(0/(^y q9. \\j'rcL^ Jperforations«, i>lissurcs« or >ifenestrEe«, and the last signification is as a rule used about unusually large and regularly arranged pores. Real pores are found in the rosette-plates, in the frontal shield of the Cribrilinidae and in the peristome of Haswcllia, Adconella elc. Uncalcified spots in calci- fied surfaces may be called wpseudoporesw. Ascopore. A pore leading into the compensation-sac. VI Marginal (or oral) spines. S])iiu's issiiiiif^ i'roni llic iniuT niarfiin of a f^yiiinocyst. In viTv rare cases fCri'piddcantlia Poissoni, Mcudporu hyulinaj they are found together with a strongly ik-vcloiu'd frontal cryptoeysl. Acropetalous spines. Spines issuing from Ihe cirtunilVrence ol a pore (pseucloporu). Bilaminate spines. Spines (generally Hat) the inner layer of which is formed by a cryptocyst while the outer layer is formed l)y a gymnocysl. They are only found in the family Cnlcimriidae and reach their greatest development in the genus Coslicclla. Lateral chambers. Bryozoids generally developed as kenozooecia, found as a rule in a number of four on each side of an internode in the family Calcnariitlae. Simple operculum. A wcll-chitinized or calcified separable operculum the hing-line of wMch stretches between the two proximal corners and as a rule coincides with the proximal edge of the aperture. Compound operculum. A well-chitinized separable operculum, the hinge-line of which is placed distally to the proximal edge. Only the distal part of it corresponds to an oper- cular valve or a simple operculum. In the Ascophora the proximal part of it, the »accesso- rial part«, serves as operculum to the compensation-sac. Peristome. A calcareous projection more or less completely surrounding the aper- ture of the zooecium. The entrance to this, often tubular, |)rojeclion is the "secondary aperturcK. Ooecium (= ovicell). A more or less calcified marsupium placed near the zoa?cial aperture, into which the eggs pass from the zottcium in order to be develo])ed into larva. Endozooecial ooecia. Internal ooecia consisting of an endooa'cium formed by the distal wall and of an cctoo(ecium formed by the covering membrane. Hyperstomial ocecia. External two-layered ooecia, consisting of an cndoocecium and a more or less developed ectoooecium. Perlstomial ooecia. Single-layered oa'cia formed by the peristome. They are found in the families Tubucellariidae and Lckylhoporidac and perhaps also the oojcia of the families Conescliarcttinidae anil Holoporellidae may be referred to this division. Endotoichal ooecia. Hollows formed by resorption in a thick calcareous frontal wall and at last opening outwards. They are found in the families Cellulariidac, Membranicella- riidac and Setosellidae. Acanthostegous ooecia. Marsupial spaces lying between the covering membrane and two series of concurrent spines. They are found in Electro zostericola and El. (Heterocecium) amplectens. Double-valved ooecia. Oa?cia consisting of two arched hollow valves (kenozooecia). They are found in Algsidium parasiticum. Basal mark. A curve seen on the basal surface of a hy|)erstomial ofecium, circum- scribing that part of the frontal wall of the zoa'cium, which takes jiart in the formation of the endoocEcium's basal wall. Basal. The surface with which an incrusting colony is fixed and the corresponding surface in a freely growing colony. Frontal. The surface opposite to the basal and that in which as a rule the aperture is placed. Sometimes, however, the aperture may be terminal, viz., ))laced in the ti]) of Ihe zooecium. VII Distal. The part of a zooecium most remote from the primary zocreium (the ancestrula) of the eolony. When used ahout the single parts of a zocreium, for instanee the s])ines, it signifies the part most remote from tlie point or the surface of fixation. — Proximal. The part of a zoceeiuni nearest to the primary zoceeiuni of the colony. While in most Cheilostomata tlie zoa'cia have separate lateral walls the terminal walls arc as a rule common to two successive zoa'cia in the same longitudinal row and there- fore the distal wall of the proximal zoax'ium is at the same time the proximal wall of the distal zoa'cium. Only in very few cases is there found separate terminal walls (see pag. 11). Morphological Part. Calcification. Different views. Different modes of calcification. IN his well-known paper on Meinbranipora membranacea H. Nitsche' expresses the view that calcification proceeds in the cuticle given off by the cells of the covering membrane, which at the places where such deposition takes place is divided into three layers and it is the middle layer characterized by its highly refracting power which is impregnated by the calcium salts. Nitsche arrived at this result exclusively from an investigation of the not yet calcified short spines, of which in this species one occurs at each of the posterior corners of the zocecium. According to Nitsche these spines are covered externally by a thick cuticle and beneath this there is a highly refracting layer intended for calcification but which does not (juite reach out to the tip of the spine. Internally the whole cavity of the spine is covered by an exceedingly thin membrane, which according to Nitsche is the innermost layer of the cuticle, whilst he calls a net-work of cellular strings in the inner cavity the endocyst. On this view however there would be no continuous covering of endocyst in the interior of the spine, which does not seem very probable and it would therefore be most natural to call the thin, innermost layer of the wall as the endocyst and the cellular net-work as a portion of this endocyst, which has been designated the endosarc or the mesen- chyme. I have not had the opportunity to investigate an uncalcified spine of Meinbr. membranacea, but if Nitsche's theory of the calcification is correct the spines when completety calcified must be covered with a cuticle. I have sought for this in vain however, both on the spines mentioned and on all other spines examined by me and I must therefore contest the correctness of Nitsche's view^ that the lime particles are deposited in a middle layer of the cuticle. ' 80. pp. 42, 76. In a preliminary note' Ostroumoff makes some remarks on the calcareous skeleton in the liriiozoa and comes to a totally dillerent result from N'itsche with regard to its formation. He has hecn able to siiow, namely, by lueans of silver impregnation, that the covering membrane of the zoocia has a distiiiclly cellular structure, over which he found a thin cuticle and under it the calcareous skeleton. He concludes from this that the chalk particles arc deposited within the ectoderm cells (»par consequence les particles calcaires se deposent dans I'interieur de cellules ectodermlques«). At another place he stales:- »Le squeletle calcaire de nos Hryozoaires se place parmi les cellules de I'exoderme. Le dernier exisle pendant toute la vie de I'animal on comme couche sous-squeletaire (MenibraiiijioraJ ou comme deux couches enlre lesquelles se trouve le s([uelette (LepraliaJ'. Later in the main work' which deals with the Brijozou from the Bay of Se- bastopol, the writer expresses his oj)inion about the same subject in this way: >in the family Escharidae (such as for instance in Lepralia) the calcareous skeleton during its formation divides the ectoderm into two layers, an exterior lying over the skeleton, and which is readily seen on the opercular wall on living individuals as well as on those treated with silver nitrate, and an interior under the skeleton which can only be seen by means of silver impreg- nation. There is only one layer of cells in Memhraniporidue, and this is only found below the skeleton «. Ostroumoff's observations are based on the small number of species which are found in the Gulf of Sebastopol, and Lepralia PalUisiana is the only representative of the sj)ccies of Escharidae which he has been able to examine; it belongs to the forms which develop a calcareous layer, the Cryptocyst, under the covering membrane of the frontal surface, but separated from this by an intermediate space, and having a cellular lining on both its surfaces. This is however not an absolute proof that calcification has taken place within the cells, so that Ostroumoff has just as little as Nitsche proved the correctness of his view. I'ergens expresses a view similar to that of the Russian writer, partly in a small prelimi- nary paper: ^ (»bei alien Arten, welche ich untersuchte, war von aus.sen immer die Cuticula und der Kalk innerhalb der Zelle gelagert«). partly in a paper concer- ning fossil Brijozoa'', where he says: »Le derme est essentiellement constilue par un nombre variable de cellules aplalies a contour irregulier^ (Ostroumoff). Mes observations sur les larves (jui viennent de se fixer m'ont demontre cpie c'est dans I'interieur de ces cellules cjue se fait le dej)6t de calcaire . In contrast ' K8, p. 291; ' 89, p. 577; " 90, pp. .J8, J9 ; * 92, p. .'iOG; ' 93, p. :t08. lo llu' two lasl iiu'iitioncd writers, Calvct andHaiiner look upon calcificalioii as a cuticiilai rormalion, but while Ca 1 v e l' tliinks that calcification at any rate in the CheUostomata takes place through the whole thickness of the cuticle, the following ohservalioii of Harmer- seems to suggest that he is inclined to share Nitsche's view of the calciiication as j)roceecling in the central part of the cuticle: in incinerated specimens the lateral walls of neighbouring zoa-cia may appear separated from one another by a narrow slit in jjlace of the laised linc<'. This is in fact the edge of a chitinous layer separating contiguous zoa-cia, and prolonged into the membranous epitheca. This agrees with the account given by Nitscbe of the calciiication of the zcxj'cia of Mcinbrdiiipord membi a certain period are se|)arated from one anollier hy sutures, and these sutures are in some cases very distinct lor a \itw^ liini', wliiUf in oilier casis Ihc^y disappear very (piickiy. 'I'liis concerns very ollcii llic liiiiilal sv:ill, and is due to (he circunistance that this is very often provided willi covering layers or sculpture of various kinds. As examples of sjiecies willi simple walls v,v. may meiilir)n Mcmhrtiiiif/oni iiieiiihrdiiiicen, Elcclra jiilimii, species of I he genera Oiiijiliocelln, ni/i/iolliati, riialfiiiioixirellti, and Slet/ii- iiiifinrclld and also il sr-ems — all memheis ol the families liiccllariidiic and Si rniioiflliii iiiliif. 'I lie p.nls inio wliich a eoiii|)oiiiid wall can he divided vary very greatly in size, and llir- smallest of them give the imjuessioii, nol only from their exci-edingly small size, hut also from Iheir shape, thai they are calci- lied cells, as they have the same ci-eiiiilalerj contour whicli as a rule seems to disliiifMiisli llie eelodi Till celK in llir Hn/ozoii. 'I'liis lonii of calcilicalion, which we niiglii I'.'ill »eell mosaic is lor instance roiiiid on llie hasal wall in Mi'iiihrimi- jKini SiiiKiili, l-'liislni (Iniliiiiliild (\'\. XIX, lig. 10 v), J'otalhi cunciniui, ni/iiJOfxidiiKi fiu'iicriisis Musk, Siiiilliiia LdiiHhoroui, as well as on the laleial walls of i'luslvd si'iriildhi. (iradiially s<'veral of tlmse very sniall cellular areas fuse logelher lo larg(!r ones, and in older zoom- i a the nniik of division may (piile ilisap|ieai'. In conlrast lo Hie very {\in- mosaic we lind in Hie jusl-mentioncd species, olhei- sjx-cies pre- seiil a mosaic c(Misisliiig of iiiui-h largi-r hut sliU comparalively small areas, which caniuil very well he regarded as cells. This form of calcilication, which we nii;',lil cill plale mosaic , wi' lind \eiy linely cisiiild iiincrsd and Anarihropord nioiiodon. In contrasl lo what occurs in /•'/. scrnrifrons none of these species show a regular arrangement of Ihe small plales, and in a nund)er of lluin (he laller appear in a very irreg- ular and variable way, as they may appear logelher willi olher forms of calci- licalion within the same colony, even on Ihe same wall. Time does not allow me lo enler inio details, bul 1 will jusi meulioii Sniillimt Irispinosd. Iliislrd scrni- Idid and /•'/. piscifiiniiis as examples of such si)ecies. While Ibe small plales in ' Til, p. •_'!(;: .').'.. |> :t. ;i mimlier of the here mentioned species show plainly concentric lines of growth, they on the other hand show a distinct radiate arrangement in Inuerxitila iiiuersd and AiKirlliropoia luoiwdnn (PI. XXIII, ligs. 10 a, 11 a). These small plates which arc only distinct in quite young zo(vcia are each i)rovided in the centre with a pore, the edge of which has radiate rods, and to judge from Hi neks' drawing the front surface in the following sjiecies descrihcd hy him is also divided into a number of small plates each of which has a pore in its centre, namely, ^Lepruli-lriincocclldrid, iiiccUdrid, C^hiiliiui. Ijujeni- pord. Scliizoporella, Siniitia. Mncronclld and Reicpovd are referred by liini to the Monoilernmta, while he classes species of the genera Cahered, Mcnihidnipord and Sclosclld to the Diplodennald. In a third paper however he has altered" his view of the extent of the Diplodenuata, in that he now classes some of the forms which in the earlier papers he placed under the Munoilenudtd lo the Diploder- inata, namely, all the families Encntteidde, Ccllnldriidde f= ScnqioceUdiiUtde). Hi- cellariidde, Noldiiuidae, Flustridae, Meiubrdiiiporidde, GemelUuiidae and Fdrciinind- riidae. While a systematic classilication on the basis of the structure of the frontal wall is still found in a work of Canu' from the year 1900, on the Brijozod of the Cretaceous period, this classification seems cjuite given up in a later coopera- tive work by Jullien and Calvet'*, which after the death of the first men- tioned writer has been carried on and published by the latter. Calvcl'' gives very important information about the structure of the frontal wall in a large work dealing with the structure and development of the ectoproct Brijozou. Be- sides in Eucrnted Lafonti. Membranipora Rosseli and the species of the genus, Cellaria, he has found a double ectocyst in the species examined by himself oi' the genera Tiihucellaria, Microporello, Chorizopora, Schizoporelld, Lepi(di(i, rniboiiidd, Retepord and Cellepord. consequently in forms which according to .In Hi en's examination have a single ectocyst, while he has found a single ectocyst in the examined species of the genera Aeled, Scnipocelldria, Caberea, Biiyiiki, Flustra, and in Meiubraiiipoid pilosd and Membr. Flemingi. As to those forms which have a double ectocyst, he gives the interesting information that the interspace between the membranous exterior and the calcified interior layer (the Cryptocyst) is every- where covered by epithelium, and moreover contains leucocytes and a mesen- chymalous tissue. Except in the Retepord where the basal wall of the colony also has a double ectocyst, he only finds such an ectocj'st on the frontal wall. The result of the investigations above-mentioned is, consequently, that we can distinguish between skeletal parts which come into existence inside the covering membrane and independent of this (the Cryptocyst), and those which arise by transformation of the covering membrane. We may call these last-mentioned parts of the skeleton whose frontal surface consecjuently has no membranous lining (an »epitheca«): the »Gymnocyst«. ' 43; - 45; ^ 11 ii; Mli ; '' pp. 103—168. Spines. Under the name of >spines« we undersland in this work only a sorl of liollow projections of the onter snrCace of the zoo-cinm, whereas we may designale all solid projections, issuing either from the outer or the inner surface, in a diU'erenl manner, for instance as spinous processes-, »denticles« or in a similar manner, according to Ihc form and size of the projeclions in ([ucslion. Such solid spine-liUe projections are present on the outer surface for instance in HoloporelUi hastigern^ Busk, Hoi cohimnaris', in the species of Farciminaria (PI. 1, figs. 10 a— 10 c) and most species of the genus Spiralaria (PI. 1, fig. 9 c), and on the inner surface e. g. in Menipea roborata (PI. II, figs. 7d — 7 e), Hincks and Men. lignlala (P]. II, fig. 8 c) Mac Gill. From the position, structure and mode of growth we can distinguish between three different main forms, which we may call marginal spines or folded spines, acropctal spines or annular spines and bilaminale spines. 1) Marginal spinex or folded spines. While these spines may appear in larger or smaller numbers on the frontal wall of species with a membranous frontal area, in the circuit of which they are placed, they may also appear in numbers of 2 — 10 in forms where the frontal area is lacking, outside the anter of the aperture. All these spines originate, as Harmer^ has already found in Memhrani- porella nitida and Crihrilina annuhtta, as crenulalions or folds of the gymnocyst margin, which surrounds the membranous frontal area (PI. IV, figs. 2 a — 2 c) or the anter of the aperture, and the two lateral halves of the fold grow finally to- gether in a longitudinal suture which is turned towards the zoa'cium, and which can often be seen for a long lime even after the spine, by continued growth at the point, has reached its full length. As the fold is closed it comes to enclose a part of the frontal area, and the growing spine will constantly be finished off by a membrane, which is the condition for its further growth in length, and which only disappears when the point of the spine calcifies. These niai'ginal spines, which are always foriued by a Gymnocyst, present a certain likeness in their mode of formation to, the hollow outgrowths of the rim which a])])ear in various snails, for instance in Pterocera chiragra. 2) Acropetal spines or annular spines. These spines which are only found in a small number of Brgozoa. begin as a ring-shaped growlh on the circum- ference of a rounded uncalcified part of a surface, and grow in other respects in the same way as the marginal spines by means of a membrane at their free end. To these belong the (as a rule) unpaired spine which is situated at the end of the membranous frontal area in the genus Electrn, the unpaired spine in ' 8, p. 192; - 8. p. 1!)4; ' 19, p. 292. 10 Escliarina spiiiifera, the two laii^e distal projections which a[)peai- in a number of species of the genus Thalamoporella (PI. Via, ligs. 4 a, 5 a) and llie two corre- sponding projections in the genus Claviporella (Pi. XX, fig. 10 a). Undoubtedly also, the very long and thin spines which appear at the edge of the calcified, arched fronlal wall of ^Lepralici< Poissoni in a very unusual way, belong to this division, and also the likewise long and thin spines which somewhat scattered and in great numbers surround the anter of the ajierture in Scliizofxirclla hiscridlis Hiucks ', and which give the impression of having been formed lound a number of the nume- rous scattered pores which appear in this species, in the same way as the very short arched projections which occasionalh' appear round ocrcial pores, for in- stance, in the species of the genus VJaviporelln. The hue acrojielal spines like the marginal ones are always formed by a Gymnocyst, but in PordUt (?) corniita (PI. XVIII, fig. () a) the endoooecium in a numJ)er of zoa^cia is furnished with one or more hollow spine-like processes which in the same manner as the acropetal spines have a ring-like origin and are no doubt formed by chalk-particles depos- ited under the membranous ectooa>cium. These projections, however, are in no inner connection with the ooecium and cannot therefore be looked ujion as true spines. 3) The bildininale spines, which have hitherto only been found in the family Catenariidce and will be more fully spoken of under this family, spring from the free margin of a moie or less developed sinus (Ihc sternal sinus), from the margin of which also an inner Cryptocyst lamina takes its origin. As these spines issue from a margin in which a Gymnocysl and a C-ryjitocyst meel, they must of course be two-layered, their outer layer l)eing formed by the Gymnocyst and the inner by the Cryptocyst. They attain their highest development in the genus Costicella (PI. XII, figs. 1 a— 1 d, PI. XX, figs. 8 a— 8 b, fig. 9 a). The morphology of the zooecium. As is known we can in the cheilostomatous Bryozoa distinguish between six, as a rule well-separated, walls, namely, the two lateral, the two terminal, the basal and the frontal. It is generally difficult however to distinguish exnclly between the lateral walls and the fionlal wall (or basal wall) in species which appear in single rows, and in those zoci'cia which arise by superficial gemmation and in most cases in moie or less erect {josilioii (I'or instance in the ('.cltcpord and Iloloporclld s])ecies) only llie basal wall is sliar|)ly hounded, the other walls ' 3U, p. 250. 11 riimiiiig into each other. It would he most natural only to count the adjacent jiarts of two neighhouring zooecia as lateral walls, and to regard the whole frontal surface of the zofX'cium as the frontal wall, even if the lateral parts of it are sometimes almost vertically ascending. In contrast to what takes place in the Cyclostomata, in which all partition walls are single and common for two adjoining zoa-cia, the lateral walls in most of the Cheilostomatd arc independent, and after treatment for some time in eau de Javelle or with hoiling alkali, most of the colonies can be broken up into a number of longitudinal rows of zooecia. Still from this rule maj' be excepted a number of families and genera, as Cellulariidce, Cateiuiriidcc. Myriozoidce, Sclero- domidcv, Tubucelloriidcv, Cniiescharelliiiidcv, SeleiKiria and Lunidites, and even within genera, the species in which have independent lateral walls, for instance Porella, we can find species e. g. P. saccata, P. compressa and P. tnbidifera, in which the lateral walls are common to two zocrcia. Such common lateral walls seem ex- clusively to appear in free growing species, while on the other hand several species with free growth have independent lateral walls, e. g. the members of the families Scriipocellariida' and Bicellariiila'. The same is the case with the free-growing species of Steganoporella and TImlainoporella. If we make a section through a decalcified colony of one or other s|)ecies which has indepen- dent lateral walls, e. g. Steganoporelht mcKjnilabris, we see plainly that there is no membrane between two adjoining lateral walls, but that each of these is in direct communication with and passes over into the frontal membrane of the corre- sj)onding zocpcium. The reason why the two lateral walls are separated by the above-mentioned treatment may be that the fluid dissolves a part of the organic matter which the walls contain, and that these then draw themselves together in a similar way as a piece of wood does when it dries up. With this also agrees that such a separation of adjoining walls takes place much easier in younger zooecia than in older, in which the calcification is more advanced. As a rule the terminal , walls in contrast to the lateral are common to two zosecia lying behind each other and there are only a few exceptions from this rule. One is presented by the species of the above-mentioned genus OmjchocdUi (PI. XXII, figs. 3a — 3d, in which this wall can also be split into two after treatment with eau de Javelle, so that we might here speak about a separate distal and proximal wall. As the genus Omjchocella commences in the Jurassic and has its widest extension in the Cretaceous period, we very likely have to do with a primitive condition. Separate terminal walls "also exist in the kenozoocia of Rete- pnra tcssellala (PI. XXIll, fig. 1 a) and lid. lata (PI. XXIII, figs. 2 a— 2 c), and 12 Memhraniponi Xornidiu n. sp. (PI. XXII, fif^s. 5 a — r> c) is also a partial i-xccplion to the above rule, as the ohliqiiely ascending frontal i)art of the terminal wall can he s|)lil into two, which on the other hand does not seem to he the case with the horizontal pari of this wall. Of the tw-o other walls we may first consider the frontal (or oral), which presents the most nnmerous modifications and is therefore systematically the most im])()rtant. In a preliminary paper' I have proposed to divide the cheilostom- alous linjozod into four groups: Mithicoxlecja, Acanlhoslcgit, (]oU\xlv(jii and Cjiumro- steya, which are to a larger or smaller degree based on the structure of this wall. Of these the first three correspond with the division instituted in this work under the name Anasca, which covers all the chcilostomatous linjozoa with no com|)ensation sac, while the fourth corresponds to the Asi-ojtlioni piovided with such a sac. Though I only intend to keej) two of these names for systematic divisions, it would be practical to use adjectives corresponding to all the four names, in order through them to indicate essential dill'erences in the structure of the frontal wall. This may namely be rej)resenfed only by a membrane (mala- costegous Cheilostomat(i) in a largei- or smaller ])art ol' its extent, or is (|uite cal- cified (stereostegous Ch.). In the latter case the chalk cover may be arched (ca- marostegous Ch), or it may be depressed and encircled by projecting margins (coilo- stegous) Ch.). Finally, above the covering membrane there may be a chalk co\er consisting of two rows of hollow spines connected with each other in dill'ercnl ways (acanthostegous ^.Vi.), and lastly, we may just recall tliat the calcareous skel- eton itself may either be a Gymnocyst, a Cryi)locyst or a compound of both. Before we try to give a view over the ap|)earance and extension of the Gym- nocyst and the Cryptocyst within the dilferent families of the cheilostomatous Krijozoa, we may discuss some criteria, which might lielj) to determine the ])res- ence of these two kinds of skeleton in cases where there is no possibility of deciding the question directly, namely, by observation of the membrane which should always cover the Cryptocyst. This ap])lies not only in most cases to the dried liryozod, but the thin membrane is also torn away from many colonies pre- served in spirit, and I may mention as an instance, that I have had to examine many spirit specimens of Iisclt(iioi(hs .hich'soni before finding the covering mem- brane. The lateral and oral spines always, as mentioned before, spring from the border of a Gynmocyst, and therefore we can with certainty take it for granted that every calcification which appears within such a spine-bearing border or from a corresponding border in a non-spinous s])ecies is a (Cryptocyst. Ilarmer'- ' 56, p. 2; - lU, p. ;i2G. 13 concludes rightly therefore in saying that the calcification, which ajjpears within the marginal spines in the primary zoircinm of Schizoporella uuUjarh, is a Cryp- tocyst, and such is found at the same place in many malacostegous Cheilostomala. A Cryi)locyst of this sort is not only very plainly hollow or depressed, which is in contrast to the arched Gymnocyst, hut also varies as a rule from the latter by having a more or less grained or rugged surface. We can find all sorts of transitions hetween a completely membranous and completely calcified frontal wall among the forms without a compensation sac, and for which we have suggested the name: Auasca. The whole calcified part is sometimes a Gymnocyst, sometimes a Cryptocyst and sometimes, both kinds of calcification may appear at the same time, the Cryptocyst s])ringing from the Gj'ninocyst where the latter passes over into the membranous area. We can dis- tinguish between a distal part, a [)roximal part and two lateral [)arts for the Gymnocyst as well as for the Cryptocyst. The distal ])art is in most cases the least developed because of the position of the aperture in the distal part of the zoo'cium, and may in the Cryptocyst not seldom be (juite missing, while the proximal part as a rule has the largest extension. A peculiar excejjtion is found in the form which Busk describes as Diaclioris magellanicd, i>. (Iistans\ but which must undoubtedl}' be regarded as an independent species. The proximal part is here very feebly develoi)ed, whilst the two lateral regions are verj' broad and only separated by a split in the middle line of the zoo'cium. hi very few cases, as in Membranipora delicatiila, the proximal part may grow out as a tree lamina which is not connected with the lateral regions, and when such a lamina again meets these (listally we have the peculiar condition known in Calesclutra denlknlala, in which the frontal wall is furnished with two long and narrow fissures. The distal part may in some avicularia, for instance in the lyre-shaped forms, exceed in extent the proximal (PI. Via, fig. la, 2a, 3a). While a Gymnocyst in the Flus- tridue is either (juitc lacking or only rej)resented by a faint marginal part, there can in a number of species, as e. g. 7*7. denticulatci, Fl. ccirbacea, Fl. serrii- lata, Fl. biseriula, Fl. cribriformis and Fl. Schenaiii, n. sp., appear a feeble, more or less knotted Cryptocyst, the proximal |)art of which is most developed. While the Cryptocyst appears very late in Fl. dei)liculata and therefore can only be found in older ])arts of the colony, we find it very early developed in Fl. serru- lala and Fl. carhasea, in which species it is only lacking in the very youngest zooecia. Longitudinal and Iransverse sections through such a colony (PI. XXI, fig. 10 a — 12 a) show that this Cryptocyst, which Waters'- calls the chitino- ' 8. p. .'ji); ■■' 109, p. 28(1. 14 calcareous band in Fl hiseriatu. begins a little l)el()\v tbe up])er edge ni" llie ver- tical wall of the zotrcia. This Cryptocysl reaches a somewhat greater develop- ment in Fl. cribriformis and /•"/. Schaiund (PI. 1, fig. 7 a, 7 c), in which it shows a varying number of lines of growth, according lo the age of tlu' zoo-ciuin. W'e may mention finally, that while the zotrcia in the free pari of Fl. [oliacea have no Cryptocyst, such is rather highly developed in the incrusling part of the coi- lony and al.so, that it is well-develoi)ed in the avicularia of this s])ecits. Of the forms which we have here classed to the i'ainily l-'nrciiiiiiKiriidnc, the fiontal wall of most of them has neither a Gymnocyst nor a Cryptocyst, or there is only a faint trace of the last. On the other hand both of them appear rathei' well-developed in Fdrciininaria appendicnlala (PI. 1, fig. 11) and in Xcllid Icnella (Pi. 1, fig. 1^). Within tlie family Bicellariidae we find a completely membranous frontal wall in most of the species referred to the genera Ihiskia, lieaniu and Diachoris. The Gymnocyst reaches its greatest development in Dintclopia and Hicellarui, because it may here attain more than half the length of the zoct'cium (PI. IV, fig. 5 and 8), while it only has a small extension in most of the Bugiilu species. With excep- tion of Bicellaria grandis (PI. IV, fig. 5 a), in which species we find a large distally freely projecting Cryptocyst lamina, I have not been able to find any trace of a Cryptocy.st in any other Bicellaria; still it seems as if a slightly developed Cryp- tocyst can be found in almost all other members of the family, at least in the older zott'cia, in which it often seems to be represented by the proximal part, which shows distinct lines of growth. The whole of the Cryptocyst shows distinct lines of growth in the figure of the zoa'cium of Maplcsloiiia simiilc.v shown in PI. IV, fig. 9 a, but the proximal part is only slightly developed. With exception of the Flustra-Vike Hoplilella armata (PI. II, fig. 10 a), in which the whole of the frontal wall is membranous, a larger or smaller part of this wall is calcified in the rest of the members of the family Scnipocellariidcc, and they have as rule a Gymnocyst as well as a rugged or grained Cryptocyst, which in Cellularia ornala even seems to form the whole of the calcified i)arl of the frontal wall. The Gymnocyst however forms most fre(|uently the major part of this wall, and its proximal part in Menipea acideala and Men. clau.sa attains nearly the two-thirds of the length of the zoa-cium. The Cryptocyst seems to he strongly developed in most of the Caberea species. While the whole calcified part of the zoa>ciimi in the Aeteidac is formed by a Gymnocj'st, the conditions are very variable within the large family Mi'inbrani- poridae. While the whole frontal wall is formed by membrane in Meinbranipora nieinbranaceu and related species, a larger or smaller part of it is calcified in most of the remaining forms, and this calcification is sometimes represented only by a Gymnocyst, sometimes only by a Oyptocyst and sometimes by both. 15 In tlie species belonging to (he genus Electra (E. pHosa, K. vcrticHUila, E. bellnUi etc.) we find a good-sized Gymnocyst, and the Cryptocyst is either (}iiite lacking or is represented only by a veiy slight margin within the spines. In the genus Cullo- pora a cryptocyst is developed in \ery varying degree and in C. lineuia, C. cra- ticiild, C Diiinerili and C aiirila it is represented only by a slight granular margin in the circumference of the membranous area, while in other species as e. g. in C. Flemiu(ji and C. trifoliiim it has grown to such an extent that the zod'cium lias only a little trifoliate aperture. Hi neks calls it in such s|)ecies »an inner lamina«. Finally, the calcified part of the frontal wall in Mcnib. (irc- tica, M. Rosseli, M. cornigerd etc. is only I'oimed by a Cryptocyst, as is also the case in the species referred to the genera Oiujchocella and Chaperia. The Gymnocyst may attain a very different degree of development in the forms of the family Cribrilinidae, and its development is naturally in inverse proportion to the extent of the characteristic area, which consists of two rows of mu- tually connected spines. While this area in some forms, e. g. Membraniporella nitida and Cribriliiia annuhitn, constitutes the whole or almost the whole of the frontal wall, a smaller or larger part of the latter is in other species formed by the true Gym- nocyst. Cribrilina Gattya- and Cr. chlitridiata among recent forms are perhaps those in which the Gymnocyst reaches its largest relative development, and its proximal |)art may here sometimes reach the same length as the area. The area is of still smaller extent, and almost to be regarded as rudimentaiy in some species from the Danish cretaceous formation. A Cryptocyst seems to appear, within this division, only in species of Membrani-porella as a narrow niarginal region round the menil)ranous area of the aperture. In the forms which we have called >coilostegous«, namely, in the members of the families Chlidoniidae, Ahjsidiidae, Cellulariidae, Microporidae, SleyanoporeUidae and ThalamoporelUdae, the frontal wall is formed by a depressed Cryptocyst, but in the last of these families the two marginal regions, which hound the opening distally and which often end in arched protuberances, are formed by a Gymnocyst and as a rule sej)arated from the Cryptocyst by a well-marked boundary line. The numerous families belonging to the division of Ascophora all have an arched calcified frontal wall, and as previously noted JuUien refers the repre- sentatives of this division, mentioned by him, to the Monndcrimda, by which he understands those forms which have no Cryptocyst. Calvet' however, for a number of these forms has proved that the arched calcified frontal wall is in reality a Cryptocyst, and according to my investigations this is the case with ■ 9, p. 16(i. 16 most ol' the families in this division; still I have not l)epn ahle to find a cover- ring menihrane in members of the families Calenariidde, Uii)pothoida\ Eunj- stoniellidae and Eulhyridoe, nor in the genera Iiwersinla and AiKirlhrojiora, and I must tlierefore ascribe a Gyninocyst to all these forms. The two divisions M(d(icnslc(ia and Cniloslt'tja in reality evenly grade into one another, and there is no doubt that the coilostegous forms have arisen from the malacostegous by the extension of the calcification all over the frontal wall. In some Tluddinoporella species, for instance in Th. e.vpansti (PI. VI b, fig. 5 a), the operculum is surrounded by a completely calcified frame-work, while in most of the species it is connected \vith a small membranous area posteriorly. We find a sim- ilar relation between the species of the extinct genus Rli(iis-\ Escharella inunersu^, Esch. stenostonur and Esch. enmcronata^. In all the hitherto found ancestrulse with a modified Tata, which belong to ascophorous families with a cryptocyst, there is found a more or less developed depressed cryptocyst, at any rate at the period when they have produced new zocecia, and the existence of this cryptocyst goes to prove, that these families descend from coilostegous forms. That Harmer" at any rate with respect to a part of these forms is of the same opinion is evident from what he says about the cryptocyst in the ancestrula of Eschariiui intlgaris: It appears to me to be of great importance to ascertain whether this calcified portion is of the nature of a cryptocyst or not; in other words whether the frontal membrane extends as far as the sharp ridge on the inner side of the base of the spines. I can hardly doubt that this is the case; and if so the Microporoid origin of Escharine forms in which the compensation sac develops as an invagination at the base of the operculum would appear to be indicated-. I may just remark, that Harmer's Microporoid series in all essentials corresponds with my division Coilostega and his Escharine forms with my Ascophora. — Such a transformation from a coilosteg- ous into an ascophorous form as that which Harmer and the author of the pre- sent work advocate, supposes, that the depressed or hollow cryptocyst of the former. ' 77a: * 45, p. 28-34; ' 100, I>1. XXVl, fig. 98; ' 100. PI. X.WII. tig. 162, 163; ' 100, I'l. XXVI, fig. 109-111; « 100, Pi. XXVll, (ij;. 167; 101, PI. XXI, fig. 31; " 101, PI. XXI, Ug. 29; ' 101, PI. XXI, tig 27; '•' Alf. p. 334. I? 2* 20 has l)een in the course of time changed into an arclied one and this change was, I tiiink, a necessary supposition for the formation of a compensation sac, which could not find sufficient room within a depressed cryj)tocyst, and ii would therefore he reasonahle to su])pose, that this has only heeii formed after the depressed cryptocyst's transformation into an arched one. While we know of no example of an ascophorous form with depressed oral wall, we can on the other hand mention several examples of forms, which though helonging to the division Coilostega (or to the related division Pseudoslega) have a more or less arched frontal wall. In such cases either the whole frontal wall may he arched within a narrow projecting rim, or such a narrow rim may he wanting, and the largest portion of the frontal wall is then arched, while there is a smaller depressed portion in its distal or central part. We can mention the recent Cellaria magmfud Busk', Macroporct centralis (?) Mac dill. (I'l. VII, fig. 1 a), Micropora noduliferd Hincks^ and Aspidostoma (jitjanteum Busk (PI. Vic, fig. 2a), and the fossil 'Ilomolosteya" erecta Marss.', Aspidostoma (?) Atalantha d'Orh (PI. VI c, fig. 5 a, b), Aspid (?) Aegon d'Orh (PI. VI c, fig. 3 a) and » A'.sc/ian) Aegte d'Orh ^ as examples of species with such a structure. In the last sjjecies the frontal wall is arched in most of the zocrcia, while in a smaller numher it is more or less depressed or fiat. In contrast to the modified 7'f//rt-form found in the genera Escliaroides, Escha- rella, Escharina and Porella (P. l(vi)is), which possesses a depressed calcareous lamina within the spines, the corresponding lamina in the modified Tata of Hippothoa hyalina found by Jullien' is not depressed but arched (bombe) and therefore does not seem to be a cryptocyst, but this corresponds very well with my exa- mination, according to which the frontal wall in that genus is a Gymnocyst. Busk" figures some abnormally developed zooecia of Electra pilosa, which are of no small interest. The spines are quite lacking in these, due to the fact that the calci- fication of the covering membrane has continued beyond the ordinary limit, so that the (lymnocyst has spread in irregular tongues over a large part of the surface, otherwise occupied by the membranous area of the aperture. In the frontal part of the two zooecia is an open .space which in shape and size might correspond to an operculum, and which is separated from the other calcified region by a low calcified bridge. It is evident that there has been an efTort here to form a zocecium with a perfectlj' calcified frontal wall, and by a similar elTort the Membvanipora species, which is rellected in the 7'((/«-form of Hippothoa hya- lina must in the course of time have changed into a Hippothoa, at the same time as ' 8, p. 93; ' 25. p. 1 1 ; ' .