LIBRARY OF THE MUSEUM OF COMPARATIVE ZOOLOGY TOs ¥ GIFT OF Wb. 'S F. Forbes N oy ‘ 24s . pai » ‘ge & \\ OCT 1 1937 A MANUAL OF THE INFUSORIA. VOLUME II. “‘ Our little systems have their day, They have their day and cease to be ; They are but broken lights of Thee, And Thou, O Lord, art more than they.” TENNYSON, J JZemorzam. A MANUAL OF THE INFUSORIA: "LS % INCLUDING A DESCRIPTION OF ALL KNOWN FLAGELLATE, CILIATE, AND TENTACULIFEROUS PROTOZOA, BRITISH AND FOREIGN, AND AN ACCOUNT OF THE ORGANIZATION AND AFFINITIES OF THE SPONGES. BY WaSAVILEE KENT. EES. FiZ.S.) Boke M.S: FORMERLY ASSISTANT IN THE NATURAL HISTORY DEPARTMENTS OF THE BRITISH MUSEUM. VOLUME, IE LONDON: DAVND: BOGUES 3. ST. MARTINS BeACE TRAFALGAR SQUARE, W.C. 1881-1882. MCZ LIBRARY HARVARD UNIVERSITY CAMBRIDGE. MA USA se MANUAL OF THE INFUSORIA. CHAPTER VItt- SYSTEMATIC DESCRIPTION OF THE INFUSORIA-CILIATA. Class AE CILIA LA. ANIMALCULES partly or more or less completely clothed with vibratile cilia, which constitute the essential organs of locomotion and prehension ; no supplementary lash-like appendages or flagella; certain of the cilia often modified in the form of sete, styles, or uncini; occasionally pos- sessing more or less distinct membraniform expansions ; a well-developed oral and anal aperture mostly present. With the class Ciliata we arrive at a group of the Infusoria with which micro- scopists will feel comparatively at home, all its members being of relatively large size, and for the most part very giants when set side by side with their flagelliferous compeers described in the preceding volume. That no hard and fast line separates the two groups from each other is nevertheless clearly illustrated by the series of forms last described under the title of the Cilio-Flagellata, in many of which it requires but the suppression of either the flagelliferous or ciliary appendages to con- vert them into ordinary representatives of one or the other of the two leading ciliate or flagellate infusorial classes. That the first-named group has been phylogenetically derived from the Flagellata is by this annectant order fully demonstrated, its existence at the same time assisting substantially in the establishment of an unbroken line of increasingly complex Protozoic organisms, from the simplest Rhizopoda up to the highest Ciliata. The probable lines of evolution by which these latter have passed onwards into the Metazoic animal series will be presently discussed. Among the numerous indications of augmented complexity manifested among the members of the class now about to be introduced, the following may be mentioned :—The cuticular or cortical element in the majority, if not all instances, exhibits a much more complex composition. In by far the larger number of instances it is delicately striate in a longitudinal direction, such striations conforming with a distinct subdivision of its substance in the direction indicated into delicate, highly elastic fibrillee, whose properties and function are closely akin to that of the muscular tissue of the Metazoa, and has in consequence received the suggestive name of the myophan layer. The oral aperture, or cytostome, with the Cilata is, excepting in the case of the endoparasitic Opalinide, always more or less con- spicuously developed, and is frequently supplemented by a complex horny buccal apparatus, e. g. Prorodontidz, Dysteriidz, or it may be by an evertile proboscis, as in Didinium. A modification in the first-named direction has been already notified in the preceding volume in connection with the flagellate genera Astasia and Anisonema. An anal passage or cytopyge, rarely recognizable in the Flagellata, is of almost uni- versal recurrence among the Ciliata, being sometimes, as in JVyefotherus, so extensively prolonged as, in conjunction with the oral aperture and pharyngeal tube, to constitute VOL. II. B 474 CLASS IT. CILIATA. a rudimentary alimentary tract. The rod-like bodies known as trichocysts, recorded in but one or two doubtful instances as yet in connection with the Flagellata (Chilomonas and Merotricha), represent a common elementary factor of the cortical layer of the Holotrichous Ciliata, and are next met with in the Metazoic section of the Turbellaria. Already, in the cases of Avisonema grande and Entosiphon sulcatus, attention has been directed to the exceptional composite rosette-shaped contour of the contractile vesicle. Among the Ciliata this organ often exhibits a yet higher degree of differentiation, not unfrequently (Spirostomum, Stentor, Ophrydium) being produced peripherally into one or more extensive canal-like prolongations, and may undoubtedly be accepted as foreshadowing the more or less complex water-vascular, segmental, and ambulacral systems of the Metazoic classes of the Turbellaria, Trematoda, Rotifera, higher Annelida, and Echinodermata. An im- portant advance in the organization and physiology of the Infusoria Ciliata has to be recorded in connection with all matters pertaining to the phenomena of reproduction. Multiplication by longitudinal or transverse fission is, as among the Flagellata, a common form of propagation. The encystment and breaking up of the entire body-mass into sporular elements characteristic of the majority of the Flagellata, and in which form of reproduction they exhibit decided vegetable affinities, is of very rare occurrence among the Ciliata, the several Holotrichous genera Colpoda, Otostoma, and Ichthyophthirius constituting the chief exceptions. In place of this, new zooids with the Ciliata are usually produced by the subdivision of the nucleus or endoplast into germinal elements, which are liberated independently from the parent animal after the manner of the ova or embryos of the Metazoa. A first progress in this direction has nevertheless been recorded of certain of the higher Eustomatous Flagellata. The phenomenon of genetic union, or conjugation, directly or indirectly associated with the reproductive faculties, exhibits likewise, among the Ciliata, a decidedly advanced formula. While with the Flagellata, so far as is known, the conjugative process is complete and permanent, according with the genetic union or so-called zygosis of unicellular plants, this process, though similarly mani- fested among certain Ciliata, such as the Vorticellidz, is more usually replaced by an incomplete and transient conjugative act that corresponds more nearly with the copulation of higher animals. Finally, while all Flagellata are essentially unicellular, possessing but a single, and in almost all instances very simple, nucleus or endoplast, among the Ciliata this structural element very commonly exhibits a highly com- plex type of composition, and being in many instances represented in plurality, demonstrates the further advance made by these organisms towards the condition of multicellular beings. The character and mode of distribution of the cilia yield reliable data for the subdivision of this class into minor sections or orders, the following plan as here adopted being in accordance with the one first introduced by Professor Stein in the year 1857. While the more characteristic members of these several orders yield features which permit of their natural and readily appreciated distinction, intermediate forms occur in each such group indicative of their close relationship and common design. Special reference is made to the more prominent of these annectant or transitional types in the general description of the respective orders. SYNOPSIS OF THE ORDERS OF THE INFUSORIA CILIATA. Cilia distributed over the entire surface of the body, similar, or differing but slightly in Order I... .. HOLOTRICHA. character. Cilia distributed over the entire cuticular sur- face ; the oral series of conspicuously larger size. | HETEROTRICHA. Cilia not universally distributed, mostly limited Aaa yall to a conspicuous circular or spiral adoral 5) LL es ee | PERTTRIGEAS wreath. Locomotive cilia, confined to the inferior or ventral surface of the body. » IV. ., .. HYPoTRicua. CLASS ff. CILIATA., 475 Before entering upon a systematic description of the Ciliata, it is worthy of remark that until within a comparatively recent date the assemblage of organisms included within this class were accepted by many eminent authorities as possessing the only sound claim to the title of the Infusoria. The Flagellata, previous to their more exhaustive scrutiny by recent investigators, were regarded for the most part as Protophytes or the so-called zoospores of higher Cryptogamic plants, while the Tentaculifera or Acinetidze were pronounced to be embryonic conditions only of various Peritricha. Undoubtedly, this section of the Ciliata is one of the largest and most important groups of the Protozoic sub-kingdom. In no other of the equivalent subdivisions is histologic differentiation carried to such a marked extent ; many of the higher forms being indeed so modified in this respect that they may be unhesitatingly cited as furnishing the most complex expression of unicellular organization. ‘To the notice of the evolutionist, to an equal or even greater degree than to the histologist, the Ciliate Infusoria deservedly commend themselves. It is beyond question to the ranks of this extensive class that attention may be profitably directed in the search after those ancient stock-forms or archetypes out of which several of the more important groups or phyla of the Metazoa have been gradually evolved. That the group of the Spongida does not, as maintained by some contemporary authorities, furnish the long sought for interconnecting link between the Protozoic and Metazoic series is substantially supported by the evidence submitted by the author in Chapter V. of the preceding volume, in which it is shown that, notwithstanding the plausibility and fascination of external appearances, these organisms remain in all structural and developmental details thoroughgoing, though peculiarly modified, Protozoa. Already, in vol. i., p. 103 ef seg., the homoplastic resemblances and possible biogenetic relationship that subsist between the Ciliate and other Infusoria and the Metazoic animal series have been discussed at some length. Further time devoted to the consideration of this important subject, enables the author to greatly extend the scope of the comparisons previously instituted, and to submit, in connection with the woodcut illustrations on p. 477, and succeeding Genealogical Table, a possible clue to the phylogeny of all of the more important Metazoic groups. That the Holotrichous Ciliata may be consistently regarded as the archetypes of the lower worms, has been frequently advocated, the likeness between the former and the simpler Turbellaria being so marked, see woodcut, Figs. 3 and 4, that many earlier authorities have proposed to include these Infusoria in the Annelidous class; K. M. Diesing, more especially, in recognition of such likeness, established for their reception the new order of the “ Prothelmintha.” As related in vol. i. p. 26, this authority included, however, in this order not only the Holotrichous Ciliata, but, with the exceptions of the Vorticellidz and Stentoride, all the Ciliate and Flagellate animalcules. In addition to the resemblances subsisting between the Holotrichous Infusoria and the Turbellaria, as manifested by their minute size and corresponding form, by their entire and even ciliation, by their common possession of trichocysts, and by the development in the members of the last-named group of a water-vascular system, which may be regarded as a modification of the contractile vesicles of the Infusoria, it may be mentioned that many of the Rhabdoccelous Turbellarians multiply as do the Holotricha and other Infusoria by the simple process of transverse fission. Taken collectively, the numerous collateral charac- teristics cited yield almost overpowering evidence in favour of the biogenetic relationship that is here advocated.