) VOLUME II. Parts 1-2.—August, 1879, to April, 1882. (Part 2 contains Title-page to Volume.) VOLUME III. Parts 1-14.—September, 1883, to November, 1887. (Part 14 contains Title-page and Contents to Volume, also Cancel Page to Part 13.) VOLUME IV. Part ; 1. On Fossil-Fish Remains from the Tertiary and Oretaceo-tertiary Formations of New Zealand. By James W. Davis, F.c.s., F.L.s., &c. Plates I. to VII. (April, 1888.) 4s. 6d. 2. A Monograph of the Marine and Freshwater Ostracoda of the North Atlantic and of North- Western Europe. Section I. Podocopa. By Grorcr Srewarpson Brapy, M.D., F.R.S., F.L.s., and the Rev. Atrrep M. Norman, M.A., D.c.L., F.L.s. Plates VIII. to XXIII. (March, 1889.) 1c. 6d. 3. Observations of the Planet Jupiter, made with the Reflector of Three Feet Aperture, at Birr Castle Observatory, Parsonstown. By Orro BorppickeEr, pu.D. Plates XXIV. to XXX. (March, 1889.) 3s. 4. A New Determination of the Latitude of Dunsink Observatory. By Artruur A. Ramsavr. (March, 1889.) Is. 5. A Revision of the British Actinia. Part I. By Aurrep C. Hannon, m.a. (Cantab.), M.R.I.A., Professor of Zoology, Royal College of Science, Dublin. Plates XX XI. to XXXVII. (June, 1889.) 5s. 6. On the Fossil Fish of the Cretaceous Formations of Scandinavia. By Jamzs W. Davis, F.G.S., F.L.S., F.S.A., &e. Plates XX XVIII. to XLVI. (November, 1890.) 7s. 7. Survey of Fishing Grounds, West Coast of Ireland, 1890. I.—On the Eggs and Larvz of Teleosteans. By Ernest W. L. Hott, St. Andrew’s Marine Laboratory. Plates XLVII. to LII. (February, 1891.) 4s. 6d. 8. The Construction of Telescopic Object-Glasses for the International Photographic Survey of the Heavens. By Sir Howarp Gruss, m.a.1., F.R-S., Hon. Sec., Royal Dublin Society. (June, 1891.) 1s. 9. Lunar Radiant Heat, Measured at Birr Castle Observatory, during the Total Eclipse of January 28, 1888. By Orro Borppicker, PH.D. With an Introduction by The Karl of Rosse, K.P., LL.D., F.R.S., &c., President of the Royal Dublin Society. Plates LIT. to LV. (July, 1891.) 2s. 10. The Slugs of Ireland. By R. F. Scuarrr, pu.p., B.sc., Keeper of the Natural History Museum, Dublin. Plates LVI., LVII. (July, 1891.) 3s. 11. On the Cause of Double Lines and of Equidistant Satellites in the Spectra of Gases. By Gxorcr JoHNSTONE STONEY, M.A., D.SC., F.R.S., Vice-President, Royal Dublin Society. (July, 1891.) 2s. 12. A Revision of the British Actinis. Part II.: The Zoanthea. By Aurrep C. Happon, M.A. (Cantab.), m.r.1.4., Professor of Zoology, Royal College of Science, Dublin; and Miss Arice M. SuHackteron, B.A. Plates LVIII., LIX., LX. (November, 1891.) 3s. 6d. Lin