^S a. PI. IX. fig. 12; * m. PI. (Uii. fig. 6: '' 4,''). p. 30. PI. I, fig. 4 ; '' 2, PI. LXXI, figs. 3, 7. 21 Ihe iiol yel wliolly calcified |)arl of the Irontal iiiemltrane has loiined a compen- sation sac by an invagination proximally to the operculum. The basal wall like the frontal may also be membranous, as in Membranipora mein- branacea and Electru pilosn, and even in numerous, well-calcified, incrusting mem- bers of the division Ascophora the basal wall is slightly calcified or jjarlly uncalcified, sometimes even quite membranous. I may for instance mention the incrusting species of the genera Eschaielbt. Escharina, Micropoielld, Hippothoa, etc. The ))asal wall in tlie calcified state seems as a rule to be a Gymnocyst, and it is only in very few cases that it is covered with a membrane in species appearing in free colonies. Harmer' has for example shown that the free, one-layered colonies of Euthyris dathratu and Eiith. obtecta (PI. XV, figs. 2c, 2d) are provided over the whole surface with a covering membrane which is kept stretched by ])ro- jections from the underlying Cryptocyst. A covering membrane over the whole surface of the colony is also j)resent in Urceolipora nana (PI. XV, figs. 1 a — 1 e) and it seems also to be found in species of the genus Cupiilaria. Under the names of Sleginoj)ora and Uisteginopora d'Orbigny- has described a number of fossil species, which have possessed a double roof, of which the lower except in .S7. irregularis seems to have quite the same structure as the roof in Cribrilinidae and thus to be formed by spines connected with one another. On first consideration of the drawings given we should be inclined to supjjose that the upper roof is formed by calcification of such a projecting membrane as the one we find in Eulhijris ohtecta; but according to Jullien's^ investigations the upper roof is formed by a partial fusion together of very large spines, broadened out and plate-like at the ends, and this view is undoubtedly right. That this roof cannot be explained in the above-mentioned way appears clearly from the fact, that the membrane which corresponds with the mentioned projecting cover in Euthgris, has its place below the fused spines in Cribrilinidae. hi a number of fossil (Iribrilina forms as well as in the one-layered Steginopora species we find a varying number of robusj projections at the back of the single zocecia, which Harmer' thinks have served as sup|)orts for a membranous cover, similar to the one which is found in Eulhgris. Against this view speaks firstly Ihe circum- stance, that while the mentioned sui)ports in Euthgris obteclu are slender, cy- lindrical rods, the projections in the mentioned Cribrilina species, with which Harmer compares them, have the form of tubercles, which are very differently developed in number and size in Ihe different species, and their rounded end- ])art does not seem to have been connected with a membrane. Further, these • 18, p. 16 and 19, pp 267, p. 277, 278: « 86, pp. 235, 498, 499; ' 44. p. 609; ' 18, p. H 22 knots may sometimes be present and sometimes absent, even in closely related species; thus while they are found in Semiescharipora ovalis^ they are wanting in Reptescharipora convexa". Secondly, we must remember that while the whole surface of the colony is covered by a continuous membrane in the Eiithijris species, every single zocecium in the mentioned fossil species has been furnished with a separate frontal membrane, which has been situated below the roof formed by the spines. As shown before, the marginal spines always spring from a Gymnocyst and we must therefore assume that the Gymnocysl, which has formed the spines of the marginal zocecia, has passed directly over into tlie basal wall of Ihe colony from the free lateral edges of these zooccia. Rosette-Plates and Pores. The adjoining zooecia in a colony are, as known, connected by chords of mesenchymatous tissue, which extend from one zocecium into another through pores in the partition-walk, but while these pores appear in the Cyclostomatu as simple perforations of the wall, they are in the Ctenostomata and Cheilostomata very fine piercings in watch-glass-shaped, concave, thinned portions of these walls. These peculiar formations have been noticed for the first time by Smitt, on the lateral walls in Flustra foliacea^ and are called bj' him commimication-pores. He has • not however seen the real pores, and seems to regard the whole, multiporous plate as an opening. Later Reichert'' in a member of the division Ctenostomata, Zoobolhrion pellucidiim, has observed the same formations, which he calls »Ro- settenplatlcns and in which he has seen the real pores. Among later writers Waters'' first drew attention to the importance of these rosette-plates for the diagnosis of species and in a series of papers he gives information on their presence in several Cheilostomata, while the writer of this work has illustrated their occurrence in the Danish species, .^s this description'' was however written in Danish, and for that reason less available, I may give here the results of those older investigations lo which I have been able to add by later studies. Though I do not find Ihe name rosette-plate good, I shall yet use it, jjartly in view of its priority and partly because Waters has used it in his many papers. The formations dealt with here may appear under two different forms, namely as common rosette-plates or as pore-chambeis, and each of these can again be divided into single-pored, or single and multi[)orous or compound. Rosette-Plates. A single-pored rosette-plate is a watch-glass-shaped, concave, thin portion of the wall, which as a rule is surrounded by a more or less devel- ' Sfi, Fl. 719; » S6. PI. 72U; ' 99, p. 426, PI. X.\. tig. 15; * 94. p. 2l>7 ; '■ 109, p. 286; •■■ 54, 55. 23 oped, more chitiiiised projecting marginal |)ortion, »the pore-rings the onter open- ing of which in the most developed rosette-plates is smaller than the size of the plate a little in from it. Within the pore-ring we can distinguish hetween two portions, differing in thickness, a thicker outer area and an inner surrounded by the other, very much thinner and very small pore-area, which is pierced by an extremely fine pore, and distinguished by a strong bluish lustre, which at lirst glance makes it seem thickened. Such one-pored rosette-plates may appear singly (the distal wall of Flnstru seciirifrons, Fl. papyred etc., the distal wall of most Reteporid(te), in a more or less numerous (of 2 — f2 plates) series (all walls in many species of Sniittina, in Adeonidae, in mosl Fliistridae), or in groups some- times consisting of more scattered, sometimes of more closely placed plates (e. g. in Cotenariidae, the distal wall in Scrupocellaviidue and Thalamoporellidae). hi cases where tiie single rosette-plates are close together, they have a scjuare or hexagonal shape, and meet in a network of elevated ridges, which must be re- garded as the ])ore-rings for the single rosette-plates. It is (juite impossible to draw a sharp limit between a group of one-i)ored rosette-plates and a multi])orous roselte-plafe, as the only character, which can be regarded as peculiar for the multiporous compound rosette-plate, namely, a common pore-ring which surrounds all the single small plates, can be developed to very different degrees, and does not always appear to be constant even in the same colony or in the same zooecium. This is the case with for instance Arthro- poma Cecili, in which species the distal wall as well as the distal half of each side wall is furnished with an elongated or oval group of numerous iiniporous rosette- plates. A pore-ring may be lacking on some walls and appear on others, not only in the same colony but also in the same zooecium, and wherever it appears, it may either be exceedingly well developed, or only slightly indicated. Within the pore-ring (PI. XVII, tigs. 10 a, 10 b) which has a similar structure as in the uni[)orous rosette-plate, we have an area, the large area, which may be tilled l)y the small plates to a very different degree, and while these for instance in Artliropomn Cecili often form only a longitudinal belt along the middle part, in ^Lepraliw Pallasiana (PI. XVII. (ig. 10 a) they fill the whole or at any rate the largest part of the plate. The rosette-plates may show many ditTerent degrees of calcification, to some extent according to the degree of calcification of the sjjecies concerned. In most members of the family Bicellnriidae, in species of the genus Onychocellci and Selenaria we thus lind rosette-plates, which with exception of the pore-ring are quite uncalcified; on the other hand we find e. g. in Fliislra foliacea and Flnstia carbacea, that the large area is calcified and the single small plates are uncalcified. The pore area is always uncalcified, while on the contrary the outer 24 area in mosl cases consists of an oiiler calcified, and an inner uncalcified part, and in strongly calcified species (e. g. ^Lepralia< Pallasiana) the inner uncalcified portion of the outer area is very small. The single small j)lates in a compound rosette-plate often show only a slight indication of a pore-ring, and when they are not much hollowed out the calcified portion of their outer area is often so little distinct from the large area, that it is only jiossihle lo find it hy very favour- able light. Just as we rather frequently find two rosette-plates fused together into a double plate with an outer area in common and two pore-areas in species, the distal wall of which is provided with a number of uniporous rosette-plates (e. g. in Fliistra foliacea, Fl. carbacea and Membranipora pilosa), we also find in a multiporous rosette-plate a fusion of two or more small plates into one. A great deal of variation and very dilTerenl kinds of fusion take place in the distal w-all in Membr. membranacea^. In this appear as a rule two pear-shaped multi- porous rosette-plates, but in many zooecia each of these is replaced by a whole series of smaller plates, of which some are uniporous, others multiporous with a very varying number of pores; the conditions may even be (juite dilTerent on the two sides of the distal wall. Pore-CJiambers. I have used this name" for the small spaces which are situated in the angle between the basal wall of a zooecium and one of the perpendicular walls. In their typical form they have a triangular tranverse section, and we can distinguish between a basal wall, an inner wall and an outer one. The basal wall is a portion of the basal wall of the zooecium, the small rosette-plates are situated on the inner wall, and on the outer wall is the entrance to the chamber (PI. XVII, tig. 10 c). If we examine their development in the newly formed zooe- cia in the growing part of the colonv', we see that the inner wall is the part first formed and that the basal wall and outer wall are formed later. We can best make sure of their presence if we loosen a colony from its supi)ort and look at it from the basal surface; for in this position the inner walls of the elongated pore-chambers form curves within the lateral margins of the zooecium (PI. IX, ligs. 11 g, 12 a, PI. XV, figs. ;5c, 4 c, PI. XVIII, figs. 14 b, 11 a). There is as a rule only a small number of sniall plates ])laced in a single row and the neigh- bouring chambers arc in most cases moved up so close together that the curves touch one another, oi' even so that the chambers have a common separating wall. While the vertical walls in all zoo'cia, which are furnished with ordinary rosette-plates, form right angles with the basal wall, the pore chambers are placed in such a way that their outer wall forms pointed angles with the ' 54, Tab. II, fi)5. 17: .55, PI. IV, fig. 5; '' 54, p. 2,50: 55, p. 7. 25 basal wall of the one and obtuse angles with the other of the two zooecia, between which it serves as connection (PI. XVII, fig. 10 c). The outer wall of the chamber forms obtuse angles with the frontal wall of the zoa>ciuni and the pore-bearing, somewhat slightly concave inner wall forms obtuse angles in- wardly and pointed angles outwardly with the base. What is said here applies to the pore-chambers of both the lateral and distal walls. Though rosette-i)lates and pore-chambers seem at first glance to be of quite different structure, they are connected by transitions. If we imagine a rosette-plate placed in such a way thai its lower edge goes down into the angle between a lateral wall (or distal wall) and the basal wall, a removal of this edge into the basal wall would produce a pore-chamber, as what is just characteristic for such a formation is, that it belongs to two adjoining walls. I have found such transitions between common rosetfe-plates and pore-chambers in colonies of ^Lepraliw^ Pallasiana from Sebastopol, which together with Electra Zostericola forms incrustations on Zostera marina. While colonies of this species from Denmark and from Port Jackson, New S. Wales, have only ordinary multiporous rosette-plales, we find more or fewer zooecia in the colonies mentioned from Sebastopol, in which more or fewer rosette-plates are replaced by pore-chambers with differently developed basal wall. We can also find such transitions in the very variable species Porella concinna between rosette-plates and pore-chambers, which replace one another in different colonies. In contrast to the multiporous chambers which can be found in ^Lepralia< Palla- siana and Porella concinna the few-pored chambers are usually constant within the species, and even sometimes in the genus or family. Besides in all members of the families Hippothoidae and V.elleporidae typical pore-chambers appear in the genera Callopora, Cribrilina, Puellina, Eschar ina and in a number of species of the genera Escharoides and Microporella. In the members of the family Celle- poridae. the colonies of which increase by superficial budding, the pore-chambers are only to be found in the zocccia which form the llrsl incrusting layer of the colony; in species of Escluirella (PI. XVII, fig. 1 c) the originally long and narrow pore-chambers, which are provided with a row of small single-pored ro- sette-plates, are divided by partition walls into a number of uniporous chambers, and the pore-chambers may be tubularly lengthened in .species of the genus Hippothoa. Before discussing the relation of a rosette-plate to the two zooecia which it connects, we may again recall that on using boiling alkali or cold eau de .la- velle we can not only loosen a colony from its support, but even as a rule sepa- rate it info single rows of zoa-cia, on which wc can without difficulty study the 2f) roselle-jilales. While Xilsche' in his nl)ove-inenli()iu'(i work on Meinhr. mein- branncca has rightly ohserveii, that the single zorecia have independent lateral walls, he gives a wrong view of the relation of the single zoa^cia to the rosette- plates. He saj's namely: »Die Rosettenplatten eines jeden Zoociuni eorrespon- diren nun mit den Rosettenplatten der uniliegenden Zoocien auf das genaueste*, and he gives in detail an explicit account of how the rosette-plales of each zoceciuni are placed opposite to a corresj)onding rosette-plate in an adjoining zooecium. If for instance we separate a row of zod-cia of a ScriijxH-clldrid form (PI. II. figs. 7 g, s, 22— M. 2.S lerminal parlition-wall helvveeii Iwo zod'cia (ils riglil ()pj)Osile to a latei'al wall in an adjoining zoa'ciuni. On the other hand, if two adjoining zoa'cia are placed in a diflerent relation to one another, the distribution of the rosetle-plates and the oj)enings will also change. Even in those colonies where the (piincunx arrangement is most regular, we will sometimes he ahle to find j)laces where more or fewer zoa'cia are arranged in a less regular way. If now two adjoining zoa'cia, for instance in Fhtxlra foliacea, are so placed in relation to one another that the one i)rojects beyond the other by a quarter of its length, this ([uarter will he provided with a rosette-plate, while the other part of the lateral wall has nothing hut 0])enings, which correspond \\\[b the same number of plates in tlie adjoining zocrcium. The law ought really to be expressed. in this way, that the part of the lateral wall of a zoo'cium, which extends beyond the distal wall of the adjoining zocecium, is furnished with rosette-plates, while the portion be- hind has openings. While most Cheilostoumla are arranged in more or less regular quincunx, there are on the other hand species in which this arrangement can only be seen here and there, while the zoa'cia are principally arranged in more or less regular transverse lines. This is for instance the case in Sinilliun (Schizoporella) linearis, and most of the zooecia here will have either only rosette- plates or only openings on the side-walls. There is also a strong inclination to such an arrangement in Memhranipora nionostachys, and it is not unusual that a whole row of connected lateral walls have either only rosette-plates or only openings. Electra pilosd forms a peculiar exception from the common rule, and very likely this is also the case with the other Electra species. Although as a rule we have the true quincunx arrangement in tliis species, yet in a whole row of zoa-cia on the same side we either find only rosette-plates or only openings. This difference is how- ever accompanied l)y another, as the lateral walls which bear the rosette-plates are always much thicker and more strongly calcified than those with openings, and the last are very thin and after boiling in alkali often partly destroyed. We can now and then find a whole row of zocecia, the lateral walls in which are thick and furnished with rosette-plates, but then both the corresponding rows of adjoining walls are thin and have openings. We have up to the present only discussed the appearance of the rosette-plates on the vertical walls, but they may appear on the basal wall (posterior wall) as well as on the frontal surface, and in tlie first case both in two-laj'ered and in one-layered colonies. Thus, in two-layered colonies, I have found tluni in SiuHtiim palinaia (PI. XIX, fig. 5 ))), Porella saccata Por. coinpressa, I'hdUujtopo- rella lioiichu (PI. VI, fig. 7 i), Sle(janoporella magnilabris (PI. V, fig. 5 b), Diinorplio- zoiim nobile (PI. IV, fig. 1 c, 1 d), Micrupurella llabellaris (PI. XV, fig. 4 c) and Micr. 29 marginata (PI. XV, fig. 'A c). On Ihe otlier hand they are lacking for instance in Fliistra foliacea and Fl. seciirijions. They appear in the same way as the rosette- plates on the vertical walls, a rosettc-j)lale on a zooeciuni in the one layer corre- sponding with an opening in the opposite layer, but in none of the mentioned species are they found in all zofficia of a colony, though for the rest they ap- pear in very varying numbers. While they thus appear very scattered in Steg. magnilabris, they are found on by far the most zooecia of Microporella flabellaris and Mic. marginata, and in the last species the connection between the zooecia is as a rule a double one, every zocecium possessing a rosette-plate as well as an opening. Rosette-plates or pore-chambers may also appear on the basal wall of colonies with one layer. We thus find a number of uncalcified uniporous rosette-plates in liutliyiis obtecta (PI. XV, fig. 2 b) and E. chhitrata ' where tiiey might be con- sidered as uniting the interior of the zocecium with the space, which is bounded by the covering membrane, while a number of basal uniporous rosette-plates in Hiantopora radicifera (PI. IV, fig. 6 b) serve as origin for the radical fibres which fasten the colony to its support. In the family which I have called Petraliidae, the species of which mostly appear in free colonies with one layer, the free basal wall is cither furnished with rosette-plates or with pore-chambers from which radical fibres sometimes issue (e. g. in Petralia tuberosa Busk^ and P. dorsiporosa Busk"). We will now consider the appearance of the rosette-plates on the frontal sur- face. Busk' has already called attention to the fact that the species which he de- scribes as Carbasea Moseleyi, possesses a number of formations in the distal half of the zocecium, which quite correspond to rosette-plates, and these plates are also found in the distal part of the frontal wall in Onchoporella boiDbijcina (PI. XIII, fig. 9 a, 9 f), Onchopora Sinclairi (PI. XIII, fig. 7 a, 7 b), CalwelUa bicornis (PI. XIII, fig. 8 a) and Onch. deirtata (PI. XIII, fig. 6 b), all of which species I refer to the family Onchoporidae, and to this family ■Carbaxea^ Moseleyi and Iclithyariu oculata Busk ' also jjrobably belong. The rosette-philes in those species examined by me are furnished with a strongly developed pore-ring projecting into the interior of the zoa'cium and are either round, uniporous or longitudinal, narrow and as if formed by a fusion together of from two to four uniporous plates placed in one row. To judge from figs. 4 a and 4 b the roselte-jjlates seem also to be uniporous in -^ (la r based" Moseleyi, and the 8 — 10 small red spots, which Busk has found on the rosette-plates of the specimen stained with carmine, ' 19, I'l. .\VI, fig. 22; - 8, HI. .Wll, fig. 7 d, PI. XVIII, fig 4 b, '■' 8. p. :>1 : ' 8, p. 48. 30 might be leucocytes, which can often be loimd fixed to the inner surfai-e of many rosette-plates and which can easily l)e taken for pore-areas. Kiithijris ohtecta (P\. XV, fig. 2 a) and UrceoUpora nana Mac Gill. (PI. XV, fig. 1 a) are also furnished with rosette-plates, and the marginal |)ores, which ap[)ear in a single or ilouble row in numerous Cheilostomata, seem always to be rosette-plates, which are usually furnished with a single pore-area. We can for instance mention Escharella immersa, Escharoides coccinea, Porella strnma and Smittina palmata. These rosette-plates are always without a pore-ring and are (|uite membra- nous, for which reason they quite disapi)ear when boiled in alkali. Some- times in many species — for instance in the species of Celleporn and Holo- porelhi — they may come to lie at the bottom of shorter or longer canals, partly by the calcareous wall's growing in thickness, partly i)ecause the calci- fication takes place in such a way that the canals leading to these rosette-plates pierce the calcareous wall under very pointed angles. Such long canals can for instance be found in Tessaradoma borealis and Escharella spinosissinm^, and espec- ially in the last species they are remarkable for their considerable length, so that even some of them may reach from the marginal portion almost right in to the middle line of the frontal wall. In other species these marginal pores are enclosed or overbuilt by small calcareous spaces which are furnished with a larger or smaller opening and which we may compare with the above-mentioned pore-chambers. We may mention Sniittina reticulata, Sm. palmata (PI. XIX, fig. 5 a), Escharella variolosa, Discopora verrucosa and Disc, pavonella as examj)les of species which possess such well-developed marginal cavities or areola'. The three or four- sided areolae are outwardly limited by a projecting line, which is simply a contin- uation of the lateral wall of the zocecium, and are separated from one another by a number of transverse buttresses, which grow in length with age and in older zoa^cia even touch one another in the middle of the zoa>ciuni. Two ad- joining lateral ridges will, as is the case with the lateral walls from which they spring, after boiling in alkali solution separate from one another, and if we look at such a separated row of zoo^cia from the side we see these lateral spaces through the wall as light canals, which on superficial observation would seem to belong to the lateral walls. Still we must remember that the rosette-plates which lie at the bottom of these spaces are really placed on the frontal wall. It is not in all cases however that the superficial pore-chambers are externally hounded by such a projecting ridge; this is not the case e. g. in Escharoides Jacksoni, in which species these spaces are short, sac-like with an aperture facing ' 34. PI. III. fig. 3. 31 towards the cenlre of the zod'cium. [ii JhiswvUin (iiistraliensis and Hasiv. coronata the frontal wall is furnished with muiuMoiis pore-canals, each ending inwardly in a uniporous roselte-plate and as the rosette-plates helonging to the marginal pore-canals have their place in the outer pari of the lateral walls, these rosette- plates thus form a connecting link hetween the common lateral rosette-plates and those belonging to the frontal wall. In species of the genus Myriozoum the whole of the frontal wall is furnished with closely placed, posteriorly directed sac-like pore- canals, each ending in a uniporous rosetle-plate (PI. XIX, lig. Hi a). In each canal is a chord of mesenchymatous tissue, which has a club-shaped widening towards the ro- sette-plate. In Srlerodoinns denticiilatux (PI. XIX, fig. 18 a, 18 b) the frontal wall of the zoo'cium is furnished with minieious curved, sac-like and widened pore-canals, which contain a similar chord of mesenchymatous tissue. Finallj', I may mention that in all the species which have marginal pores and at the same time a median avicularium proximally to the aperture, the avicularium stands in connection with the llrst or sometimes also with the second pair of superficial rosette-plates, respec- tively through two or four shorter or longer canals, which issue from the distal part of the avicularian chambers. This is the case for instance with most species of the genus Porella. AH other so-called pores in the Cheilostonmta are, as Per gens has already remarked, not real pores, and when this writer' states »ces petits pores sont, en realite, des cavites intersqueletliques occupees par du tissu epidermiijue, en con- nection avec ies parties scjuelettiques et avec le parenchyme«, this so far agrees with my observations, as I have always found the bottom of these pores closed by a membrane, which adheres directly to the calcareous skeleton and may with age be calcified to a more or less extent. In some of the species, for instance in 'Lepralid' Pallasiana, a larger or smaller number of these pores may eventually become closed, and in Siniltina jmrifera they may assume a very dilTerent appea- rance according to the different manner in which calcification proceeds. This membranous area in Microporina horealis is divided into a number of small areas by radiating calcareous ridges. The difference between such a j)ore and a rosette- plate is therefore only, that the latter is furnished with one or more very fine perforations, which are absent in the former. The pores as well as the marginal rosette-plates may as time goes on become surrounded by small chambers, and for instance in Sinittiim povifera and ■ Lepralia« Pullasinna a meshwork of ridges is formed over the whole surface. Regarding the pores of the ooecia, I need only remark that they are similar to those of the zoo^cia. ' 93, p. 308. 32 The Compensation-Sac. The compensation-sac was first noticed by Jul lien', hut llie descrip- tion which tliis writer f^ives of this iniporlaul organ is not very detailed, and this might be one of the reasons why Jul lien's discovery has either been quite overlooked or received with distrust by all later writers, until Harmer- redis- covered this organ and gave a fuller account of it. While I do not agree with Harmer in his view of the structure and development of the compensation-sac in Discopora verrucosa and the forms grouped with this species, my investigations agree otherwise with the general view he gives of this organ. It is a large thin- walled sac, which in the Cheilostomata provided with an arched calcified frontal wall (Ascophora mihi) lies immediately under this in the whole or the largest part of its extent and oj)ens outwards either immediately jjroximally to the o])erculum, or occasionally further back, through an unpaired median opening, an ascopore« (Micro- porella, Inversiiila, Tiihucellarid, Onchoporella, Haplopoma, Adeona). Its inner wall, which is attached distally to the proximal edge of the operculum, is on each side furnished with a row of muscular bundles, which in arrangement, grouping and attachment to the inner surface of the calcified lateral walls, correspond perfectly with the parietal muscles in the Malacostega, and there is no doubt that they have the same signification as the.se, because their contraction will extend the sac, thus causing it to be filled with water through its external opening with the final result that the polypide is extended. The observations made with regard to the first l)eginnings of this sac scarcely leave any doubt, that as a rule it is formed as an invagination of the original membranous frontal wall of the zooecium, whether the wall later on retains its membranous condition as in all groups furnished with a cryptocyst, or later becomes calcified as in Hippotlioulde and Cdleiutriklitc. The first trace generally appears rather late, either distally to the operculum or to the median pore, and from there it gradually .spreads over the rest of the frontal wall. A somewhat ditfex-ent mode of formation is found however in Disco- pora verrucosa and related forms. While Harmer"' looks upou the compensation- sac as a true sac provided both with an inner and an outer membranous wall in all other forms examined by him, he has quite a different view of the corre- sponding formation in the above-mentioned forms. He states namely, that in these the membranous frontal wall provided with parietal muscles, which is seen on the (piilc young zoo'cia, later becomes covered by a fold, springing from the proximal and lateral margins, the inner lamella of which is calcareous and the superficial layer membranous, and the compensation-sac formed by Ibis ' 45 a. p. 67—68; ' 18 and 19: ' lit, p. 293—297. ;53 process possesses only an inner, membranons wall. Ihe outer being calcareous. According to my investigations the fold wbicb gradually covers the original membranous frontal wall is an evagination of this wall itself and therefore con- sists of two nienibranous layers, an inner which together with the primary frontal membrane forms ■ the compensation-sac and an outer which forms the frontal membrane of the adult zooecium. The calcareous layer seen within the covering membrane in the proximal part of the zoai-cium, is a cryptocyst which grows into the cavity of the fold but only reaches its tip in the adult zoa^cia, and therefore in all not quite developed zooecia we see a curved or angularly bent line marking the free edge of this calcareous layer (PI. XIX, lig. 2 a) proxi- mally to the growing edge of the fold. To make certain I have examined a number of longitudinal sections made with the aid of the microtome of L'nibonuld pavonella (PI. XIX, fig. 2 b), in which the compensation-sac seems to show the same conditions as are found in U. verrucosa. The reason why I preferred the former species is only that our Museum's spirit-material of this species is of somewhat more recent dale. Though the sections examined are not good, they are sufficient to establish the correctness of my view. While all the membranous or cellular portions are strongly stained and easily recognizable, which for example ajjplies to the frontal membrane and the compensation-sac, all the calcareous walls appear as faintly stained, verj' fine lines. The ascending distal walls are more or less broken or folded in most of the sections, and this is also the case with the cryptocyst (cr) lying in the interior of the frontal evagination. Sections of younger zooecia are only different in that the evagination is shorter. Harmer has already drawn attention to the fact, that the above-mentioned 'Miicronellu< pavonella must be referred to the same genus as Ihnbomila verrucosa (Discopora), and to the same genus I must also refer the species of v. Lorenlz's' genus Ramphostomella. In all the.se species the primary frontal membrane forms an evagination which encloses the cryptocyst and in young zocecia of a certain development we see the free edge of this cryptocyst proximally to the free edge of the evagination (PI. XIX, fig. 19 a). Vestibulum. Within the recent Bryozoa, as is known, an operculum only appears in the Cheilostomata, which in other respects are distiuguislu-d from the Ctenoslomala ' 58, p. 34 by being more or less calcified as well as by having avicularia and ooecia. The possession of an operculum has been rightly regarded as the most important of the characters mentioned here, and it is Iherelbre so much tlie more of interest that ^^'aters' has shown that an operculum is lacking in the nutritive individuals of the genus Buyiila. Nevertheless, that the species of this genus must certainly be regarded as Cheilostomota is evident, not only from the fact that they ])oss('ss the other Cheilostome characters and are very closely related to the Bkelluria and other genera with an operculum, but also from the fact that they all have avicu- laria, ■which always have an operculum. Nitsche^ has pointed out, and other writers confirmed, that the tentacular sheath from the proximal part of the zooecium whence the polypide originates, grows forward as a solid chord, which is fastened to the inner frontal surface of the zooecium in its distal part. Later, this chord obtains an inner cavity, whicli opens outwardly through a slit in the frontal wall of the zooecium, and it is evident from this that the difference be- tween the structure and development of the aperture in the CheilostonuiUt and CJeno- stomata is conditioned by the difi'erent ways in which this chord-shaped formation is fastened to the inner surface of the zooecium. In the Cheilostomata this attach- ment lakes place in a semi-circular line and this results in the formation of a semi-circular opercular valve. As is known'', we can distinguish in the tentacular sheath between two difi'erent regions: the true tentacular sheath, which in the retracted condition of the polypide encloses the tentacles, and a distal region, the vcslihulum, which can be shut off from the true tentacular sheath by a mus- cular segment, the diaphragm, and as we shall see later the vestibulum may even in certain cases have another closing-apparatus j)laced distally to the diaphragm. As I have nowhere found in the literature a satisfactory account of the way in which the vestibulum is connected with the operculum as well as with the aper- ture of the zooecium, I will try to give such here. If we imagine a zooecium with the operculum (|uite open, but with the [lolypide drawn in, we can distinguish in the vcstibuliun between an inner or zocecial, and an outer or opercular portion, of which the lirst is fastened to the edge of the aperture, and the latter to or a little within the edge of the operculum. liesides the two portions mentioned we also have on each side a triangular lateral portion (PI. XIII, fig. 7 a) which con- nects the zocecial and the opercular portions with each other, and which is folded into the vestibulum when the operculum is closed. The comparison between the vestibulum and a valved purse, the two metal guards of which might respectively correspond with the rim of the aperture and the rim of the operculum, which is '111, p. 12; ' 8U, p. JJf— >S; ^ 19, p. 272. 35 used by several writers, is therefore not quite correct, and it would be far more correct to compare it with a division in a modern purse, in which the lateral walls when the purse is closed are folded into this. To explain the formation of such a vestibulum a simple horizontal dividing of the flat vestibular rudiment is not sufficient, as this would only lead to the formation of the zocecial and the opercular walls. To explain the formation of the two free lateral walls it must, I think, be necessary to suppose that an invagination on each side has taken place togetlier with the division of the chord-shaped rudiment. The distal part of the vestibulum presents a number of dilferences, partly in the way in which it is fastened to the operculum, partly in its structure and nature, and we may here shortly mention some of the differences, the closer study of which however will recpiire fresh investigation-material. While its frontal wall in a number of forms is fixed directly to the free edge of the operculum, as in most Fliistra species, Membrduipora meinbranacea, Electra pilosa, Geinellaria loricata, Micropoiiim boredlis, Sciiticella platjiosloma, Retepora Beaniaiui, etc., in a number of other species it is fixed at a shorter or longer distance within the edge, in such a way that we must conclude that the frontal and liasal walls have moved from each other after the division of the vestibular rudiment. For instance we find this the case in Fliistra abiisskoht, 11. carbasea, in numerous members of the family Membraniporidae {Callopora mirita, Tctjelbt unicornis, Memb. arctica etc.), in the family Scriipuci'lldriidae, in the genera Stajdnopurella, BicdUiria and Discopora, in 'Lepraliu' Palhisiana, Tiibiicellaria opunliuides etc. In most of the Cheilosloinata, and as it seems in all Anaska as well as in numerous Ascophorn, the part of the frontal wall of the vestibulum, which adjoins the operculum, is more or less chitinized, whether this connection takes place in or within the edge of the oper- culum, and when such an operculum is isolated the chitinized portion of the vestibulum adheres to it as an arched chitinous ridge (the -opercular arch< ) rising from its inner surface, which is lowest at its distal, central [>art, but which gener- rally on each side ends in a more or less triangular »flange<=, which is a part of the above-mentioned lateral wall of the vestibulum and which goes directly over into the membranous part of this. If we compare opcrcula of the youngest and the oldest zooecia in a colony, we sometimes (e. g. in Microporina borealis) find that the opercular arch is higher on the latter, and now and then this opercular arch shows distinct lines of growth. There is a cavity between the operculum and the frontal part of the veslibulum, the opercular cavity, and into this extend the occlusor muscles of the operculum, which in the forms with a well-developed opercular arch are generally fastened to this; if not, the oi)ercular muscles are attached to the inner surface of the operculum itself. 