* Other Metazoic groups, in addition to that of the Turbellaria, would seem to possess a substantial claim to an Holotrichous ancestry. In the sub-kingdom * The near approach of the Ciliate Infusoria to the structural plan of the lower Turbellaria is briefly indicated by Professor Huxley at p. 678 of his ‘ Anatomy of Invertebrated Animals,’ ed. 1877; while, in a communication addressed to the author since the publication of the first two parts of this Manual, this authority has more distinctly referred to the Holotricha as probably constituting, in connection with the Turbellaria, the proper line of evolution from the Protozoic to the Metazoic series. The Spongida are further alluded to as occupying in such case, with reference to the Metazoa, a position equivalent to that held by the Tunicata in relation to the Vertebrata. B 2 476 CEASS Tf. “CLELATA. Ccelenterata, including the Corals, Sea Anemones, and Hydrozoa, the initial term or larval form common to the group is an ovate, evenly ciliated body, or so-called “ Planula,” woodcut, Fig. 1, differing entirely from the parent organism, but in all ways comparable with a mouthless Holotrichous Infusorium, as delineated at Fig. 2. Ina similar manner, the mostly endoparasitic Scolecida (Trematoda and Cestoidea) are traceable to a like origin, many Trematodes, such as Jonostomum, giving birth to simple holotrichously ciliated embryos, while the aberrant Opalinide, with reference to their often highly differentiated organs of adherence and, in certain instances, e. g. Anoplophrya prolifera, peculiar mode of reproduction, indicate a no very distant connection with the Cestoidea. It is worthy of remark that while many of the higher Annelids, Lumbricus and vais, commence life as similar holotrichous infusorium-like embryos, others, including the majority of the marine worms or Polycheeta, conform for the most part, as do the larvee of the Echinodermata, with the Peritrichous infusorial formula. The order of the Heterotricha, whose members unite, in their plan of ciliation, both the Holotricha and Peritricha, do not at present suggest any distinct Metazoic affinities. It is at the same time perhaps deserving of attention that the ciliated lappet-like appendages developed in the larval stage, or so-called “* Piliditum” of the Turbellarian genus Ziévews, recall to some extent the ciliated lobes of the peristome developed in the Heterotrichous genus follicularia. While, in the preceding volume, Joc. cit. p. 103, a passing reference was made to the affinities of the Peritrichous Vorticellidz with the Polyzoa, suggested by both L. Agassiz and K. M. Diesing, such faint external likeness as subsists between the adult structures and gave rise to such correlation, was not considered worthy of serious entertainment. Since then, however, it has occurred to the present author that from an entirely diverse standpoint the relationship suggested may be substantially upheld. A first impression in this direction was derived from a recognition of the close correspondence in external contour presented by the motile larvze or so-called Trochospheres of the Polyzoon Alcyonidium gelatinosum, as delineated in a notebook placed at the author's disposal by Mr. H. E. Forrest, and reproduced at Pl. XXXI. Fig. 53, and such a free Peritrichous Infusorium as Zrichodina pediculus. Following out this newly indicated clue, it was next found that the larval conditions of numerous other Polyzoa, as recently figured and described by Barrois,* bear out ina most remarkable manner the premised affinity. This last-named authority, further- more, reduces all of the more or less modified embryos of this zoologic group to an ideal type, see Fig. 11 of the accompanying woodcut, which, without a pre-existing knowledge of its true import, would unhesitatingly be accepted as a slightly modified example of the ordinary Vorticellidz, as given at Fig. 12. It is highly interesting to find that the class Mollusca, whose intimate relationship with the Polyzoa is universally conceded, abounds with larval forms reducible to the same Peritrichous formula. A suitable illustration of this fact is afforded by the figures representing the early larval condition of Chiton cinereus, as delineated by Lovén, and reproduced in Huxley’s ‘ Manual of the Invertebrata,’ and in other zoological textbooks. Yet another leading section of the Metazoa, that of the Echinodermata, would appear to admit of being retraced phylogenetically to the group of the Peritricha. Here, as in the preceding instances, the clue has to be sought among the larval or embryonic, and not among the adult organisms. The embryo Echinoderm, or so- called Echinopeedium (Huxley), on leaving the egg, is altogether distinct from the parent, consisting of a laterally symmetrical, ovate body having usually two, four, or more girdle-like bands of cilia. Through the process of histolysis or atrophy, this primary integument with its ciliary girdles becomes speedily obliterated, but there can be no doubt that during such transient larval existence the young Echinoderm resembles in a truly remarkable manner such Peritrichous Ciliate Infusoria as Uvocen- trum turbo, Pl. XX XIII. Figs. 7-9, and Didinium nasutum, Pl, XXXII. Figs. 50-57, and woodcut, Fig. 10, the latter type more especially being characterized in its normal * ©Recherches sur l’embryologie des Bryozoaires,’ 1877. CEASS Hi CILIATA- 477 condition by the possession of two, and, preceding the act of fission, four, ciliary girdles. An approximate estimate of this resemblance may be gained by a comparison of the figures just cited with the accompanying woodcut illustration, Fig. 9, of the earliest larval or Echinopeedium phase of a Feather-star, Comatula, reproduced from Haeckel’s ‘ Natiirliche Schépfungs-Geschichte.’ The Echinus, the Star-fish, or the Holothurian, one and all, present an identical or but slightly modified initial structure, and may therefore be consistently regarded as the descendants of a similar simple Peritrichous archetype. a 12 The figures, bracketed in pairs, represent six larval Metazoa, with their respective Infusorial isomorphs, as cor- related in the accompanying text. } , Fig. 1, an Astomatous larval Coelenterate or Planula; Fig. 2, an Astomatous Holotrichous Infusorium, Opalina ; Fig. 3, a larval Aproctous Turbellarian ; Fig. 4, a Stomatode Holotrichous Infusorium, Paramecium ; Fig. 5, a larval Nemertian, Cephalothrix, after Macintosh; Fig. 6, a Cilio-Flagellate Infusorium, Melodinium ; Vig. 7, a Telotro- chous Annelid larva, after Gegenbaur; Fig. 8, a Peritrichous Infusorium, Telotrochidium ; Fig. 9, a Mesotrochous Echinoderm larva, after Haeckel; Fig. 10, a Peritrichous Infusorium, Dzdimzusm (prior to subdivision); Fig. 11, a typical larval Polyzoon, after Barrois ; Fig. 12, a Peritrichous Infusorium, Vorticella. The letters ov and az indicate respectively the oral and anal apertures. The small group of the Gephyrea, including notably Szpunculus and Priapulus, frequently cited as possessing structural modifications that unite the two groups of the Echinodermata and Annelida, is of interest in connection with the present subject of discussion since the embryonic zooids, in at least Sipunculus, accord in their Peritrichous plan of ciliation with those of both the first-named group and the Polychetous section of the Annelida. The ciliated embryos of the Polycheetous Annelida, while thus conforming to the Peritrichous type, are found within such limits to exhibit three somewhat diverse modifications. As explained by Professor Huxley in his ‘ Anatomy of the Invertebrata,’ p. 243, the cilia in some cases form a broad zone which encircles the body, leaving at each end an area which is either devoid of cilia, or, as is frequently the case, has a tuft of cilia at the cephalic end. Such larvee are termed “ Atrocha.” In other embryos the cilia are arranged in one or more narrow bands which surround the body. Where two bands of cilia are developed, the one encircling the body immediately in front of the mouth, and the other around the anal end of the embryo, the larvee are called ‘‘ Telotrocha.” In the third modification one or many bands of cilia surround the middle of the body between the mouth and the hinder extremity, such larvee being distinguished by the title of “Mesotrocha”; a supplementary tuft of cilia also, in the case of the Telotrocha, being not unfrequently attached to the centre of the przestomium or pre- oralregion. While such Peritrichous Infusoria as Uvocentrum and Didinium conform more essentially to the Telotrochal larval type, in the intermediate structural form Calceolus (Peridinium) cypripedium of H. James-Clark, Pl. XXXII. Figs. 23 and 24, having, with the exception of a bare cap-like anterior region, the whole surface of the body clothed with vibratile cilia, a decided approach is made towards the 478 CLASS II. CILIATA. Atrochal formula.* It is a further significant fact that in this type a fascicle of long whip-like cilia is developed from the oral region, which may be regarded as homologous with the terminal tuft common to both the Atrochal and Mesotrochal Metazoic larve. A yet more interesting and significant modification of the Telo- trochal plan is perhaps exhibited by the recently discovered Peritrichous Infusorium represented by Fig. 8 of the accompanying woodcut, and upon which, with reference to the likeness indicated, the author has conferred the generic name of Ze/otrochidium. While somewhat resembling at first sight a temporarily detached Vorticella with a supplementary posterior ciliary circlet, it differs fundamentally from such a type in that the anal aperture does not open, as with the typical Vorticellidz, upon the oral vestibulum, but at the posterior extremity of the body and to the rear of the hinder circlet of cilia. The anal passage following upon the aperture is conspicuously visible for some distance within the surface of the cuticulum, and, as will be at once recognized, it requires but a further prolongation and juncture of the oral and anal passages to produce an organism indistinguishable from Gegenbaur’s representation of a Telotrochous Annelid larva, reproduced at Fig. 7. A remaining and very important section of the Metazoa, with which as yet no attempt has been made to demonstrate an infusorial phylogenetic origin, is that of the Arthropoda, including most notably the Crustacea, Arachnida, and Insecta. Such a connection, nevertheless, is, in the author’s opinion, obscurely traceable in the direction of the Hypotricha, the interval separating the first-named highly differentiated Metazoa from the Protozoic order being bridged over by the group of the Wheel-animalcules or Rotifera. The passage from the Hypotrichous Ciliata to the Rotifera is indicated in two completely distinct directions. Firstly, in such a type as the Dysteria armata of Huxley, Pl. XLII. Figs. 27 to 30, in which the complex buccal armature and jointed caudal style are so strongly suggestive of its Rotiferan affinities that the animal was originally referred by Mr. P. H. Gosse to the class in question. Secondly, in that aberrant group of the Rotifera, including Ichthydium, Chetonotus, Turbanella,and a few others, recently incorporated together by Metschnikoff and Claparéde under the title of the Gasterotricha,t which are all distinguished by the absence of the customarily developed trochal discs and complex mastax, while the entire ventral surface alone is clothed with fine vibratile cilia after the manner of the most simple Hypotricha. It is at the same time necessary to observe that among the generality of the Rotifera, both in their larval and frequently in their adult state, the cilia form a single terminal wreath around the so-called trochal disc, and consequently correspond closely with the Telo- trochous larvee of the Echinoderms and Polychztous Annelida previously described.t In common with these larve, they are likewise apparently phylogenetically derived from the infusorial order of the Peritricha. In this connection it may be further remarked that the two endoparasitic Peritrichous genera Offryoscolex and Lnto- dinium, distinguished by the possession of indurated carapaces and variously modified spinous appendages, were originally referred to the Rotifera. In one of these genera it is interesting to find that a second girdle of cilia is developed round the centre of the body. ‘The affinities of the Rotifera with the Crustacea are, as indicated by Professor Huxley,$ possibly manifested in ‘‘ Pedalion, with its jointed setose appendages and curious likeness to some /Vauplius conditions of the lower Crustacea.” It might be further added that many Rotifera, in common with * The so-called Atrochal larva of the Chetopodous Annelid Sevfz/a, as originally figured by Stossich, and reproduced in F. M. Balfour’s treatise on Comparative Embryology, vol. i., 1880, conforms entirely to the Holotrichous plan of ciliation, and with its ventral oral, and postero- terminal anal apertures, may be directly compared with a Paramecium, or an embryo Turbellarian. + ‘‘Beitrage zur Kenntniss der Entwickelungsgeschichte der Cheetopoden,” ‘ Zeit. Wiss. Zool.’, Bd. xix., 1869. t{ The resemblance between Rotifers and the larvee of Echinoderms was pointed out by Professor Huxley in his account of Lacimudlaria socialis in the ‘Transactions’ of the Microscopical Society for the year 1851, and is further advocated in his ‘ Anatomy of the Invertebrata, p. 193, 1877. § ‘ Anatomy of Invertebrated Animals,’ p. 193, 1877. (eurqaowy) Vdo0d0OZIHa CLASS [f. CILIATA. On ™ ET << : VLVTISOVIS-O1dV4 : VLVTIE9V1I-0Z1HY VOZOLIOAWN VLVWOLSOLNVd-VLVITAD V1 - SS SSE VINVIOIGVY VLVWOLSNI-VLVTTIOVIS ! VLVTTADVI-ONVOHO VLVITEDVT4-O1TI9 ; VaIONOds VLVITIO-VINOSNANI VHOINLOdAH VHOINLOYWALIH VHOIN.LOTOH : : : VHOMLIYAd a ee VGINITVdO | VYAATINOVINAL VdIWAAIG VUTIILOW | VAINAHIIO : VIMVTIETYAL VOZAT0d a : ———— ~VAIOETOOS ; a VLVUGLNYTDO VLVWUYACONIHOA VadOdOUHLUV Se : VILVOINAL ‘VAITANNV VOSN TION VLVUFTHLAAA ‘VIVUFIALYAA FHL OL VIYOSNANI AHL HONOYHL VdOdOZIHY AHL WOUT NOILATOAY AO SANIT OILANADOTAHG AIAVAOUd ONIMOHS AIWAVE TVOINOTVANAY 480 CLASS IL CILIATA. Nauplian Crustaceous larvee, are characterized by the possession of only a single median visual organ. Many of the higher Hypotrichous Ciliata, e. g. Stylonychia and Euplotes, would finally, by virtue of their not unfrequently branched setose appendages, appear to exhibit a latent Arthropodous bias. With the aid of the evidence submitted here and in the preceding volume, it is finally found possible not only to predicate the probable lines of evolution by which, out of the Holotrichous, Peritrichous, and Hypotrichous orders of the Infusoria Ciliata, all of the more important Metazoic groups have been evolved, but also to produce a genealogic scheme, see p. 479, indicating an unbroken chain of animal organization of gradually increasing complexity from the lowest Rhizopod up to the Vertebrata. The broad and seemingly almost insuperable hiatus which, failing the group of the Spongida, seemed to intervene between the Protozoic and Metazoic series, need no longer present any substantial obstacle to the taxonomist. or while the three foregoing orders of the Ciliata still remain undoubted and easily recognized Protozoa, it as evidently needs but the interposition of some innate force, akin to that of crystallization, to transform their plastic and comparatively amorphous protoplasmic bodies into mullicellular aggregates or Metazoa. Nay more, numberless examples of the Ciliata are multinucleate, and therefore potentially multicellular, and furnish, by reason of such differentiation, the most perfect possible links of connection between the Protozoic and Metazoic series. Where, consequently, as in the several cases here submitted, these Protozoic organisms are more or less perfect isomorphs of the mature or larval phases of Metazoic structures, it may be consistently predicated that they are phylogenetically connected with them. A beautiful and highly instructive illustration of the manner in which a unicellular and simply nucleated protoplasmic body may pass first into a multinucleate and then into a multicellular condition is afforded by the figures given by Metschnikoff,* copied in F, M. Balfour’s ‘Comparative Embryology,’ and herewith reproduced, of the segmentation of the ovum of the Rose Aphis, 4f/is rose. Fig. 3 1n this series is Figs. 1 to 4, illustrating four successive phases of the segmentation of the ovum of Afhizs ese. A granular central yolk mass and an outer protoplasmic layer are distinctly visible in every instance. In Figs. 1 and 2, two and four nuclei have respectively appeared within the outer protoplasm. In Fig. 3 a number of nuclei have arranged themselves at regular distances throughout this region, while in Fig. 4 the protoplasmic layer has become divided into a number of columnar cells, which correspond with the nuclei (after Metschnikoff). Fig. 5, an adult example of Dicyema typus, whose histologic composition accords closely with that exhibited by the aphis ovum represented in the preceding Fig. 4; ax, central nucleated axial cell; ec, multicellular ectodermal layer (after Ed. Van Beneden). more especially noteworthy, since it corresponds with a typical Ofa/ina and depicts that multinucleate and potentially multicellular state that is definitely assumed in the succeeding phase as delineated at Fig. 4. Metazoa whose adult structure may be said to be scarcely in advance of what obtains in the simplest multicellular condition of the ovum delineated at Fig. 4, are found embodied in the two recently discovered orders of the Dicyemida and Orthonectida. Both of these consist of mouthless, elongate ovate, more or less completely ciliated, essentially endoparasitic organisms, the former as yet having been obtained infesting exclusively the renal organs of various Cephalopoda, while the latter more extensively distributed * «Embry. Stud. Insecten,” ‘Zeit. Wiss. Zool.,’ Bd. xvi., 1866. CLASS Il. CILIATA. 481 group affects the intestinal viscera and surrounding tissues of various Nemerteans, Turbellaria, and Ophiurida. In the case of Dicyema, see Fig. 5 of the accom- panying woodcut, histological differentiation, as attained in the adult, takes the form of a single peripheral cellular layer, within which is enclosed a single long cylindrical or subfusiform axial cell. With the Orthonectida, Afopalura, a slightly more complex structural formula is introduced through the subdivision of the central axial cell into cellular elements. The external resemblance that subsists between Dicyema and certain ciliated Infusoria was held by Claparéde and Lachmann to be so close, that these authorities figured and described one species, D. AM/welleri, in their ‘Etudes sur les Infusoires, as a type whose nearest affinities were probably to be sought for amongst the Opalinidz. As constituting a stage in advance of these Ciliata, equivalent to that held by Fig. 4 with reference to No. 3 of the segmentation phases of the aphis ovum here delineated, this interpretation of Dicyema may perhaps be not inconsistently maintained. It might be further suggested, with reference to such affinity, that the single axial cell, the sole representative of the hypoblastic element or entoderm in Dicyema, is to some extent foreshadowed in the remarkably prolonged and correspondingly axial so-called nucleus, as developed in the more abnormal Opaline genera Anoplophrya and Hoplitophrya. In recognition of the essentially intermediate structural position with reference to the Protozoa and typical Metazoa, that is occupied by the Dicyemida, Ed. Van Beneden* has proposed to assign it to an altogether distinct and intermediate sub-kingdom, that to be distinguished by the title of the “Mesozoa.” Professor Huxley t is likewise inclined to support this view, though with reference more to the remarkable developmental phenomena. In so far as the germs in Dicyema are produced from within the single axial cell, such reproductive cell is correlated by this authority with the central ‘‘capsule” of a Radiolarian; while the peculiar manner in which the peripheral cells in the embryo grow round and partly enclose the axial one, he maintains, corresponds with the phenomenon of “ epiboly” as it occurs in many ordinary Metazoa. The embryological evidence so far at disposal, as now submitted and indicated in the accompanying table, unquestionably points to the derivation of the Ccelenterata, Turbellaria, Cheetopodous Annelida, and Scolecida from a Holotrichous archetype ; the embryos in examples of all these Metazoa being completely clothed with fine vibratile cilia, and scarcely distinguishable from Holotrichous Infusoria. In a second series, including more especially the Polyzoa, Mollusca, Echinodermata, typical Rotifera, and many Polychzetous Annelida, the larval forms are characterized almost exclusively by their Peritrichous plan of ciliation and remarkable conformance with certain members of the Peritrichous Infusoria ; while in the third Ciliate group, that of the Hypotricha, there is an apparent modification in the direction of the Rotifera, and through them to the Arthropoda, ‘Taken collectively, it is clearly shown that the peritrichously ciliated larval form represents a preponderating factor in the onto- genetic history of the Metazoic series; its protozoic isomorphs, as typified by a Peritrichous Infusorium, being, in accordance with the fundamental laws of evolution, the archetype or stock-form from whence the principal Metazoic groups were primarily derived, and out of which, as shown in the accompanying table, the genealogy even of the Vertebrata may with facility be defined. Though the biogenetic scheme here introduced is mainly tentative, and necessarily imperfect at many points, it may be confidently anticipated that a more extended acquaintanceship with the Ciliate Infusoria and initial or larval phases of the Invertebrata will be productive of data permitting of a yet closer and more perfect amalgamation of the Protozoic and Metazoic groups. In many instances, through the epitomization and abbreviation of their developmental course, the clue sought for is dim or even altogether obscured, but in other cases it is manifested with an amount of perspicuity that can scarcely escape the recognition of the earnest interpreter of Nature’s problems. * “Recherches sur les Dicyemides,” ‘ Bull. de l’Acad. Roy. de Belgique,’ tom. xli. No. 6, and tom. xlii. No. 7, 1876. t ‘Anatomy of Invertebrated Animals,’ 1877. 