3* 36 Just as the part of the frontal wall of the vestibiiliim, which is connected with the operculum, may he chitinized, this may also he the case with a larger or smaller part of the inner wall of the vestihulum, as e. g. in Euthyris clathrata described by Harmer', in which species this writer has described a vestibular sphincter apparatus, similar to that which Hi neks'- formerly noticed in Eiirysto- melhi hihihiatd. In E. clalhrala^ the somewhat chitinized inner part of the vesti- hulum (irsl bends inwards and downwards into the zod'cium and then again bends forwards and upwards in a semicircular fold, the chitinized part of which (labium) in the closed condition of the vestihulum, (its closely to the above- mentioned opercular arch, which in this way forms an under lip, while the labium forms the upper lip. Also in Euthyris ubiecia according to Harmer's investigations there is a delicate labium. Hincks was the first to find a two-lipped vestihulum in "Lcpraliu" bilabiala, and as I have been able by the great kindness of Professor Whi leaves to examine Hincks' original specimen, I can confirm that the sphincter-ap[)aratus like that in E. clathrata consists of an upper lip (labium), formed by the inner j)ortion of the vestihulum, and an under lip, formed by the opercular arch, which Hincks calls »a semicircular chili- nous rim, as it were soldered to the inner surface of the operculums. I have found a quite similar two-lipped vestihulum in the closely connected species Li'pralia' foraminUjerd, while I have found a vestibular two-lipped Sphincter- apparatus of an essentially diilerent structure in the genus Sleyanoporella. It is placed at the proximal part of the operculum, and consists of two (juite similar semicircular lips slightly chitinized at the free margin, both of which are folds of the vestihulum and have no connection with the opercular arch. From the zooecial aperture's distal rim or anter in quite a number of forms there sj)rings a more or less developed, calcified portion reaching into the zocecium, in most cases in the form of a low, arch-shaped calcareous ridge, which seems to have originated from a partial calcification of the inner or basal portion of the ves- tihulum. Such a structure, which we may call a »\estibular arch«, is found in the family Reteporulae (PI. XXill, figs. 4 a — c), where it is as a rule crenulated, in Macro- pora centralis Mac Gill. (PI. VII, fig. 1 a), in most species of the genus Microporella (PI. XV), and in the genera Escharina (PI. XVIII), Escharella (PI. XVII) and Eschuroides (PI. XVII, figs. 5 b, c). It reaches its highest development in the two last-menlioned genera, and it is shown plainly in a number of figures in Busk's Crag Polyzoa '. The species which shows the highest degree of development of this portion is Escharella iliaphana Mac Gill. (PI. XVII, figs. 1 c, 1 ri), and it is here in llie same ' 19, p. -HMS: 5 .il p. >S^ ' 7, I'l. VI, ligs. 4. 8; I'l. VII, litJs. 1, ;t etc. 37 manner as the above-mentioned chilinous region in Eiilhyris cUithiuUd bent strongly basally and afterwards again frontally so that it forms a hood-shaped cavilv with a frontal concavity. This vestibular arch, which arises from Ihe distal rim of the primary aperture must not be confounded with the arch-shaped cryplocyst-ridge, which in a number of species of the genera Stetjanoporella (PI. V, ligs. 5 a, G a, 3 a) and Thalamoporella is placed between the basal (horizontal), and the frontal (obliquely ascending) portion of the distal wall. Waters' who was the first to speak about it calls it an oral shelf. It was later mentioned by Harmer^'. The operculum. In lis simplest form the operculum is a semicircular membranous valve, which passes evenly over into the frontal membrane and is only cbifinous where it meets with the opercular arch. We might give a line running belween the two corners of the opercular valve as a border towards the frontal membrane, and round this line, the hinge-line, the valve turns during the folding in and out of the polypide. Such an opercular form can be found in most of the Malacostega, in a number of Coilostef/a, as also in not a few members of the division Ascophora. In contrast to the oj)ercular form just described, in other forms we meet with an opercular valve which is separated in different ways from the frontal mem- brane, and in the simplest cases by its proximal rim being furnished wilh a chitinized thickening (basal sclerite, Harmer), which on each side is connected with the chitinous opercular arch. Besides in Clilidonia Cordieri and most Stega- noporella species (PI. V, fig. 3 c) such an operculum is found in a number of species of the genus Thalamoporella, e. g. in Th. e.vp(iiis(t (Pi. VI b, fig 5 b), Th. iimmillaris, Th. Jervoisii (PL Via, fig. 4 c), etc., while in other Thalumoporellu forms the operculum is only partially separated from the frontal membrane by means of a shorter or longer basal sclerite on each side (see PI. VI b, lig. 6 a). The opercular valve can also be seen either entirely chitinized or calcified, and I have already mentioned earlier the few recent species which possess a calcified opercular valve. Within the group Malacostega I have found a completely chiti- nized operculum both in some, not yet described Oiujchocetla-spcvies (PI. XXII, rig.;U)) and in some members of the family Scrupocellariidae, namely in Caberca Uoryi and Cab. Darwini Busk and in a new Scrnpocellaria species. In these three species the operculum is enclosed by a comi)lelely calcified rim, the proximal jiarl being bounded sometimes by two projections from tlie calcified lateial parts of the zocecium (C. Darwini), sometimes also by the here higlily developed plate-like • 107 a, p. .'•.1; " 17, p. 227. 38 spine, which as is known appeal's in very different degrees of development in a number of members of this family. As a similar enclosure of the operculum is also found in Menipea liausd Busk ', Men. Je/freysi Norman - and Scnipocellaria mar- supiata Jull.^, it seems i)robable that the operculum in these species has a similar structure. Besides in the species just mentioned, we find an independent opercular valve in the Coilostegous genera Micrnpora and CeUiilarut, and in the genera of the division Ascophora: Microporellu, IiuxTsiiila, Onchopora, Vrceoliporu, Clwrizopora, Haplopoma, Adennellopsis and Tubncellarin. While we may briefly call such an operculum as appears in most of the Malacostei/d an opercular valve, I would propose the designation »simple o])erculum« for any opercular valve, which is distinctly marked off from the frontal, membrane, and can consecjuently be isolated as an independent formation. While the proximal edge of such an oi)erculum forms as a rule a straight line it is more or less concave in a number of sj)ecies of the genera Celliilaria and Tlutldinoporella, so that the hinge-line falls a little proxi- mally to the edge, and in such cases the sim])le operculum does not fill the whole zoa^cial aperture, the proximal part of which is filled by a membrane. Within the division Ascophora the same thing appears in a new form from Singa- pore belonging to the family Petraliiilae. Jul lien' has founded a genus: Clui- perio, the species of which were formerly referred jiartly to Membrnnipora, and partly to Monoporelhi, and Waters'' says regarding this genus: This group was indicated by Jullien under the name of Chaperia, but while he based it upon two lateral plates, which I have shown are for the attachment of the oj)ercular muscles, and do not occur in all species, the important character is the form of the operculum, which is separable, and which has at each side an elongate pro- tuberance for the attachment of the muscles. « hi oi)j)Osition to Waters I would maintain that the most important generic character is the two plates mentioned, which I have found in all sjiecies I have examined, whereas the operculum according to my investigations is subject to a fairly considerable variation. As Waters refers both Meiiib. (j(ih-ala and Menib. crislata to Cli. cium at its j)roximal portion. An operculum like that here mentioned we may call a compound operculums understanding therewith an oper- cular formation in which the opercular valve is fused together with an adjoining portion of the original membranous cover to form a single, more or less strongly chitinized plate, in which we can distinguish between the valvidar portion and 40 the accessory portion. Within the division Anaska such a compound opercuhim appears not only in the mentioned Chaperia species hut also in Megapora ringens and Foveolaria eUiptica (PI. VII} fig. 7 h), hut in these two species with the peculiar modification, that the valvular portion and the accessory portion are here con- nected by a low linear belt of thinner material in their whole breadth. Besides in the members mentioned of the division Anaska a compound operculum appears in most members of the division Ascophora, and it may here be charac- terized as a double operculum, as it really has a double function. While the accessory portion of the operculum, which is placed proximally to the hinge-line in Ihe Anaska forms mentioned, is connected with the covering membrane of the zoo'cium, it is continuous with the basal or inner wall of the comjjensation-sac in the Ascophora, while the frontal wall of this sac is connected with either the distal rim of the covering membrane (in the forms which possess a Cryptocyst), or (where such is lacking) with the distal rim of the calcified frontal wall (Hippo- thoidae and Catenariidae). This was already shown by Jul lien', who calls attention to the fact that the hinge-line of the operculum does not coincide with the proximal rim of the operculum, but lies more distally, while the opening which leads into the compensation-sac is placed immediately proximally to the operculum. When the valvular portion of such a compound operculum emerges from the zou'cium, the accessory portion will on the other hand go down into it and thus open the compensation-sac, to which it serves as operculum. In all such ca.ses where an operculum ends in a proximal convex rim or a rim furnished with a projecting median portion, as for instance in all the species referred to the genera Lepralia and Schizoporella, it is evident that we have to deal with a compound operculum, as a simple operculum must always end in a proximally straight or concave edge. On the other hand, the presence of such an edge does not exclude the possibility, that the operculum may be compound, and the only certain way to settle the question is to find the hinge-line of the operculum. An articulation similar to that which lakes place between the valvular portion of the operculum and the accessory portion in Megapora ringens and Foveolaria clliplica occurs within the division Ascophora in the genus Arthropoma, which includes the two species A. Cecili and A. circinata, because the small proximal process of the oper- culum is connected in a similar way with the valvular portion of the operculum. We have already under the compensation-sac discussed the well-known fact, that a series of forms have a median pore, placed at a greater or less distance from the zooecial aperture, which leads into the cavity of the zooecium. II has ' 45 a. 41 been proved for some of these forms Ihal the compensation-sac opens out through this pore and there is hardly any leason lo doul)l, that this applies to all. Most of them have a sini])le operculum, and a compound operculum is only found in species of tlie genera Onchoporclla and CalweUia (PI. XIII). Just as a sim{)le operculum may either be quite chitinized or only separated from the covering membrane by a basal sclerile, a compound operculum may also be formed in these two ways. While for instance we have a completely chitinized operculum in the genera Schizoporella, Eschariiui, Microporella, Myriozonni as also in certain Cluiperia species, the compound operculum in other forms is membra- nous or very slightly chitinized and only separated from the basal wall of the compensation-sac by a basal sclerite. This is the case for example with the oper- culum in Enriislnnielld fornminiriera, Hippopodina fegeensis, Cheihpora sincera, Smittina porifera, in numerous species of the genus Holoporella and in all mem- bers of the family Onchoporidae. In most species of the genera Escharella and Ksclmroides, in all species of the genus Discopora and in a number of species within the genera Smittina, Holoporella and Petralia the aperture is covered up by a membranous operculum, the distal part of which is formed by an oper- cular valve, while the proximal portion goes immediately over into the compen- sation-sac. The connection between the operculum and the zooecial aperture in the Cheilostomata may take place in two different ways, which in a few instances are used at the same time, namely partly by direct connection between the proximal edges of the aperture and of the operculum, and partly by a connec- tion of very slight extent which occurs at each end of the hinge-line. The first mode of connection is found in all the Anaska. and in those Ascophora in which the compensation-sac oj)ens out through a median pore separated from the aper- ture of the zooecium. The simultaneous occurrence of both modes of connection is found in a number of acanthostegous and coilostegous forms, for instance in FiLepralia-^ restita and Ptcrocella nlcita (PI. XXI, fig. 4 a) as examples of species with large and strong hinge-teeth while on the other hand tlic hinge-teeth are quite lacking e. g. in species of the genera Discoporci and Eschaioiiles. hi the forms which have no opercular arch at all, or in those with an imperfectly developed one, the connection lakes place either on the very margin of the operculum or within this, and the first of these cases we find in the genus Porella. hi P. struma for instance we find in each of the proximal corners an elongated thickening, which forms almost a right angle with the muscular ridge and which is in connection with the aperture. In Mijriuzoum Inincatiiin on the other hand the proximal part of the operculum is on the inner surface surrounded with a strong marginal thickening and in the distal part of this on each side is found a rather large oval pit into which a rounded hinge- tooth is immersed. The aperture, besides being furnished with hinge-teeth may have other protub- erances or teeth, and of these we may now mention some which from (heir position must be supposed to support the operculum, or to counteract an ex- ternal pressure on the latter. Such formations, which have their place either within the proximal or within the distal rim of the operculum, may appear sometimes in pairs, sometimes as a single, low plate, and are found in forms which have a simple operculum (Celhilaria, Microporella, Micropora), partly in forms, the aperture of which has a small but sharply marked sinus (Arthropoma, Escharimi. Schizopordla). In the Celhilaria species, where in a smaller number of cases they may be found both within the proximal and the distal rim, they most frequently appear as small, paired, rounded or conical teeth, which may occasionally be long, like canine teeth, as in C. rujida (PI. VIII, fig. 1 a), where they appear both proximally and distally. In a few species such a pair of teeth is replaced by an unpaired low plate, which is proximal in C. aiujiistilolnr , distal in C. CharlesworthiiK In the species of the genus Microporella (PI. XV), Nve gene- rally find in the whole breadth of the proximal margin a more or less devel- oped supporting beam, sometimes with two small conical teeth, and such is also found in Micropora centralis (PI. VII, fig. 1 a). To the same sort of foim- ations as those just mentioned we must probably also class the curved and pointed tooth, which is placed on each lateral rim of the aperture within the ' 19, PI. XVI, fig. 20-'21. ' X I'l- III, fig. 16^^ » 7, PI. X, lig. 4 a. 7fc 43 operculum in Pelrnlid pornsa, Pel. /'uZ/ur and in a new species from Singapore. These teeth, which without closer examination would be regarded as hinge-teeth, have really nothing to do with the suspension of the operculum, which takes place distally to them. While these teeth all have their place on the inside of the operculum we also on the outside find unpaired as well as paired ones. A median tooth is found as is known in numerous species within the genera Esclmrellu (PI. XVII), Escharoides (PI. XVII), Exocbella (PI. XVII), Smiltina (PI. XVIIl, fig. 12 a), Dis- copora etc. and its frequent presence in species which have a membranous or slightly chitinized operculum, shows that it must be regarded as a protective formation. Lateral teeth appear on the peristome in certain species of the genus Escharoides (PI. XVII), besides in the species of the genus Exochella (PI. XVII), and Jullien' considers these teeth in Ex. Umtjirosiris (PI. XVII, figs. 9a, 9c) to correspond with the hinge-teeth in Sinittind, although they can grow together with the median tooth. We have already called attention to the fact, that the occlusor muscles are most often fastened to the opercular arch, where such is in any way well-devel- oped, and they are then as a rule fastened to the apex of a more or less devel- oped triangular lateral portion, well-developed in Euthyris clathrata, but only slightly indicated in the low, but strongly chitinized opercular arch in the Steyanoporella species, which is often placed a good way within the free margin of the operculum. Where the opercular arch is wanting, or only slightly devel- oped the occlusor musics are as a rule fastened to the inner surface itself of the operculum, and we can here again distinguish between two cases, according as they are fastened to special ridge-shaped protuberances or to a pair of small, pit-like spots, which Waters has called >>muscular dots«. Such muscular dots can for instance be found in the genera Cellepora, Lekythopora, Avthroponvt. Con- escluirelliiui and Schizoporella (PI. XVIII, figs. 3 e, 4 c, d), while muscular ridges appear in the genera Porella, Eschdiina (PI. XVIII, fig. 2 c) and TubrndUirui. We must finally remark - upon the fact that the operculum in a number of Coilostegous forms consists of two layers, namely an external membrane, which forms a continuation of the covering membrane of the frontal wall, and an inter- nal chitinized or calcified layer, which we must regard as the operculum's crypto- cyst. Such an operculum with two layers is found, besides in the species of the genus Celhdaria, in Microporina borecdis, Micropord coriacea. M. Sormani n. sp. (PI. VIII, figs. 3 a, 3 b), M. perfondci, as also in a species described in this work which I have identified with Macrupora centralis Mac Gill. (PI. VII, figs. 1 a, 1 d). In the last ' 45, p. ,^5. 44 as well as in Micioponi Xoriwmi (PI. VIM, fig. 3 b) the deeper layer of the oper- culum is calcified and has quite the same appearance as the cryptocyst of the frontal wall. In a figure drawn by Calvel', representing a longitudinal section through Celliilaria fistnlosa, it is seen very plainly, that the two layers of the oper- culum meet in the distal and the proximal rim, l)ut that they are also separated by a space. Within the division Ascoplwra an operculum with two layers has hitherto only been found in the interesting species Eiithijris cldlhrctta Harmer. It consists of two chitinized layers which are fused together along the proximal rim of the accessory portion of the operculum and in a median part connected with this, but otherwise they are separated by a distinct space. We cannot leave this section without touching upon the terminology used for the description of the opening in the zoa-cium which is covered by the oper- culum and by the frontal membrane. While Johnston'- generally uses the word ♦aperture* not only for that portion of the zoo'cium which is covered by the frontal membrane in the Malocnstega, but also for the opening which is covered by the operculum in the Coiloslega and Ascopora, Busk' in his catalogue only uses this name for the zocecial opening in the Malacostega and the word »mouth« for the opening which is closed by the operculum in the Coilostega and Ascophora. Hi neks* consistently maintains a similar distinction, using however the word »orifice« instead of »mouth«, and he also indicates by this the opening covered by the opercular valve in the frontal membrane of the Malacostega. In his general review of the genus Membranipora he makes the following statement: >The terminology employed in describing the members of this genus requires a word of explanation. The area is the portion of the cell surrounded by the raised margins. The aperture is that part of it which is not closed by a calcareous wall; and on this is placed the true orifice — a semicircular opening, with a valvular operculum*. Apart from a few inconsistencies Busk follows Hincks' terminology in his work on the Bnjozoa of the 'Challenger* Expedition; while Waters in his numerous works describes the opening which is covered by the operculum as an »oral aperture*, or simply as »aperture«, and he also uses the latter for the zooecial opening in the Membranipora. Finally, Mac Gillivray'' in a work on the tertiary Bryozoa of Victoria has felt himself obliged to replace Hincks' term »orifice« with a new term »thyrostome«, concerning which he writes: »The nomenclature is thai in general use. The only innovation of any consequence I have made is the introduction of the term »thyrostome« (Ovga aiofia) for the ' 9, PI. VI, fig. 11. ■' 41 a. '2. ■• 22. ^ J< p. 2. 7fc 45 opening through which the tentacles and oral extremity of the polypide are protruded. The terms orifice, oral aperture and mouth are inaccurate and con- fusing and the proposed name will I think prove ad\antageous«. It is evident from the above morphological considerations on the operculum, that when we exclude the small number of species which are furnished with a simple operculum, we have in all other Cheilostomatous Brijozoa, on the frontal side of the zocecium, a larger or smaller opening (viz. an uncalcified portion) which is covered by an operculum in connection with a larger or smaller portion of the original frontal membrane. The relation between this portion and the opercular valve may be very different both in regard to the mutual size of the two portions and to their nature. In the Malacostega both are generally mem- branous and the opercular valve is as a rule many times smaller than the rest of the cover. We lind a comj)letely chitinized opercular valve however in a number of Onijchocelhi species (PI. XXII, fig. 3 b), as well as in a number of species of the family Scrupocellariidae, and in quite a number of Meinbranipora forms the suplementary cover is greatly reduced in extent. This is for instance the case in Callopoia luina.v, C. trifolium, certain varieties of C. Fleniincji, Kosscliaiui Rosseli and Membvaniporina artjentea Mac Gill. ', in the last of which it may be smaller than the opercular valve. In the Ascophora the suplementary cover, or as we before have called it the accessory portion, is frequently fused together with the oper- cular valve to a well chitinized, compound operculum, but in quite a number of forms (e. g. in Discopora species, certain l'^schidcs species, etc.) the structure of the operculum is not different from that we find in the Malacosleija, because the opercular valve as well as the suplementary cover is membranous. On the other hand we find in a smaller number of Malacoslega a well-chitinized, compound operculum, as in Cluiperia s])in()S(i, Cli. aipensis and Me<]upor(i rintjens, and 1 do not doubt that ^LepruUct^ Poissoni and Dorij/xtrella spathiilifera', both of which have a well-chitinized, compound operculum, must also be classed with the division Mdlctcoslec/a. For these reasons we propose to keep the term > aperture «. which Johnston uses, for the frontal zoreciai opening in all Cheilostonutta; for, even though it might be right to use a special term for the o[)ening covered by a simple operculum, two separate terms would i)e unpractical, as the forms provided with a simple operculum occur as a rule in families together with forms which have a compound operculum. It can always be settled, by examination of the form of the oper- culum and the aperture, the position of the hinge-teeth ami ol the corresponding ' 74. vol. T, PI. SI, fig. 2 - 84, p. lOfi. 46 parts of the operculum, which part of the aperture corresponds to the opercular valve, and if we require a special expression for this we may call this »the valvular aperture-. Polymorphism in the Bryozoa. As is known polymorphism also occurs in the ISriiozoa, but in contrast to the case in the Hydroid polyps it is not present in all species, even not in all genera or families. We can distinguish between four main forms of individuals (Bryozooids): Aiito:oa'cia (Auiozooids), which contain a polypidc, consisting of a tentacular apparatus and a well-developed digestive canal. Heterozowcia (Heterozooids), which have no intestinal canal, and at most have a trace of a polypide in a small cell-body, furnished with a circle of fine bristles. The chamber contains a strong muscular apparatus for moving the operculum, which sometimes only covers the aperture, in which case the Heterozooecium is called an Avicularium, and sometimes extends beyond this in the form of a whip, as in the so called vibraculum, but otherwise there is no sharp limit between these two forms of heterozooecia. Kennzoa'cia (Kenozooids), which not only have no polypide, but as a rule no aperture and always no operculum. While the Autozoo^cia might be regarded as alimentary individuals, the Heterozooecia as defence individuals, the Kenozoojcia must be regarded as supporting, fastening and connecting individuals. To this class of individuals belong: the segments which compose the thread-like basal parts in numerous CJenostomala, in the Cyclostome genus Crisia, and a smaller number of Cheilosionmtn (Hiiskia, Alijsidium etc.), the segments which form the upright stems in Slirparia, Ahjsidiiim and CIdidonia, and certain portions of the branches of the last, the radical fibres and the chambers for the insertion of the radical fibres in Scnipocellariidae, Caleiuiriidae etc., the peculiar lateral compartments in the Catenariidae, the modified marginal individuals, which appear for in- stance in Flustra securifrons and Fl. carbasea, the small chambers which form the encrusting base and the outer (ba.sal) layer of the Reteporn colonies, the peculiar cavities which appear among the zocecia in Membranipnra Lucroi.vi, Cribrilina Udimnryinata etc., the supporting tubes in the Cijclostonudd, as also the small chambers which surround the oa-cia in the family llippollwldae, in nuuiy species of the family Cateiutriitlae etc. (see under ooecia). As a fourth class of colonial individuals we may perhaps in many species regard the egg-producing individuals (Gonozmn-ia). While in numy cases, e. g. in Meiubniniponi meinbraiiuceu, all individuals in the colony seem able lo produce 47 eggs, this function in otiier forms is in charge of special individuals, which may often differ greatly from the ordinary zooecia (Adeonidae, Catenariidae, certain Hippothoa species), and which occasionally have no polypide (Hippothoa /iy«/i/ia). They are in most cases furnished with separate marsupial clianihers, the so- called oci'cia. I may now make some mainly comparative observations on the structure of the Heterozocrcia. It we look at the frontal surface of an avicuiarium, the oper- culum (or mandible) of which has been removed, we find that a greater or lesser part of this surface is occupied by an aperture covered by a membrane, within which there is often found a more or less developed cryptocyst. This part corre- sponds with the membranous area in the zooecia of a Meinhninipora, but while such an area in the zocrcia is only found in the division Mulacostega, it is found in the avicularian chamjjer in all Cbeilostoniatous Bnjozoa. We may further discern between two different parts of this area, a distal, the opercular area, which is covered by the operculum and a proximal, the subopercular area, and the border between the two areas is formed by the hinge-line, which coincides with the proximal edge of the operculum. This border is in all Ascopbora with the exception of the Adeonidae and of Leicschava criistacen also indicated by a calcareous cross-bar, arising from the prolongation and amalgamation of the two hinge-teeth, and besides in the genera Nellia, Finiilina, Arachnopnsia, Miciopura, Microporina and a few Meinbraniporina (e. g. in M. crassiinaryinfdd) species, in which such a cross-bar is also present, the two hinge-teeth are separated in all other Anaska. Waters has already called attention to this difference. The cryptocyst, which can be present both in the opercular and the sub- opercular area reaches its highest development in the heterozoa>cia of the genera Onychocelld ' and RluKjasostomii, the former of which is mainly and the latter exclusively represented by extinct species. The cryptocyst is here, as in certain fossil species, which for the present I refer to the genus Aspidostoma (PI. VI c, figs. 3 a, 4 a), extended over tbe greater part of the frontal wall of the chamber and is only provided with a small opening of varying shape, which is intersected by the hinge-line of the operculum and through which the muscles make their way out to the operculum or mandible. In the avicularia of Fliistra foliacea the cryptocyst extends over most of the subopercular area and something similar takes place in the avicularia in several Thalamoporella species (Fl. VI a). A well- developed cryptocyst is also found in the opercular area of the large avicularia in Flustnt (dujssicola as well as in that of the large lyriform or spoon-shaped .S(), PI. 07.'), ligs. 2, 15. 48 avicularia which occur in ThalamoporelUi lioticho (PI. VI), Thai, novae boUandiae (PI. VI a), Cribrilina fiyiilaris etc. On the other hand, a cryptocyst is quite lacking in the heterozooecia in the families liicellariulae, Scnipocellariidae, Catena- riidae etc. On account of the free movement recjuired by the operculum (mandible) of the heterozod'cia, this is always simple (pag. ;?S), and naturally ends in a straight proximal edge. While the basal and frontal wall of the vestibulum in an ordinary zooecium are connected by two free lateral walls, which on the closing of the operculum are folded, the latter are absent in a helerozooecium, and the vestibulum is consequently here developed in the shape of two separate laminje of which the basal takes up the opercular area, while the frontal, which proximally is joined to the basal, extends over the internal surface of the mandible. We saw above that in an ordinary zooecium the frontal wall of the vestibulum may sometimes be attached to the edge of the operculum, sometimes at a greater or smaller distance within this. This is also the case with the helerozoa»cium, only that the variation is still greater here. While for example the frontal lamina of the vestibulum is attached to the edge of the mandible itself in the small avicularia with a semicircular mandible, which is found in most species of Fhistra, Porella, etc., in the large avicularia of Flnstra abi/ssicola (PI. XIX, fig. 13 a) it is only attached to a triangular median belt, which decreases in breadth distally and does not reach right out to the tip of the mandible and the latter is thus provided with two wing-shaped latei-al parts. In the Onychocella species (PI. XXII, fig. 3d) the frontal lamina is only attached to the proximal part of the mandible over a small triangular area, and still further proximally the attach- ment takes place in the llagelliim of the real vibraculum. As the vestibulum in the heterozooecium as already stated consists of two separate laminae and does not, as in the zooecium, form a funnel-shaped tube, the frontal lamina^ comes into closer relation to the mandible, and for that reason the latter obtains the charac- ter of a two-layered plate, which between its two layers encloses a .space, the mandibular cavity (PI. XIX, 10 b, 13 a, 14 a, 15 a, 15 b), corresponding to the opercular cavity. While the mandible itself is always more or less strongly chitinized and as a rule provided with a rounded spot of thinner nature (the so called »lucida«), near its proximal portion the vestibular covering of the man- dible may sometimes be perfectly membranous, sometimes more or less strongly chitinized over a larger or smaller portion of its surface. It seems thus to be completely membranous in the large avicularia found in a number of Cellepora species, while we very often find in the small avicularia with a semicircular mandible, which so frequently appear in b'liislru, Purella and Cellepora, a dis- 49 tiiicHy chitinized marginal region, which consequently conesponils to llie previously mentioned opercular arch. There is also a distinct contrast between the marginal region and the median region of the vestibular layer in the above-mentioned avicularian mandibles of Fliistra (ihiissicohi and Onijchocella sp (PI. XXII, fig. 3 d), because the marginal portion, which forms the lateral walls in the mandibular cavity is strongly chitinized and shines through the surface of the mandible as two brown ribs converging towards the apex. In the elongated pointed mandibles of Fliislra denticiilata, Microporelht imirtjimita, Schizoporella lonyirostris and Scnti- cella iilagiostoiua the vestibular layer is chitinized over the greater part of the length of the mandible, although at the proximal part of the mandible it changes to a softer part, and a longitudinal section through such a mandible (PI. XIX, fig. 10 b) shows that the inner cavity towards the apex of the mandible dwindles to a very fine canal; this seems to suggest that the narrow solid tip is formed l)y a fusion of the two layers. It is not always, however, that such translucent lines arise from the vestibular layer, as many mandibles may be provided with two distally converging ridge-shaped thickenings which, like the ridges mentioned under the zocEcial operculum, are projections from the inner surface of the mandible itself. Such converging ridges are found in the mandibles in most species of Porella, in Discopora, etc. Time does not permit us to enter into further details liere regarding the muscles of the avicularia, and we may just recall that for the movement of the mandible there are abductors or openers, and adductors or closing muscles. While the lirst are always double, Ihe latter are sometimes single, sometimes double, and in many cases two separated muscles are attached to the mandible by a single tendon. More rarely we also find parietal muscles (Fliislnt species, Fscluiroiiles coccinea). Waters, as is known, has shown that the cavities provided with an elongated triinigular opening in the extinct Eleidae, which were formerly taken to be oircia, must in reality have been avicularia-like formations; they dill'er however from the cheilostomatous avicularia, in always lacking a membranous suboper- cular area. In a number of these species I have found a calcified mandible. Ooecia. Before giving a comparative account of the structure of the oa-cia, we may summarise what the literature and especially the older contains regarding these formations. The first writer where we have been able to find anything about the 4 50 ooecia, is John Ellis', who in his well-known work on the Corallines not only treats of the hydroid polyps, coral algae, varions Oclacliniae, sponges etc., hnt also of a number of Unjozoa. hi a number of species of the genera Buyiila, liicclUiria and Scriipocellaria he has noticed and figured the ooecia, which he terms « Malls, testaceous Spherules', or »testaceous Figures* '; but while he recognised, although in an imperfect way, the importance of the gonothecae for the reproduction of the hydroids polyps" (»I discovered that they were Matrices or Habitations of young Polyi)es, which are produced here and there, on the Sides of the Parent, as in the Freshwater Polype*), he does not seem to have reached to a similar comprehension of the ooecia. He only speaks in detail about the owcia of a tropi- cal Bmjula species, R. neritiiia ' and expresses here the very remarkable view that they are a sort of small snails, from the eggs of which the colony originates: »I plainlj' discovered it to be the connected Niduses or Matrices of certain testa- ceous Animals, like small snails or Neritae* . . . »()r let us suppose, that the testaceous Animal . . . lays its eggs; these turn into vermicular-shaped Polypes, whicli, after they have fixed themselves to some marine Substance, rise up, and push forth into branches of small Polypes in their Cells«. The oa'cia are thus figured on the accompanying drawings as small .S/j/ror/i/.s- or PUiiiorbis, and from this description Linne gave to this species the name »nerj7i/ia«. Ellis expresses elsewhere a supposition that a similar relation obtains between certain Bripzoa and Bivalves: »The next class, which is the Esclutra deserves our notice» . . . »There appears a great probability of some of these being the Matrices or ovaries of certain Species of Shellfish, perhaps of the Bivalve Kind^ On Flnstra (Eschara) foliacea he further writes"": »Upon examining some specimens lately, I discovered at the Entrance of many of the Cells a small testaceous 13o(ly, like a bivalve Shell «. As appears from the figure to which the writer refers, there is no oa'cium whatever but an oj)en zoa-cial aperture, in which consequently the orifice itself represents the one, the operculum the other sheU. Pallas'' suggests the view that the ooecia are ovaries, a view retained to the time of Huxley. It was however chiefly the oa>cia in the incrusting forms (»£sc/ior««), which he was disj)osed to regard in this way, whereas on the other hand he is more doubtful on the question, whether the free plant-like forms ('('.ellahirid ) are provided with such. In iilurimarum, presertim lapidescenlium Eschararnm anli(iuioribus cruslis passim, ad singiilarum cellularum oscula, ohser- vari solet bulla galeae instar cellulae ostio imminens, substantiae Escharae homo- ' I'J, p. ;!:)— .19. •- 12. Introtiiu-tidii p. IX. ' 12, p. 35. ' 12, liitioduclioii p. XV '■' 12, p. 71. pi. XXIX, K. "91, p. :»;. 51 genea & continua. Vascula sen Galericulae in Cellulariis staliin considerandae, subanalogae; has in Eseharis bullas ovaria forte esse suspicionem injiciuiit'. It is very intelligible that the free, prominent, somewhat stalked (xrcia in Ihujiila and Bicellarut would make a dilTerent impression on an observer than the od'cia in the incrusting forms. Also, Ihey appear sometimes (in liiiijiild nerUind and Bicellaria ciliata) not on the top of the zooeciiim but fixed to (he one side. In that case they correspond in their position as well as in their equipment with a stalk-like portion with the ^bird's head« avicularia in Bugiila and Bicelliiriu, and Pallas considers them therefore as organs of related nature. His above-quoted view, in which he terms these ditferent stalked formations as organs somewhat related (subanalogae) to the otrcia in Escluira is further explained in another place', where he suggests that they are of service in fertilisation (seminilicationi). On account of the resemblance to the gonothecae in the hydroid polyps he is disposed to consider the gonozooecia in Crisia as ovaries'. Ovariorum qvae in Sertulariis videbimus similes vesiculas in sola C. (Crisia) eburnea & falcata obser- vatores invenerunt. An aliis qvo(}ve speciebus contigerint incertum. Reperti vero in C. neritina & avicularia Galericuli sen Calyculi singulares, in recenti stirpe spontaneo motu priediti, singulisque cellulis adpositi, qvorum certus usus hucus- qve nos latet, seminilicationi in his speciebus destinata organa fortassis esse repe- rienlur«. It is evident from what he says further: ^Lateralis inspectio .. . docet, bullulas istas esse galericulis s. neclariis caput aviculae referentibus, in G. avi- cularia, analoga organa'"', that he considers the ooecia in BiujnUt neritina as or- gans of a similar nature as the 'bird's head« avicularia. This view, that the ooecia and the avicularia are related formations we tind again in several later writers, and with regard to the designation »Nectarium which Pallas often uses for the .stalked otecia and avicularia, we find an explanation in Ellis and Solander's work. In this work, published by Ellis' daughter after the death of the writers', it is said regarding Flnstra: The ovaries appear to be the pearl-like studs, which we find at the tops of the cellss and regarding >(>//(/;•;>(.: »lhe ovaries are uncertain, but most probably the little hemispherical covers, thai appear over the cells, do that officer. Ellis returns here again to the od-cia in /)'»(). ■■ ill. p. i;s. •' i:i, pp- 11. 10— 20, •-'ii. 52 ones of .such ;i small kind of slicll-lish. Hut l>y c-ouipaiing tluMii willi liic figures of others of this genus, they appear rather to he what we have called Ovaries. Or pcvhaps they arc young of the animal dclcnded by a testaceous covering like a little shcU-lish, which at tiic time of its maturity separates from its umbilical cord IVom whence it drops and soon adheres to a pro])er substance as a base, beginning to form a Coralline like the parent animal.- There is discussed here also another peculiar view regarding the oa'cia and the avicularia, both having been considered as nectaries: »A later writer, who is a strong advocate for the vegetation of Zoophytes, supposes these little pearl-like figures as also those like the heads of birds in the Birds-head (Coralline (or OUaria avicularis) to be their Nectariums, analogous to what is so called in the flowers of some plants." Lamouroux' also mentions the oa-cia in li. neritiiui, and introduces us to several hypotheses regarding the functions of these formations. On les a con- siderees comme des opercules que le polype construit a voionte, soil pour se metlre a I'abri du choc des corps exterieurs, soil i)our liiverner, soit encore pour fermer sa demeure lorsqu'il a cessc de vivre. II est probable qu'aucune de ces hypotheses n'approche de la verite, et je pense que ce sent des ovaires renfermant les germes de nouveaux individus; j'ai observe (jue ces corps vesiculaires sont quekjue-fois tres-entiers, et dans ce cas je les ai toujours vus remplis de petits corps globuleux; il parait que ces ovaires s'ouvrent par une fente transversale; toutes les Ibis i|u'elle existe, les ovaires sont vides. Milne Edwards- considers tlie oa'cia in F.schdid as well as the avicularia on the zooecia as "vesicules gemnnferes«, or »capsules gemniiferes«. »Les obser- vations de Loefling et de i)lusieurs autres naluralistes nous out a|)|)ris cpie ces vesicules (ofpcia) sont des capsules gemmiferes, el par eonseepient nous sommes porte a croire (|uil doit en etre de meme ici, et que le tubercule pyrifornie, dont nous venous de decrire les divers etats (the avicularia in E. sulcata) doit etre considere comme elant un receijlacle conlenant les gemmules et servant a leui- livrer passage. Lamarck' also uses the name »vesicula' gemmilei;e , but just as oflcn the name ovaria for the oa^cia as well as for the gonothecie in the hydroid |)olyps. The same doubt, which Pallas had, as to whether the free, plant-like forms (Cellaria) possess such formations, is repeated here: '>Vesicula; gemmiferu' nulla', nisi bullic qv;e in nonnullis speciebus extant. lieid' studied living specimens of BiujiiUi (iniciildria with eggs in the oti'cia. ' .'I'j. p. l.-ili— 134; -■ 77, p. 48: ' .'.1. ji. 174: ' <).->. 53 Nevertheless we can only understand his view of the striichne ol' the od-iiiini, and of the relation of the eggs to it, after reading Nitsehe's later but fuller description of the oa'cium in BiceUaiia ciliaUt, which is built in a similar wav. Busk' introduces the name »ovicells«, which is still used by some writers, for the here discussed formations, but the older view of Ihem as capsules, con- taining the ovaries, was first altered by Huxley's": Note on the reproductory organs of the Cheilostome Polyzoa.« He pro])oses here the now prevailing view of the ocTcium as marsupial chambers, into which the eggs arc brought from the zon-cium to develop into larvaj. He found namely in Hiignla aniciihirid, that the egg is formed in the zoa^cium where it is attached to the funiculus near the stomach and also that the originally empty oa'cium at a certain time was seen to contain an egg, which was more developed than the one observed on the funi- culus, and which after cleavage became an embryo provided with cilia. Against Huxley's view Hincks' maintains, that the eggs from which the ciliated embryos are developed according to his investigations are formed in the oa-cia (ovicells) of a shapeless, grained mass. As to the eggs which Huxley found in the zooecia Hi neks states that they are most common in zoo^cia, the occcia of which have emptied their contents, and they can even be found in zou'cia, the polypide of which are dead, from which it must be concluded that they are only set free on the dissolution of the soft content of the zooccium. They are never ciliated at any stage of their development. The first detailed account of an otrcium is given by Nitsche*, who describes the development and structure of the ooecia in Bicellniia ciliata. He represents it as formed of two hollow, two-layered, bladder-shaped outgrowths from the margin of the zoa-cium; the smaller, which is membranous, is grown over by the larger, the outer wall of which is calcified, and which in the full-grown condition forms a helmet-shaped body connected by a short stalked portion with the zooecium. The membranous bladder serves as an operculum for the helmet-shaped portion, and its interior is penetrated by a muscular chord, by the contraction of which its rim withdraws from the edge of the oa'cium so that the larvie can get out. hi the above-meulioned work of Re id attention had already been called to the fact that this membranous operculum of the ooecia in Biigula ciniciihtrid. which contains larva\ undergoes rhythmical contractions (This membrane was observed in a few instances where the ova were fully formed to contract and relax at intervals, and in this way it may assist in the escape of the ovum«. Without knowing Huxley's observations Nitsche arrived at the same result with regard '3; ^ S9, » 37; ' 7i). 54 to the fuiH'lion of the ocecia. He has seen the formation of the egg in the zocecinm and while the ooecium originally was empty he found it at a certain lime containing an egg, without heing able to ascertain how it came there. He expresses the following supposition: »wahrscheinlich zwangt sich das Ei durch den hohlen Stiel der Ovicelle und tritt durch eine OefFnung, welche ich an der Stelle, wo die beiden Blasen zusanimenhangen, gelegcn vernuillie, in den Raum zwischen den beiden Blasen." Nitsche tries to explain Hincks' different view, that the eggs are formed by a granular mass in the ooecium in the following way, that the egg after its transference to the ooecium instead of developing further, sometimes dies away and dissolves into a shapeless mass. Finally, he states that the supposed eggs, wliich Hincks has observed in zocccia without polypide, are only peculiar bodies which liave arisen from a retrogressive metamorphosis of the polypide. In ^Contributions to the liistory of the Polyzoa«, where Hincks* introduces the new name »o(rcium«, he admits the correctness of Nitsche's assertion, fliat the supposed eggs, which he had discussed earlier, are really the so-called » brown bodiesits interior is in direct communication with the perigastric cavity«), but otherwise there is no further information on the structure of the ooecia. They are indicated as prominent*, "sul)immerse(l < and »immersed< {Fliistra, Cellaria), according as they are more or less prominent on the surface of the colonj' or hidden within this. Vigelius-' in his investigations on Fliistra inembrnnaceo-lnincala has given a description of the structure and develo]Hncnt of the on>cia in this species. While the oa'cium and its operculum in BicclUirid ciluita arise as two outpushings from the frontal wall of the zooecium, the ooecium in this species arises as an inva- gination from this wall, a short way dislally to the operculum and it thus conies to protrude into the zoa'cium as a hollow bladder, the interior part of which enters into connection with the distal wall of the zooecium, which is here formed in a peculiar way. It consists namely of a horizontal, under part, which oi'igi- nally reaches right to the frontal wail of the zoa'cium and of a distally and slightly basally inclined part, which grows together with the ooecial bladder. » 38; « 22; ' 105, p. 55 Laler the horizontal part of the distal wall and the rronlal wall of the zod'cium separate from one another. While the distal half of the oa^cial bladder calcifies, the proximal half continues to be membranous, and Vigelius thinks that the egg passes along from the interior of the zoa>cium upwards towards the otrcium between the distal wall and the frontal wall of the zooecium by which action it i)ushes the membranous part of the ocecial bladder in front of it; he thinks that this membranous part is later reabsorbed, which enables fertilisation of the egg to take place through the aperture of the oa>ciuni. The portion of the frontal wall of the zooecium, which is situated between the operculum and the free edge of the ooecium, acts as operculum for the ooecium. This operculum is provided with two muscular bundles, which reach from its free edge to the basal wall of the zoa^cium and which by their contraction are able to draw it inwards. The present writer" in three papers, the last of which is a preliminary note has given a series of investigations on the oa'cia and has shown there, that with the exception of oa-cia, which are covered by kenozooecia, the oa»cia have no such inner connection with the zooecium as Huxley, Nitsche, Hincks and other writers have supposed. In all other cases therefore the egg must pass into the ott'cium through the outer opening of this marsui)iuni. In the last paper the author has set up eight different types of oa'cia, two of which (the epistomial and the mesotoichal) in the present work are classed under the hyperstomial. In an important memoir chiefly dealing with the inner structure and with the embryology of the Cheilostomatous Bryozoa Calvet" has examined the ooecia of twenty one species belonging to the genera Biigula, Flustra, Membranipora, Micro- porella. Chorb.npora, Schiznporella. Lepralia, Uiubonula, Retepora and (k'Hepora. With the exception of ^Lepralid Pallasiana, in which he has found a membranous one- layered marsupium formed by a basal evagination of the vestibulum and of Cellarid fisliilosa he has found the oo-cium formed by two two-layered bladders, a superior more or less calcified and an inferior membranous one, the last of which is ])rovided with muscular strings destined for the opening of the ocecial cavity during the setting free of the larvae. He has not been able to find any coninuinication between the ooecium and the zocecial cavity and he therefore thinks that the egg, to get into the oa>cium, must perforate the membranous bladder. As to the ooecium of Cell, fistulosa he states that an opening exists in the wall between the oa>cium and the zoctcium. In a very interesting paper Harmer^ has set forth the supposition, thai the ooecia may be looked upon as formed by hollow spines and he founds this view 54, p. 253. 55, p. 25 and 56, p. 11 — 18; ' !l. p. ^ 19, p. -283—284. 56 especially on the structure and development of the ooecia in Aliisuliiiin jxirasili- ciim and Euthiiroides episcopalis. Before trying to give a division of the dilTerent forms of orrcia, I must ex[)res my regret, that the material at my disposal has not allowed me to give a fuller account of these formations, of which in many cases I have only been able to examine the calcified portions. I hoj)e, liowever, that my investigations will to a certain degree facilitate the work of the investigators who may be able to com- bine the desire to continue these studies witli favourable conditions of procuring suitable material. Endozooecial ooecia (PI. XXIV, figs. 6 — 11). We indicate by this name the ort'cia which are immersed in the zon^cia, gene- rally, however, in such a way that they appear more or less distinctly on the surface of these. Their main portion, the endoooecium, is formed by the zoffcium's distal wall, which in the free, frontal edge of the ooecium passes over into the much less developed ectooa'cium, together with which it forms a fold, the od'cial fold. In the majority of cases the distal wall has a short horizontal portion, provided with rosette-plates, which bends over into the helmet-shaped or cup-shaped ooecium, and it is only in species of the genus Retiflustra (PI. XXII, figs. 1), 2 a), that the basal rim of the distal wall lies higher than the free frontal edge of the ooecium. If we only pay attention to the calcified portions, we should think that these ooecia were in internal connection willi the proximal zoa'cium, but with the exception of those oojcia, which are covered by kenozooecia, there seems really always to be a mendiranous separaling-wall between the zoo'cium and the ott'cium. We can divide these oa'cia into lw(3 groups, according as the distal oi' the two chambers, which bound the oo'cium, is an ordinary zocecium (autozooecium), or a kenozoa'cium. Wc must also refer the oo'cia, which are enclosed in the avicularia, to this last-mentioned group. a) Endozooecial ooecia, which are enclosed in autozooecia. In the historical introduction we have referred to Vi gel ins' account of an oa^cium belonging to this type, namely, the ocrcium in Fliistra membranaceo- tnincald, and need only recall here that Ibis oo'cium, according to the description of that author, is formed by a bhulder-sliaped infolding of the IVontal membrane of the zoo'cium meeting the distal wall. As our Museum does not possess colonics of Ibis species with developing ooecia, but on llie other hand those of Fliistra seciirifrons, Ihe oa'cia of which have essentially the same structure, we may te.st the correctness of Vigelius' investigations by means of this species. The 57 ooecium in Flustid seciirijruns (PI. 1, figs. 5 ;i, h, c, PI. XIX, figs. 8 b — 8 n) whose inner pari may be loolved upon as a transformed distal wall, is a helmet-shaped calcified bladder, the basal portion of which issues from the short and horizontal |)ortion of the distal wall at a pointed angle, while its free, frontal edge passes immediately over into the frontal membrane of the zoa'cium, together with which it forms a fold, the od'cial fold. We may indicate the calcified bladder as the endoott'cium, while an ectooo^cium is only represented by the portion of the frontal 'membrane, which covers the distal pari of the endooo^cium. Between the operculuiu of the zoa'cium and the free rim of the ooecium we see a membranous portion chitinized at the distal edge (Pi. I, fig. 5 b), the ooecial operculum, which is connected with another membranous region, the ou'cial membrane (PI. 1, fig. 5 a. Pi. XIX, fig. 8j), which issues from the basal wall of the endooa-cium and forms a complete separaling-wall across the oa-cium. While this was originally situated close to the roof of the oa-cium, in an egg-bearing oa'cium it inclines the opposite way, so that it forms the fioor of the ooecial chamber (PI. 1, fig. 5 a, fig. 2 a). In the angle between the owcial operculum and the ooecial membrane is attached a muscular chord which originates from the basal wall of the zooecium, and when it contracts, the oa-cial operculum is drawn inwards and thereby permits the larva to escape. Finally, it may be mentioned that from the lateral walls of the zoa'cium issue two flat, sloping calcareous ribs which as a rule meet in a suture distally to the zoa-cial operculum (PI. 1, fig. 5 a, 5 b, 5 c, dw.). The very earliest trace of an ooecium to be seen in Flustra seciirifrons from the surface of the colony, is a slightly inclined curved line, which at a distance from the operculum nearly equal to its height unites the two lateral borders of the zocecium and rises from the attachment of the distal wall to the inner sur- face of the frontal wall of the zoa'cium. PI. XIX, fig. 8 b shows a longitudinal section through an early stage of an oa-cium, which is a little older than thai just mentioned and shows a distal wall, Ibe basal portion of which is horizontal, while the rest rises distally forming an angular arch and joins the frontal wall, which slill forms a straight line at this place. On the other baud, lig. 8 c shows a small indentation proximally to the frontal end of the distal wall, and this indentation increases in length or depth in the following figures 8 d, 8 e and 8 f, the last of which represents a longitudinal section through a completed ooecium. While it is quite easy to understand that Vigelius, who examined longitudinal sections of decalcified colonies, considered the indentation mentioned to have risen by an invagination of the frontal membrane, it is cjuite evident from the longi- tudinal sections (8 b — 8 f) given here that the endoooecium is only formed by a continued growth of the distal wall, which however at the same time undergoes 58 a strong llexioii and alleralion in shape. Thus, wliili' Ihe angle between llie liori- zontal and vertical portions of tlie distal wall in fig. 8 b is right, and in lig. 8 c obtuse, it gradually becomes more and more acute on account oC the endooo'cium bending backw^ards towards the basal wall of the zoa^cium, without doubt be- cause of the counter pressure brought about by the growth-tension. While the portion between the horizontal part ol' the dislal wall and the jjoinl of the indentation has nearly the same length in the examined longitudinal sections, the indentation on the contrary increases in length, and lastly the oa-cial fold grows down over the oa-cial membrane, which not long before occupied most of the frontal wall of the deveio|)ing oojcium. At the same time as the developing orrcium is undergoing these ailerations in shape, the whole zoa'cium increases considerably in size, and the horizontal part of the distal wall in length. As already mentioned in the above reference to Vi gel ins" investigations, he believes that the ocrcial membrane dissolves later, so that the egg from Ihe zon^^ cium can reach into the oo^cium, but this view clearly proves to be wrong from the fact, that I have found eggs lying in the oa>cia in Fl. secnrilhuis and Fl. memhranacco-tnincnla (PI. I, fig. 2 a), the floor of which is formed by such an ooecial membrane on which the egg rests. The egg must therefore have come into the ooecium from outside through the oax-iai ai)erture, and possibly Ihe altered position of the ou'cial membrane is due to this transference. Fig.s. 8 g— 8 n show a series of developmental stages of the oo'cium mentioned, seen from the surface of the colony. In the earliest of these (8 g) the ascending part of the distal wall has nol yet l)egun lo calcify, and the deej) sinus between the (wo rounded projections comes from the not yet closed uniporous rosette-plate. The other figures show the formation of the owcial bladder, its partial closure and the formation of the two calcareous ribs. While the rest of the oa'cinm-bearing members of Ihe family have essenlially the same structure of the ocrcia as Fl. securifrons, we find a rather difierent structure in Fl. folincea (PI. I, figs. 8a, 8 b; PI. XXIV, fig. 8), as the oa-cia here have an irregular egg-shape. Whilst, as already mentioned, a pair of cryptoeyst- ribs occur in /•"/. securifrons proximally lo the operculum of the zocecium, in a number of species, e. g. in Fl. ineinbranaceo-trimcata (Pi. I, figs. 2 a, 2 b, PI. XXIV, fig. 6), 7-7. Barleei (PI. I. fig. ;5 a), /•'/. Schonatii (PI. I, fig. 7 c) etc., a more or less developed cryptocyst-belt occurs just dislally to the free edge of the oa^cium, between this and the covering membrane; the originally separated lateral halves of this belt later fuse together. This belt reaches its highest development in /•'/. fliislruides (PI. I, fig. 4a; PI. XXIV, Lig. 7) and it may in lime quite cover the ooecia, which in this species exceptionally project distinctly on the surface 59 of the colony. In some species, Fl. denticiildta (I'l. I, fig. 9 c), Fl. florea and partly in Fl. fliistroides (PI. I, lig. 4 b) tlie oa'cia are situated inside (he avicularia. With exception of the Farcimiiiaria species (PI. I, figs. 10 a — 10 d), in whicli the ocTcium is enclosed in a kenozooecium, tlie ocecia in the other members of the family Farcimimtiiidae seem to have essentially the same structure as in the Fhistridae, but all of them project more or less on the surface of the colony. In the species of the genus Columnaria n. g. (PI. I, figs. 12 a — 12 d; PI. XXIV, fig. 9), a part of the inner (basal) wall of the ocecium is on each side covered by a triangular cryptocyst-plate, which from each of the lateral l)orders of the zoa'cium pushes itself in between the ectoooecium and the endoon^cium and in Nellia simplex var (PI. XXII, fig. 6 a) the frontal wall of the ocrcium is provided with a cryplocystic belt, like that founil in many Flnstridac. I must also refer to this group the ooecia in Micropora Nonnani (PI. Vlll, figs. 3 a, 3 b), Micr. perforata (PI. VIII, fig. 4), liosselia Rosseli, Biujidopsis Peachii, Buy. ciispidata, Menipea cervi- coriiis (PI. II, iig. 4 b), M. Bu.ski (PI. II, fig. 3 c), Urceolipora nana (PI. XV, figs. la — 1 c, PI. XXIV, fig. 11), Cheilopora sincera (PI. XXIV, fig. 4a), Gephyrophora polijmorpha, the oa'cia in the species of the genus Oniichocella (PI. XXII, figs. 3 a — 3 b, PI. XXIV, fig. 10), in all members of the family Sclerodomidae (PI. XIX, figs. 18 a, hS b), as also in numerous members of the family Catenariidae, for in- stance in Hincksiella pnlchella (PI. XII, fig. 9 a), the sj)ecies of the genus Ptero- cella (PI. XII, figs, oa, 6a), most of the Catemiria species, (PI. XIII, figs. 2a, 3a, 3b) etc. In the majority of the mentioned forms the ocecium projects more or less notice- ably on the surface of the respective zocEcium, and it is only in a small number of cases, e. g. in Urceolipora nana and in the mentioned species of the Catenariidae, that it is ([uite hidden within this. While in a number of cases we only have to do with a membranous ectoocecium, as in Micropora perforata, Bnyulopsis Peachi, Cheilopora sincera, etc., the ectoooecium in others is wholly or jiartially calcified, e. g. in the mentioned Calenariidae, in Biiguhpsis cuspidala and Menipea cervi- cornis. Finally, in both cases there may appear between the endoooecium and the eclooa'cium a more or less developed cryptocyst, as in Bay. cnspidata. Menipea cerricornis and Gephyrophora polijmorpha^ . in the last of which the crypto- cyst covers the whole frontal wall of the endoooecium. The cryptocyst in Urceoli- pora nana on the other hand has (juite a dilTerent position, as it here covers the basal wall of the owcium right down to the place where the oa>cium issues from the short horizontal portion of the distal wall. b) Endozooecial ooecia, which are surrounded by kenozooecia or heterozooecia. ' no, PI. 11, fig. 22. 60 Tlu' eiulood'ciiiiii, as in llu' loii'i^oiiij; i^roup, is I'oniu'd l)y llif dislai wail iii'- tween two chambers lying in llu- same longiliulinal row, bul while the ecto- oa>ciiiin in that groii]) was only represenled by a more or less distinctly limited part of the frontal mcmiirane of the covering zoo'cinm, it is here so lo speaii represented by the whole covering chami)c'r, which is a Ucno/Od'ciuni. W'c find everywhere a common operculum for the kenozorecium and the owcium. Such oa'cia are found in Didymia simplex (PI. IV, fig. 7 d), Eiwratea chelata, likcllarin infnndilnildld (PI. IV, figs. 4 a— 4 d), Menipea crijstallinu (PI. IV, ligs. 1 a, 1 b), Ciiltiilinit piincldld (PI. IX, iig. lib), Cr. dnnnlatd, Cr. (idltijiiv (PI. I\, lig. 12a), Escharella diiiphana (PI. XVII, fig. 1 a), Ksch. abyssicoUi (PL XVII, lig. 2 a), Enriistonielld fordimnicierd (PI. XVIII, figs. 14 a — 14 b), E. hilahidtd, besides in the Farciminarid species (PI. I, figs. 10 a — 10 c), most members of the family Catena- riidae (Pis. XI, XII, XIII, XV), and the members of the family Ilippothoidae (Pi. XXI, figs. 8e, 8 b, 9 a, 9 c). The fact that the endoooecial ocecia, besides appearing as a rule in certain families, appear sporadically in more or fewer forms in a number of other families would seem to suggest Ihal they rei)resenl an old oau'ial type, which perhaps was at some lime general, but which later has been replaced 1)\' others. It deserves to be mentioned in this connection Ihal they apjjcar together with hyperstomial (xrcia in Cribriliiia punctdtd (1^1. IX). 2) The hyperstomial ooecia (PI. XXIV, figs. 12 — 18). These oa>cia like the endozocecial consist of an endoooecium and an ectoooecium, which join at the free frontal edge of the oi)ord Sarsi (PI. XXIV, fig. '2 a) and I'orclld cdiujircs.sn lakes pari in the ' SI, p II.-). 65 formation of the ooecial cover nnd in Porella saccata we meet with an ooecial cover with many laj'ers, because thin calcareous plates are constantly growing over the ooecium from the three surrounding zooecia. A similar, many-layered ooecial cover seems also to be the rule in the family Reteporidae. An oa'cial operculum (PI. XXIV, figs. 6, 7, 9, 10, 13, 14, 16 o.o.) has u|) to now only been found in Bicellaria ciliata, Biigiila Sahatieri^, Callopora (Memhranipora) Fle- ntincii^ and Microporella M(tliisi\ and it consists in these forms only of an cvaginafion from the proximal zoa-ciiim's mem])ranous wall, as a rule distally to its oper- culum. Into this evagination extends a muscle, which is able to withdraw it and thus open the oa'cium, both for the egg to enter the latter and for the larva to escape. The oa'cial operculum seems to he quite lacking in Porella saccata and in the members of the family Reteporidae, and it is very likely to counter- balance this, that the ooecia in this family are furnished with a more or less developed, screen-like continuation, directed inwards, of the rim of the opening. In Tlialamoporella we find a well chitinized ocEcial operculum, which at its proxi- mal part is connected with the zocecial operculum, and which seems to be pro- vided with a muscle on each side (PI. VI, figs. 7 e, 7 o, 7 n, 7 g, 7 h). 3) The peristomial ooecia. These ooecia, which only consist of a single cal- careous layer and have no covering membrane, are formed by the peristome, and may otherwise be very different in shape. In the family Tiihiicellariidae* (PI. XVI, figs. 3 b, 4 a, 4 b, 5 a, 5 b, 5 d) they have the form of an irregularly pear-shaped expansion open at the end, while in the genus Lekytliopora (PI. XVI, figs. 6 a, () b, 7 a) they form a semi-globular expansion on the frontal wall of the long tube-like peristome. I must for the present also refer the helmet-shai)ed or cup-shaped ooecium in the genera Holoporella and Conescliarellinu (PI. XXIII, fig. 8 a) to this type. 4) The endotoichal ooecia. These ooicia which are only found in the genera Celliilaria (PI. VII, figs. 4 a— 4 f, PI. VIII, 1 a— 1 c, 2 a— 2 c) and Membranicellaria (PI. VII, figs. 2 a— 2 c) are cavities in the thick frontal wall of the zoii'cium, and it looks as if they are formed by a gradual resorbtion of the calcareous material of this wall. Thus by grinding longitudinally the older and younger parts of a colony we can find these ooecial cavities in all possible sizes, from quite small ones, situ- ated in the middle of the thick wall, u|) to a size which takes up the largest part of the thickness, and opens outward. According to the investigations ofC^alvet'* ' il, p. 57. ' 9, p. 262. ^ 9, p. 1(19. ^ My (.'Xiiinination cium has no polypide but contains an ovary, and he supposes that the tentacular sheath is of service to the egg by carrying it over into the ocpcium. A similar direct trans- ference probably occurs also in all the cases where endoocecial ooecia are present with an operculum in common with the zoa-cium (llippotlioidac, ('.iilrniiriulnc. etc.). ' 90, p. 19. '' 4,5. p. 31. 67 On the other hami, we have noticed that the endozooeclal ooecia in Fliistra are quite separated from the cavity of the zocx^ciuni by the ooecial membrane, and a transference of the egg from the zoa'cium into the ooecium can therefore only take place by tiie egg iirst leaving the zoa'cium through its aperture and after- wards entering the oa-cium on the withdrawal of the operculum of the latter. As we have nowhere been able, except in the above-mentioned case, to find an inner connection between the zoo^cinm and the ooecium, we cannot doui)t but that the egg elsewhere always leaves the zooecium through its aperture. This is undoubtedly most evident in the pcristomial and the doul)le-valved oa'cia, be- cause the zod'cial aperture leads directly into them, and the same is the case with the ooecia in Tbalamoporellii; but neither can we in any other /^n/ozoo find in the relation between the zooecium and the ooecium any difficulty for such a transference. Without entering in particulars I shall here only state that in all the species with ottcia, examined by me, the position of the ooecium in relation to the zoo-cial aperture is a such that when the operculum opens to a certain extent the egg will have no difficulty in reaching into the od'ciuni, whetber the transference be etTected by aid of tbe tentacular sheath or by an independent movement of the egg. Especially in tbe Ascophora this passage seems to be secured in the best possible way as in most members of this division the zoa>cial oper- culum in a certain position closes a space which can be looked upon as a common vestibulum for the zooecium and the ooecium, and a completely covered passage is thus formed between them. Least safe the passage seems to be in the family Reteporidae and the genus Exochelht as there is a rather long way be- tween the zooecial aperture, and the oa-cium and the zorecial operculum cannot close the space between the zooecium and the owcium. The systematic characters in the Cheilostomatous Bryozoa. While we sometimes find in the literature, as in Hi neks. Waters, JuUien and other writers, views concerning the larger or smaller value of different syste- matic characters, the systematic importance of a single character being some- times dealt with, sometimes the relative importance of several characters, yet any connected or more complete review is lacking of those characters, which in the present state of our knowledge might be used for systematic purposes, as also a valuation of their relative importance based upon a sufficient number of examples for it is only in this way, that tbe reader becomes able to judge in the matter. We shall endeavour here to give such a review and we shall first distinguish between two dilVerent categories of characters, namely the »colonial» and the »zooe- cials meaning i)y tbe first those which can be referred to colonial forms and the 5* 68 colony's composition of one or more difTerent, individual forms, while the last are those which are found in the structure of liie single zoo'cia. Colonial form and mode of growth. Throughout the organic world wherever single individuals are uniteil into colonies or in florescences we lind a repetition of the same colonial forms oi' forms of growth. The colonies may he incrusling or free foliaceous or branched in various ways, the single indi\i(hials arranged in one layer or two, in one, two or more rows etc., and this harmony in Ilie outer arrangement may often produce a surprising likeness between animal forms very different in slructure, occasionally even between certain animal and plant forms. It is therefore easy to understand that the lirsl investigators of the numer- ous aggregate animals of the sea, the single individuals of which only reveal their peculiarities on very close examination, have tried to arrange this varie- gated multitude after likeness in the colonial form. We may for example refer to Ellis' celebrated work on the Corallines', under which common name be not only classes hyilroid polyps, Bvijozoa and corals, but also certain calcareous algae. By and by as knowledge of the single individuals of the colonies advanced, the systematic importance of the colonial form becomes more and more limited, as it is gradually used for less and less extensive systemalic units, and in the pre- sent day /Jryoroa system, which is founded on Smitt's and Hincks' well-known works, it occupies a very subordinate position. As there is nevertheless too much importance still attached to the colonial form as systematic character, not only within the Bryozoa, but also within other aggregate animals, for instance the hydroid polyps, I do not think it unnecessary to discuss this question here, and I may first quote some observations concerning this made by Hincks-. After having spoken about the slight hel|), which the j)olypide, and the avicularia give us in systematic regards, he says: »There remain the characters of the cell itself and the habit of growth. It can hardly be deemed doubtful which of Ihem should have the |)recedence in a natural system; we may go very much furlhei-, indeed, and say llial in such a system the latter must hold a very secondary and subordinate place. The essential structure of the cell, as one of the primary zoa'cial forms, must certainly be accounted the most imj)ortant point, holh in it- self and as a clue to relationship. The mere habit is, so to speak, a suj)erinduced condition, which may be difTerent in the most nearly related and similar in the most divergent forms; and groups based on it, instead of fitting in with natural affinities, are found to traverse them at all points*. A little further on' he also slates: »In the Escharine group it seems to me that the families and genera r.' ' •>•>. Introtiiiclioii. p CXXVIII, ' p CXXX. 69 should l)e based almost wholly on the zoa'cial characler; but I am certainly not prepared to hold that other structural elements should never be taken into ac- count. The Flastridae, which seem to constitute a most natural grouj), have a true Membraniporidan cell, and hold their separate place by virtue of their corneous and foliaceous zoaria<'. As a consequence of the weight the writer attaches to the colonial form in the family Flastridae, he refers an incrusting species Fliistra (Memhranipora) /liistroides Hincks, which in its essential characters is a Fliistra, to Meinbivtnipora at the same time that he indicates in its specific name its likeness or relationship to other Fliislra species. Gemelhiria is also a genus, which in Hincks is based essentially on the colonial form. A. M. Norman' takes up a somewhat similar standpoint to that of Hincks, which he expresses as follows: »It has been argued by recent writeis that the form which a colony of a polyzoon belonging to the Cheilostomala assumes is of no moment in generic character. Electro piloxn lends strong support to this view. Yet it is a view nevertheless in which I am not prepared in all cases to acquiesce. The zon?cial characters are unquestionably all important, hut no lasting classification can be based on any part of the zooecium, whether it be the mouth- o])ening, wall, rosette-plates or anything else. Why also in all instances is the ultimate growth and form of the zoarium to be excluded from generic character among certain families of the Cheilostomatu, and at the same time to be recogni- zed among the Cyclostomata and Ctenostomata, and even other groups of the Cheilostomatd'! This is surely scarcely consistent. In some instances, as for example in Electra pilosa, the form of the colony is of no generic and specific value, but in other cases it may be and, I believe, is«. To judge from this statement this writer seems more inclined than Hincks to use the colonial form as a .syste- matic character, and this appears also in his last paper' on the Brijozoct, since he here maintains the old Fliistra genus Cnrhasea rejected by Hincks, which is only based on the fact that the colony has a single layer. There is of course no doubt, that any character constantly appearing in a systematic division must be regarded as being of systematic value, and the same must also be the case with the colonial form. Wherever therefore this appears constantly within a genus or family it ought to be emphasized in the diagnosis. But the proof that the respective genus or family is a natural one is only given when evidence has been obtained of sufficiently great agreement between the single species in regard to the structure of the colonial individuals, since for instance the same form of colony may appear in the Brijozoa not only within the three natural main divi- 82, p. 122. ' 8,'!, p. 581. 70 sions: Clieilostoimitd, Ciicldstoinald and (Itenoslomatd, ))iil in the first division also within a scries of widely dilTerent families and genera. Thus the nel-like connec- tion of the hranches of the colony, so common in the family Retci)t>ri(l(ie, we also find in several Ciiclosloinata {ReiicuUimni, livlicrisina, Retihornerd), in several species of the family AdeonUUie (e. g. in Ailcona (irisca, A. dppemliculitld, A.WUsnni), in the species of Ri'lijhixlra as also m Mciiihrdniixira sigilldtd^ i\nd Pelrdlia iiiidata. A colony consisting of cylindrical, or })olygonal internodes generally connected by flexible chitinous bells is found in such widely difTerent forms as most spe- cies of the genus Celhildrid, species of the genus Tnhiuelldrid, the species of the genera Fdrciniiiiaria and Nellia, Microporiiia borcdlis, Schizuporella ininiersd and species of the Ctenoslome genus Fliistrella (Fl. dichotoma and Fl. Binder!). We have here only mentioned some of the most peculiar forms of colony; for of the more common, e. g. free colonies with Ihxt branches, we might cite numerous examples. This colonial form is the most prominent in the families Fliislrirellid(ie. They appear for instance constantly in the genera Callopord and Exuchella, while they are absent in the genera Membrani- poru (s. str.) and Electra. The oci'cia present a similar inconstancy in their occurrence to the hetero- zoo'cia, as they are (juite absent in a number of families (e. g. Adeonidae. Slegano- porellidae and Aeteidcie), genera (e. g. Hecial forms. While the hcterozod'cia within the division Ascophora, where Ihej' are mostly developed as avicularia, only very seldom show so great a modification in their structure that it can be used by the separation of families and genera, there is a much larger diversity in the structure of the heterozorecia in the division Anaskti, and most of the heterozooecia, which by their {)eculiarities help to characterize the families and genera, are vibracles. While the peculiar, freely moveable, bird- headed avicularia are characteristic of the family IVuellnriidac, we lind more or less peculiar vibracle forms in the genera Caberca, Scrupocellaria, Oiujclwcella, Selei}(iri.semicircular« is thus used to charac- terize the form of the aperture in eight of the ten genera here mentioned, either alone or in connection with the designations: 'suborbiculars semielliptical and »subquadrangular«, of which the first appears in the diagnosis of four, the second of two genera. We can easily see that the differences in the form of the aperture, which Hincks put down for the genera mentioned, are loo vague and indefinite to be of any use in their distinction. hi contrast to the holostome the schizostome aperture has on its proximal edge a more or less deep sinus. If we take our starting point from a form such as Arlbropoma (Scliizoporella) Cecili or Schizoporclhi sjionyiles, in which the sinus is very narrow, almost slit like, and if we imagine this as gradually widening on both sides, we will have a series of apertures with varying breadth of sinus until at last this disappears, because its sides run into the lateral edges of the aperture. On further extension the sinus becomes wider than the rest of the ajuMture, as it is in some of the species referred to the genus Lepnilui. Still this picture only gives us a fractional part of the variations, which the schizostome aperture in reality presents, because a similar variation lakes place ])artly in the depth or height of the sinus partly in the shape of its proximal rim, which uuiy some- times be straight and sometinu-s uu)re or less curved. It is clear, IIkiI the schizo- stome aperture otTers a far greater possibility for variations lii;in the holostome, ') 22. 