482 ORDER HOLOTRICHA. Order IJ. HOLOTRICHA, Stein. Animalcules free-swimming, more or less completely ciliate throughout ; cilia alike or differing but slightly in character from one another, sometimes supplemented by a variously modified extensile or undulating membrane ; oral and anal orifices usually conspicuously developed; the cuticular layer or ectoplasm not unfrequently containing trichocysts. The order of the Holotricha was originated by Stein for the reception of all those animalcules in which the surface of the integument is completely clothed with cilia that agree entirely with or differ but slightly from one another in size and character. It undoubtedly embodies the most simply organized members of the class Ciliata, the series as a whole, however, being subject to considerable range of complexity and offering a tolerably uniform series of gradations from the most simple types towards the succeeding order of the Heterotricha. In those forms, more especially such as Lembus, Pleuronema, Panophrys, and Cyclotricha, in which an extensile or undulating adoral membrane is borne in addition to larger adoral cilia, the highest differentiation and closest approximation to the Heterotrichous formula is apparently arrived at. It is noteworthy in connection with this circumstance that the larger adoral fringe of cilia in both the Heterotrichous and Hypotri- chous orders of the class, as typified by the two genera Stentor and Euplotes, is represented in its earliest or initial state by a similar membraniform expansion. Evidence indicative of the comparatively lower organization of the Holotrichous group of the Ciliata, is afforded by their occasional sporular mode of reproduction. This, while common to the Flagellata previously described, is as yet unknown among the higher sections of the Ciliata. Illustrations of such exceptional developmental’ phenomena are hereafter recorded in connection more especially with the four genera Colpoda, Otostoma, Ichthyophthirius, and Amphileptus. In accordance with Stein’s scheme of classification of the Ciliata,* reproduced at page 210 of vol. i, the order of the Holotricha is, exclusive of the Opalinidz, sub- divided into the four minor groups or families only of the Trachelina, Enchelina, Parameecina, and Cinetrochilina. It has been considered undesirable, however, to adhere strictly to that scheme in this volume, and this in consequence not only of the discoveries of numerous Holotrichous types requiring independent family grouping, that have been made subsequent to the appearance of Stein’s work, but on account also of the evident incongruity in many instances of the generic groups united under his proposed family headings. Examining these five family groups in successive order, it will be found that the title of the last one, that of the Cinetrochilina, has to be entirely abandoned, since Cinetrochilum and its supposed near ally Glaucoma can no longer be accepted as independent generic types but as being developmental conditions only of certain Hypotricha. lewronema and Cyclidium, again, differ so remarkably in the character of their membrani- form appendages from ZLembadion, Ophryoglena, and the several other generic types with which Stein associates them, as to demand independent family dis- tinction. In Stein’s fourth family of the Paramecina a still more heterogeneous assemblage of generic forms is encountered, the proposed group including, in addition to the simply and evenly ciliate Paramecia, the diversely ciliated Enchelys, Nassula with its fish-trap-like pharyngeal armature, the membranous flap-bearing Panophrys, and various other distinct types. His third family of the Enchelina is composed of equally inconsistent elements as typified by such entirely dissimilar generic types as Prorodon—which is immediately allied to Wasswla—Coleps, Lacrymaria, Perispira, and Actinobolus. The last-named generic form would seem indeed to have no * ‘Tnfusionsthiere,’ Abth. ii., 1867. GENUS PARAMECIUM. 483 claim for admission within the ranks of the Holotricha, but to be referable, if any- where among the Ciliata, to the Peritricha. Stein’s second family, of the Trachelina, is the only one which may be said to embrace generic groups that fairly harmonize with one another; even here, however, one out of the five genera named, Loxodes, is now shown by Wrzesniowski to belong to the Hypotrichous Ciliate group, while Dilepitus cannot be generically separated from. Amphileptus. While receiving its title and definition from Professor Stein, it is worthy of remark that, in common with the Peritricha, the order of the Holotricha is one of the important groups that yet awaits systematic description by that eminent authority. The accompanying table of classification may now be submitted as embodying what, in accordance with our existing knowledge of the Holotricha, would appear to constitute the most natural family grouping of the numerous genera, while it at the same time provides a concise clue to their distinction. In accordance with Stein’s classificatory system, the mouthless Opalinidz are here admitted among the Holo- tricha, being regarded by the author as either peculiarly modified members of the order, which by long maintenance of an endoparasitic mode of existence, have become accustomed to absorb the nutrient juices of their host through the general surface of their integument, and thus gradually dispensed with the need of a distinct oral aperture, or which possibly, through having been primarily brought into existence amid similar surroundings, have failed to develop the requirement of such inceptive orifice. These alternative interpretations are discussed at length in connection with the systematic description of this singular organic group. Fam. I. PARAMZKCIIDA,, S. K. Animalcules free-swimming, more or less flattened and asymmetrical, ciliate throughout, oral and cuticular cilia alike ; dorsal and ventral surfaces distinct, the oral aperture opening on the ventral surface. GENUS I. PARAMECIUM, Miller. Animalcules free-swimming, ovate or elongate, asymmetrical, more or less flexible but persistent in shape, finely ciliate throughout, the cilia of the oral region not differing in size or character from those of the general surface of the body; an oblique groove or buccal fossa developed on the ventral surface, at the posterior extremity of which the oral aperture is situated ; cortical layer usually enclosing trichocysts ; contractile vesicle and endoplast conspicuous, the former under certain conditions sometimes assuming a stellate outline. Inhabiting fresh and salt water, and abundant in vegetable infusions. Paramecium aurelia, Mill. PL. XXVI. Fics. 28-30, Body elongate-clavate or subfusiform, slightly compressed, about four times as long as broad, narrower and truncate anteriorly, the posterior half somewhat inflated, terminating in a conical point; buccal groove prolonged, extending from the left side of the anterior extremity obliquely backwards on the ventral surface, towards the right-hand side, beyond the centre of the body ; oral aperture situated at the posterior termination of the buccal groove ; anal aperture ventral, situated midway between the oral orifice and the posterior extremity ; contractile vesicles two in number, stellate when compressed, situated respectively at a distance of about one-third of the smeayjygokysy2y many hy goxoT snggapiy guy *SNUaYIDA T "pIUuDYD "SIUUASDT ‘DUAADI YT ‘DUYDIYT *DIADUAAIDT "DIAIIO[IY IDA T, *ppogjo7 "OULTEL "shay goupy *vAIgst hag *SusMavjayy *sMayIUT “soyrey og "uosogorsviq *sZ2j02 "DY IAJOL/) *uopokzay Iu sy inp hy Jojay IVA 7, “puLojsomyazy *DUuLojsOo1E) ORDER HOLOTRICHA. *whayGJojoxy "DY IAJOST "2unuojsojp4nD *DINSSOAT *UuOposodg *sndiyjyPoyIuoy7 ‘SNIDIT *snpDoy J220x0T "UNLIDUVADT "SAND + (oe) > “15 “of 6z 92 ‘le{ ‘Qe “Surmuitms-oy ‘Arvj1[0s saynopeuntuy J‘ [eatwsayqns yoy snonoidsuo9 oz ve yey 61 ‘SI 7a | ‘or sor VI ‘cr oI ‘II ‘Ol oe oe ee oe ae ‘ULLOJI[NGvIo0e ‘9AIsoype uoIsaI [AQ ** BITIO asojas Suljerper ATPAVMUT YITA SIP [LIQ ‘WAIIMIHLHAOKHLHO] ‘TTA ‘weg OYl[-[UN.A} ou ynq ‘a}yenus}}e uordser 1OMOjUW piste rane 3 Op $00. CO arr ssadoid oyry-37Uny ‘giqixey ‘oyeduoja ue se posonpoid uordser ioazyuy sete te eee ee QyBTNOaI IO Iejonova ATYSIY vurAyousieg ayeord jou 4y10ys xudieyg )-oa0019 ieynuue ** aqvord AT[vurpnysuoy ‘pasuojoid xudreyg } [eorde on **uun1d9Y}00z Suryouviq payoriye ‘QAO0013 IvNUUL uv Suyiqeyur ‘fe1o0s sarnorewuy jeoide ay3 ur Suruedo ‘uonesuojoid ro1se}Ue dyI[-3UNIy w3zJ0 pue 9}enus}}2 uv Jo aseq oY) Je pa}enyIs 91n} -rade ye1o { oysepo ATYysty ‘ayeSuoyo sopnopeuUy ‘WCAILTHHOVUL “ILA ‘Wey ‘snosuasomoy eudyouoie g oe ee oe oe. ee ee oo we ‘O[qIXop pu yos dovjANS AvpNoyNd £ [euIUIID}-qns 10 [eUIUIIE} ‘2A0013 ainjiode [eto £ aAoois Iepnuue [eolde ue pue Iepnuue ha JOII9}UB 9YT]-yoou pasuojoid v YIM Ajensn ‘aj}esuoja 10 padeys-ysey sanopemmuy "WAIOUAIOTAHOVAL “LA ‘Wey te 3 \ " -o1}xo jeoidy gyIsua}xe puv osvja ApYysry uonsod ayy-yoan) YIMo] : ** OMT-Yod ‘feoujoururdse oanjzode [eso asessed jeasudreyd payeyyio v yy a) ** asessed [vosudivyd payer on .e oo oe *pexqu9A IO [¥19}8] qynoy ‘ayeAo ATUAAD ainjziode [eiQ *O[QIXOY puv jos dovjAns 1epnoyNd fye1oyey IO yeururis} oinjyrode yeio £ souUeUT ayI]-peu B ur peonpoid iou ‘aaoo1d sIepnUUe ue Aq Apoq 9y} wor poyeredas jou Ajru91;x9 [eoide 94} aids pasuojorid v Suruts0f vipIo [e1O ** uorser 101103sod ayr]-3sh9 a1vq & YIM ‘9}vAo ATUaAO soTNofeMUY PE BB 8G AGRON OR NI SHYEB) -uny Ajanbyqo ‘wu40jsuAd somnopeuuay oe ee ee ee ee ee ‘ayeAO SSdT IO d1OW saNoTeUIUy ‘OSULIF Ie[NIII ‘WAILTAHONY ‘A ‘wey ajduus e SUIULIOF VITIO TLIO *[BUlUII9} no, Byas [won 10 IOII9}UB SnondIdsuod & YITAA sassaooid snourds ynoyyM aoedeieg **sassao0id snourds yim doedvies *po}VINPUL 9OVJINS Avpnorns £ PeuTUIID} ainjiode [eio £azevAo ATTeoLJoWWAS sopNoyeUTIU\ ‘WAIdHIOD “AT ‘weg \ "eas [eIoNq IO IOIIO}Ue ON ** vjas [epnvo snonordsuoo v yy ‘odvys ut yuoystsiod sarnoyeuuy ‘sts ** uorjeduojoid oyT-y90u ON \ OG sco GC UOISa1 a¥yI][-you pasuojoid v yA, ‘jeururio} ommjrode [e1o £ aye[090uvT 10 podevys-ysey sopnopeuIUy ‘WAITIAHAOTAHOVUL [IT Wey ** g[tovI]U0D pur oysvya ATysry sopnoyeuUuy oIMXIY [Vprloorjay wv ur Surjeururss} ‘Suoy xudeyg } *poarno ** + padevys-1va Jo aynjoauos 41oys xudivyg J XUAreyg | sein SO OGD FAUT, Signe yeayele Ferd [e10 “a[ovIyUOD pure oN}seIa sofnopvuIU ‘yYSTeys *Y]99} OYI]-por YIM powre uayo “ounsrp ee [eUluII19}-qns IO [e19}e[ o1nzA9dv xudivyg xuAreyd § [etaye, IO yeurut1s} ainjiode yei0 je1o ‘advys ur juaysistad sopnopeumuy ¢ jeotpuryéo Io ayeao ATyeotjouuds sarnopeulUy ameivey, tocuae is Rasta cc [e19}2] YNow ‘onsvya pue Ios poms ‘WAILNOGOUOU ‘JI “Wey eo 00 ee te wee re ra1~T TINO y TESTS DOIN } "WLLOJ Ul