82 because besides Ihe variation in the distal part or the aperture, we also have the possibility for a so to spealv endless variation in the extent and shaj)e of the sinus. That such a variation is not merely an abstract thought but really exists, will be admitted by all who on the one hand have examined large (pianlities of Bryozoa, and at the same lime also have studied the considerable literature on this subject. The majority of those species, which have a schi/oslome aperture are referred by Hi neks and later writers to the two genera SchizoporelUt and Lepraliar Though Hincks considers them to belong to two distinct families, it is in many cases a matter of guesswork, whether to class a species to one of Ihe genera or to the other, because they can only be distinguished by a dilVerence in the shape of the aperture. Yet the diagnoses of the two genera seem to be quite ditTerenl, as a Schizoporelld aperture is considered to have a sinus on the proximal edge, but Lepidlia a horseshoe-shaped aperture, contracted at the sides. Since, however, such a proximal part of the aperture, so contracted, can in reality be regarded as a sinus the difference between the two kinds of apertures is reduced to a difference in the width of the sinus, and species with a narrow sinus have thus been referred to Scluzoporella, and those with a wide sinus to Lepralia. The result of Ibis consideration is then thai the shape of the primary aperture, on account of the practically endless variations to which it is subject in the Cheilo- stome Bnjozoa, cannot have any great systematic importance, and that it can at the very most only be used as a more or less constant, auxiliary character in Ihe diagnosis of the genera. We arrive at the same result on considering the question from another point of view. If we examine the aperture in a large number of forms belonging to a series of families, we find that cjuite corresponding forms of aperture, holoslome as well as schizostome, reappear in all families which are rich in species, and we may thus draw the conclu.sion, that the.se different forms of aperture in each of these families have ari.sen inde|)en(lently. To mention some of the most |)romi- nent forms of aperture, we lind for instance an aperture with a sinus in the following families: Cribrilinidae (e. g. in Cribrilinu clUhridiata Waters), Thalamo- porelliddc. Miiriozoiihic, Eschnrellidde (in Scluzoporella and Kscluiriiui), Snnlliitidae (Sinitliiia linearis, S. porifera etc.), Hippothoidae (Hippnlhoa, Triiposleija), Adeoiiidac (.several Adeonella species), Releporidae (lielcpora iiiiperati. Ret. simiosa, Rhiincho- pora, »Sc/H'ro/)0/-e//rt« scintillans, etc.), Catenariidac {Cjdpidiiim, CAavipurella, Ilincks- iella, etc.), Eiitbijridae (Urceolipora nana) and Celleporidae. A .semicircular a|)ertnrc with a simple operculum, which is furnished with a straight or slightly curved proximal edge, is found further in the following families: 'rhalanioparcllidae (Tlud. expansa, Tlud. Jervoisi), Microporidac. Cellnlariidai; Escharelliilae (Micropordla, 83 Inuersiiila), Hippothoidae (Haplopoma, Chorizopora), Adeonidae (Adeonellopsis) and Onchoporidae (Onchopora). Besides the shape of the aperture we must also consider its teetli-shaped projections, and I have already called attention to the fact, that we can distin- guish between hinge-teeth, supporting teeth, and such protecting teeth as are placed outside the operculum. Teeth-like projections of different kinds are occa- sionally used by different writers, e. g. Smitt, Hincks, Waters, JuUien, as generic or family characters, and JuUien' has for instance founded a family Stnittiddc merely on the presence of a median tooth (lyrula) and two side-leeth (cardellae). To judge from the name he gives the two side-teeth (cardellae, from cardo a hinge), we would imagine (hat he regarded them as hinge-teelh, but in Exochelld they belong to the jteristome, and may even join togethei- with one another or with the median tooth (K.v. lonyirostris). For the rest the author writes regarding all the three teeth: »c'es( Ic (levelloppemenl du jeune peristome qui contribue a former la lyrula et les cardelles dans la famillc des Smittiddei. There is no reason for attaching much systematic importance to these teeth-like projections, and they can at most be used as more or less constant auxiliary characters, particularly in the diagnosis of genera. Hinge-teeth seem to appear constantly, but in somewhat varying shape in the genus Smittina and to be wanting in the genus Discopora. In the genus Tludamnporellri tliey are very di- stinct and well developed in a series of species, whilst in other species they are very slightly develo[)ed or absent, ami Ihey seem to ajjpear very seldom in the genus Holopordla. Supporting teeth seem to appear conslanliy in the genus Cellularia, but as already mentioned they vary in shape and number. The median tooth, to which the greatest importance has been attached, seems to appear within most families which are rich in species, but in families which are only tolerably rich in s|)ecies, it never seems to be constant, and it is not even always constant within the species. It is found in the family lisclmrclliddr. in most species ol the genus Escharella, in the family Discoporidae e. g. in Discopora pcwonclUt, I). sc(d>r(i and D. plicaUi, in the family Petraliidae e. g. in Petralin casla- neii and /-•. hisiiuicdd, in the family UolopovvUiddc e. g. in Holoporclla Iridcniiciihda, in the family Relefxtridae e. g. in Retepord noude ZeUmdide, in the family Adeonidae e. g. in Brdcchridijid piirifonnis, and in llie family Crihriliniilde in a variety of the fossil Mciubrdiiijiorelld crcjiiduld Hog. As examples of species, in which the median tooth is sometimes present, sometimes absent, we may mention l)esiilcs the last-menlioned : I'luclla coiniircssd, ■1 ' 45, p. 52. 84 P. coiuinixi, Smittina palincila, Discopora scabra and D. plicata. In llie two lasl- nienlioned species there may even in lliis regard l)e a dilTerence between the single zoa-cia in the colony. In connection with the aperture, we have still to nienlion as systematic character the i)reviously discussed vestibular arch, which seems lo appear con- stantly in the family Rete})orid(ie and in most genera of the family EscIvircUidde. The peristome or the secundary ai)erture, which forms a more or less perfect vestibulum lo the true or primary aperture, appears only within the Ascophora and is even within this division represented in a very irregular way, as it may sometimes be absent in whole families (Catenariiddc, Pdidliuldc. Holoporrllidae), or genera {MicroporclUt), whilst in others it appears to a very variable extent. A peristome may sometimes be developed round the whole circuit of the primary aperture (^Lcpralid" cfinthdrifonnis, the species of the genera Hnswellia and Tuhii- cvlliirid. liclcpora prctiiuild KirU, etc.), sometimes over only a larger or smaller portion of this, being somelimes interrupted distally (»P/ii//«c/e//a« hdirosa, »7-'/i.« cnlldris, "Schizoporelki- drnudd Yar.), or [)roximally (many species of Smittiiid and Retepord). In some cases it is formed by continued growth of the edge of the primary aperture ("Leprdlid P(dl(isidiui Xiw, »Lep.<^ cdulhnrijoimis, Esclvninii sim- plex), whilst in other cases it forms a wall outside this rim ( Phi]ldclelld< lahrosd, »Pli.' colhtris, "Scl}iz.« drmdki Var). It may be low. circular (Escluirinn siiuple.v). funnel-shaped ('Lep.< canllidrij'orinis), or tube-shajjed (Retepord pectinala, Ret. phoeniced, Eschnreltd spinosissititd, Phijlacleltd' (/eoiuctrica) and in a number of cases provided with a pore on the frontal wall. It is occasionally furnished wilh teeth-like projections, which in number and position are like those, which in certain genera belong to the primary aperture. This applies for example to the genus Exochelld and certain species of the genus Eschdrnides. As the peristome is often very obvious il is easily undersh)od why il has in many cases been used as a systematic character at the cost of others more im- portant, but less prominent, and in Hincks' great work the following genera are besides the family Porinidde entirely or chielly based on the structure of the peristome, namely Poriiui, Ldijempora, Schizotheai, Porelld. Eschdrnides, Snullid. PluildctcUd, Mucronelld, Palinicelldiid and RliiinchoptH^. Of these genera I am onlv able to retain Porelld, in the limitation given by Hincks. In discussing the cpiestion of the systematic importance of the peristome, we may first call attention to the fact that the same peristome forms recur within a series of widely dilferent families and genera. We thus find a collar-shaped I)eristome. i'urnishcd wilh a frontal incision in many members of the familv 85. Ret('lMri(l(te, in a series ol' species of Ihe genus Smitliiiu, in PorclUi coiujiressu and Discopuni Sarsi. A shorter or longer liibe-shapeil peristome willi a pore on tlie frontal wall is found in the genera Adeonclhi, Hasivcllid and Ttihiicellaria, in cer- tain Retepora species (R. cellnlosa, R. Coiichi, R. complanata etc.). in Tessaradonui bovealis, 'Porinao tiibiilosa, Sinittina Lanshorovi, var. persoiiata), whilst a long tube-shaped peristome without pores is found in certain Retepora forms {R. pecli- naUi, R. phoenicea), in certain Cellepora forms (Cellepora tiibulosa, C. bicornis), Lekijthoj)(>r(t hi/strix, TPhijladellai^ geometrica etc. Next, I would point out, as a general result of my investigations on this point, that the peristome in many cases is very inconstant within the genus (e. g. : in the genera Escharella, Sinittina, Discopora, Petralia, Cellepora, etc.), and Hi neks even mentions a series of cases where the peristome in the same sjiecies may sometimes he present, sometimes absent, which for example is the case in '■Lepralia- Pallasiana, Sniiltina trispino.sa and Escharina Diitertrei. Whilst the above-mentioned small peristomial teeth are found constantly in the small genus K.vochella, their appearance is very incon- stant in the genus Escharoides, and on the whole like Waters I cannot attach very great importance to the peristome, which however does not exclude the possibility that ils apperancc may be constant in a series of genera, e. g. in Adeonella, Hasuwllia and Tiibiicellariu. The operculum. As all that has been said regarding the systematic impor- tance of the form of the aperture, also holds good as a rule for the form of the operculum, we may here merely take note of the other ditTerences, which a])pear in its structure. As already mentioned, we are able from the difierent relations of the operculum to the frontal cover and the compensation-sac to distinguish between an opercular valve, a simple and a compound operculum. These dille- rences have however only partially a systematic importance. We have a series of examples of the fact that an opercular valve and a sim|)le o[)erculum may appear within the same genus: e. g. in Sleganoporelln and 'I'ludamoporetld, and especially in the last-mentioned we find a series of intermediate forms between the two kinds of operculum. We have other examples in the i)reviously men- tioned species of Caberea and Scruj)ocell(tria, in which the |))esence of a simple operculum seems to be dependent on the strong development of the covering spine. That an opercular valve and a compound operculum can appear in the same genus, we have examples in the genera Adeona, Porella, Escharella, Escha- roides, Snuttina, Holoporella and Chaperia. Whilst for example we as a rule find a compound operculum in Porella and Adeona, there is an opercular valve in Porella la'vis and Adeona violaceu, and while there is generally an opercular 8(> valve in EscbareUu unci Escharoides we liiul a well-chilinized compound oper- culum in Escharella polita and Escharoides saurocjlossa. But the contrast between a simple and a compound operculum is of greater systematic importance, and it seems as a rule to be an expression for a generic difference. We find a simple operculum within a series of Ascophore families {Escharellidae, Hippolhoidne, Onchoporidue, Adeonidae'), and it is generally accom- panied by a different mode of opening of the compensation-sac, which in these forms with a simple operculum with a single exception (Chorizopora), opens out through a median pore (see pag. 32). In spite of the above examples of varia- tion, llie structure of the operculum seems as a rule to show more constancy within the genus than for instance the shape of the aperture and the peristome and must he regarded as one of the best distinguishing characters. Referring for the rest to the separate families, we may just mention as examples that while a well-chitinized, compound operculum is found in Schizoporelln, Porella, Cellepora and Adeono, a membranous operculum, which is not separated from the compensation-sac, is the rule in the genera Escliarella, Escharoides and Discopora. The mode of attachment of the occlusor muscles seems also to be rather constant within the genus, and we niaj' cite as examples that there are special muscular ridges or muscular processes in the genera Porella, Escharina and Microporella, while Schizoporella, Cellepora, Arthropoma and Conescharellina have muscular dots. The rosette-plates are interesting examples of a structural feature which, though subjected in a number of cases to considerable variation within the genus, and even within the species, proves in most cases to be constant, not only within the genus, but also within the family. It is specially the rosette-plates of the lateral walls, liowever, which show this constancy, as those which appear on the distal wall in many cases show great variation, and we may cite the rosette- plates on the distal wall of Membranipora membranacea as a very ])ronounced example of such a variation ([>. 24). Referring for the rest to the diagnoses of the separate families and genera, we may here cite the following families and h\ genera, partly very rich in species, in which the rosette-plates of the lateral walls especially show eitlier perfect constancy in structure and ap])earance, or only a small degree of variation, namely: Farciminariidae, Scriipocellariidae, Bi- cellariidae, Cellulariidav, Stcfiaiio/iorcllidae, Thalamoporellidae, Adconidae, lieteporidae, Catenariidae, HippaUundae, (lelleporidae, Holoporellidae, Onchoporidae, Conescharelli- ' see pag. 38. 87 nidae, Mijriozoidde, Escliarella, Escharuide.s, Pori'lla, Omjchocclhi and Calloporti. On the other hand, the rosette-plates show variations in the families Fhislridae, Membraniporidae, Cribriliiiidae and Micioporidae, l)ut in slill higher degree in the genera Schizoporella and Sniittiiia. hi these some species have single-pored, others multiporous, and again others mixed rosette-jilates, and colonies from different localities may show a distinct difference in the number of pores in the rosette- plates e. g. in Schizop. unicornis, Sch. sanguinea and Sch. longirostris. Synopsis of the Fa mil of Cheilostomatous Biyozoa licnlcn ies and Genera I of in llu- present work. Subordo Anasca. 1. Division: Malacostega. f '' ' j, -u F;im. Aeteidae: Gen. Aelea. rf>M^ Fani. BiceUaiiidae: Gen. l)imor))ho- zoiim n. g., Biujiila Oken, Stolo- nella Hincks, lieania Johnst., Hiantopora Mac Gill., Chaperia Jullicii, Petalosleifux n. i^., Hdlojiliiht Busk, Motdinia Flcm., Gemellaria Sav., Hrctlici Dyster, Cornucopina n. g., Didijmut Busk, Eiicralea Lamoiir., Dinw- topia Busk, Kincloskids Kor- Dan., liirellfirid Blainv., Btign- larid n. g., Bicclhirina n. g., Walersiii n. g., Deiidrobeania n. g. Fani. FarciniiiKiriidac: Gen. Farciiui- iKirid Husk, Columwirin n. g., Nellia Busk. ' * Fam. Flastridae: Gen. Fliislrn L., Sdisilhistra Jullien, Kenelhi n. g., Relifluslra n. g., Spirahi- ria Busk, Heterojlnslid n. num. Subordo Ascophora. "^ Fam. Calenariidae: Scnticella n. g., Crihricelld n. g., Costicella n. g., Claviporella Mac Gill., Pterocella n. g., Calpidium Busk, Hiiicksielld n. g., 6'o/p- /mr;V( Sav., Stro])hipora Mac Gill. Fam. Onchoporidde: Gen. ddweUid Wyv. Th., Onchopord liusk, Onchoporelld Busk, Oncho- linroides Ortin. Fam. Eiitliyruiddc: (Jen. Knlluiniidcs Harmer. Fam. Fiitliyridde: Gen. FncoUpord Mac Gill., Eulhijris Hincks, PIcnrotoichiis n. g. Fam. Sdi'ignfit'llidae n. f . : Gen. .SV/- I'ignijella n. g., Hcdijsisis Nor- nuin. Fam. Hippothoidac: Gen. flippnlluxi Lamour., Chorizopoin Hincks, Hdplopoma n. g., Tryposfega n. g. l-X"^ 89 \ (Anasca). yO Fain. Scriiimcclldriidae: Gen. Scriipo- celluria Van Ben., Canda La- niour., Bugiilojisis Verrill, Ho- plilella n. g., Rhabdozoiim Hincks, Caherea Lainour., C(i- bvriellu n. g., Menipca La- mour. ,m3 Fain. Memhraniporidae: Gen. Meiu- branipora L., Electra Lamoiir., Cidlopora (Gray) Norman, Metjaporu Hincks, Tef/ella n. g., Caleschara Mac Gill., Oiiijcho- cella Jullien, Cnpularia La- moiir., Lunularia IJusk, Sele- n(tri(t Busk. Fain. Cribrilinidae : Gen. Meiubidiii- porella Hinclvs, Cribrilina Gray, Piu'lliiKi .lullien, Fiipilind Jul- lien, Aspidclecii-d n. g., Aracli- nopiisia Jullien. 2. Division: Coiloslega. ^ ic( u J Fain. Microporidne: Gen. Micropora Gray, Macropora Mac Gill., Fleniiseptella n. g., Forainin- ella n. g., Calpcnsia Jullien. f.W" Group Tublfera: Fain. Stc(jaiwporellid(ie: Gen. Slccjd- I noporella Smitt., Siphonopo- rella Hincks. Fain. Aspidnstontidae j;^ ^: Gen. Aspidosloma Hincks, Labinpora n. g., Crateropora n. g. Fain. Th(d(imop()renidae.pGen. Thala- vL moporelln Hincks. ,«\)Fani. Chlidnniidnc : Gen. Chlidonia f Sav. (Ascophora). Fain. Adeonidac: Gen. Adeona La- inour., Adeonellopsis Mac Gill., Adeonelki Busk, Bracebridgia Mac Gill. Fain. Retepovidav : Gen. Retepnra Lnperato s. ext., Rluinclw- pora Hincks. P'' Fam. Myriozoidae : Gen. Leiescharn Sars, Mijviozonm Donali, //o,s- wellia Busk, Gephijvophora Busk. I'";un. Sclciiidoniiditc: Gen. Sclero- doniiis n. g., Tessdrddomci Norman. Fam. Tubmrlhiriiddc: Gen. Tnbu- ccllnrid iVOrh. /rnbij)(>iclla n.g. Fain. Conescharellinidae n. f. : Gen. Conescharellind d'Orb., Bipovd Whitel., FIdbellipora d'Orb. Fam. Liriozoidae: Gen. Liriozoa Ellis-Sol., Geinellipord Smitt. Fam. Lekijthoporidae n. f. : Gen. Leki/thopord Mac Gill. Fam. Eiirystomellidae n. 1".: Gen. Eiirystomella n. g. Fam. Escharellidae n. 1'. : Gen. Eschn- rella Gray, Anarthropord Smitt, Invevsiula Jullien, Escharoides Milne Edw., ZJ.ro- chelld Jullien, Schizoporella Hincks, Escluirina Gray, Mi- croporella Hincks, Artliro- poma n. g., Eniballotheca n. g., Cyclicopord Hincks. Fam. Smittiniddc: Gen. Porella (Gray) Hincks, Smittina Nor- man (n. nom.), Discopora Lam. .^ (Anasca). Fam. Aliishliiddc u. (limn Busk. 90 1. ; (k'li. Alijsi- ^,~ - 3. Division: Pseiuhslega. Fain. Mviiihrdnicelldiiitlde n. I'.: Gen. Membranicelhiria n. g. Fam. Celliihiriiilde: Gen. Cellidaria Pallas. 'V (Ascophora). Fam. (lellcjMriddc: Gen. Cellepoia L., Siniopdtd n. g. Fam. HoloporeUidac n. f. : Gen. lloloporeUa Waters. Fam. Pctraliidae n. f. : Gen. Petra- lia Mac Gill. Fam. Hippoporinidae n. f. : Gen. Cheilopora n. g., Hippopodina Systematic Part. Order Cheilostomata. The zoacia, to a larger or smaller extent calcified, as a rule furnished with an operculum (except Bugula). There can he found four different forms of indi- viduals: uulozoa-cia, heterozooecia, gonozoa-cia and kenozooccia, and in many cases the eggs are matured in special, outer or inner, calcareous marsupia, the so-called ooecia. The separating walls between the individual zocecia are furnished with rosette-plates, and in colonies consisting of more rows we can as a rule distin- guish between a horizontal or oblique distal wall and vertical lateral walls, which are most frequently independent. More rarely a lateral wall is common to two adjoining zocecia, which on the other hand is almost always the case with the distal wall. Suborder Anasca. A compensation-sac is wanting, and the frontal wall is either wholly or in part membranaceous, or calcareous, depressed and surrounded by raised margins. In the heterozoa'cia the opercular and the subopercular areas are as a rule not separated by a continous calcareous bar, but only partially by the hinge-teeth of the operculum. 1st Division: iVlalacostega. The individual zoa-cia are plainly marked olf on the surface of the colony. The frontal wall quite or partially uncalcified and the operculum as a rule a membranous valve, the rim of which is chitinized, but which proximally passes over into the frontal membrane. 92 Family: Aeteidae. (I'l. VI c, liji;S. li ;i-(i (1). The zoa'via, wliicli liavc no spines and the calcareous wall of wliicli is (icnscly covered willi j)oies of dilTerent form, consist of Iwo portions inclined towards one another at an angle, the lower of which is as a rule decumbent, adherent, while the upper, mostly tube-shaped part is provided at its expanded end with a small membranous frontal area. No cryplocyst. The diajjhragm has a structure similar lo thai in the Ctenoslonicita. The heterozoivcia and (mvcui wanting. The distal wall furnished with a row of uniporons rosette-plates. The colony creeping, forming a meshwork of single rows of zoa-cia, from which free in-anches some- times issue. The partly thin, thread-shaped adherent part, from which the free upright part of the zocecia arises, is by Flincks compared lo a stolon bul this name can only be used for a basal portion, consisting of kenozocrcia, as found within the order Ctenostoniatct in the families Vesiciihtriklae, Trilicellidae, Valkeriidae and Mimosellidae and within the Cheilostomcitd in the genera Chlidonia, Liriozoa and Stirpaiid. In .4e/('a the whole colony is built up by autozoa'cia, and the fact, that the proximal part of the zoa?cium is thin and uuich elongated, does not entitle us to sj)eak of a stolon in these sj)ecies any more than in the species, which Hincks refers to the genus Hippolhou. The adherent parts of two successive zooecia are separated by a wall, which in Aetea dilatata is furnished with a row of 7 uniporous rosette-plates, and a similar separating wall is found everywhere, where one zo(]eciuni issues from another. In Aetea triincnta according to Hincks new free zooecia maj' issue from the basal side of the ascending [)arl of the zooecium. The calcareous wall of the zooccium is richly furnished with ])ores, which in dilferent species can appear in diderenl ways. Thus, while the whole calcareous surface in Aetea dilatata is furnished with round jjores, the form of the pores varies in many other species at different places. For example, the distal part of the zoa'cium in Aetea aiuiiiina and also the broadest part of the adherent portion are furnished with small round or oval pores. In the narrower jiart of the adherent portion they fuse together to longer, slit-like spots (fig. (id), and in the largest part of the ascending portion (fig. 6 c) they become continuous, ring-shaped interruptions, and therefore the calcareous portions ai)pear as a row of free rings situated above each other, which can be isolated without great diffi- culty. Sometimes however we find a short connecting branch between two succes- sive rings, or a bifurcation of a single ring. Waters' has found an egg enclosed ' 111, p. 5, Fl. I, ligs. 1—0. 93 ill a spherical, transparent body near llie lip of the basal side of the ascending part of the zoa-ciuni in a large numi)er of specimens of Acted angiiina, and con- siders this to be an ooecium. The great transparency of this little globe, which has enal)le(i Waters to count the cell-divisions of the egg, seems to indicate, tlial it is not calcareous, and this fact in connection with its for an oa'cium, very unusual position on the l)asal side of the zoa'cium, speaks decidedly against the ocecial nature of these globes. I must therefore regard the supjiosed ovicellular wall only as a shell membrane surrounding the egg. Smitt' has already called attention to Ihe great agreement between the members of this family and the Ctenostoiiuitd; but when he specially compares Acted with the family Vesiciilariidae, we must remark, that this genus shows a much greater agreement with the families Ciitindroeciiddc and Victoretlidae, in which the zooecium according to Hincks also consists of an adherent and an ascending j)orlion, while they have no real stolon. In all Ctenostome families, where the zorecia issue from a stem or stolon consisting of kenozooecia, the zooecia die away and can be renewed, whilst such a renewal does not take place where there is no stolon, as in the two above-mentioned families, and according to this, the peduncles in Tvitkelln must belong to the stolon and not to the individual zooecia. Smitt' has also called attention to the fact that Acted, in the cylindrical form of the zooecia and the rich development of pores, shows agreement with the Cijclostomatd, and he imagines the possibility that the latter may have had a Ctenostome origin. Without entering further into this question I wish only to point out in this connection that in the Cyclostome species Stomatopord cia. The colonies free or creeping, generally branched ami frecjuently provided with radical fibres. • With a few exceptions (e. g. Hiantopora and Cbaperia) the calcification in this famil}' is very feeble, and the least calcified Cheilostoniala known are undoulitedly the Beania species, of which some contain so little calcareous material that it is only by using hydrochloric acid that we can make sure that there is any calci- tication at all in their walls. Whilst the whole frontal wall in the Beania species, in Dimorphozoiim nohile and Watersia mililnris. is membranous, in most members of the family a larger or smaller portion of it is calcified and forms a gymnocyst, which may sometimes, for instance in (icmcllaria loriatta and certain Corniicopinu species, occupy two-thirds or three-fourths of the whole length of the zoa'cium. From this gymnocyst in older zooecia there arises not so seldom a small secund- ary cryptocyst (e. g. in Duhjiiua simplex, Geiiiellaria loricala, Deiulrobeania Miirnnj- and). Except for the species of the genus Beania in which the individual zocecia are connected by cylindrical tubes, two zoo'cia in the same longitudinal row are in all other cases connected by a distal wall, which is always more or less ascending from the basal towards the front wall so that the distal end of the lower zocjecium projects more or less over the j)roximal end of the zocecium above. It is usually furnished with a number of uniporous, more seldom with one or two multi- porous, rosette-plates and not rarely {Bmjula, Halophila, Didijmia, Bicellariu, Bicel- larina, Bnc/nlaria) the basal edge shows a peculiar angular bending (PI. Ill, figs. 1 c, 2(1, PI. V, ligs. la, 2 1)). Each lateral wall is as a rule provided with 1 or rarely with 2 multi])oious rosette-plates. Except for the pore-ring they are as a rule membranous, and it is therefore difficult to decide, from spirit-material, whether they ai'e uni- or mulliporous. In all cases where they are calcareous, e. g. in Dendrobeania Miirraijana, l)in}(irj>hi>zount nohile, Biujularid dissiniilis etc., they are however multiporous. Whilst the dependent avicularia in most Cheilo- stonuitd attain their greatest breadth where they are fixed to the zoa'cium, most avicularia in this family are provided with a shorter or longer movable peduncle or the ])roximal part of the avicularian chamber is slender pedunculiform. While the first have tlie j)eculiar resemblance to a bird's head wliicli has given rise to the name > aviculariiim» the others which increase gradually in breadth toward the distal end have been described as trumpet-shaped. (>ommon sessile avicularia 95 appear however in Hianlopora, RiujuUirUi (PI. V, fig. 2 a), Petalosiegiis (PI- IX, figs. 8 a, 8 b) and .sometimes in Chai>ericia in the one layer of the colony are built in quite the same way as in an Alcynnidiiwi, whilst in the opposite layer they possess an operculum, avicularia and ocecia. For the rest, however, the diaphragm in these zotecia seems to be Ctenostome-like. We should also remember that an operculum is absent in species of the genus Bmjiiki, as also that the diaphragm in Eiicrdled cheMd is said lo be built in the same way as in the Ctenostonuitd. The generally slight calcification also agrees with this view, and finally a series of forms in this family shows quite similar modes of connection between the zoa'cia as those we know in the majority of the Cfeno- stomdld. Thus, Bednia corresponds in this regard with the Ctenostome genera Ardchnidium and Biiskid, whilst the stolon or stem, which consists of kenozoiecia and which is widely distributed in the Ctenostomatd, is again found in ^Bkelldvid' (jldbi-d, Biujidd (Stirpdrid) Hdddoni and B. (Stirpdid) cdrdibicd. When Busk, Hincks and other writers refer a number of genera of the family (Eiwrdled, Ccmelldrid, Notdinid, Didijmid, Dimetnpid etc.) lo other families, I lie reason is, thai these writers have laid greater stress on the form of colony ' 'r.i. p. s'i 96 or on the modes of connection of the zoa-cia. In their whole structure these forms undouhledly belong to the family BiceUurwUte. The peculiar contrast in Episto- mia and Sijiiiiotiim^ between the proximal cylindrical and the distal widened portion of the zmecium as well as the possession of |)e(lunculate avicularia, shows that the position of these genera is near lo (lormicopiiui. hi Gemellarid the dislal wall is as in Biu/iilci: angulale and furnished with a series of uniporous roselte- plales. We also find an angular distal wall in Didymia, the oa-cia of wliicli, like those in Einrateo and Coniiicopiiia, are surrounded by kenozooecia, and Dimetopia has like most of the Bicellariidae, free orocia. Finally, I have been obliged to set up new genera for the old F/«s/r«-species, Fl. nohilis, Fl. dissiniilis and Fl. militaris as also for BiujiiUi Mnrraijnna, BicelUiria Alderi and ('.iilewtiia" hicornis. It is however with some doubt that I refer the last sjiecies lo Ihis family. In the following synopsis of the numerous genera of Ihe family, lo which I have been ijnder the necessity of adding 6 more, I have as main characters in the separation of the genera mainly used diderences in the structure of the zoa'- cia themselves, as e. g. the presence or absence of an operculum, the division of the zooecium in different segments by constrictions, the structure of the dislal wall, and next the differences in the character of the occcia. I have used the piesence or absence of ooecia and avicularia, as well as Ihe dilVerences in the structure of Ihe avicularia, as auxiliary characters. Synopsis of the Genera. 1) The colony consists of two layers, the zowcia of which are of very different kinds (Ihe zod'cia in one layer are quite uncalcilied, without operculum, in the olher layer they are of the ordinary type; the distal wall consists of a horizonlal. basal iiorlion wilh a mulli- porous roselle-[)late, and of ii fronlal ascending portion; free oa-cia, freely movable avicularia) Diiuorpliozoiim n. g. 1) If the colony consists of two layers, the zocecia of the two layers are of the same kind: 2) Zooecia without operculum; (the edge of the dislal wall is angu- lar; within this a row of single-pored roselte-plales; free Od'cia, freely movable, cai)itate avicularia, radical fdnes issue both from Ihc fVoiilal, basal and lateral aspects of Ihe colony) limjiiln Okcn (Lev. mod). 2) zocecia wilh an operculum: ' 111, p. 14. i)7 3) The colonies, which never Iiave a free, upright growth, are ex- clusively attached l)y radical fibres which either issue from a creeping stolon or from the basal surface of the individual zoa?cia: 4) the colony is attached by radical fibres which issue from a creeping stolon; (the zoa-cia which issue separately from the stolon, are furnished with two rows of spines, joined together in pairs and separated by a single row of transverse slits; no avicularia, no ocrcia. . . StoloneUa Hincks. 4) the colony is attached by radical fibres which issue from the basal surface of the individual zooecia, and these are generally connected with one another by shorter or longer, wider or narrower tubes to form a network with larger or smaller apertures: 5) the zooecia very slightly calcified; the connecting tubes between the individual zooecia distinct; ocEcia wanting; as a rule pedunculate, freely movable avicidaria lieania Johnston (Diachoris). 5) The zoa>cia strongly calcified; the connecting tubes between the single zooecia indistinct, broad and short, and only visible from the basal surface; ooecia may be present; sessile avicularia; (from each avicularium issues a spine which is often much branched and may conceal a larger or smaller portion of the frontal membrane) Hiaiilopora Mac Gillivray. 3) the colonies have a free upright growth or are incrusting. 6) The distal part of the zooecia provided internally with two lateral spaces open towards the frontal surface (sometimes combined to one single, horseshoe-shaped space), formed by two calcareous plates which issue from the lateral walls and converge towards the distal wall; avicularia and free ooecia may be present; the colony incrusting or laminate) Cluipcrin Jul lien. G) The distal part of the zooecia without lateral spaces: 7) There is a frontal shield, formed by five broad hollow spines lobed at the edge and separated bj' rows of jiores; (a simple com|)lelely chitinized operculum; sessile avicularia) Petalosteyiis nov. gen. 7) No frontal shield: 8) No ocecia : 9) The distal, broader, more or less .symmetrical part of the zoa'cium is separated from a nearly as long, proximal, narrow, cylindrical part by a constriction: 10) The ba.sal edge of the distal wall is angular; no avicularia; a con- striction jusl (listally to the distal wall Halophila Husk (Lev. mod.). 7 98 10) The basal edge of the distal wall not angular; long-slalked fixed aviculaiia; no constriction dislally to the distal wall... EpisiomUi Fleming. 9) Tlie zott'ciuni not divided into a {)roxinial, narrow cylindiical and a distal wider part (no avicularia). 11) The basal edge of the distal wall angular; (radical fibres issue from the lateral margin in the proximal jiart of the zoa>cium . . . (leiiicllarid Savigny. 11) The basal edge of the distal wall not angular lirellid Dyster. 8) 0(rcia present: 12) The oa'cia, which do not issue from the boundary between two zooecia placed in the same longitudinal row, are covered by kenozooe- cia; (the proximal part of the zorecium separated from the distal by a more or less distinct constriction a little distally to the distal wall). 13) The ooecia are placed on zoa'cia of ordinary size; zoa'cia very asymmetrical, from the narrow tube-like proximal part widening into an obliquely funnel-shaped extremity, furnished with spines; as a rule there are found avicularia, the radical fibres, which go down along the l)asal surface of the colonj', issue from a rosette-plate a good way distally on the basal aspect of the zo(L'cia Conmcopina n. g. 13) The ocecia are placed on zooecia of smaller size; zoa;cia sym- metrical or only a little asymmetrical; no sj)ines; no avicularia. 14) The basal edge of the distal wall angular; the oa'cia-bearlng zooecia placed between two zoa'cia in a bifurcation; (the frontal wall of the kenozooecium membranous, furnished proximally with two calcareous ]irocesses; (no rosette-plate between two neighbouring zooecia Didijinia Husk. 14) the basal edge of the distal wall not angular; the oa>cia- bearing zooecia attached either j)roximally to the frontal area or to the basal surface of other zocecia; the frontal wall of the kenozoa>cium calcified Eucralea Lamouroux. 12) Free oa^cia issue from the boundary between two zooecia placed in the same longitudinal row: 15) The distal wall furnished with four uniporous rosette-plates, each of which is jjlaced at the bottom of a se])arate chamber; (no avicularia) Dimclopia Busk. 15) The distal wall not formed in this way: 16) Each zoa»cium has a strong muscle, which at its distal end is attached to the inner side of the external wall of the zoa'cium, and at the other to a conical ])rojecti()n from the distal wall of the next 99 lower zo(Pciuni; two successive zofccia separaled by a small iiiicalci- fied space; the distal wall has an uncalcified multiporoiis losette-plale; the radical fibres which arise from the hoiiiidary between two zo(L'cia at their rim, run proximally and join, filling the spaces between the branches in the proximal part of the funnel-shaped colony) .. . Kineloskids Koren- Danielsen. 16) No such muscle; no uncilcified space between the zoa3cia: 17) Each zoircium consists of three sections separated by constric- tions, of which the middle one is elongated, cylindrical, while the distal one is obliquely funnel-shaped (avicularia freely movable; the basal edge of the distal wall unequally asymmetrically angular; the radical fibres issue from the basal side of the zofrcium BicclUuin Hlainville (mod.). 17) The zooecia not divided into three segiuents separated by con- strictions: 18) The basal edge of the distal wall is angular: 19) Distal wall with two multiporous rosette-plates; sessile avicu- laria Biiyiilaria n. g. 19) Distal wall with small uniporous rosette-plates; free avicularia; (zooecia widening from a narrow cylindrical [)ro\imal [)arl into an obliquely funnel-shaped extremity; radical fibres issue from the lateral margins of the zoa^cia) Bicellarina n. g. (B. Alderi Busk). 18) The basal edge of the distal wall not angular: 20) Distal wall very slightly ascending, with several uniporous rosette-plates; no avicularia; radical fibres issue everywhere from the covering membrane of the frontal surface in the two-layered colony . . Wdlcrsid n. g. 20) Distal wall consisting of a basal, horizontal part with a muili- porous rosette-plate, and a frontal strongly ascending part ; freely movable avicularia ; radical fibres issue from the second (more seldom also from the first) rosetle-i)lalc of the marginal zocecia DendrobcanUt n. g. In the al)ove synopsis of the genera, in which the degree of relationship is not expressed by their consecutive order, 1 have not been able to take account of a series of earlier described forms, which I do not know from |)ersoual obser- vation. So far as Hnxleya is concerned, this genus is said to have a completely calcified, arclied frontal surface, and does no! seem to belong in any way to 100 this family. Brcllui liibcvformis seems according lo Hi neks' figure lo liave an angularlj' bent dislal wall and would therefore, according lo the above given synopsis, have to he referred to Genwllaria. Regarding Syniwtiini aviculure I have no information about the structure of the distal wall, and if this, as in Gemellaria loricdta. is angular, there might be some ground, in spite of the presence of avi- cularia, to refer il to the genus Gemellaria. A closer examination of those mem- bers of the family, which Busk has described in the Challenger Expedition's Bryozoa will no doubt lead to the setting up of several new genera, and Busk explains also that to avoid doing so he made his definition of the genus Biigiila very elastic, whilst at the same lime dividing the species into four groups. It will for these species be of j)rincii)al interest to lind out whether they have an operculum or not, and also how their distal wall and ooecia are constructed, hi Biujiila iniiabilis and '•Biigiila<' leontodon, of which two species I have been able to examine a small fragment without ocrcia, there is an operculum as well as an angular distal wall, and these together with two other species are referred to Busk's first group, where the ooecia which only a])j)ear in the median row of the colony, are enclosed in the proximal part of the higher placed zocrcium. The question is therefore, whether these si)ecies form a new genus or whether they can be included under Diclymia, the ooecia of which however are surrounded by kenozoci'cia. In Biigiila bicornis the higher j)laced zorrcium arises far back on the basal side of the lower and meets with this in a circular disk. The form, which Busk mentions under the name of Diachoris nuHjellanica, v. distans. but which he has not made the subject of any description, seems, to judge from Ihe figure given, not only to be a separate species, but also to represent a new genus. The whole frontal wall seems namely to be calcified except for a median longi- tudinal slit, which proximally is much widened, and in front is continued right to the aperture, which is provided with a sinus. Bugula Oken, char, emend. The zo(vdiiiu without an operculum. Distal wail with a basal angular edge within which there is row of uniporous rosette-plates. Freely movable capitate avicularia; free (xvcia. The colonies free, branched, the zooecia in two or more rows. Waters as is known has shown, that an operculum is wanting in Biujula, and Calvet has confirmed this observation lor Ihe French species. Whilst I am certain that an operculum is absent in Ihe other /J(/.(/H/«-species, which are found in our Zoological Museum, I am not (luile so sure of this for B. calicnlala, be- ini cause llu' individual zud'cia in Ihe badly prt'served colonies seem lo nie lo show a trace ol' an operculum, and if lliere is nol an even transition in this regard within the species we must very likely form a new genus for the species with an operculum. The angular bending of the distal wall may reach its maximum in li. (Ii'uldld Lamx, where the two lateral halves in some zorecia almost reach the proximal end (IM. V, figs. 1 a b). Bugula caliculata n. sp. (PI. Ill, figs. 1 a-1 q.) The zooecia, which from the narrow, proximal end increase in width distally, have on the outer distal angle a very short, curved spine, and on the inner a very long thread-like spine a little lower in position. In very j'oung and developing colonies however the first 3 — 7 zooecia have 2—3 long spines, and in such colonies the ancestrula is even provided with 6, of which the third (the lowest) on each side is placed at double the distance from the second as the latter from the first. The membranous portion of the frontal wall which in the ancestrula occuj)ies nearly half the length of the zoa>cium has in the common zooecia a much larger extent, hi the few single zooecia succeeding the ancestrula there is found a constriction in the proximal part (figs. 1 d, 1 e). The avicularia occur only in a relatively small number, and are situated a lillle within the outer lateral margin and a little distally to the proximal end of the zooecium. Each zooecium of a pair, where the bifurcation commences, is in most cases furnished with an avicularium, a rule, however with not a few excep- tions, especially at the last bifurcations. Besides these, a number of avicularia occur apparently without any very definite position. Ooecia small, globular, and their longitudinal axis is a continuation of that of the zooecia. The stem is jointed and consists of a row of long, narrow segments (keno- zocecia) widened a little at both ends and rounded quadrangular in section. The distal end of such a kenozoa-cium is provided a little proximally to the joint constriction (fig. 1 1), with a distal wall, saddle-shaped from side to side and from the front to the base, which on each side is furnished with 4—5 small, uniporous rosette-plates, all of which may sometimes be separate, sometimes con- nected together in groups. This calcareous distal wall is continued internally along each of the two lateral surfaces of the kenozocecium as a calcareous band (fig. 1 (j) which as time goes on increases in width and in thickness. The two bands join together to a ring-shaped portion (ligs. 1 1-1 m) at the proximal part of the segment, and the intention with the whole of this arrangement is evidently 102 to strengthen the resisfiiig power of Ihe otherwise slighlly calcilieii stem. Along the middle of tlie frontal surface of each segment we find an exceedingly nar- row membranous frontal area, which even in its distal part is furnished with parietal muscles (figs. Im — In), which Kirkpalrick has also found in B. (Stirparia) Hnddoni. New colonies arise from the stems of the older, taking their origin between two contiguous segments, and the j'oungest, which have a very small number of zoa>cia, possess only a single stem-segment, which in time increases in lenglh and seems to be formed by a constriction of the j)roximal pari of Ihe anceslrnla (figs. 1 c, 1 d, 1 f). After the ancestrula follow two still solilaiy zooecia, after which Ihe first bifurcation commences. The older colonies, with from 3 — 17 joints, have only one solitary zoa'ciuni, which according to the age of the colony sometimes has altogether 2 — 3 spines, and sometimes none at all, while Ihe distal wall, as in Ihe segments is connected with two calcified bands whicli are fused together in Ihe jiroximal part of the zoa^cium into a ring. A larger or smaller number of the older zoo?cia according to their age show a similar Iransformation, and a comparison between the youngest and oldest colonies leaves no doubl about the fad, Ihal the solitary zooecia in Ihe proximal . portion of the colony are in time transformed to segments, while the proximal segment arises from a constriction of the proximal part of the ancestrula. I cannot determine with certainty how the other segments are formed, but as new colonies can arise between two segments, it seems reasonable to suppose, that new seg- ments can also be formed between two older ones, and the fad that the seg- ments may have a very dilTerent length favours this supj)osition. Neveitheless, I have nowhere found Ihem so short that I could consider them as just beginning. The radical fibres, which in the older parts of the stems issue in numbers from uniporous rosette-plales in the areas between the two strong, calcified bands, are simple calcified fibres, which partly cover the trunks, partly project freely from these, hi some places they are pear-shaped, swollen in a part of their course and contain a strongly refractive, shining mass, while such swellings at other places project freely and thereby assume a great likeness to the gonothecae in Ihe Hydrozoa. As far as the physiological importance of these swellings is concerned, I would j)ut forward the supposition that they serve for the accumu- lation of reserve materials. Waters' has found (juile similar formations in liu- gnla (Stirpciriri) glabra Hincks. The colonies are frequently compound, and Ihe small colonies have the form of stalked caliculate tufts, the branches of which show (5 bifurcations in the ' 111, p. 20, fig. 1. 103 largest ones. In the largest the stalk or stem has a length of ill mm., and tlie cup a height of 75 mm. It is not quite clear to me whether the above-mentioned, (juite young colonies have arisen by budding from the older colonies, or whether they originate from larvaj which have attached themselves. The fact that they arise as a rule be- tween two segments, whilst a single one of them issues from the frontal surface of another zoaxiuni in a somewhat young colony, speaks in favour of the lirsl view. While the one stem-segment in the very young colonies is very thin and rather short, I have observed in various colonies, both in young and in somewhat older, a thick and long, newly formed segment with a distinct terminal growth, arising sometimes between two stem-segments, sometimes between a stem-segment and the ancestrula, or between the two oldest zoa'cia (fig. 1 g). In these cases the colony always seems to commence with the formation of a stem. A number of colonies of this species were collected at Hongkong in shallow water by Captain Suenson. I originally believed this species to be identical with Stirjxirict Huddoni Kirk- patrick\ and the figures of this species are therefore indicated by the latter name on Plate III. A closer comparison with Kirkpatrick's description and figures has however convinced me of the independency of the species here de- scribed. Si. Haddoni not only lias no avicularia or spines, but differs further from B. caliciilota in the strongly arched basal surface of the zocecia. and their strong turning inwards towards the middle-line of the branch. In both these features B. Haddoni shows a great resemblance to the new species B. candhica to be described later. Bugula glabra (Hincks). Slirparia glabra Hincks, Annals, nat. hist. 5. S. Vol. XI, pag. 196, PI. VI, fig. 2. Bicellaria glabra (Bicellaria stylites in tai)ula) Busk, Challenger, Zoology, Vol. X,^*in>g- •^i'. !''■ VI, fig. 1 a. Stirparia glabra Waters, Journ. Linna;an Soc, Zoology, Vol. XXVI, pag. 19 (I'l. Ill, lig. .Sa). I have examined a very young colony of this species with S stem-segments and only 3 full-grown zoircia, in which the ancestrula has only 3 long spines on each side, whilst a larger number (5—7) occur in the specimens examined > 49, p. 603. 104 by Ilincks and Busk. The dislal wall is anf;ulaily l)eiil, and lo judgi' from the slrucliiiT of these zoa'cia this species can he rct'erred neither lo Hiccllnria nor lo Conmcopina. The sliiiclure of the oa»cia is not known. Tlic stem-segments have a structure cjuite similar to tliat of llie last sptcies, and the above-expressed suggestion, that new segments may be inserted lielween the older ones, is streng- thened by the fad that every second segment of the specimen examined by Hi neks is scarcely half the size of the others. There is also a very small seg- ment (the tifth) in the colony examined by me. According to Waters' investi- gations, the radical libres quite agree with those in li. cdlicuhiht and have especi- ally the same kind of pear-shajjed ex])ansions. The small colony which I have received through the kindness of Miss Jelly, comes from Port Phillip, Australia. Bugula caraibica n. s\^. (I'l. Ill, ligs. 2a-2n). The zotecia, which increase in width distally from the nari-ow ])roximal end, are turned inwards towards the middle of the branch, in sucli a way, that the frontal areas of two neighliouring zoa'cia form nearly a right angle with one another, and they have thus, to judge from Kirkpa trick 's tigure, been subject to a much smaller turning than the zoa'cia in B. Hmliloni. The frontal end is cut off straight and the basal surface strongly arched with an almost semicircu- lar transverse section. Almost in the middle of the distal margin of the basal wall there is in numerous zoo-cia a rather strong s|)iiie (fig. 2b), which may grow longer than the zoo'ciuni, but is often very short. It seems to be (juite wanting however in other zooecia. Theie is very seldom a very short, external corner-spine. The distal wall is insymmetrically angular (fig. 2 d), and somewhat distally from this there is a ring-shaped constriction. The avicularia, which occur in very small number, are placed outside the membranous frontal area in its proximal portion. The ooecia. the outer layer of which is calcified, are nu)ie than half the length of the zooecia, elongated, strongly arched and marked with radiating striae. They are placed obliquely relatively to the zoa'cia, and turned so much outwards that they can be seen in the wdiole of their extent from the basal as- pect of the colony. The segments (Kenozooecia) of the stem are, seen in transverse section, circu- lar or perhai)s slightly (juadrangularly rounded. Here also we find two calcified thickenings internally, arising from the distal wail and showing lines of growth. They meet in a ring at the j)roximal end of the segment, but otherwise they 105 (iilVer from the coii-es|)onding thickenings or bands in ]i. niliciihild in several ways. Tluis, their thinner middle portion passes evenly over into two thicker, rounded marginal portions (fig. 2 k), and further they are much broader, occu- pying more than half the periphery of the whole segment. They divide this into lour, unequally large areas, of which the largest lies on the basal surface of the colony and the narrowest on the frontal surface. This last area which does not seem to have any membranous jjortion at all or to be jirovided with parietal muscles is not rarely divided into two or more areas behind one another, as the two calcareous thickenings may be connected by one or several transverse bridges. The distal wall (figs. 2 1 — n, 2 j), which is saddle-shaped fiom side to side, is over its whole surface provided with extremely numerous, small uniporous rosette- plates, so that the whole di.stal wall migiit really be regarded as a large multi- porous rosette-plate. In its whole extent it is attached internally to the wall of the segment by ascending, often branched chitinous rods, which are apparent from the outside anil produce digitate and lobate figures. The colony consists of a nunil)er of jointed stems which have two alternate rows of llahellate branches with lour to five bifurcations and up to 40 linear segments with biserial zooecia. Each of these branches is in connection with the stem through a multiporous rosette-plate, which is placed a little proximally to the end of a stem-segment (tigs. 2 n, 2 i, 2 j), and such a rosette-plate is only found on that side of the segment where a branch issues. I have only in a few cases found two successive branches arising from the same side but never two branches placed at the same height. From each stem again 2 — 5 new stems arise, in most cases just opposite a branch, more rarely alternately with these, and in a few cases I have found a new stem arising just proximally to a branch. New stems which are in connection with the main-stems through multiporous rosette-plates seem to arise in a doul)le way, partly by transformation of branches and partly independently. While the common branches are fixed by a zocecium, the proximal part of which is provided with two rings, I have seen a number of branches only ditferent from the others therein that 1 — 2 slender segments are interposed between the zoo-cium and the stem, and most likely these branches are about to be transformed into new stems. A great number, however, of the young stems, which issue fiom the main-stems and for instance those, which are seen in fig. 2 a, cannot well have arisen in this way, which in the first instance may be inferred from their being generally placed opposite the branches, as two branches are never [)laced at the same heiglh. In the next place these stems are characterized by their being provided with branches only at a very late period though there is a rather large ditlerence in that respect. Only in a single stem 106 with two segmenls I ha\e louinl ;i lilllu leriniiiiil bianch showing a double l)i- liiicatioii while a eoinmon hianeli on a niain-sleni as already said shows 4 — 5 bifurcations. In all the other young stems tlie tip is devoid of a branch, which no doubt has fallen of. While a terminal branch is a direct continuation of a stem and does not arise from a losetle-plate, the formation of a rosette-plate always precedes the formation of a branch, and even if all the lateral branches have dropped of, as is the case in many of the stems examined, their position and number is indicated by the respective rosette-plates. The examination of a number of stems shows that the first rosette-plate appears proximal ly to the partition-wall between the end-segment and the one next to it, and that the development of these formations goes steadily downwards. I shall here give a few instances showing the difference in the appearing of the rosette-plalcs. a stem witli : 6 joints Tlie fifth segment with a beginning rosette-plate. 7 — Rosette-plates on the six segments. 9 — A Rosette-plate on the seventh segment. The partition wall between the eighth and the ninth segments is not wholly developed. 11 — Rosetplates on the nintli and the tenth segments. 13 — Rosetplates on the eleventh and the twelfth segments. The number of segments in the trunk gradually increases by division of the older segments, and when two short segments follow one another this is a sign that a division has taken place lately. The proximal segment of the two has then not yet got the lateral rosette-plate, and the proximal end of the distal seg- ment does not yet show the rounded swelling defined by a more or less distinct constriction, which is seen on the completed segment. A division like this is always introduced by the two strongly calcified lateral belts on each side sending ))rolongations towards one another, which at last join together to form a bridge. The radical fibres, which issue from the proximal end of the stems serve exclusively to attach these to the surroundings. They are much branched, furnished with irregular expansions and swellings, and like the stem divided into sections (kenozooecia), which inlernally are separated by multipbrous rosclte-j)lates, l)ut externally have no distinct constrictions. We further find a muiliporous rosette-plate everywhere where a new branch arises from an older one. While the radical fibres have in Ihe beginning on arising from the stem a struc- ture similar to the latter their wall soon becomes evenly calcified over the whole of its surface. 107 - The colony examined consists of c. 20 zod-c-ia-ljearing main Irnnks, of which the longest have forty odd segments and a length of l(i.5 etm. The segments have a length of 3 — 5 mm. Christiansted lagoon, St. Croix (Fishery hispector Mag. Chr. Lofting). Dimorphozoum nov. gen. The colony consists of two layers, the zoa-cia of which are of exceedingly diverse natnre. In the one layer (the Ctenoslome) they are quite uncalcitied and have no operculum, whilst in the other (the Cheilostome) they have an oper- culum and the structure general in the family. The last layer has besides the following characters: the distal wall consists of a basal horizontal portion with a multiporous rosette-plate, and of a frontal ascending portion; free oarui; freely movable, club-shaped aviciilariu. D. nobile (Hi neks). Flustra nobilis, Hincks, Annals nat. hist, fi Ser. Vol. 7, 1891, pag. 288, PI. 6, fig. 5. Waters Journ. R. micros. Sj/c. 1896, pag. 281, PI. 7, fig. 10—11. (1^1. IV, figs. 1 a^l f). The Clieilosloinc latjer: The zooecia are elongated hexagonal, and the frontal wall membranous in al- most its whole extent. The distal edge furnished with 4 spines, which may vary considerably in size, and of which the middle ones are the longest. When they are not very small, each one of them sends out a small, distally directed branch from its proximal half. There are as a rule 4—6 bifurcated spines on the distal half of each lateral edge, which also vary considerably in size. The inner branch is generally the longest, and may occasionally reach more than half-way over the frontal area, it may als,o however be (piite absent. The distal wall ends basally in a straight edge, and there is generally a more strongly calcified belt (fig. 1 d) both proximally and distally. It is provided with a very large, multi- porous rosette-plate (fig. 1 c) and such is also found in Ihe distal half of each lateral wall (fig. 1 b)'. On the basal wall of a great many zoa-cia there are 1—4 ' When I give the number of rosette-plates (109, j). 281) in tlie distal lialf •.)! the lateral walls it is because in species with independent lateral walls it can easily be seen (p. 27) that the rosette-plates (or at any rate their main parl^ as a rule belong to the distal half of the lateral walls, the proximal part only possessing a corresponding number of openings, each surrounded by a pore-ring. In species with common lateral walls only the rosette-plates in the distal half of a lateral wall have their con- vexity turned inwards. lO.S niultiporous roselte-plales, which serve as conneclion with the zou-cia in the second hiycr, and are convex towards Ihese (fig. 1 c). The avicularia wliich Hi neks wrongly gave as niemhranaceous do not seem to occur on all zoa'cia, hut are in most cases represented l)y two. ^^'e can occa- sionally find 4. They are not, as represented by Hi neks, attached to the basal surface of the lower zocx'cium, hut to the proximal end of the liigher. Each lateral edge namely sends out a narrow prolongation directed inwards, to which the avicularia are attached, and at the place of attachment of each avicularium we find a small uniporous rosette-plate. The avicularia are conical or club- shaped with a straightly cut frontal area, and the operculum, which is broadly chitinized in the margin, has in its proximal part a half-moon-sha|)ed lucida (fig. le). The ooecia which up to the present have been overlooked, are free, without slrialion, provided with an uncalcilied ectoocecimn and very low. They are how- ever somewhat higher when seen from the basal surface. The Ctenosloiite luycr consists of quite uncalcified, elongated liexagonal zotccia with a two-lipped aperture, and they are in all respects much like the zoa-cia in an Alcijonidiuni. I can give no information about the rosette-plates, as I have only examined dried colonies, and it was only after moistening these that the dried-uj) zoix'cia of this layer showed their real nature. I have twice received material of this species from Miss Jelly, once a large colony labelled South Africa, and an- other time a number of fragments together with small colonies of CJutju'rid copensis, labelled Port Elisabeth. All these specimens, of which the last were richly furnished with ooi'cia, were quite covered with the layer of uncalcilied zoo-cia, and as the basal surface of the other zoa'cial layer is at the same time richly furnished with rosette-plates, I have no doubt that the two layers really belong together; but it would be very desirable to make an examination of fresh material in order to determine this (juite unique dimorphism with cer- tainty. The colonies are foliaceous with slightly lobate margin, attached by a dense mass of radical fibres, which in the Cheilostome layer arise from the margin of the zocrcia in their distal half. Bugularia nov. gen. The distal wall angular with two niultiporous rosette-plates; the oo'cia free; (whuliivia sessile, not peduiu-iilnte. 109 B. dissimilis (Busk). Carbasea dissimilis Busk, Catalogue of Mariue Polyzoa, Pari 1. Clieiioslomata pag. 51, PI. 50, figs. 4 — 7. — — Busk, CiuUlenger, Zoology, Vol. X, Pari I, pag. -5fT. S's Fluslra dissimilis Waters, Journ. R. Micros. See. 1896, pag. 282. (PI. V, fig. 2 a— d). The zooecia elongated, quadrangularly tongue-shaped, with as a rule a niucli narrower proximal half, of which a larger or smaller part is calcified. Three pairs of spines may occur, of which fre(iuently only a smaller number is devel- oped. In colonies without oa'cia only the first pair is generally present, but even tliese may be lacking or rudimentary in many zocecia. In colonies with ocecia, it is rather difUcult to find this pair of spines from the surface of the colony, as they are placed in a hollow on each side of the oa>cium. The marginal zorecia which are longer than the others, are drawn out into a plump corner- spine. The distal wall, which is furnished with two multiporous rosette-plates, is much bent angularly, and has besides a distinct saddle-s]iaj)ed curve from the front to the basal side (fig. 2 b, 2 c). Each lateral wall is furnished in its distal half with two multiporous, strongly projecting rosette-plates. The basal surface of the zooecia is coarsely striated transversely (fig. 2 b). The avicularia which are placed in the middle of the proximal, calcified portion of the zowcia are attached by means of a rather wide proximal part and the tii)s are turned in diil'erent directions. The ocecia are not as fiee as they are in Biujula, rather a large part of their basal wall being firmly connected which tlie higher zoa'cium. They are very large, furnished with an uncalcified ectooo'cium, and the endoooecium besides a distinct double striation also has a cliaracteristic system of lines bounding triangular or s([uare api)arently impressed meshes. Cornucopina nov. gen. Bicellaria p. p. (PI. IV, fif^s. 4 and 5). The zixrcid widening from a long, tube-shaped proximal end obliipiely up- wards, funnel-shaped, with a ring-shaped constriction at a greater or less distance from the distal wall. The mrcift, which are not placed between two zocecia in the same longitudinal row but on the zoa-cial distal margin, which is directed outwards from the middle of the colony, are surrounded by kenozo(x'cia. In most 110 species appear nviciilaria, which are generally capitate and pedunculate or trumpet- shaped. The radical fibres, which run down along the basal side of the colony issue far distally on the individual zoa'cia. The colonies are elegant tufts with biserial branches. This genus which will most probably be split up later into several includes the majority of the species in the old genus Bicellaria\ and the only species known to me which remains in this genus is B. ciliata. One of the characters which, in a narrower sense, separates the genus Bicellaria from Cornncojnna, is the sharp constriction between the wider funnel-shaped terminal portion of the zoa>cium and the proximal cylindrical portion, and Corniicopina yrandis in this structural feature approaches Bicellarid, as we lind at the same place internally a narrow, ring-shaped, oblique, chitinous thickening. This species also occupies a special position within the genus in having a cryptocyst (fig. 5 a), already ob- served by Harmer-, which extends under the larger part of the frontal mem- brane and reaches almost to the operculum. It is provided with hnely curved and dentated edges, and it rises dislally from the deeper, proximal part to end in a free, shovel-shaped plate. Two successive zooecia are connected by a multi- porous rosette-plate, which is surrounded l)y a calcareous ring, and this is again connected with a similar ring surrounding the adjacent rosette-plale of the lateral wall (fig. ii a — 5 b). Busk has overlooked the very large plump avicularia, which in this species here and there issue from the basal surface of the zooecia a little proximally to the outer margins (fig. 5 c). Beania Johnston. Diachoris. The very slightly calcified zon-cia are mutually connected by cylindrical lubes to a more or less open network, which is attached to the underlayer by radical fibres arising from the basal surface of the individual zocjecia; each lube is fiirii- ished with a multiporous rosette-plate; no oa-cia; as a rule freely movable avicalariu. While all the species, which I have been able to examine of this genus, have an operculum, such according to Busk's^ account and figures, is lacking in Diachoris tmujclUtnicn, in which the aperture is said to be surrounded by a circu- lar thickened rim. If this account is correct, this sjjecies must jjrobably be re- garded as the re[)resentalive of a s])ecial genus, and this inii;lil tlu'ii retain the old iianie Diaclwris. — In the sj)ecies from Ita[)allo, which Waters calls />'. ' 8, p. 31. - 111, p. .cjii Ill nui(jelhuiic(i\ ami of which species this wriler has been so kind lo send nie a fragment, there is an operculum: Hiantopora Mac Gill.', char, emend. The strongly calcified zooccia are connected by cylindrical processes, each of which is provided with a multiporous rosette-plate. The oo'cia tree; sessile avi- cularia; the colony attached by radical fibres, which issue from the basal wall of the individual zorecia. From the proximal portion of the avicularium rises a hollow spine, which as a rule is strongly branched and may cover over a larger or smaller part of the frontal membrane. H. radicifera (Hincks). Membranipora radicifera, Hincks, Annals nat. hist. 5 S. Vol. 8, 1881, pag. 5, PI. 2, figs. (J, 6 a, (i b. (PI. IV, figs. 6 a— 6 c). The zooecia are broad, hcxagonally rounded, with two short, blunt spines and a little further proximally on one, generally the left, lateral margin with a short l)ifurcated spine with two unequally long branches. The strongly arched basal surface runs out into six, a little lower placed, but also arched, .somewhat broad and short tubes which are separated by broad and deep pit-like depres- sions and meet with corresponding processes from the neighbouring zooecia. At the bottom of each pit is an oval hole, which opens on the frontal surface of the colony, but on account of the somewhat imbricate position of the zo(Bcia, these holes are not very distinct. They open on each side of the distal end of the zoiL'ciuni. Each tube is furnished with a large, multiporous, strongly calcified rosette-plate, occupying the whole of its breadth, and the arched basal surface of each zod'cium is furnished with 4 6 uniporoiis rosetle-])lates, which serve for connection with the numerous radical fibres, by the aid of which the colony is attached to its underlayer. The avicularia are large, proximally furnished with a small, curved spine, and provided with a mandible, which is inclined to one side. Each zoa'cium has such an avicularium attached along the one lateral margin and directed oblicjuely inwards, opposite the above-mentioned bifurcated spine. The ooecia, which Hincks does not mention, are free, widest at the proxi- mal end, cup-shaped or semi-conical, furnished with an obliquely ascending in. p. iCi, - 7.'). p. .a^ 7(i. pp. (id— (ii. •208 112 frontal surface, and with a calcified, rugged ectoooecium. On each side of the oa'ciuin is a small ohli([uely placed si)ine. 1 have been able to examine a colony ol' Ibis species from Port Phillip, Vic- toria (Miss Jelly). To the genus Hinniopora, which Mac Gillivi-ay lias founded on "CrihrUhui' fero.v, I must, besides Ibis sj)ccies, also refer Mcnibvdnipord rddicifent as well as the form which Kirk])a trick has described under Ibe name M. nuiicifcra, v. intermedia, and which he considers as an intermediate form between //. /c/o.r and H. radicifera. I agree willi Ibis writer as to tiie necessily of referring all three forms to the same genus; bul whilst he refers them to Meinbranijmrd, I must, partly on account of their points of agreement with lieania, partly because of the free ott'cia, refer them to the family liicellariidae, and although they must come close to Beanid, they camiot for several leasons be included under this genus. Some of these reasons are: the strong calcification, llu- |)resence of oa-cia, wbicb however have hitherto only been found in H. radicifera, and finally the ])resence of the sessile avicularia (in conlrasl to the pedicellate inovai)le ones in Ileania). Lastly this avicularium is in all three species furnished with a spine, wliich in each attains an extremely variable development, and in //. fero.v coxers (be greater part of the frontal surface with its branches, and Ibis is the reason why this species was formerly referred to the genus Cribrilina. In //. radicifera it is rallier small undivided, conical, whilst it is much larger and richly branched in //. intermedia, but in contrast to the spine in //. ferax it projects fieely bere. Of H. ferox besides Kirkpalrick's original specimens I have been able to examine two others, namely one from Port Phillip (Miss Jelly) and another from Port Phillip Heads (Mr. J. Gabriel); they show all dilferences in tbe shape and development of the aviculaiian s])ine, so that the species seems to undergo great variation. It may be possible to set up several dilferent species. All three species agree however in that tbis hollow aviculaiian spine wbicb may in realilv be looked upon as a hollow, branched continuation of tbe avicularian cband)er, is not, as Kirkpatrick seems to believe, connected with the opposite margin of the respective zocKcinm, but nuiinly witli parts of the surrounding zott'cia, |)ailly with their distal spine or distal margin, |)arlly with their avicularia or with the branched prolongations of these. The tip of the avicularian .spine is however often fused togelbei- witb a small branched spine, which ari.ses from the distal half of tbe opposite margin of tbe zoo'cium. Mac (iillivray', who originally i-el'erred tbe genus liiaiihiiinrii to IJic I'amilv ' 75, i).,4«r rot 113 Cribrilinidae, has in a later paper' made this genus into a special family Hianlo- poridae, to which he also, besides some fossile forms, which I Iiave not had the opportunity to examine, refers Cribrilinn monoceros, and Hincks'-' stated already in an earlier work that the two species ought to be united into one genus, and that this genus ought to represent a new family. I cannot admit, however, that there is any relation between the two species which only show the external agreement, that a larger or smaller part of their frontal membrane is covered by branched projections; but whilst these are hollow and originate from the avicularia in //. ferox, they are solid and originate from the lateral margins in C. monoceros. They thus show a difference in the only structural feature, which could be in favour of their being united to form one genus. As the genus Hiantopora, accor- ding to the foregoing definition naturally belongs to the familly liicelhiriidae, I am unable to adopt Mac Gillivray's family. Brettia Dyster. ? Maplestonia, Mac Gillivray. (PI. IV, figs. 9a-01}). The distal wall is not angular; o(vcia and avicularia wanting; the colony with single-rowed zoa-cia. I must for the present refer Maplestonia to this genus, as there is nowhere in the diagnosis given by Mac Gillivray a character sufficient to separate it from Brettia. I have been able to examine a small fragment of a colony of M. simplex with some few zociecia, the frontal membrane of which is surrounded by a more strongly calcified cryptocyst with fine lines of growth, which also surrounds the distal wall. Otherwise the two species M. cirrata and M. simplex seem to show great differences, and the first' resembles Catenarin in its whole mode of growth. The form, which Waters^ has named llrellia friijida and of which he has been so kind to spare me a little branch, is, as he has himself supposed, identi- cal with Smitt's liiigula qvadrideiitata, wliich is only a growth-form or variety of Dendrobeania Miirraijnna. This species sometimes appears with mulliserial (4 — 26 rows), sometimes only with uni- to fourserial branches (H. qvadridentata) and of the last form I have through the kindness of Prosessor Theel, Stockholm been able to examine colonies from Spitzbergcn. In contrast to the species of the genus Bmjnla as defined here, the distal wall in I). Miirraijana is furnished with a multiporous rosette-plate, and in the distal part of each lateral wall, we find two ' 7G, pp. GO— Gl - :!8a, p. 479. = G7, p. 92. * 114, p. jl. 114 such plates, placed close together on a more strongly calcified and proxlnially sharply defined part of the zoa^ciuni. The same is the case in Brettia fri(jida, and I shall only mention further, that whilst the zooecia in the uniserial hranches are as regards rosette-plates provided in (juite the same way as the zooecia in the many-rowed hranches, they lack the holes on Ihc other hand in the proximal portion of the lateral wall, which in the zoa?cia with several rows, correspond with the rosette-plates on the neighbouring zooecia. Petalostegus nov. gen. Catenaria p. p. The membranous frontal area is covered by a circle of mulually connected plate-like or leaf-like hollow spines; a slightly chitinous, semicircular, simple operculum; sessile avicularia; free (?) ooecia; zooecia in one row. P. bicornis Busk. Catenaria bicornis Husk, Challenger, Zoologj', Vol. X, PI. 1, pag. 14, PI. 2, figs. 2 a, 2 b. — — Waters, Challenger, Zoology, Vol. XXXI^, p. 9, PI. 1, fig. 1. (PI. IX, figs. 8 a, 8 b). The zooecia widened upwards from a long, narrow, tube-shaped proximal part, oblique quadrangularly oval, strongly arched especially on the frontal sur- face, the largest part of which is formed by a membranous area, covered by five mutually coalesced hollow spines. These, which spring from the rim of the frontal area with a relatively narrow proximal part, have a broad rhombic form and are therefore in the marginal part of the frontal area separated by four wide, but low interspaces, which are bounded externally by the edge of the frontal area, internally by the proximal edges of the rhombic spines. At the two distal spines the corresponding space is formed by the aperture itself. The distal much longer portions of the spines are each furnished with 2 — 3 very short projections, which meet wilh corresponding projections from the adjacent spines, and the five radial sutures are thus j)rovided with 2 — 3 larger or smaller oval pores. Of the five spines the proximal is the largest, and meets with the two distal in a triradiale suture, whilst the two others which are the smallest do not reach in lo the middle of the area. The rhombic form of the three larger spines thus becomes somewhat modified, in such a way that the proximal s])iiie is strictly irregularly hexagonal, and the two u])per pentagonal. The aperture, which is placed a little proximally to the distal edge of the zocecium, is almost semi- 115 circular, though in such a way that its distal curved edge (the anter) meets with the almost straight proximal edge in two almost parallel lateral margins. The aperture is occupied by a membranous opercular valve with a chitinous rim. On the basal surface in the distal part of the zooecium between the two avicularia we find a small, more calcified, quadrilateral area. The avicularia which are placed on each side of the distal part of the zooe- cium, are somewhat strongly compressed with an elongated oval frontal surface which is tuined outwards. Seen from the side they are trapez-shaped with a small hook-shaped curve. The ooecia are lacking on the branches examined by me, but according to the description (»galeriform, lofty, terminal*) Busk gives, there is hardly any doubt that they are free. The colonies have uniserial branches, and from each zocecium issue two new ones, one from the tip, and one from a triangular projection on one (the right and the left in turns) of the lateral walls, a little above the centre of the wider terminal part of the zoojcium. I have been able to examine a small branch of this species from the Chal- lenger's station 280, which has been kindly placed at my disposal by Mr. Kirk- pa trick from the British Museum. In favour of its reference to this family speak not only the agreements in mode of growth and zooecial form with Bretlia, but in still higher degree the free ooecia, since free ooecia do not appear in any other Malacostege family. Chaperia Jullien ^ The distal part of the zocpciiiiu is furnished internally with two lateral spaces open towards the frontal surface (sometimes coalesced to a single horse-shoe- shaped one), formed by two plates which project from the side-walls and converge towards the distal wall. Each distal wall has 2 multiporous rosette-plates and the distal half of each side-wall a single one. Hyperstomial free oacia with a com- pletely calcified ectooa'cium. The zod'cia which may sometimes have a membranous opercular valve, sometimes a chitinous comj)ound operculum, are generally strongh' provided with spines and have often a well developed cryptocyst. Avicularia sometimes trumpet-shaped, not always present. The colonies are incrusting. To this genus belong the following species: Ch. annulus Manz (^ Ch. (juleata Busk), Ch. cristatn Busk, Ch. ceruicornis Busk, Ch. cijUndracea Busk, Ch. albispina M. Gill.', Ch. capeims Busk, Ch. patiilosa Waters', Ch. tropica Waters^ etc. ' 45, p. Gl. ' (14, p. 116, pi. fig 10. ■' 11,'), p. :!3. * 110 a, p. 168. 