JUDISISIOg xudieyd ** [VUIULI9}-qns IO [eUTUIID} YINOT! p : ** padojaaop Ayysty xudreyd ‘orntsvieg ** xuAivyd younsip ou “Suruum1ms-901,7 ce OKOO TG TELO DELO Nu Rien oe a ** 9A0019 [eiope onbiyqo ue yIIA, } pue yjos } Spee ear geps APTN) *TeI]USA oINjJode perio { suoTsaI [eIUDA pu [esiop JOUTSIP WTA ‘PeorjouruAse sapnoyeuUy ‘WALOWNVUV_ ‘[ “Wey Sider sovjims § avpnoyns ‘VHOIALOTOH-VIVITID 40 VYaNAD ANV SAITINVA *IV[IUISSIP VITIO UV[NIINI pur [e1O ‘OY LIPID U[NOIYNI pur [VIO *ATUO eITIO suivog a 485 ORDER HOLOTRICHA. ** suvs10 ofisusyaid = Areyuour -o[ddns qjIM popraocig wtsygojygoyy “LS ** ** ** ** wIOJIOUN sueSIO oTISMOYIIG ‘wiaygognyy ‘gS = ** ** ** WIOFITNGvjoov suBdIO oTISUDYoIg ; : te te ee #* nadozaaap ATsnonotdsuoo otaygopgoupy *SS { ysv[dopua ‘sapoIsoa o]IJOVIYUOD OIOUT IO DUO PRAT EG, pe snonordsuos oye Ajaivr ysetdopus uasqe s[oIsea ay1j9v1}U0D ** suvo10 ayisueyaid =yeteds ou Suissassod ‘ayer1o ATduig ‘VLVWOLSV-VHOIXALOTIOH— V ‘nygunuauig *€S “‘pulauosAhg “tS °° ‘wyduiuoynT “YS ** fe ‘yoadsv payerias v Surussord yuoq ory. Apoq Jo saspy jaiee a[Surs v ‘+ yaprog [eI9}e, SuHvnpun snonoidsuoo v Suravyzy J Suruts0y vryp1D SOLIS JOUT}SIp IMoj 10 do1y} A[JUaIedde Sururo0f vy vjas [epnvd puv osepuodde wo; ISIp Jo9}UL UY YT eyas Tepnvo 10 adepuodde wuojntsip rowoyue ON $077/d2S00 04-7 © ci *s1guaT ‘6D ee ee ee oe ee ee oe [eUTUIID} dULIquIDUT 9yT]-pooy puv sinziade [LIQ STNLAGIA puL IqIXoY VITID elas [ep set? TeAJUIA 9UPIG UID UT "“unipy It) ‘or { -nvo poSuojord v wt, Sasoyas ‘prSur emp ) PUT POoU pue ainjyiode [v1 *‘ejas [epneo & NOY *uLIOJTINGeI0V xorduo09 wumnpiuong 3b °° “* °° LEO @) Thy, OO 22 “‘mutauoanag “Sv *QOVJAINS [CIJUIA mumiuosoymg “vv poue}epy pue ‘umipyryoinag “€v ** padeys-rvo J PSS°F TRO } Jesiop xaauos aoe Tea® % YIM ‘ULI0F My OS “unuopsoppusny) “ev ** ayeao Atduns wssoy [210 } tysiqns kpog { P80 sraqueis ‘unuojsossiuayy ‘1b ** «6 ** xudxeyd younsip on “3]BA0 oumeTqMze I) 30 ye19qe] ‘ygosyg ‘ob ** xuAreyd yoursip ® yA } Ajusao Apog Yo] wSSOy [TLIO “mnipiqjo7 cola WO IOUULUE O¥I[-ensu0, v ut Sutpnajoid ouvaquiayw ** snorovdes AI9A vssoj [v.10 { 9}vAO ATWAAD JOpIOg IOMOUW \ ‘TeUTULIO} ** [Tews vssoj [ero £ 9yv0uNI} Ajonbr,qo Aep10q Aowajuy ) YINO]N - y : ae - ¢ ee oe ee 99119 ard MYM D O°) ons @ Suru10j vio [eropy ‘uoupnguaT “Qf “ppoy rid [, “LE ee ** ITI [e1OpB IOSUO] YIM Py(ce: eum a nesed ‘TCUTUIID} has se{ -sip Aqends eyo pexopy Aatoit ‘mugsohsygQ “VE ** %* s* %4 «8 se «4 wntg TeLOPS JOSUOT JNOUITAA ‘aInjiode [v.10 JOUT}SIp OU Surssassod ‘orytsvredopua £ jnoysnory} 9ye1[19 ATUsAD pue ATSuy sarnoeuMy ‘WCAINITVdO “[ITX ‘Wey XIGNGddV ‘ouBIquIOUL SUT -ye[npun snonordsuod ssoq 10 a10w AQuosedde uv pur SUSU] SNOLIVA Jo vITIO Sutrvaq £ SuryyIM ‘ysissnqs SjusuaAour f onisvredopusa “avfnoturioa sopnopewmiuy “WAIHAWANOHOIVYE, "[][X “Wey ‘tapiod OFT] -jso19 posuojoid v Surursoy ouviquiout { sno1031a UOHLU “AV[MOTWIDA “SUTUTUIIMS- day saTnoTeuMIUy ‘WAIGNAT ‘TX ‘wey “IQUULUL DYI[-POOY & UI BSSOF TLIO 9Y} punore pue jo yuo ul Surpus}xe ‘a[ye1qrA-uoU suLAqUIOTT ‘WCINANOWNATY *X ‘Wey ‘uorsuedxa WIOF -luvIquisUur ® pue vIqIO Suwog ‘a "eSSO} Jeaseydosao 10 [v10 dy} puokeq AT YSsys Surjoefoid IO UIY}IM pasopous ‘oyy-dey ‘opyerqiA ouBIquIOy\, ‘WAINATNOAUHdO ‘XJ ‘We 486 ORDER HOLOTRICHA. entire length of the body from the anterior and posterior extremities ; endoplast ovate, subcentral ; trichocysts numerously developed, forming an even, vertically disposed, subcuticular layer; natation vigorous, rotatory. Length of body 1-120" to 1-96". Hazs.—Pond water and in vegetable infusions. This type, commonly known as the “Slipper Animalcule,” is one of the earliest observed and most widely distributed members of its class. It occurs in countless numbers in artificial vegetable infusions, as also in its natural condition in stagnant marsh and pond water. Viewed by transmitted light the dominant colour is golden-brown, while by direct reflection it presents an almost opaline appearance ; this circumstance, combined with the elongate contour of the animalcules, won for them from Joblot and other earlier writers the popular name of “gold and silver little fishes.” The stellate contour of the two contractile vesicles at diastole, referred to by most authorities as an essential characteristic of this species, scarcely appears to belong to the natural or persistent state, but would seem to be the result merely of artificial and abnormal pressure. The examination by the author of numberless examples with the highest magnifying power, confined in space sufficient to allow of their free movement, has failed to elicit in connection with these structures otherwise than a perfectly even, spheroidal outline. Under those artificial conditions in which the assumption of a stellate contour has been observed, the contractile vesicles exhibit phenomena agreeing with those recorded later on of Trachelophyllum apiculatum, Enchelyodon farctus, and other types ; minute, lateral, pyriform sinuses make their appearance round the periphery of each vesicle at the time of full diastole and, according to Carter, extend as thread-like canals through the substance of the parenchyma. With the act of systole, the central spheroidal portion of the vesicle disappears, leaving the stelliform peripheral sinuses, which now flow together and form the next central vesicular dilatation. During the process of transverse fission, as observed by Claparéde and Lachmann, two new contractile vesicles make their appearance in advance of or anterior to the two old ones, these latter, on the accomplishment of the act, occupying in each instance the posterior region of the two newly developed zooids. The phenomenon of so-called longitudinal fission, Pl. XX VI. Fig. 30, accredited to this type by Ehrenberg, is now demon- strated, as in the succeeding species, to indicate the act of conjugation between two independent animalcules. The trichocyst layer in Paramecium aurelia is very distinctly developed, taking the form of an even series of minute rod-like bodies disposed vertically immediately beneath the surface of the cuticle. An interesting account of the earliest record of the existence of these structures, with the descrip- tion of a simple process by which the animalcule may be induced to extrude them, as communicated by Sir John Ellis to the ‘ Philosophical Transactions’ for the year 1769, will be found at pages $1 and 82 of the preceding volume. The Paramecium caudatum of Ehrenberg, distinguished by its more attenuate posterior extremity, is regarded by Claparéde and Lachmann as a mere variety of this species, if not, indeed, exemplifying its most characteristic form. Paramecium aurelia, as figured by these last-named authorities, is represented as possessing a conspicuous brush-like tuft of longer cilia at the posterior extremity. The author has recently met with examples having this posterior brush-like tuft, and is inclined to regard the same as signalizing a well-marked local modification, but certainly not the predominant type of this cosmopolitan species. Paramecium bursaria, Ehr.sp. Pi. XXVI., Fics. 31 AND 32. Body pouch-shaped, depressed, little more than twice as long as broad; rounded posteriorly, narrowest and obliquely truncate at the anterior extremity ; buccal fossa infundibulate, very wide anteriorly, extending obliquely backwards from left to right to beyond the centre of the body ; GENUS PARAMECIUM. 487 oral aperture situated at the posterior extremity of the buccal fossa, followed by a distinct pharyngeal passage; anal aperture postero-terminal ; contractile vesicles two in number, spherical or stellate; endoplast ovate, with a laterally attached endoplastule ; trichocysts abundantly developed ; endoplasmic and cortical layer in adult individuals usually coloured green through the presence of enclosed chlorophyll-like granules. Length of body 1-280". Has.—Marsh water. This animalcule is referred by Ehrenberg, in his great work ‘ Die Infusionsthiere,’ to the genus Zoxodes ; Focke, in the ‘Isis’ for the year 1836, being the first to distinguish it by the generic and specific titles that are here given. A highly characteristic feature of this species, and one which attracted the notice of the earliest investigators, is the powerful circulation of the endoplasmic constituents, constantly and uniformly maintained within the interior of the animalcule’s body. Associated with the usual brilliant green hue of both the moving corpuscles and those of the more firm and motionless cortical layer or exoplasm, this circulating phenomenon imparts te the animalcule an aspect highly suggestive of the cyclosis or rotation of the cell-contents of certain aquatic plants, such as Avacharis and Valisneria, A similar circulation obtains, but is not so conspicuous, in the young and colourless individuals. As shown by Stein’s figures, and confirmed by the author’s investigations, this rotation of the body-contents exhibits a uniform motion, ascending on the left side and descending on the right when viewed from a dorsal aspect, and may be thus described as in conformity with the apparent motion of the sun or the hands of a watch when facing the observer. The reproductive phenomena of Paramecium, as manifested more especially with the present species, have received a considerable amount of attention at the hands of recent investigators. Balbiani’s name is more especially worthy of notice in this connection, he having been the first to demonstrate* that the previously so-called process of multiplication by longitudinal fission of one animalcule was really the more important act of conjugation or genetic union between two independent zooids. In the accomplishment of this conjugative act two animalcules apply themselves closely to one another by their oral or ventral surfaces, the parts thus brought into immediate contact becoming intimately fused or united with each other. In this closely united state the two animalcules may remain for a period of five or six days or more, but ultimately separate and resume their previous inde- dendent career. As the result of this conjugation the endoplast and endoplastule undergo an important modification. Originally it was thought by Balbiani that the last-named of these two structures was interchanged by the two united animal- cules, and fulfilled the part of a male fecundatory capsule or testis with reference to the endoplast, which remained stationary and was supposed to enact the réle of a female organ or ovary. As fully related, however, in vol. i. p. 94 e¢ seg., more recent investigation has not tended to confirm this hypothesis. At the same time it has been demonstrated by Balbiani and numerous other later authorities that during or subse- quent to this process of conjugation both the endoplast and endoplastule become turgid and enlarged, the latter assumes usually a more or less striated aspect, while the former breaks up into a variable number of spheroidal bodies, which become separated, and are ultimately cast out of the body, and probably constitute reproductive germs or ovules. In accordance with an earlier interpretation, it was assumed that the endoplastule, in its striated condition, represented a bundle of spermatic elements. The fact, however, that a similar striate aspect is frequently distinctive of this structure during the more simple process of multiplication by transverse fission, as also under like conditions of an ordinary cell-nucleus, has rendered this assumption no longer tenable. The similarly manifested process of conjugation of Paramecium aurelia, as delineated by Ehrenberg, is reproduced at Pl. XXVI. Fig. 30. ‘Comptes Rendus,’ 1858. 488 ‘ORDER HOLOTRICHA. Paramecium putrinum, C. & L. This species is described by Clapar¢de and Lachmann as corresponding in external form with Paramecium bursaria, but as differing from that animalcule structurally by its non-possession of trichocysts and by the presence of a single contractile vesicle only, which is situated near the anterior body-half; the anal aperture is located on the ventral surface, though not so far forward as in P. aurelia; endoplast band-shaped, curved, accompanied by an oval endoplastule. Has.—Stagnant water, among decaying vegetable matter. Paramecium glaucum, C. & L. Body ovate or elliptical, rounded at each extremity, the anterior one slightly the narrower, about twice as long as broad ; cortex enclosing tricho- cysts; colour glaucous green; buccal groove longitudinal, the oral aperture situated a little in front of the median line; two posteriorly situated, stellate, contractile vesicles. Length of body 1-147". Has.—Salt water: Norwegian coast (Claparéde and Lachmann). Paramecium marina, S.K. Pu. XXXII. Fic. 9. Body elongate-ovate, subclavate, about five times as long as broad, rounded and widest posteriorly, tapering and slightly curved in the anterior region ; oral groove extending backwards to the centre of the body; con- tractile vesicle single, of large size, posteriorly situated ; endoplast ovate, subcentral. Length 1-240". HAB.—Salt water. This species was obtained in some abundance in the small rock pools refilled only by the spring tides, at both Teignmouth and Anstey’s Cove, South Devon, in July 1879. The motion of the animalcules in these pools, as observed with the aid of a pocket lens, was highly characteristic, consisting of progress backwards and forwards for long distances, and in the same straight line, accompanied by rotation on their longitudinal axes, after the manner of various Bacteria and Vibriones. Supplementary Species. The Paramecium inversum and P. ovale of Claparéde and Lachmann are referable to the genus Z7yichoda of Stein, while the Paramecium microstomum of the same authorities would appear to belong to the genus /sofricha. The Paramecium chry- salis of Ehrenberg is now referred to the genus Plewronema, and his Paramecium colpoda to Colpidium. GENUS II. LOXOCEPHALUS, Eberhard. Animalcules free-swimming, persistent in shape, elongate-ovate or sub- cylindrical, having an oblique constriction at a little distance from the anterior extremity, and bearing in this region, on one or both sides, one or more short, curved sete ; the anterior extremity somewhat obliquely truncate, and bent slightly to one side; one or more long, hair-like caudal sete developed at the posterior extremity ; cilia of the cuticular surface fine, even throughout ; endoplasm more or less granular and opaque; oral aperture ventral, subterminal, indistinct. GENUS PLACUS. 489 Loxocephalus luridus, Eberhard. PL. XXXII. Fic. 16. Body elongate-ovate, subcylindrical, three times as long as broad, widest centrally, tapering gradually towards the two extremities; the oblique anterior constriction bearing on the side nearest the apical ex- tremity two short, conspicuous, adcurved sete; four long, straight, hair-like caudal sete developed from the posterior termination; endoplast sub- spherical, situated in the median line at a distance of one-third of the entire length from the anterior extremity ; endoplasm granular, very dark and opaque. Length 1-75". Hab.—Infusions with vegetable matter. This species is figured and described by Dr. Ernst Eberhard in the ‘ Oster- Programm der Herzogl. Realschule zu Coburg’ for the year 1862. Loxocephalus granulosus, S.K. Pui. XXVI. Fic. 47. Body elongate-ovate or subreniform, two and a half times as long as broad, widest posteriorly, the anterior end curved slightly towards the left, the oblique anterior constriction bearing on each side, as viewed from a dorsal aspect, a single, short, adcurved seta; a single, straight, hair-like caudal seta projecting from the posterior termination ; contractile vesicle situated in the median line at a distance of one-third of the length of the body from the posterior extremity ; cilia short and fine throughout ; parenchyma coarsely granular, dark and opaque. Length 1-428", HAs.—Marsh water with decaying vegetation. The animalcule connected with the above title was obtained by the author in some abundance in marsh water from Le Marais, Jersey, November 1878, in com- pany with Spzrostomum ambiguum, Paramecium aurelia, Urocentrum turbo, Pleuronema chrysalis, and other pond-frequenting types. The general contour, as seen with moderate magnification only, agrees so closely with that of Co/pidium or Pleurochili- dium, that at first sight the desirability of referring it to one of these two genera was anticipated. On closer examination, however, it was found to be entirely wanting in the special oral structure that distinguishes these latter. No trace of an undu- lating membrane or of a pharyngeal passage could be detected, while even with a magnification of eight hundred diameters the position of the oral aperture in the antero-ventral region could be predicated only by the more active ciliary vibration at that point. The two short adcurved setz projecting from the anterior constriction, accompanied by the presence of a long hair-like posterior seta, demonstrate that we have here an animalcule closely allied to the Loxocephalus luridus of Eberhard, but from which, as a species, it may be at once distinguished by its considerably smaller size, and by the diverse number and disposition of the setose appendages. When disturbed the animalcules swim to and fro in a straight line with considerable rapidity, but otherwise remain quiescent in some selected spot, numerous examples being often found in close proximity. In consequence of the dense granular character of the endoplasm, some difficulty was experienced in ascertaining the position of the contractile vesicle and endoplast. GENUS TIT. PLACUS,- Cohn. Animalcules free-swimming, ovate ; cuticular surface indurated, reticu- late; oral aperture inferiorly situated ; fine, short, vibratile cilia distributed throughout the cuticular surface, none of a specialized character in the neighbourhood of the mouth ; endoplast and contractile vesicle conspicuous. VOL, II. € 490 ORDER HOLOTRICHA. Placus striatus, Cohn. Pi. XXVI. Fics. 39 AND 4o. Body ovate, slightly flattened, about twice as long as broad, the two extremities rounded ; oral aperture circular, situated on the ventral surface at a short distance from the anterior extremity ; cuticular surface furrowed obliquely in opposite directions, and so producing a reticulate aspect. Endoplast spherical, central ; contractile vesicle posteriorly situated. Move- ments swift, in a straight line, rolling or rotatory on its long axis. Length 1-780". Has.—Salt water, among Conferve. Excepting for the absence of the vibratory oral membrane, Cohn* regards this form as most nearly resembling Glaucoma ; the indurated and reticulate cuticle at the same time corresponds to some extent with that of Co/eps. Genus IV. CONCHOPHTHIRUS, Stein. Animalcules free-swimming, persistent in shape, ovate or suborbicular, _ with a convex dorsal and flattened ventral surface ; oral aperture situated within a more or less funnel-shaped fossa or depression on the ventral surface, followed by a tubular, recurved pharynx ; cuticular surface indurated, delicately striate and ciliate throughout; cilia fine, thickly set, usually presenting a tufted or matted aspect; endoplast and contractile vesicle conspicuous. Occurring within the body-mucilage of various Lamelli- branchiate and Gasteropodous Mollusca. Conchophthirus anodontz, Ehr. sp. Pr. XXVI. Fic. 33. Body elongate-oval, depressed, about twice as long as broad, bluntly rounded at the two extremities ; oral fossa spacious, occupying the centre of the ventral surface, the pharyngeal tract recurved, extending to within a short distance of the posterior extremity; contractile vesicle simply spherical, subcentral ; endoplast globular, posteriorly located. Length of body 1-200". Hap.—The body mucilage of Anodontide and other fresh-water Mollusca. This animalcule, selected by Stein as the type of the genus Conchophthirus, is identical with the Zeucophrys anodonte of Ehrenberg, and apparently also the Plagiotoma acuminata of Claparede and Lachmann. ‘The illustration here given of this species is reproduced from T. W. Engelmann’s “Zur Naturgeschichte der Infusionsthiere,” contained in the ‘ Zeitschrift fiir Wissenschaftliche Zoologie’ for the year 1861, where it is figured by way of comparison with Conchophthirus curtus, described later on. Conchophthirus Steenstrupii, Stein. Pi. XXVI. Fics. 34 AND 35. Body broadly oval, depressed, equally rounded at the two extremities, about one and a half times as long as broad ; oral fossa widely infundibular, somewhat rectilinear, occupying the first third or quarter of the right-hand * «Neue Infusorien im Seeaquarium,” ‘ Zeitschrift fiir Wissenschaftliche Zoologie,’ Bd. xvi., 1866. GENUS PRORODON. 491 lateral border of the ventral surface ; cuticular surface delicately striate longitudinally, cilia closely set, long, fine, and matted; the anterior ex- tremity apparently bearing a small fascicle of longer setose cilia ; contrac- tile vesicle spherical, subcentral, exhibiting at diastole minute, supple- mentary peripheral lacune ; endoplast consisting of as many as seven nucleus-like corpuscles, disposed in a row parallel with the posterior and right-lateral border. Length 186" to 1-270". HaB.—Body-slime of Succinea amphibia, and also that of many land snails, including Helix hortensis. The more anterior location of the oral fossa, together with the animalcule’s separate habitat, serves to distinguish this form from the two accompanying repre- sentatives of the genus. Conchophthirus curtus, Eng. Body shortly oval, nearly as broad as long, equally rounded at both extremities, the dorsal surface highly convex, the ventral one flattened ; oral fossa subcentral, very small, continued into a long, recurved, tubular pharynx ; cuticular surface delicately striate longitudinally, clothed through- out with long, fine, matted cilia; endoplast oval, subcentral, contractile vesicle located a little behind this structure, stelliform or rosette-shaped at the time of diastole. Length 1-200.” Hap.