116 Family Farciminariidae Busk. (PL I, ligs. in-in). The zoa'cia as a rule slightly calcified, occasionally with a small secondary cryptocyst, without true spines, furnished with an ohliipu-ly asceiuiing distal wall, and separated by common lateral walls which are furnished with a small number (2 — 4) of uniporous rosette-plates. The aviciilaria dei)endent, sometimes depressed, sometimes strongly projecting. The o lucida' . The ooecia are large, broad, flatly arched, rugged, and furnished with a pro- truding proximal rim, which is separated from the other part by a ring-shaped impression. From each of the distal zowcium's calcified lateral margins issues a narrow, obliquely triangular calcareous plate, which pushes in between the endo- oa'cium and the ectooa-cium, and comes to lie over the former with its concave lower surface. It is furnished w'ith a shorter inner, and a longer outer, free marginal edge. The colony is bifurcated u]i to three times and the zofx-cia arranged in four longitudinal rows. A single colony of this species was taken by the Ingolf Expedition at hit. 600 17/ N jQ„g^ 540 05/ y^r at a depth of 1715 fathoms. All the Farciminaria species which Busk has described in the Challenger Report except F. atlantiai undoubtedly belong to this genus. Farciminaria Busk p. p. The zou'cid have a larger or smaller number of small, spine-like processes, which are placed either on the frontal membrane or on the lateral margins; the (Hx'cid are surrounded by kenozoa'cia; an (tinciilariiiin similar to that found in Coliimnaria occurs in a few cases; the colony not jointed. F. uncinata Hincks. Annals Nat. Hist. ser. 5, Vol. XIV, 1884, pag. 277, PI. VIII, Og. 2. (I'l. I, lijcia. The distal wall between the ooecium-hearing zooe- cium and the kenozooecium is, as in F. unciiuita, much bent at an angle and I'urnished with a thickened margin. The kenozooecium has no operculum as it has been figured by Busk. The colony has a similar structure as in the foregoing species, but the zooe- cia are arranged in 6 longitudinal rows. A colony from Port Phillip Heads, Victoria (Miss Jelly). According to information kindly sent me by Mr. K. Kirk])atrick I must also refer F. atlaiilica Busk' to this genus. Nellia Busk. Farcimia, Pourtales. The zod'cUi without spinous processes; the distal wall has at its inner corner a single rosette-plate; the ooecla are in almost their whole extent immersed into the proximal i)arl of the ordinary zoa'cium, and project only very little on the surface of this; the avicularia are attached by a wide base or partially immer- sed, with calcareous transverse bar; the colony jointed. N. appendiculata Hincks. Annals Nat. Hist. ser. 5, vol. XI, 1883, pag. 199, PI. VII, fig. 4. (PI. I, figs. 11 a- 111)). The zocecia wide, rounded rhombic, with a memlManous frontal area which occupies almost the three-fourths of their length, and which, except for the pro- jecting distal edge, is furnished with an immersed cryplocyst in the remaining marginal part. Each distal wall is furnished with one, and the distal half of each lateral wall with a single uniporous rosette-plate. The avicularia which occur in pairs for each zooecium are elongated, some- what curved, tapering towards the proximal end and furnished with an arched outer surface. They are placed in such a way that with their inner lateral edge they border on the distal half of a lower zooecium and with their outer lateral edge on the proximal half of a higher zorecium in a neighboining row. At the distal end there is an elongated frontal area perpendicular to the longitudinal axis of the avicularian chamber. The triangular mandible, which is directed obli- quely outwards and proximally and which is furnished with a Uuida, has like ' 8, p. 49. 120 the corresponding part of the avicularium a little hook. In a large number of avicularia the membranous covering of the frontal area is transformed into an acuminated tenfaculiforni process and in such avicularia there is no trans- verse bar. The ooecia are almost semiglobular, but in the greater part of their extent immersed and only projecting externally as a slightly i)rominent pent-roof-shaped portion distally to the zoa^cium, which portion is at the sides bordered by the avicularia. This projecting portion consists of two calcareous layers, the ectozooe- cium being also calcareous. The colony consists of somewhat short, cylindrical club-shaped segments with four rows of zocecia and 3 — 4 zod'cia in each low. Port Phillip (British Museum). N. tenella Lanik. Nellia oculata Busk, Catalogue Marine Polyzoa, Cheilostomata, pag. 18, PI. LXIV, tig. (5, PI. LXV (bis), fig. 4. (I'l. I, figs. 13 a— 13 c). The zooecia elongated, quadrangularly rounded, with a proximal, calcareous portion, which may occasionally reach nearly one-fourth of the whole length of the zoa^cium. The elongated, oval frontal area is surrounded by a thin projecting rim, and at its posterior marginal portion there is a small .secondary cryptocyst. The distal part of the frontal area, which includes the operculum, is on each side separated from the remaining part by a small tooth-shaped projection of the lateral margin (fig. 13 c). The distal wall and the distal half of each lateral wall is furnished with a single uniporous rosette-plate. The avicularia which appear in pairs on the proximal, calcareous part of the zooecium, are rather small, and have a large part of their chamber immersed in the colony, which part is apparent, funnel-like, through the lateral walls of the zooecium (fig. 13 b). At their proximal part Ihey are provided with a small pit for the insertion of the radical fibre (lig. 13 e), and al their distal part some- times with an oval, .sometimes a pear-shaped frontal area. The mandible which has a similar, variable form and is furnished with a small, beak-like hook is turned away from the zoo'cium. The ooecia are immersed for the larger part of their extent and can only be seen from the outside as short, pent-roof-shaped projections (fig. 13d), which on each side are separated from the lateral walls of the lower zooecia by a curved suture (fig. 13 c). This projecting portion consists of two calcareous layers, as the ectooceciuin is 121 also calcareous; but it often however shows a narrow, uncalcified transversely placed area (fig. 13 c). The colonies consist of four-rowed segments, and the individual rows may contain 4 — 12 zooecia. The species is represented in our Zoological Museum from the Bass' Straits, Port Denison, Queensland, Texas, ^^'est-hulies (St. Thomas), Ceylon and Siani, and colonies from dilTerent places show differences, partly in the size, position and shape of the avicuiaria, partly in the more or less strongly ascending distal wall, and in the nuni])er of zoa>cia in the individual rows. N. (?) simplex Busk. Catalogue Marine Polyzoa, Cheilostomata, p. 19, PI. LXV, fig. 1; PI. LXV (bis), fig. 3. (PI. XXII, fig. 6 a). The zooecia are elongated, narrow, tongue-shaped or roundedly rectangular, surrounded by projecting edges, wliich in their proximal half are sometimes slightly sinuated. Within each lateral wall in the whole of its length there is a low longitudinal ridge, and from this issues a cryptocyst, whicli especially distally is rather deeply immersed and attains more than half the length of the zocrcium. The aperture of the latter is almost half the breadth of the zoa^cium. The distal wall is in its innermost corner furnished with a multiporous rosette-plate, while the distal half of each side-wall has a single uniporous plate. No avicuiaria or ooecia. The colonies have ipiadrilateral branches with 7 to 16 zoa^cia in each row. The Formosa-Channel, 35 fathoms, Suensson, lat. 32" 22' N., long. 128" 42' E., 170 fathoms (Suensson). Kirlipatrick has referred fragments of a colony from Mauritius to this species, and the British Museum through that author has kindly permitted me to examine tlie preserved and mounted small branches, on wiiich the account of Kirkpa trick is based. As I have not been able to examine this form completely, however, I can only say here, that the outer resemblance is suflicienlly great to justify considering this form as a variety of N. simplex. The cryptocyst however is far less develoi)ed. The proximally slightly projecting ooecia are in the largest l)art of their surface only covered by the frontal membrane of the distal zooecium (the ectoooecium), but a little proximally to their distal end also by a crypto- cyst-bridge, which connects the two lateral margins of the zooecium and is lowest in the middle, and which in K irkpat rick's figure is seen as a low, and not 122 very distinctly marked transverse Ix-ll almost midway across the frontal surface of the oa>cium. The jiart of the ooecium lying proximally to this is furnished along the middle with a narrow ridge. This cryptocyst-hridge must undoul)tedly have arisen from a fusion of two triangular lamina> like those we have described in Coluinnaria borealis. Family Flustridae. The zoa'cia slightly calcified, with an aperture whicii occupies Ihe whole frontal surface, or at any rate its largest pari. Occasionally there is found a secondary cryptocj'st. The distal wall is always provided with a varying number (1 — 13) of small, uniporous rosette-plales, and such also appear as a rule on the side walls, which only in a few cases are furnished with mulliporous rosette- plates. Vicarious or independent avicularia. The owcia are endozocccial and immer- sed, generally in ordinary zooecia, occasionally in avicularia or kenozooecia. The colonies are in a few cases incrusting, in most cases free frondose, more or less richly branched, and with the fiee margin consisting of kenozoa^cia. As the family is defined here, the main weight is laid on the possession of immersed orecia and vicarious avicularia, as well as on the slight calcification and the large frontal aperture, and I have therefore also referred ^Meinbranipora' fltistroides Hincks and M. serrata M. Gill, to this family: the latter species has been considered by Waters also as a Fliislnt. In conformily lo the above defini- tion of this family, I have been obliged to separate out a number of species, which partly have external ooecia, partly dependent avicularia. »F/Hs/r«« militaris, ^Fl." irassd, F/.o dissimilis and »F/. < nobilis are Ihus referred to the /JiVe//ar/iV/oc and ^Fl.'^ armata lo the Scnipocellariidae. Since however the ooecia and avicularia are lacking in a number of species of this family as in most other families, and as a number of Memhranipora species can have vicarious avicularia as well as a quite uncalcified frontal wall, it is difficult to draw a sharp line between this and the family Menihraniporidae. Memhranipora serrulata Busk is a species which has been regarded both as belonging to Memhranipora and to Fhistra. According loBusk"s original description it possesses immersed oct'cia, and if this were cor- rect, il would have to be regarded as a Fhistra. but I have not succeeded in finding ooecia in any of the specimens of this species, which our Museum has from the Fvara Sea or from Greenland, nor are they found on Husk's original specimens in the Brilish Museum. The species appears incrusting as well as in free, bilaniinate growths, but it differs from the Fhistra species, known to meg'in having mulliporous rosette-plates on the distal wall, as well as fully developed marginal zooecia, and I therefore find it more natural lo look upon it as a Mem- 123 branipora. Whilst the side-walls in the majority of the Fliislridae have uniporous rosette-plates, we find multiporous ones in the three species Fl. foliacea, Fl. car- basea and Fl. abijssicola, and it might be considered as part of the evidence for the systematic importance of the rosette-plates, that none of these three species have the cap- or cup-shaped ooecia, which are common in the family. Only in Fl. foliacea (PI. I, figs. 8 a— 8 b) we can find ooecia of a very peculiar egg-shape, which must have arisen in this way, that the distal wall has simultaneously formed an upper as well as a lower cap- or cup-shaped expansion. The peculiar apparatus for the ejection of the larvae, which Jul lien has shown in Fl. abyssi- cola, also seems to suggest a very distant relationship to the other Fliiatridae, but for the rest, we shall not here enter further into these questions. In many cases the proximal portion of the ooecia is covered by a low cryptocyst-belt (PI. I, figs. 2 b, 3 a, 6 a, 7 c), which originally arises out of two lateral halves which finally fuse together. It increases in height with age and may in time in Fl. fliistroides (PI. I, fig. 4 a) completely cover the oa?cium. On the other hand, there is in Fl. seciirifroiis a pair of fiat, oblicpiely placed cryptocyst-processes distally to the zooecial operculum (PI. I, figs. 5 a— 5 b, d. w.). In all the species, which occur in free colonies, their margin is formed by kenozooecia ,which for the rest can appear in very difi'erent ways; sometimes (Fl. foliacea, Fl. membranaceo- triincata, Fl. securifrons) as chambers of a similar form and structure as the other zocecia, but without an operculum, sometimes (Fl. biseriata, Fl. cribriformis) as narrow, tube-shaped marginal ridges, which here and there show internal sepa- rating walls. While such modified marginal individuals appear at several places within the division Ascopiiora, for instance in Onchoporella bombycina and Micro- porella flabellaris, I have not been able to find them in any members of the families Bicellariidae or Scriipocellariidae, and their presence or absence seems thus in doubtful cases to be available as a distinguishing character for these families. I must thus emphasize the fact, thai I have not been able to find such marginal zoa'cia in any of the above-mentioned species which up to the present have been incorrectly referred to the Fliislridae, and that their appearance has nothing to do with the number of rows of zoa^cia in the colony, is evident from the fact, that on the one hand they are lacking in the species mentioned, but on the other hand appear in Fl. bi.seriata, the true zocecia of which are two-rowed. Jullien has made a beginning with the splitting up of the old Fhistra genus by founding the genus Sarsifhistra, and I will here propose the setting up of 4 other genera (or subgenera?), of which one must keep the name Fltistra, as it will contain the species Fl. foliacea, on which the genus was originally based. As we thus have no name for the rest of the species, which not yet have been 124 separated into genera and which accordingly must provisionally be characterized mainly in a negative way, I shall pro[)ose for these the name Heterofluslva, and the introduction of such a provisional name seems to me necessary in ail simi- lar cases. Synopsis of the genera. 1) The side-walls with multiporous rosette-plates; if orecia are pre- sent, they are egg-shaped, the distal wall forming at the same time a distal and a proximal cup-shaped arch; 2) the larv?e are ejected through a chitinous tube, which opens distally to the zooccial operculum, and may be covered by a movable, calcareous valve; avicularia of the same size as the zorecia, lyriform; the operculum with two large wing-shaped lateral expansions. . . Sarsifliisird .lull.' '^^'"^''''^ (S. abyssicola Sars). 2) No such apparatus for the ejection of the larvae; egg-sha])ed ocEcia may occur and smaller avicularia, the operculum of which has no lateral expansions Fhistra (L.) Lev. (Fl. foliacea, L. - carbasea, Ellis and Sol.) 1) The side-walls have uni[)orous rosette-plates; if ocrcia are pre- sent, they are cup- or cap-shaped, the distal-wall only forming a single arch : 3) The oojcia immersed into the bottom of kenozooecia (no avicularia, colony with two-rowed branches) Kenella n. g. (K. biseriala Husk.) 3) The oa?cia immersed in ordinary zooecia or in avicularia (the colonies with several rows). 4) The distal wall, at any rate in the onecia-bearing zoa'cia, very often also in the ordinary zocecia, meets with the basal wall in an angularly bent or curved line; the free edge of the onecia on the frontal side of the colony lies much lower than the basal edge; the avicularia have the same size as the zooecia, (the colonies much branched dichoto- mously, with frequcntlj' the branches meeting and thus forming an open network; radical fibres occur in the angles of the branches).... Relifliistra n. g. 4) The distal wall horizontal or very slightly curved; the free, ' 4(i, p. 4;i 125 frontal edge of the onccia is almost at the same height as the basal; the avicularia smaller than the zooecia: 5) The lateral walls within the covering membrane generally with numerous spine-like processes; the margins of the zooecium have as a rule more or fewer (occasionally numerous) spines; the avicularia generally with a pointed mandible; the oircia not rarely immersed in the avicularia Spiralaria Busk. (Hincksina Norm.) 5) The lateral walls never have spine-like processes, at most a single pair of spines: the mandible of the avicularia rounded, ooecia never immersed in avicularia Heterofhistra nov. nom. Spiralaria Busk, char, emend. ? Hincksina Norman \ (I'l. I, fig. 9 a). The lateral walls with as a rule a row of spine-like processes (or denticles) a short distance within the covering membrane; the edges of the aperture as a rule furnished with spines, sometimes over their whole length; the avicularia generally with beak-shaped, pointed mandible; the owcia most often immersed in avicularia; the side-walls have numerous uniporous rosette-plates. As will be seen from the above diagnosis, the characters on which the genus is l)ased are not constant; but as these characters in the species which I refer to this genus supplement one another in such a way, that there can be little doubt that these species are closely connected, I must consider this genus as well-established, though its limits are not sharp. Besides in the species, which Busk originally described as Spiralaria florea-, the above-mentioned, spine-like processes on the side-walls are also found in Fl. denti(jera^, Fl. Hpii}iili[icra^, Fl. dentictilata^, to the last of which Busk has referred two fairly distinct forms, and it seems on the whole to, be subject to considerable variation. I may men- tion here the most important characters for the three forms in our Zoological Museum, which can be referred to .S. deiiticnlala. A form from the Challenger St. 163 (var. inermis). There are no spine-like processes in a larger or smaller distal portion of the zoa'ciiiin, whilst in the proximal portion 1 — 11 appear on each side; no spines; typical (ivicularia, no (Hvcia. A form from Bass' Straits. Strong, spine-like processes in almost the whole ' S.'i, p. .^S.'). ' (i, p. If)!!. ■' lOi). 126 length of the zoa'ciiim (up to 18 on each side), one or two pairs of spines on the distal part of the zooecium, typical ainciikiria, the oa'cia immersed in the avicularia. A form from Victoria. The spine-like processes are much reduced and cannot be seen from the surface of the colony, appearing merely as small knobs. They seem also sometimes to be in very small numbers. Broad, flat, pointed spines appear in the whole length of the zowcitiin. Typical avicularia, the 0(ecia immersed in the avicularia. The form which Busk' described in 1852 differs from the last mentioned in that the teeth are well-developed and the spines partially widened at the tip, with two or three branches. Very close to .S. denticiilata is S. florea, which has well-developed, hook-shaped, denticles, 1 — 2 spines, typical avicularia and the oa'cia immersed in the avi- cularia, whilst the ocecia are immersed in the ordinary zooecia in S. dentigera, S. spinuligera and S. serrata^, the last of which lacks the denticles, unless, as in the above-mentioned species from Victoria, they are here also so small that they cannot be seen from the surface of the colony. This last species, in which the aui- cularian mandible is much more beak-like than usual and elongated, is very variable in regard to its armature, as within the same colony we can find zooecia with 1 — 2 or with numerous spines, widened at the end and branched two or three times. The above diagnosis has been designed so as also to include ^Membramporu< flustroides and Fl. octodon^, but the connection of these two species, and especi- ally the last, with the others is not without some doubt. Instead of the typical, beak-shaped, elongated avicularian mandible they have rounded ones, and in the case of Fl. oclodon it is really only the elongated form of the zoa'cia and the possession of, for a Fluslra, an unusually large number of spines, which can be taken as in favour of its relegation to the genus. Besides the presence of nume- rous rosette-plates and spines, the fact that some of the owcia are enclosed in avicularia, a character not found outside the genus Spiralaria, is in favour of the relegation of M. flustroides to the genus. Retiflustra n. g. (PI. I, figs. 6 and 7, I'l. XXI, ligs. 1 and 2). The distal wall, at any rate in the ooecia-bearing zoa-cia and in most cases also in the others, meets with the basal wall of the colony in an angularly bent or curved line; the free edge of the owcia, which are placed on the frontal side of the colony, is much lower than their basal edge; the zooecia have no spines; ' 2, p. 49. ' GI, p. 1.31 .iiul 04. p. ;i " 2, p. 49. 127 the colony is strongly dichotomously branched with generally the branches con- nected so as to form an open network. Radical fibres arise from the marginal belt consisting of kenozooecia in the approximal corners of the angles of the branches. It is possible that we may be able to add to this diagnosis still one or more characters, taken from the structure of the auicularia ; but for the present I only know the structure of the avicularia in the new species R. Schonaui. R. Schonaui n. sp. (PI. I, figs. 7 a-7 d). The zooecia are of somewhat variable form, in most cases elongated, rect- angularly oval, with a distal curved margin, often a little irregular, especially in the marginal portion of the branches. There is a more strongly developed crypto- cyst than in any other member of tlie family. It appears as a marginal region along the whole extent of the zooecium and shows distinct belts of growth; these are specially obvious in the strongly developed proximal region. The larger part of the basal wall of the zooecium is uncalcified and has an oval form (fig. 7 d), only a belt along each side and a larger or smaller (Vsth — ^Ui'd) proximal por- tion being calcified. Owing to the slight strength of the calcification this oval only becomes distinct after it has been boiled in potash and only with reduced light. The calcareous part of the basal wall of the zooecium, and especially its proximal part, shows occasionally a number of transversely or obliquely placed coarse strije. The distal wall, which is angularly bent and saddle-shaped in the direction from front to back, is furnished, with a transverse row of 6 — 1. XXII, li^. 2 a). The zooecia have a very variable form, most often elongated hexagonal, oflen rather irregular, wilh a straight distal margin. There is a faintly developed cryp- tocyst in the form of a narrow marginal expansion, the proximal i)art of which is a little more developed. The basal side of the zooecia, which is more calcified than in the foregoing species, has a narrow, median uncalcified, longitudinal belt, which begins at the angle of the distal wall and as a rule reaches almost to the middle of the zotrcium. It is generally narrowest at the middle and widest proximally. On both sides of this we generally find a nundjer of transversely or oblicjuely placed, coarse stri;c, which in difl'erent zooecia may have a very dilTe- rent strength and occupy a very different part of the basal side, and which aiT in reality more calcified and thickened regions of this. In a fragment from Port Darwin this system of stripes is so strongly developed wilh such a pronounced whitish colour, that the whole of the basal side of the colonv' seems even with naked eye to be spotted with white. Besides the longitudinal belt mentioned this fragment by reduced light under the microscope shows a large, pear-shai)ed, dark spot, the proximal border of which meets with that of the longitudinal belt, but is broader than this. It arises from the contrast between a more strongly 129 calcified outer and a more slightly calcilied inner (median) part. The distal wall is acute-angled and the two arms are a little concave. As in the loregoing species, it is at the same time saddle-shaped, and furnished with a transverse row of (up to 12) uniporous rosette-plates. The distal half of each side-wall has ca. 6 rosette-plates. The marginal region, which consists of kenozoo'cia, only differs from the marginal region in the preceding species by the part, which ap])ears on the basal side of the colony, being much calcified and furnished with similar stripes to the zowcia. On the other hand, it has no distinct cryptocyst. The radical fibres issue from the proximal corners of a number of fenestrse. Avicularia have not been found hitherto. The ooecia are high, dome-shaped, with indistinct radiating stria? and gener- ally in the middle provided with a shorter or longer, sometimes rather irregular ridge. A low cryptocyst belt covers their |)roximal part. Also here the basal part of the distal wall lies higher than the top of the ocecium and is thus seen dis- tally to the latter at a deeper level (PI. I, fig. 6 b, PI. XXII, fig. 2 a). The distal wall belonging to the oa>cium forms an angular .or sometimes almost arched mark on the basal side of the colony, and the two arms are not concave but convex. The ocecia-bearing zoo'cia are, when looked at from the basal side, larger than the others, and the distal half of the above-mentioned uncalcitied longi- tudinal belt is generally very broad. The colonies have the same slruclure as in R. Sclwiuun, l)ut the fenestrje are very much smaller and generally much narrower than the segments between them. Of this species I have examined a fragment from Torres Straits (Cambridge) and one from Port Darwin (Ihitish Museum). R. reticulum Hincks. Flustra reticulum Hincks, Annals Nat. Hist. .ser. o, Vol. X, 1882, p. 163, PI. YII, fig. 4. (I'l. XXII, lij^s. la-lc). The zooecia of rather varying form, most often irregularly pentagonal or hexagonal with an evenly rounded frontal edge. A cryptocyst appears as an extremely slight marginal expansion. The basal wall is uniformly, but not strongly calcified with the exception of a rather small, round (circular, oval or pear-shaped) uncalcified spot almost proximally to the distal wall. Very rarely a few short, coarse stripes appear here and there. Contrary to the case in the two other species the distal wall is generally straight in the ordinary zocrcia, and it has about 10 uniporous rosette-plates, some of which are placed opposite 9 130 each lateral margin. The distal half of each lateral wall has 5 — 6 rosette- plates. Avicularia wanting on the fragment examined. They have been described and figured by Hincks, but require a closer examination. The ooecia are rather large and not rarely of an outline describal)le as quadrangularly rounded. Along their proximal margin two indistinct cryptocyst processes are seen, which are rather large at their starting-point but quickly become very low. A little distally to the proximal margin of the oo-cium an extremely small pore is generally seen in the central line surrounded by a thickened portion, and from Ibis a number of partially coarse striae radiate. In contrast to the distal wall in the ordinarj' zooecia the ooecia-forming distal wall meets the basal wall of the zocrcium in a curved line, which is sometimes on a level with the top of the ocecium, sometimes somewhat lower than the latter, but at all events considerably higher than the proximal margin of the ocecium. Contrary to the case in the two foregoing species the whole of the distal wall is transformed to an oaH'ium. It is accordingly convex in its entire extent and has no saddle-shaped basal part with rosette-plates. The colonies, which are branched dichotomously, differ from those in the two preceding species therein, that the separate branches do not meet. The marginal portion, which consists of kenozoa'cia, is wholh' calcified on the basal side and most thickened in its outer half, for which reason the colony is seen surrounded by a white margin. I have examined a fragment of this species from Victoria (The Zoological Mu- seum of Cambridge, Dr. S. Harmer). Family Scrupocellariidae. Cellulariidae Hincks. (Pis. II iirid XXII). The zooEcia are as a rule strongly calcified, with a membranous frontal area occupying a larger or smaller part of the surface. An arched gymnocysl of larger or smaller extent is found in most species proximally to the frontal area, and there is usually a more or less well-developed, most often finely granular second- ary cryptocyst. The margin of the aperture has as a rule 1 — 2 pair of spines distally, while from the approximate centre of the inner margin a spine, plate- like widened oi- branched at the end, very often arises and may cover a larger or smaller part of the frontal area. The distal wall, consisting of a horizontal basal and an obliquely ascending frontal part, has usually numerous, small, scattered, uniporous rosette-plates basally, while the distal lialf of each lateral 131 wall has one multiporous plate. Besides dependent auiciiliirid, found in most species, vibraciila may also occur on the hasal surface of the colonj% and these are connected with the colony by an independent wall. The oa'cia are generally hyperstomial with a wholly or partly calcified ectoooecium, more seldom endo- zod'cial. In the latter case they are sometimes enclosed in kenozooecia. As a rule radical fibres occur, sometimes springing from a rosette-plate (or a pore-chamber), sometimes from a separate chamber connected with a vibraculum. The colonies are always free, very branched, most frequently with uni- or few-seried zocecia, generally consisting of a single layer and in most cases jointed by means of chitinized transverse belts. While a smaller number of species (e. g. Hoplitella arniala, Menipea flabellum, Men. spicata'^ and the Canda species), have a membranous frontal area, occupying the whole or almost the whole of the frontal surface, a larger or smaller part of the latter is in the other species occupied by an arched gymnocysl which in some species (e. g. in Menipea aculeittd Busk and Men clausa Busk) may be up to two- thirds of the length of the zooecium. While the cryptocyst in many species (e. g. in the Scruiwcellaria species, in Caberea Ellisi, Menipea acnleata, M. cirrata, M. palagonica) forms only a small depression in the margin of the aperture, it may in other species fill a larger part of the aperture inside the membranous fronlal area in the form of a somewhat depressed, generally finely granular lamina. This cryptocyst attains its largest extent in Menipea spicata, Caberea Darwini and in the Canda s|)ecies, but also in Men. flabellnm, Men. rohorata (figs. 7 b, 7 c), M. crystallina, M. liuski and several other Menipea si)ecies it may attain a consider- able development. We have already mentioned that a number of species possess a wholly chitinized, simple o[)erculum. As in Dimorpbozoum nobile and Dendro- beania Murraijana the distal wall consists of a basal, horizontal or slightly obli- (pie and a frontal, strongly ascending i)art (PI. II, figs. 7 g, 7 h, 8 c), but while in these two species the former portion is furnished with a single, large, multi- porous rosette-plate, it has generally in this family a great number, of single- [)ored plates which are variously grouped. On examining a zocrcium from the frontal surface (PI. II, fig. 7 a), the horizontal pore-bearing i)art of the distal wall is seen at a deep level at some distance proxinially to the distal end of the zool;- cium, and this is seen most clearly after a previous boiling in caustic potash. The avicularia always have their inner wall in common with Ihe zooecium on which they are placed; but as I have succeeded in isolating Ihe vibracula in some species {Caberea Ellisi, Canda arachnoidea, (kiberiella benemnnila, Scrupo- ' 69, p 132. 9* 132 cellaria scahrd) it seems natural to suppose that these hefeiozoa^cia in this family always have an inner wall of their own. In Caherea and CaberielUt I have found a septum dividing the vibracular chamber into two, of which only the distal may contain the muscles. While the od'cia in the majority of this family are hyperstomial, they are endozooecial and more or less deeply immersed in Biujii- lopsis Peachi, Ihigulopsis cuspidala, Menipea criistdllina, M. cernicornis, M. Biiski. M. triseriata and M. spicata. In M. crystallina they are enclosed in kenozoa'cia with a large membranous frontal area, while in the others they are immersed in ordinary zoa'cia, in such a way, however, as to appear more or les promi- nent on the zooecial surface. In M. Hiiski and M. cervicornis the distal part of the ocHcium is covered by a granular cryptocyst. In a smaller number of species the ectood'cium is wholly calcified, e. g. in Scriipocellaria levnatu^, Scrupocellaria reptans and Scnip. scruposa, but in most cases a larger or smaller [iroximal part is membranous and accordingly appears as a rounded or triangular area, clearly distinguishable from the calcified distal part. This is seen e. g. in Caheriella benemiinita (PI. XXII, fig. 8 a), Menipea roboratu (PI. II, fig. 7 a) and M. ligulata (Pi. II, fig. 8 a). This famih' is one of the most natural and most sharplj' delimited, and the differences shown by the zooecia in respect to the armature of spines, develoj)- ment of gymnocyst and cryptocj'st etc., are all subject to such great variation from species to species that no generic importance ought to be attached to them. The division of the genus has therefore hitherto been based chietlj' on the struc- ture and appearance of the heterozooecia, and for the present I am unable to delimit them in a more natural way. In earlier as well as in more recent times attempts have been made to divide the large genus Menipea, e. g. by Gray, Mc Gillivray and Waters. But as I consider it superfluous to enter into a critical examination of the genera Emma' and Craspedozoum^, proposed by the two former authors, I shall limit myself to a closer examination of the divisions made bj' Waters^. This author discusses the subject as follows: »In the descri[)tion of the species, it is now shown that in the Celhilariidae there are two distinct kinds of articulation. In the larger number the new branch is given olf from a small chamber formed for the purpose. As the type of this section Menipea Baski is figured (PI. I, fig. 10); aiul I propose to restrict Menipea to those forms having this kind of articulation; and it will then include ^1/. Buski, Mac (1., ^1/. crystal- lina. Gray, M. njatluis, Thompson, M. ceri>icornis, Mac. G., M. conipacta, Mac. G. — ' In tilis species which has hitherto Ijccmi referred to the genus Meiiijwa, I liave found a viliia- cuhiiii, but without nagcllum. - 2, p. 27. " G9, p. 131. ' 111, p. 2. 133 On the other hand, probably M. cirrntd, Lamx., M. gracilis, Busk, M. patagonica, Busk, M. fimiciilata, Mac. G., M. triseriatd, Busk, M. flabellnm, L., M. ternata. Ell. & Sol., must, on this account, he elsewhere located; and in fact, before noting this distinction, it had been felt, that several species should be removed from the genus«. In another section, including ScT((/)oce//f/r/«, the jointing consists of nothing more than a partial breaking through or thinning of the walls of the zocecia near the commencement of the branch. In the zocecia in which this breaking through of the wall of the zoa^cial chamber has commenced, the polyp- ide is seen unalVected, parth' above and partly below this incipient division (see PI. I, figs. 11, 12). < In a subsequent work' he calls the group of species to which M. flabellum belongs by the temporary name Flabellaris. In all Bryozoa that occur in jointed colonies, the jointing takes place in the same way, viz. the following. The zoa'cia, which are situated on the boundarj' between the two joints and which we may call 'joint-zooecia< , have a shorter or longer, wider or narrower, uncalcified, chitinized and accordingly flexible trans- verse belt, which may sometimes be situated more distally, sometimes more proximally, but which alwavs divides a joint zon?cium into a distal and a proxi- mal part, each belonging to its own 4«i»4-. Thus, what Waters in Menipea Bnski and other species calls a small chamber,- is in reality only the proximal part of a joint-zoa'cium, and its proximal boundary is just the distal wall between the joint-zoa>cium and the zooecium on the proximal side of the latter. This arti- culation may show an apparent, but in fact very insignificant dilTerence, when the colony is regarded from the frontal side, as the outer joint-zowcium in such species as M. jhihcUum, M. cirrata, M. jxilagonicd etc. commences with a chitinized belt, while in such species as M. Biiski, M. ceruicornis and M. criisttilliiKi it begins with a small calcified portion, the '>chamber« mentioned by Waters. In this however M. cyalhits agrees with the species of the latter group, though as regards structure and form of colony it is more closely allied to the former. As mentioned before, the ooecia in a series of Menipea species are more or less deeply immersed but as a rule distinctly prominent on the surface of the zocecia. Even apart from the fact, that, by a division of the genus Menipea on the basis of this fea- ture, we should be at a loss what to do with the species lacking ooecia, it is evident, that such a division must seem rather unnatural, as M. cijathns, which has hyperstomial ooecia by this proceeding would be separated from such species as M. cerricornis, M. Buski and M. crgstallina, to which it is undeniably closely related. ' 112, p, (;72. 134 Synopsis of the genera. 1) On the basal surface a larger or smaller number of zocrcia with a vihraculum connected with a chamber, from wliich a radical fibre may issue (avicularia always present): 2) The true vibraculum (the chamber for the radical fibres not in- cluded) divided by a septum into a distal and a proximal space, the former containing the muscles: 'A) The very large, claw-shaped vibracula, present on all zoa'cia, are directed obliquely inwards and basally, and meet from both sides at acute angles in the middle of the basal side of the colony, which they almost cover; the flagellum on one margin generally with pointed teeth; the radical fibres, which spring only from the chamber con- nected with the vibraculum, run down along tiie middle of the basal side of the colony as a continuous, raised bundle; (the colony not jointed) Caberea Lamouroux. 3) The small, curved or angularly bent vibracula, not present on all zoa'cia, are far from reaching the centre of the colony; the fiagel- lum without teeth; the radical fibres, of whicii some spring from the chamber connected witli the vibraculum, others from a rosette-plate on the marginal zoa-cia, form a bundle along each lateral margin of the colony Cnberiella n. g. 2) The true vibraculum not divided into two spaces (the llagelhim without teeth; the colony generally jointed; the vibracula covering only a smaller part of the basal surface of the colony): 4) The od'cium enclosed in tlie widened proximal half of a large avicularium, the distal, cap-like part of which bears the mandible and encloses the muscular apparatus. The frontal areas of the two rows of zooecia meet at obtuse angles; the radical fibres, given off from and ending in a chamber connected with the vibraculum, form jjarallel connecting threads between the neighbouring l)ranches (Ainda Lamouroux. 4) The oo-cium not enclosed in an avicularium; the frontal areas of the two rows of zotrcia on the same level; the radical fibres form no parallel connecting threads between the neighbouring branches. . . ScrupocclUiria van Beneden. 1) No vibracula: 135 5) No avicularia; (the ocecia more or less deeply immersed in the zooecia) Bugulopsis Verrill. (Cellularia Hincks). 5) Avicularia occur: 6) Each marginal zooecium with a large marginal avicularium, the greater part of which is immersed in the zooecium and shows a strongly arched wall inside the latter; (the other zooecia with a completelj' membranous frontal area and no avicularia; no spines; no ocecia; tlie colony with multiserial branches) Hoplitella n. g. 6) Where marginal avicularia are found they are never partially immersed : 7) A number of zooecia on one margin of the branches have two huge, hollow spines on the proximal side of the frontal area; (a free stem formed by numerous radical fibres, etc.) Rhabdozoum Hinclcs. 