—Mucilage of the fresh-water mussel Unio crassus, in company with C. anodonte. Although found in company with Conchophthirus anodonte, Engelmann considers that the shorter or more orbicular contour of the body, together with the smaller comparative size of the oral fossa, distinguishes it sufficiently for separate specific recognition ; the character of the contractile vesicle affords another point of differentiation. Fam. II. PRORODONTIDZA,, S.K. Animalcules free-swimming, symmetrically ovate or cylindrical, entirely ciliate ; oral and cuticular cilia alike in size and character; oral aperture terminal or lateral ; pharynx distinct, usually plicate or armed with rod-like teeth. This family group coincides most nearly with the Decteria of Max Perty (vol. i. p. 204), which is restricted exclusively, however, to those genera in which the pharynx is armed with rod-like teeth. By Stein, the very closely allied genera Proro- don and Wassula are, as shown in his classificatory system, reproduced at page 210 of vol. i., distributed among his two very heterogeneous families of the Enchelina and Parameecina, GENUS I. PRORODON, Ehrenberg. Animalcules persistent in shape, symmetrically ovate, cylindrical or slightly compressed, rounded at the extremities, entirely and evenly ciliate throughout; the oral orifice situated at or closely adjacent to the anterior pole, and the anal aperture at the opposite or posterior one; pharynx strengthened by a special induration consisting usually of rod-like teeth, but sometimes Cc 2 492 ORDER HOLOTRICHA. taking the form of a simple corneous tube; contractile vesicle mostly single, located close to the anal aperture; cortical layer sometimes enclosing trichocysts. The apical position of the oral aperture alone distinguishes the representatives of this genus from those of JVassu/a. Most of the species frequent pond and stagnant water. Their motion in the water is rapid, and chiefly rotatory on the longitudinal axis. One form only is as yet recorded as having a marine habitat. Prorodon niveus, Ehr. Pi. XXVI. Fics. 36 AND 49. Body elliptical, compressed, about twice as long as broad, oral aperture terminal ; pharyngeal armature consisting of a short, compressed fascicle of numerous closely approximated rod-like teeth; endoplast band-like, curved, often S-shaped ; contractile vesicle single, spherical, postero-terminal ; no trichocysts; colour white. Length of body 1-72". H ap.—Bog water, amongst Conferve. The large size of this animalcule, and the high development of the pharyngeal armature, readily distinguish it from the other members of the genus. Seventy and eighty-three of the characteristic rod-like teeth are reported by Ehrenberg as being respectively present in the one half only of the rod-fascicles exposed to view in two examples that were made the subject of careful examination. Prorodon teres, Ehr. Body ovate, cylindrical, twice as long as broad, slightly narrowed anteriorly ; oral aperture exactly terminal ; pharynx enclosing an elongate cylindrical fascicle of rod-like teeth ; endoplast ovate ; contractile vesicle single, postero-terminal ; no trichocysts. Length of body 1-140", HAb.—Pond water. The cylindrical fascicle with which the pharyngeal cavity of this species is strengthened has been estimated to contain from twenty to as many as forty-five of the characteristic rod-like teeth. Encystment, accompanied by the partition of the animalcule into two equal halves within its cyst, has been reported by Cohn.* Prorodon griseus, C. & L. Body ovate, cylindrical, rounded at the two extremities, slightly the widest anteriorly, from two to two and a half times as long as broad ; cuticular surface finely and closely striate longitudinally ; oral aperture subterminal; pharyngeal rod-fascicle large, cylindrical, slightly curved ; endoplast oval, enclosing a small endoplastule ; contractile vesicle single, postero-terminal, of large size; colour clear brown when viewed as a transparent object, white by reflected light ; no trichocysts. Length of body 1-250". Hab.—Stagnant water: Berlin (Claparéde and Lachmann). Prorodon armatus, C. & L. Body nearly globular, slightly compressed, oral aperture subterminal ; pharyngeal rod-fascicle cylindrical, wide, and comparatively short ; endoplast * ¢ Zeitschrift fiir Wissenschaftliche Zoologie,’ Bd. iii., 1853. GENUS PRORODON. A93 elliptical, of small dimensions ; contractile vesicle single, postero-terminal, communicating at the time of systole with three or four spherical lateral sinuses; numerous trichocysts enclosed in the cortex of the anterior half of the body, none in the posterior one. Length 1-250’. HAB.—Pond water. Prorodon edentatus, C.& L. Pri. XXVI. Fic. 43. Body elongate-ellipsoidal, cylindrical, nearly three times as long as broad, transparent, surface of cuticle longitudinally striate, striae separated considerably from one another; oral aperture terminal, slightly eccentric ; pharyngeal armature consisting of a simple, conical, corneous tube developed backwards to the centre of the body and gradually diminishing in size as it approaches the posterior end ; endoplast oval, elongate ; contractile vesicle single, spherical, postero-terminal ; no trichocysts; cilia of the posterior extremity longer than those of the general surface, produced in a tuft- like manner. Length of body 1-250". HAB.—Pond water. Prorodon marinus, C. & L. Body elongate, cylindrical, from two to two and a half times as long as broad, the cuticular surface not longitudinally striate ; oral aperture exactly terminal; pharyngeal tube simple, edentulate, very small and short; con- tractile vesicle postero-terminal; endoplast ovate; colour transparent, enclosing numerous dark, refringent granules. Length of body 1-250”. Has.—Salt water: Norwegian coast (C. & L.). Prorodon margaritifer, C.& L. Pi. XXVI. Fic. 44. Body elongate-elliptical, subcylindrical, three times as long as broad, slightly widest anteriorly ; cuticular surface finely and closely striate longi- tudinally; oral aperture subterminal ; pharyngeal tube large, consisting of numerous, short, rod-like teeth; contractile vesicles very numerous, com- paratively small and spherical, distributed throughout the substance of the cortical layer ; no trichocysts ; endoplast double, consisting of two obliquely converging elliptical bodies, separated from one another at the nearest point of convergence by a smaller spherical body which apparently represents the nucleolus or endoplastule ; colour of the general substance of the body clear brown, contents of the contractile vesicles pinkish. Length 1-75.” Habitat unrecorded. In the number of its contractile vesicles this species stands almost alone among those representatives of the class Infusoria with which we are as yet familiar. ‘The figure here reproduced from Claparede and Lachmann’s treatise,* shows over forty of these vesicles on that side only of the animalcule which is exposed to view, so that very few short of one hundred may be accepted as the total number of these structures contained within the cortical layer of a single zooid. These vesicles do not appear to have any communication with one another, but expand and contract independently. A closely similar but less numerical development of the contractile-vesicular system has recently been found by the author to obtain in Zrachelius ovum. Clapartde and Lachmann * «Btudes sur les Infusoires,’ 1858. 494 ORDER HOLOTRICHA. have remarked of the singular-shaped endoplast of this species that it is not, as in most instances, imbedded within the cortical layer, but lies loosely in the semifluid internal endoplasm, permitting the body to revolve freely over and around it. This phenomenon of the revolution of the body over the endoplast has been reported by Siebold in connection with other infusorial types, but has been explained by Eckhard as being a mere optical illusion, Claparéde and Lachmann are, however, so thoroughly convinced of the free suspension of the endoplast in this instance, that they are disposed to accept Siebold’s statement ascorrect. It is a matter of regret that the discoverers of this species have omitted to place on record both the dimensions and habitat of this highly interesting type. Judging from the size of three species of the same genus, Prorodon marinus, P. armatus, and P. griseus, delineated in their treatise, it would appear to considerably exceed these in size and to most nearly approach P. nzveus. Doubtful Species. The Habrodon curvatus of Max Perty, ‘ Kleinster Lebensformen,’ 1852, charac- terized as follows, would appear to be rightly referable to the genus Prorodon : “ Body subcylindrical, slightly curved, thickened posteriorly, mostly truncate in front ; oral aperture anterior, associated with a very delicate dental apparatus ; anal aperture postero-terminal ; cilia disposed in longitudinal rows, colour grey or pale green ; movements slow. Length 1-390” to 1-132”. Hab.—Spring water, with Czara, Bern.” GENUS II. NASSULA, Ehrenberg. Animalcules ovate, cylindrical, flexible but not polymorphic, usually highly coloured ; oral aperture lateral ; pharynx armed with a simple horny tube, or with a cylindrical fascicle of rod-like teeth ; entire surface of cuticle finely and evenly ciliate ; the cortical layer sometimes containing tricho- cysts ; contractile vesicle single or multiple. Inhabiting fresh water. A prominent characteristic of the genus JVassz/a is the normally bright colouring of the parenchyma or body-contents—rose-colour, red, green, blue, yellow, and violet being separately developed or variously combined in the several species. In that form, JV. ornata, with which the colour violet is more usually dominant, this pigment occurs distributed in scattered vesicular patches, which are most abundant in the anterior region. Ehrenberg was led to regard these coloured vesiculz as glands possessing probably a biliary function. By Stein, however, both the generally dispersed and vesicular aggregations of colouring matter are pronounced to be merely the product of incepted food-material; certain Oscilla- toriz devoured by one variety, JV. ambigua, having been observed by him to pass successively through the tints of green, blue, and red during the process of digestion. Claparede and Lachmann, while endorsing Stein’s views so far as relates to the coloured material within the semifluid endoplasm, and which is in a constant state of circulation, are inclined to attribute to the stationary pigment-corpuscles imbedded within the cortical layer the character of organs whose special function is not as yet determined. Stein has recently proposed to separate Vassula ornata, LV. rubens, and all other members of this generic group in which trichocysts are abundantly developed, under the distinct title of Acidophorus. Such importance is not, how- ever, here conceded to the presence of these structures, their development being subject to considerable variations even among individuals of the same species. The distinct lateral location of the oral aperture serves to readily distinguish this genus from Prorodon. Nassula ornata, Ehr. Pui. XXVI. Fic. 42. Body ovate, cylindrical, two or three times as long as broad, brownish- green, variegated with violet vesicles ; pharyngeal rod-fascicle forming an GENUS NASSULA. 495 even, straight, undilated tube; contractile vesicle single, spherical, sub- central; numerous vesicular spaces, with violet-coloured contents, usually present in the anterior region ; no trichocysts. Length of body 1-96”. HAxB.—Pond water. The Wassula elegans and NV. conica of Ehrenberg appear to differ from this species merely in the subordinate character of colour, the former variety being white or greenish and the latter yellow or brown. Nassula flava, C. & L. Body elongate, cylindrical, three or four times as long as broad, slightly depressed in the antero-dorsal region ; colour mostly yellow or brick-red ; pharyngeal armature consisting of numerous rod-like teeth, the tube they form being much dilated at the distal end; anterior extremity of the cortical layer usually containing numerous violet-coloured corpuscles, which do not circulate with the general contents; contractile vesicles two in number, simply spherical. Length of body 1-240" to 1-125". HAsB.