7) No hollow spines proximally to the frontal area Menipea Lamouroux. Caberiella n. g. Small, narrow, curved or angularly bent inbracula appear on the basal side of a number of zowcia. They are divided into a distal and a proximal cavity by a septum and occupy only a small part of the basal surface of the colony. Avi- cularia occur. The radical fibres are given off partly from a chaml)er connected with the vibraculum, partly from a pore-chamber. They form a bundle along each lateral margin of the colony. C. benemunita Busk. Menipea benemunita Busk, Challenger Zoology, Vol. X, Part 1, pag. 19, PI. IV, fig. 4. (PI. XXII, fig.s. 8 a-8 h). The zooecia are long and- narrow with a gymnocyst occupying about two- thirds of the entire length of the zocL'cium. There is a well-developed, deeply immersed, secondary cryptocyst, which is densely and finely granular especially in its distal half, and provided with a finely dentate inner margin. Right at the distal end it appears as a more deei)ly-placed, curtain-like lamina, the free margins of which end in 6 — 8 teeth. Besides the large, long, scutiform opercular spine, furnished with a bifurcate hollow and covering the greater part of the frontal area, the zooecia have 3 — 4 spines distal ly, one on the same side as the opercular si)ine and 2 — 3 on the opposite (i. e. outer) side. Three spines only on the nuirginal zoo'cia. 136 The avicularia, of which there are two i)roxinialIy to the frontal area, are in the oa'cia-hearing zoa-cia situated on the distal part of the ocrcium. The vibracula are not found on all zoa-cia, hut seem to ai)i)ear rather fre- (juently and may be seen sometimes on 2 — 3 successive zooecia. They are narrow, most often angularly bent and situated in such a way that their inner part is turned obliquely inwards and towards the proximal end. A radical libre takes its origin from their outer part, while other radical fibres spring from a pore- chamber in the zooecia, that have no vibraculum. The ooecia are provided with fine radiating striae, and the largest part of the ectooa-cium is uncalcified. The calcified jjart terminates in a somewhat projecting, angularly bent or arched, often somewhat sinuated margin. The colony is not jointed. Its branches may have up to 7 rows of zooecia. By way of exchange I have acquired a small fragment of this species (from Challenger, St. 313) from the Zoological Museum at Dundee. Hoplitella n. g. Avicularia appear only on marginal zoaxia which all have a large avicularium, the inner half of which is immersed; the distal wall has on each side a long, narrow continuation running along the corresponding lateral wall; the entire frontal surface membranous; no oa'cia; the colony not jointed. H. armata (Busk). Carbasea armata Busk, Catalogue of Marine Polyzoa, Cheilostomata, p. 50, PI. L, figs. 1, 2. Flustra armata Waters, Jom-n. R. Micros. Soc, 1899, p. 279— 2Sfi. (I'l. II, figs. l();i — lOo). The zooecia, the entire frontal surface of which is membranous, are rhombic- like oval, each of their lateral margins, when seen from the frontal side, ending in an almost rectangular edge, bounded l)y two curved lines. While this edge in the zooecia in the median part of the branch is generally situated a little distally to the centre on the inner and a little proximally to the centre on the outer lateral margin, it is, on approaching the margin of the colony, situated higher up on the former and further down on the latter, and this contrast is always greatest in the parts of the colony, which have the largest number of rows of zocecia. The marginal zoa^cia are much broader than the others, as they partly enclose the large avicularia, and as they stand in close relation to the avicularia, it will be more natural to treat them together with these. Immediately proximally 137 to the distal edge of the zooecium a large, semi-circular opercular valve is found. The basal horizontal part of the distal wall has a large, somewhat curved trans- verse group of up to 70 uniporous rosette-plates. On the boundary between the horizontal and the obliquely ascending part of the distal wall two narrow, tubular cavities issue (figs. 10 b, 10 d), which from each zooecium sink down into the subjacent one. They are bounded outwardly by the lateral wall of the zooe- cium and inwardly by a continuation of the distal wall, and in a transverse section proximally to the latter they are seen as two small, round holes (fig. 10 c). They touch the basal edge of the rosette-plate of the lateral wall and generally end just proximally to it (fig. 10 d). On the basal side of the colony the edge of the distal wall shows a number (6 — 10) of small, distally pointing, short, broader or narrower, sometimes bifurcate crenulations (figs. 10 b, 10 c), which are really outpushings from the lower into the higher placed zooecium, and alternating with them is seen a number of much more faint ones pointing proximally. The avicularia, only occurring on the outer lateral margin of the marginal zoa'cia, are very large, turned towards the frontal surface of the colony and furnished with a well-developed beak and mandible hook. A great part of the avicularian cliamber is enclosed in the zooecium, and its strongly arched endozocecial surface lias about 10 scattered, uniporous rosette-plates (fig. 10 e). The marginal zooecia have an obliquely triangular transverse section, ending outwards in a rounded edge, and (he outer of the two above-mentioned, narrow lateral cavities passes obliquely across the basal side of the avicularium, being only visible from the basal surface of the colony. On the basal side the zooecium is separated from (he free part of the avicularium by the just mentioned cavity, and on the frontal side by its upper lateral margin, which runs obliquely outwards to a small indentation in the approximate centre of the lateral margin of the avicu- larium. A corner is formed here corresponding with that of the other zoa'cia. In the outer half of a marginal zocrcium we may distinguish between a frontal and a basal, distal lateral margin, which together enclose the avicularium and mark the boundary between the free part of the latter and the part immersed in the zoa'cium. On Ihe other hand there is but a single proximal lateral margin, as the frontal and the basal lateral margins are here run together in an edge. Instead of the calcified lateral wall in the other zoa-cia we thus find here but a strongly calcified rib, which however generally shows a distinct separation into two lateral halves, enclosing between them a rosette-plate (fig. 10 e). No ooecia. The colonies are unjointed, single-layered, dicholomously branched with 138 5 — 14 rows of zooecia in the separate segments. The radical fibres spring from a pore-chamber in the proximal part of the marginal zocecia. In the older part of the colony they form a Hat bundle on the basal surface, immediately within each lateral margin, with oblique transverse connections at the base of the sep- arate segments. The colonies examined originate from ('ape Town. Menipea Laniouroux. It will be evident from the above summary of the genera that the genus Menipea like the genus Heteroflustni is only negatively characterized, as it com- prises all the species that cannot be referred to any of the other genera. M. roborata Hi neks, Membranipora roborata Hincks, Annals Nat. Hist. ser. 5. Vol. VIIl, 1881, pag. 128, PI. 2, fig. 3. Flustra membraniporides Busk, Challenger, Zoology, Vol. X, pars 1, pag. 54, PI. XXXII, fig. 7. Flabellaris roborata Waters, Journ. Linnean Soc, Zoology, Vol. XXVI, 1898, pag. 672, PI. 48, figs. 10—11; PI. 49, figs. 7 — 11. (PL II, figs. 7 a-7 k.) The zooecia long, hexagonal or hexagonally vase-shaped, often with an acutely projecting corner between the distal and the proximal part. The gymnocyst is very slightly developed on the zocrcia with no avicularia (e. g. some marginal zott'cia) and may on those with avicularia occupy about one-fourth of the whole length of the zooecium. In the entire periphery of the frontal area a distinct, granular cryptocyst is seen, deeply immersed and strongly developed especially at the proximal end, and attaining its highest development in the marginal zoav cia. There may be four spines distally. The two central ones are very small and bud-shaped, but often wanting, while the other two are rather short, as a rule present, but often wanting in the marginal zocrcia. The marginal zocrcia, which are larger but rarely longer than the other zoa'cia, are very asymmetrical and their obliquely oulbending lateral wall has a straight or slightly convex frontal margin. On isolating a row of zoa?cia after boiling in caustic potash it will easily be seen thai the inner surface of the zooecia (figs. 7 d — 7 h) has a some- what varying number of solid calcareous processes of dilTerent length and thick- ness, of which generally 1 — 4 may be seen through each lateral surface. In many zooecia a larger or smaller part of such a calcareous process may protrude on 139 each side of the proximal pari of the aperture distally to the cryptocyst (figs. 7 b — 7 c). The basal, horizontal part of the distal wall has a transversely oval or triangularly rounded, multiporous rosette-plate, generally with a frontal concavity (figs. 7 f, 7 h). In most zooecia the distal wall between the rosette-plate and the basal wall is provided with a little rounded (sometimes two) pore-chamber de- scending into the lower zocecium (figs. 7 d — 7 e) and in its bottom furnished with one or more small uniporous rosette-plates. The avicularia occur in two different forms of which one is found in the cavity of the zorecium, while the other in zooecia without oa?cium is found on the proximal side of the membranous area, and in ooecia-bearing zooecia on each side of the distal part of the ocecium. The external avicularium, which has a well-developed hook as well on the mandible as on the corresponding part of the chamber, is placed so, that the mandible is turned obliquely outwards and distally on the ofrcia and obliquely inwards and proximally on the zooecia. The boundary between the opercular and the subopercular area is formed by two nearly always concurrent, narrow, cylindrical, generally bent and often very ir- regular processes, of which one is usually longer than the other (figs. 7 c, 7 i). On the proximal side of the frontal area we find very seldom two, generally but a single avicularium which is then most often situated on the outer side (the one nearest the margin of the colony) and occupying more than half the space. If found on the marginal zooecia it is however placed On the inner side, the reason of which may l)e, that there is a large pore-chamber on the outer side, from which a radical fibre takes its origin. In the ordinary zooecia, at the proxi- mal end of which there is but a single external avicularium, and in the marginal zooecia with no external avicularium, an internal one is always found, arising from the internal side of the surface which from its position seems intended to have an external avicularium. The latter, which has both a mandibular and an avicularian hook, is oval, with the mandible pointing obliquely distally and in- wards, and with but two short teeth on the boundary between the opercular and the subopercular area (figs. 7 d, 7 e, 7 g, 7 k). The ooecia are rather high, rounded and the ectoooccium has a proximal, rounded triangular, membranous area, while its calcified part terminates in a somewhat projecting, angularly bent margin. The colonies are bilaminate, dichotomously branched and their branches have up to Hi rows of zooecia. A bundle of radical fibres springing from the pore-chambers in the proximal part of the marginal zooecia runs along each lateral margin. 140 I have been able to examine a colony IVom Napier, New Zealand (Miss Jelly) and another from Port Jackson, New South Wales (Mr. Waters). M. ligulata M. Gill., Craspedozoum ligulatum M. Gill., Transact, and Proceed. R. Soc. of Victoria, Vol. XXII, 1886, pag. 132, PI. I, fig. 3. (I'l. II, li^s. 8a-8c). In respect to form and development of spines, gymnocyst and cryptocyst the zooecia essentially agree with the foregoing species. The marginal zoo^cia are however generally furnished with all four spines, the two on the outer margin attaining the greatest development. A rather long, calcareous process, pointing basallj' and obliqueh' proximallv, springs from the inner surface of the frontal wall on the proximal side of the zooecial npening It consists of a long, narrow, compressed rod, terminating in a quadrangular expansion with a finely dentate and striated margin (figs. 8 c, 8 e). This expansion again is composed of two unequal lateral halves, bent against each other in the shape of a roof, with the hollow downwards. These processes, which can easily be seen through the wall when an isolated row of zooecia is viewed from the side, are subject to some variation, both as regards the absolute length and the proportional size of rod and terminal expansion. The lateral walls on the other hand have no processes. The distal wall has a large, broad, multiporous rosette-plate (fig. 8 d) deeply sinuated frontally, and as in the foregoing species we find one or more pore- chambers (fig. 8 d) between the rosette-plate and the distal wall. These are however generally larger and often of a peculiarly sinuated or twisted form (figs. 8 b, 8d). The avicularia, of which only a single form is found, have a long, narrow, triangular, j)ointpd mandible and two small hinge-teeth on the boundary between the opercular and the subo])ercular area. In the zoa'cia without ocrcia there is generally only a single, rather large avicularium |)roximally to the membranous frontal area. It occupies the whole space in the proximal part of the zowcium, and has not as in M. roborala a distinctly delimited, but em|)ty area at the side. The mandible is most frequently turned to one of the sides. There is no internal avicularium, but in some few cases a small avicularium occurs in the distal part of the outer margin of the marginal zoa'cia. Above each od'cium generally two small avicularia with the mandible turned obliciuely distaily and outwards. The ooecia have as in the preceding species a proximal, membranous area which is here rounded and not bounded by an angularly bent distal margin. 141 The colonies are imilaininate, dichotomously branched and their branches have up to 8 rows of zooecia. They are as in the foregoing species bordered by a belt of radical fibres. Of this species I have examined some colonies from Napier, N. Zealand, for which I am indebted to Miss Jelly. Canda Lamouroux. (PI. II, fig. 9 a). The zoa'cia are on the basal surface furnished with a inbraciiliiiu which (apart from the adjacent chamber of radical fibres) only contains a single cavity; the flagellum is not dentate. The frontal areas of the two rows of zoa^cia form obtuse angles with each other, and the neighbouring branches of the fan-shaped colony are connected by parallel radical fibres, which are always given off from or terminate in the chambers connected with the vibracuhi; no marginal uui- ciiUiria. The zoa>cia have at the distal end a shorter or longer spine on each side. They have no frontal gymnocyst, the calcification of the frontal surface being exclusively formed by a more or less granular, asymmetrical, deepened crypto-, cyst, the extent of which is ditTerent in the various forms. The on>cia are endo- zocjecial, being enclosed in avicularia, and in the latter we may thus tlistinguish between a proximal, wider j)art, the ectoooecium, whose frontal wall is furnished with a rounded, uncalcified portion, and a distal, cap-shaped part, the real avi- cularium. The boundary between the two parts is formed by an angularly bent transverse belt in which the ectooa'cium and the endoooecium have coalesced. To communicate with tlie avicularium the zoo^cium has a small rosette-plate. Of this genus four species have hitherto been described, chiefly on very rela- tive characters and without any large material, and it may accordingly be diffi- cult to decide for certain, how many of these species are maintainable. Our Mu- seum is only in possession of a plentiful material of a West hidian species, besides a colony from Bass Straits of C. arachnoides and a small fragment of C. retiformis, sent from the British Museum. From the same Museum I have bor- rowed a preparation of (lundu siiuphw Busk, for examination, but it was covered with heterogeneous bodies to such an extent, that it was imjiossible for me to decide whether this form, as I think probable, is identical with the above-men- tioned West Indian, which accordingly I must give a special name. On the basis of this material I may now give the following synopsis of the Canda species. 142 1) The colony jointed, the two inner zooecia in each bifurcation being divided into a distal and a proximal calcified portion, connected by a chitinous tube; the vibracula far from reaching the central suture of the branch. (The cryptocyst occupying about one-fourth of the whole length of the zoa^cium. The proximal margin of the vibraculum sei)a- rated from the distal wall on the jjroximal side of it by a distance which is at least half as large as the breadth of this wall; not in- frequently avicularia along the middle of the branch; no opercular spine) C. arachnoUes Lam. 1) The colony not jointed; the vibracula almost reaching or sur- passing the central suture of the branch ; 2) The zooecia with a hammer-shaped ojjercular spine; the proximal margin of the vibraculum is separated from the distal wall by a dis- tance which is about half as large as half the breadth of the latter; the vibraculum almost reaching the central suture of the branch; the cryptocyst is a little shorter than half tlie lengtli of the zo(r- cium C. retiforinis Smitt '. 2) No opercular spine; the proximal margin of the vibraculum almost reaching the distal wall; the vibraculum reaching or surpassing tiie central suture of the branch; the cryptocyst occupying about one- third of the whole length of the zouicium C. caraihica n. sp. ? C. simplex Busk'-. V C. tenuis M. Gill.l On account of the remark made l)y Husk", that the avicularia in the sutural line of the branch in C. arachnoides do not seem Id be developed in connection with the separate zocrcia, I may here call attention to the fact that Husk is wrong in his supposition. On splitting a branch into its two lateral halves it will easily be seen that lliese strongly compressed avicularia are given off from the free continuation of the inner lateral nuugin of the zoa^cia. Rhabdozoum Wilsoni Hincks, Annals Nat. Hist. V Ser., Vol. X, pag. 160, PI. VIII, fig. 4. This peculiar form, of which I have been able lo examine specinuMis from Western Port and Port Phillip, Victoria, which I owe to the kindness of Mr. J. Gabriel and Miss Jelly, is by Hincks wrongly referred to the Eiicniliidac, a ' 102, p. 16. - 8, p. -JG. ' (i8, p. 107. 143 family including some of the genera which have been referred by me to the family Bicellariidae. That it must be referred to the Scrupocellariidae and not to the Bicellariidae is sufficiently evident from the stronger calcification and the structure of the distal walls, the auicularia and the owcia. The last mentioned, which are hyperstomial and the basal wall of which is a part of the frontal wall of the zoa-cium, have a mostly membranous ectoooecium, which has only a calcified marginal portion. The frontal gymnocyst is unusually large, whereas there is but a very slightly developed secondary cryptocyst, which in the oldest zocecia terminates in a number of tooth-like processes. The basal wall of the zooecia is acutely arched, transversely striated and each radical fibre takes its origin from a [)roximal pore-chamber. Family Membraniporidae. This family comprises all the Malacoslegous forms which can neither be refer- red to the Cribrilinidae nor to any of the above-mentioned iiimilies, and which in contrast to these can only be characterized negatively, viz. l)y their not possess- ing the combination of characters peculiar to any of the above families. It shows greater variation and wider contrasts than any of the other Malacostegous families. The frontal wall of the zoacia is sometimes quite membranous, sometimes to a greater or smaller extent provided with a calcareous layer, which may be sometimes a gymnocyst (Electra), sometimes a cryptocyst (e. g. Omjchocella) and most often a combination of both. Spines are sometimes wanting, sometimes found in great numbers in the whole periphery of the frontal area. The separate zooe- cia communicate sometimes by uniporous or multiporous rosette-plates, some- times by pore-chambers. The heterozocecia have in some cases a calcified trans- verse bar and may appear both as avicularia and as vibracula. They are sometimes independent (vicarious), sometimes dependent, and sometimes both forms are found together (Callopora craticula). The ocEcia are usually hyper- stomial, in a single genus acanthostegous and in some cases endozoa-cial {Cale- schara Rosseliana), sometimes (Oochiliiui) surrounded by kenozoa>cia. The colonies are most frequently incrusting, but in many cases free and then either laminate or forming richly branched tufts. Within this seclion so rich in species no small number of genera and a few families have subsequently been set up or proposed, e. g. by Busk, Waters, JuUien, Norman and others. Neither time nor my material permit me to give a criticism of all the genera proposed, but I must confine myself to set up a few new ones and to give new diagnoses of some older ones. A grouping of the numerous species described, according to their 144 relationship, will require a considerable amount of work and much critical sense on account of the great variation within a series of structures. Membranipora L. Billuslra d'OrJj (p. p.), Busk, Smitt. Nichtina Canu.' The zuwcku the aperture of which is to a greater or smaller extent surrounded by a granular or denticulate, cryptocyst margin, have 2 spines at most, which are situated in the two jjroximal corners. On each side of the distal wall one niultiporous rosette-plate or a series of uniporous or partly multiporous; each lateral wall with 2 — 4 multiporous plates. No aincnUtria; no owcia. In M. nicmhrdnacea the cryptocyst appears only as an extremely narrow mar- ginal portion, while in other si)ecies it attains not only a greater breadth, but also forms a large, proximal expansion, often terminating in a larger or smaller process. This is most strongly developed in M. ilenticulald (ilanica) v. sciiliitd'-, in which it almost reaches the operculum as a free, quadrangular lamina. It is less developed in M. delicatiila Busk. The cryptocyst attains its highest develop- ment in M. ohionya Busk', which represents a Micro/;or(/-like development of the genus. The two spines, which constantly appear in M. membranacrd and in M. tuberciilala and which in a number of species are more or less tuberculiform, attain their highest development in the latter species, in which they often coal- esce into a single very large tubercle, and a similar coalescence takes jjlace in a number of zocecia of ^1/. Lacroixi Aud^ (non Busk, nee Hincks), ligured by Savigny, the spines of which generally seem to have a triangular transverse section. In M. Savarti and M. denticiihita these spines are not constant, and in a series of undescribed forms, which must be referred to other species, they are altogether absent. In my description of M. membranacea in »Zoologia Danica* I have already called attention to the great variation in the rosette-plates of the distal wall in this species. On either side there may be sometimes a large multi- porous rosette-plate, .sometimes a series of smaller, uniporous or partly multi- porous ones. In all the forms examined by me multii)orous rosette-plates are constantly found on the lateral walls. As in all the numerous forms, I have had the opportunity of examining, no ooecia were found, which however are said to be present in the species from ' 11 a, p. 380. '■' 55, p. 54. ' 7, p. 34. ^ While the .species of Savigny is furnlslicd with two spines which in some zocecia are coalesced into a semiglobo.se tubercle the species, wliiih lliiicks calls Memb. iMcroixii, lias a greater or lessci' luinihei' of small triangular hollows Uc'nozodrawer<); but there is, I think, no reason to doubt the correctness of the figure. Membranipora limosa Wafers. Journ. Linnean Soc, Zoology, Vol. XXXI, 1909, p. 140, PI. 12, figs. 1—5. (PI. XXII, figs. 5 a-5 c). The zooecia, which are separated by distinct (in fresh colonies brown) sutures, are rather long, generally hexagonally rectangular with a curved distal edge. The narrow aperture, which is half as broad and a little more than half as long as the frontal wall, is provided with a semicircular oral valve. The whole of the calcified part of the frontal wall is formed by a cryptocyst, in which we can distinguish between a broad raised marginal portion furnished with parallel series of more or less coalesced tubercles, and of a depressed median pari, the distal margin of which is armed with a little process of varying shape, most often bifurcate, sometimes almost fan-shaped with a number of small projecting teeth. The obliquely ascending distal wall, the triangular basal part of which may be split into a distal and a proximal half after treatment with Eau de Javelle, has in its inner part two (more seldom three), fine, slender, erect, somewhat curved calcareous rods, bent at the end like hooks, which project inlo the proximal i)art of the distal zooecium and have the hooks directed away from the frontal wall. Each distal wall has in its inner, more horizontal part inside the posterior margin 6 — 7 uniporous rosette-plates or a smaller number of plates, of which some are multiporous. The distal half of each lateral wall has generally 2 (rarely a single) rosette-plates with 2 (1) — 6 pores. The colonies unjointed, slender, richly branched, with bifurcate branches which bear from 4 — 5 rows of zocecia. The number of zocecia in the separate rows is from 4 — 14. The Formosa-channel, 30 fath. (Suensson), Nagasaki (Suensson). As M. meiubranacea L. must be regarded as the type of the above characterized genus, and the name Membranipora ought therefore in future to be used only in this more restricted sense, we shall want a name to designate all such species as cannot be referred to particular genera. As such a temporary name I propose » Membraniporina « . ' 98, PI. 10, fig. 9.2. '' 103, p. 18. 10 146 Electra Lamour. Tendra Nordin. p. p., Pyripora Mc (^oy p. j)., Heteroceciuni Hincks. The frontal calcification of the zoa-cia is essentially or exclusively a gynino- cyst. There may be a circle of spines round the frontal area, of which an un- paired proximal one is generallj' the most constant and often the only one pre- sent. The distal wall is furnished within its proximal margin with a transverse row or a transverse belt of uniporous rosette-plates; the lateral walls have 2 — 15 multiporous plates. No anicularia. (hecia absent or acanthostegous. To this genus I refer E. iwrticillala, E. pilosa, E. bellnUt, E. tiiacdiillui, E. lUstorla, E. zostericola, E. (imj)lectens, E. njonostachys, E. fossttrUi and E. catenu- luriii which like E. fossaria has a calcified operculum and can only be regarded as a form of the latter. I have .some doubt whether the species, which has hitherto wrongly been called M. Lacroixi, and for which I projiose the name of M. bippopiis, can be referred to this genus. E. zostericola Nordmann. Tendra zostericola Repiacholf, Zeitschrift fiir wissensch. Zoologie, 25. B., 1875, pag. 129, Tab. 7—9. Membranipora (Tendra) zostericola Oslroumoff, Die Bryozoen der Bucht von Sebastopol, pag. 18, Tab. 1, Fig. 13—14. (PI. IX, figs. 2 a-2 b). As shown by the above-mentioned authors there is among the ordinary zooecia, which have generally only two distal and sometimes one proximal, unpaired spine, a smaller number, in which as in the Mcinbraniporella species the mem- branous frontal area is covered by two rows (10 — 17 pair) of hollow, very thin- walled s|)ines, which meet in the central line of the zocecium. Their form is extremely' variable in the same zorecium, as they are sometimes broad, some- times narrow, sometimes single, sometimes bifurcate in a larger or smaller part of their length. Two opposite spines most often meet in a truncated terminal part, but it is not infrequent, that a greater or smaller number of them stretch a thin point across the end of an opposite spine. The bright spots seen at the outer part of each row are the translucent cavities of the separate spines. Of these the distal ones are the shortest, and the gymnocyst projecting here into a triangular portion, which has a curved margin distally, leaves a small trans- versely oval area for the opercular valve. The two rows of spines form a some- what arched roof across the frontal membrane, and thus a space is formed which 147 opens outwards immediately on tlie distal side of the operciiluni of the proximal zocEcium. These zooecia. of which several may sometimes occur in succession, are supposed by Repiachoff to be equivalents of o(rcia. But while according to the description of this author we should think that the cavity of the zooecium itself acts as oojcial cavity, Ostroumoff informs us of the fact, that the em- bryos and larva; are situated in the space between the spines and the frontal membrane. He speaks on this as follows': »The lattice-like zooecium (cellule treillissee Nordm.) serves as ovicell for the zooecium on its proximal side. The cavity of the ovicell is formed on one side by the surface of the mantle (i. e. : fron- tal membrane), on the other by the concurrent spines. The egg, which is ex- truded from the lower zooecium by the tentacles, comes into this cavity, and this may be easily seen by a transverse section through a lattice-like zooecium containing embryos. Some embryos are usually found in this cavity. « On my enquiry Ostroumoff has however informed me, that he has not observed such a transference of the egg. Besides the ordinary zooecia with 2 — 3 free spines a smaller number may be found, in which the frontal area is surrounded or par- tially covered by 1 — 9 pairs of spines of varying length, which however meet neither the spines springing from the same nor those from the opposite side. A number of colonies of this species from Sebaslopol were kindly sent to me by Dr. OstroumotT. E. (Heterooecium) amplectens Hincks. Membranipora amplectens Hincks, Annals Nat. Hist., ser. 5, Vol. VIII, 1881, pag. 129, PI. Ill, fig. 7. Heterooecium amplectens Hincks, Annals Nat. Hist., ser. 6, Vol. IX, 1892, pag. 195. (PI. IX, figs. 1 a-1 c). The ordinary zooecia are pear-shaped oval and provided with a membranous frontal area occujjying half the breadth of the zooecium and between half and one third of its length. It is surrounded by seven spines, of which six are short and a proximal one long and strong. From the inner surface of the frontal area more than 30 small dentiform processes issue, of which the two distal ones are the longest. They are arranged in an oval which is not entirely closed proxi- mally, and the distal half of which is immediately within the margin of the frontal area. The ooecium-bearing zooecia are broadly oval and have somewhat proxi- ' 90, p. 19. 10* 148 mally to the centre an opercular valve, on the proximal side of which there is a long, strong spine. The two rows of flat spines, which cover the area on the distal side of the valve, generally meet in truncated ends. We may how- ever sometimes, as in the corresponding formation in E. zostericola, see a spine stretching its terminal part across an opposite s\nne. The basal wall is only calcified in the distal, ribbed half of the zoa'cium. A small piece of this species was kindly placed at my disposal by the late Mr. Peal. Var. brevispina n. (fig. 1 c). The ordinary zooecia are larger, narrower at the base, the frontal area sur- rounded by 8 — 9 short spines, the proximal one but slightly stronger than the others. The dentiform ]n-ocesses are represented by about 10 extremely small tubercles, situated within the margin of the frontal area in the distal half of the latter. The orecium-bearing zooecia are larger than in the principal form, have fewer spines and a semi-circle of o short spines proximally to the aperture. A few colonies of this form have been found on Honnophora Anstralasiae in the herbarium of alga; in the Botanical Museum. Although we do not under- stand the significance of the situation of the aperture behind the area formed by the spines, we must still group this form of oojcium with the one found in E. zostericola. Electra bicolor Hincks. Membranipora bicolor Hincks, Annals Nat. Hist., ser. 5, Vol. VII, 1881, pag. US. (PI. IX, figs. 7a-7c). The zooecia very long, narrow (the length larger than the breadlli by about 3^2 times), somewhat lyre-shaped, with a longitudinally oval, membranous frontal area, occupying about three-fourths of the whole length of the zooecium and bounded by somewhat convex lateral walls. The smooth, arched gymnocyst passes into a cryptocyst, which first sinks obliquely distally and inwards and finally gives off towards the basal wall of the zooecium a horizontal lamina ending in a denticulated margin (fig. 7 c). On the boundary between the oblique semi-elliptical and the horizontal denticulate part of the cryptocyst a triang- ular calcareous lamina takes its origin. It consists of two lateral halves, bent against each other at an angle open outwardly, and which meet in a thickened central ridge (figs. 7 a, 7 b). In rare cases the gymnocyst has a small tubercle-like expansion distally. The frontal margin of the distal wall is strongly thickened and crenulated, and on the proximal side of it the operculum is seen 149 with a strongly chitinized margin. The lateral margins of the operculum form right angles with the distal margin. The distal wall has within its basal edge a transverse row of 3 — 5 small uniporous rosette-plates, while the distal half of each lateral wall has 2 multiporous ones. The colonies examined form incrustings on Amansici pinnalifida from Austra- lia. (The herbarium of algaj in the Botanical Museum). This species is most closely allied to Membranipora nitens Hincks, which must also be referred to the genus Electra and shows more distinct signs of the relationship than E. hicolor. It has as in E. pilosa an obliquely ascending distal wall, and the three promi- nent spines, so often occurring within the genus, viz. the unpaired proximal and the two distal, are here represented, the former by the large conical expansion and the latter by two somewhat compressed tubercles, which are connected by an arch-like ridge. The rosette-plates are of the same structure as in E. bicolor. E. angulata n. sp. (PI. XXII, fig. 4 a). The zooecia of varying form and dimensions, with a distal arch-like or angulate margin and with a large, most often oval, membranous frontal area, occupying the greater part of the frontal surface. There is a slightly developed, granular, dentate, secondary cryptocyst. In respect to development of si)ines the zooecia show great ditTerences. The best provided ones, which in the colonies examined arc in a great minority, have on the margin 12 not very thick spines, which reach the middle of the area or even surpass it. A larger or smaller number of them is however often wanting, and many zoa-cia are altogether without spines. On the proximal gymnocyst we find in most zoa?cia 2 (more rarely a single median and still more seldom 3) short, thick, conical spines, generally open at the end, which are situated half-way between the central line and the lateral margins. These spines may sometimes be rudimentary, and in many zoa>cia (with or without marginal spines) they are absent. The distal wall, which is generally ascending towards the frontal surface and angularly bent from side to side or arch-like, has on either side a rather large, multiporous rosette-plate situated in one of the basal corners of the distal wall. The distal half of each lateral wall has a single multiporous rosette-plate. On a ligneous core taken on the surface of the water near Koh Samit, Siam (Dr. Th. Mortensen). In a variety of this species from lat. 22° 10' V. long., 114" 30' E. (Captain Suensson) the separate zooecia attain considerably larger dimensions and are in the examined colony all provided with 20 — 24 marginal spines and with 1 — 3 150 short and thick proximal ones. The distal wall is more bent (at a right or an acute angle), and the distal half of each lateral wall may have 1 — 2 rosette- plates. In referring the species, described above, to Electrn, although the distal wall has two niultiporous rosette-plates instead of a row of uniporous ones, the reason is that the rosette-plates of the distal wall in many species show rather great variation even in the same colony. Otherwise this species is most closely allied to E. monostacliiis. The peculiar doubling of the j)roximal spine may possibly explain the origin of the two proximal corner-spines in Mcnihranipora lueiiihrdiui- cea and may then be considered as evidence of the development of Memhidiiipord (sensu stricto) from Electro. Both genera agree in jjossessing few multiporous rosette,-plates on the lateral walls and in their constant lack of avicularia and hyperstomial ooecia. Callopora (Gray) Norman ', char, emend. Alderina Norman", Amphiblestrum Gray p. p., Ramphonotus Norman', Doryj)orella Norman*. (1^1. IX, figs. :i^i). The zocecia, which may have a varying number (0 — 1(5) of spines and a cryptocyst developed to a varying extent, are provided with a small number (5 — 6) of large few-pored pore-chambers. The owcia are hyperstomial. The ccto- ooecium, the calcified part of which often ends in a projecting margin, has a larger or smaller uncalcilied frontal portion. Dependent (wicnUiria generally appear, more seldom independent ones as well. The former may appear distally to the ooecium in an oblique position ami singly or in pairs, while in zocecia without ooecia they may appear singlj- and in different positions on Ihe proximal part of the zooecium. Of species known to me 1 must to this genus refer Callopora lineata, (',. crali- cida, C. Diimerili, C. aiirita, Amphiblestrum Fleiniiuji, A. Irifoliitm. lidiiiphonoliis mina.v, Alderina imhellis and Doryporelhi spathnlifera. Despite the great variation in a series of structures all the above-mentioned species are so closely con- nected that it apj)ears to me to be necessary to refer them to the same genus. In all of them there is a small number of few-pored pore-chambers, and they all have hyperstomial ooecia \vith a partly uncalcified ectoooeciuni, which how- ever may be of very varying extent. The calcification of the ectoofrcium is least developed in C. Diimerili, in which species it appears only as a narrow mar- 83, p. 588. ' 83, J). 596. '■' 83, p. 597. * 84, p. 106 151 .^ f ginal portion, and most developed in C. aurila (fig. 4 a). In C. ininax its extent is similar to that in (J. inibellis but is often indistinct, as it is not always sharply defined. In all of them there is a cryplocyst, the development of which is however not only different within the different species, but also varying ac- cording to locality and age of zooecia. Its development is slightest in C. craticnia and (L lineata, in which it is only a narrow marginal portion inside the spines, greater in C. Diinierili and C. aiiritd, and still greater in C. Flemingi, C. trifolium, C. imhellis and C. iniiKi.v. The last four species are evidently most closely allied. In the last-named species we find a strongly developed avicuhuiiim with an unusually high chamber (mounted on a pedicel-^ Norman'); but in this dille- rence I cannot find sufficient reason for setting up a new genus. A later examination of some good colonies of Doryporella spnthiilifera has corro- borated my view as to the systematic position of this species which I must refer to the present genus. As I am later to give a full descrii)tion of this species in a work on the Ingolf Hiyozoa I may here just mention a few points of its structure. The so-called median pore is the aperture of an avicularium of the same form as those found in the distal part of the zooecium and corresponding to that found proximally to the aperture in C. Fleniinrii, C. minax and C. lineata, and in the last species there may also as in C. sjiathulifera be found a spine distally to the avicularium. There are 6 rosette-plates in the proximal half of the zooecium. In old colonies of C. Flcminyi, C. minax and C. spathulifcra there may be found a compound operculum, the opercular valve and the membrane filling the rest of the aperture being fused together into a separable chitinous lamina. Megapora Hincks. The zooecia have a strongly developed, partially depressed cryptocyst and an aperture surrounded by spines and with a well-developed vestibular arch. A compound operculum in which the valvular part and the accessory part are connected by a joint. A few few-pored porC'Chambers. No auicularia. Hyper- stomial o