—Pond water, among Oscz/latoria. This species, while differing from WV. ornata Ehr., as explained by Clapartde and Lachmann, in the form of the pharyngeal tube and the possession of two contractile vesicles, approaches it so closely in all other details as to render it doubtful whether it must not be regarded as a mere local variety of that type. Nassula ambigua, Stein. PL. XXVI. Fic. 41. Body shortly oval or elliptical, cylindrical, equally rounded at both extremities, not quite twice as long as broad; pharyngeal armature con- sisting of a simple horny tube dilated at its anterior extremity ; contractile vesicle single, spherical or assuming a stellate outline, medianly located. Length of body 1-240". HaAxs.—Pond water. A species, apparently identical with this form, recently obtained by the author from ditch water at St. Heliers, Jersey, exhibited numerous trichocysts in the substance of its cortical layer, and was coloured deep green, more especially in the posterior region, through the inception of food-particles, While the first example observed showed apparently a simply tubular pharynx, other specimens, examined with a higher magnification, revealed the presence of the rod-like teeth characteristic of the two preceding forms. Nassula rubens, C. & L. Body elongate, cylindrical, three times as long as broad, equally rounded at the two extremities, brick-red or rose colour; pharyngeal armature con- sisting of separate rod-like teeth, the tube formed by them being slightly dilated anteriorly; trichocysts large and abundant; contractile vesicle single, spherical, subcentral. Length 1-500”. HaB.—Pond water. This species is identified by Clapartde and Lachmann with the Cydogramma rubens of Perty. The genus Cyclogramma, as instituted by the last-named author, was distinguished from /Vassw/a by the presence of concentric striz in or upon the cuticular substance. These apparent strize are now shown to represent the im- perfect optical aspect of the closely approximated trichocysts, as seen with an insufficient defining power, that occur so abundantly in this and other species of the 496 ORDER HOLOTRICHA. genus. While most usually of a brickred hue, Clapartde and Lachmann mention that the colour in this species is sometimes entirely absent, while in other instances, through the presence of enclosed Oscillatoriz, it assumes a brilliant glaucous hue. Nassula lateritia, C. & L. Body ovoid, cylindrical, twice as long as broad, rounded posteriorly, the anterior border obliquely truncate ; pale red or rose colour; mouth opening on the truncate anterior portion; pharyngeal armature consisting of an anteriorly dilated tubular fascicle of rod-like teeth; contractile vesicles two in number, spherical; endoplast discoidal, posteriorly situated ; trichocysts numerous, relatively smaller than in WV. rubens. Length 1-500". Hap.—Pond water. Nassula microstoma, Cohn. Body persistent in shape, oblong, slightly compressed, the anterior extremity bluntly rounded, the posterior one somewhat pointed ; a depressed area, which conducts to the circular oral aperture, developed on one side, near the anterior extremity ; pharyngeal tube obliquely directed, simple and unarmed, dilated posteriorly ; endoplast subcentral, obliquely placed, having an attached endoplastule; contractile vesicle small, spherical, located at a distance of one-third of the entire length of the body from the posterior extremity ; surface of cuticle finely striate or furrowed longitudinally ; cilia fine, set in these furrows, equally clothing the entire cuticular surface ; colour flesh-red. Length 1-240". HaB.—Salt water. Cohn * remarks that this type most nearly resembles the Prorodon marinus of Clapartde and Lachmann, and may possibly be identical with O. F. Miiller’s Para- macium chrysalis, or the Panophrys chrysalis ox rubra of Dujardin. Doubtful Species. The Liosiphon Stromphii of Ehrenberg, separated from JVassala on account of the great projection of the anterior region beyond the oral aperture, scarcely appears to possess a sound claim for separate generic distinction. Its form is obtusely ovate, colour green, length 1-432", hab. pond water ; the tubular pharyngeal passage encloses a cylindrical or somewhat clavate fascicle of rod-like teeth, as obtains among the majority of the members of the present genus. GeNusS III. CYRTOSTOMUM, Stein. Animalcules ovoid or elliptical, highly contractile ; oral aperture lateral, taking the form of a longitudinal cleft ; pharynx tubular, its wider anterior extremity armed with two closely approximated rows of short, rod-like teeth ; cilia of cuticular surface disposed in even longitudinal rows ; tricho- cysts usually present. Inhabiting fresh water. This genus, as founded by Stein on the Bursaria (Frontonia) leucas of Ehrenberg, differs chiefly from JVassw/a in the highly elastic consistence of the cuticular invest- ment, which allows the animalcules to assume a variety of polymorphic contours. a ‘Neue Infusorien im Seeaquarium,” ‘Zeitschrift fiir Wissenschaftliche Zoologie,’ Bd. xvi. 18 GENUS ISOTRICHA. 497 The oral apparatus, though described as consisting of two closely approximated rows of rod-like teeth, is, as distinctly indicated in Ehrenberg’s original drawings, a mere ovate-shaped modification only of the subcylindrical rod-fascicle distinctive of the genera JVassula and Prorodon. Cyrtostomum leucas, Ehr. sp. Pui. XXVI. Fic. 37. Body ovoid or ellipsoidal, usually wider anteriorly, about twice as long as broad; cortical layer enclosing numerous trichocysts; oral aperture elongate-ovate, its lower extremity pointed. Length of body 1-144”. HAB.—Fresh water. This species, accepted by Stein as the representative of the new genus Cyrto- stomum, is identified by that authority with both the Bursaria leucas and Bursaria vernalis of Ehrenberg (Panophrys do. do. Dujardin), the latter form, as also attested to by Claparede and Lachmann, being a mere variety coloured green through the ingestion of chlorophyllaceous food-substances. An account of the minute histology and behaviour of the trichocysts so abundantly developed in this species, as carefully worked out and described by Professor Allman, is contained in the section treating of these structures generally in pages 80-84 of the preceding volume, while a reproduction of that authority’s figures of these elements is included in the supplementary plate at the end of the atlas devoted to the delinea- tion of histological details. GreNuUS IV. ISOTRICHA, Stein. Animalcules free-swimming, obovate, persistent in shape, depressed or subcylindrical; oral aperture ventral, subterminal, followed by a short, smocth, tubular, membranous pharyngeal passage ; anal aperture postero- terminal; cuticular surface clothed throughout with long, fine, densely disposed cilia. Occurring mostly as endoparasites within the first stomach or rumen of various higher Ruminantia. In general contour and habits, and in their long, dense ciliary clothing, the animalcules of this genus are reported as closely resembling the Opalinide ; the presence of a well-defined oral aperture serves, however, at once to distinguish them from the members of the last-named group. Isotricha intestinalis, Stein. Body obovate, slightly flattened, longitudinally striate ; oral aperture ventral, situated within a semilunar depression at some little distance from the anterior border; cilia long and fine; contractile vesicles numerous, distributed chiefly in the anterior region; endoplast elongate oval, asso- ciated with a small, subglobose endoplastule. Dimensions unrecorded. Has.—Endoparasitic, within the first stomach or rumen of sheep and cattle. Isotricha prostoma, Stein. Having the oral aperture at the anterior extremity, nearly in the axial line. All other details, including habitat, corresponding with those of LT. intestinalis. 498 ORDER HOLOTRICHA. Isotricha (?) microstomum, C. & L. sp. PL. XXVI. Fic. 38. Body subcylindrical, equally rounded at both extremities, slightly con- stricted centrally ; about two and a half times as long as broad; cuticular surface finely striate longitudinally, entirely clothed with long, fine, even cilia; oral aperture minute, situated at a distance of one-third of the length of the entire body from the anterior extremity, followed by a short, tubular, backwards-directed pharyngeal tract; contractile vesicle single, spherical, located a little behind the centre of the right-hand border. Length 1-250". Has.—Salt water: Norwegian coast (C. & L.). This species is referred by Clapartde and Lachmann to the genus Paramecium, from all the typical examples of which it, however, differs in its symmetrical contour and in its simple tubular oral aperture, unassociated with any adoral groove. This combination of characters accords so closely with those of Stein’s genus /sofricha that it becomes requisite either to refer it to that group, or, in virtue of its non-endoparasitic habits, to establish a new genus for its reception. While the former alternative commends itself most favourably for adoption, it must at the same time be observed that the induration of the short tubular cesophagus is alone wanted to convert this type into a normal member of the genus Wassu/a, and it is just possible that such a structure has been overlooked by its observers. Among the examples of this animalcule examined by Clapartde and Lachmann several were distinguished by their yellow-brown tint. GENUS V. HOLOPHRYA, Ehrenberg. Animalcules free-swimming, ovate or globose, elastic and changeable in form, entirely ciliate ; the mouth situated at the anterior pole, and the anal aperture at the opposite or posterior extremity ; pharynx simple, having no corneous tube or rod-fascicle; no specially large cilia developed round the oral aperture ; multiplying by transverse fission, and forming spherical encystments. Chiefly inhabiting fresh water. The members of this genus somewhat resemble those of Prorodon, the most essential features of distinction being the unarmed character of the pharyngeal passage and elasticity of the cuticle, which permits the animalcules, as in Cyr¢o- stomum, to assume a great variety of outline. Holophrya ovum, Ehr. Pui. XXVI. Fic. 45. Body ovate, more or less cylindrical, about one and a half times as long as broad; surface of cuticle obliquely striate or corrugate ; cilia short, fine, and closely set ; colour green or transparent ; oral aperture apical, its border slightly projecting ; contractile vesicle single, spherical, situated posteriorly, _ close to the anal aperture ; endoplast rounded or ovate, subcentral. Length 1-210". HAB.—Pond water, amongst Conferve. Although an ovate outline represents the typical contour of this species, it frequently assumes an inflated, subspheroidal shape, the characteristic cuticular strize becoming entirely obliterated ; it is often impossible, under these conditions, even to recognize the position of the mouth, the animalcule having the aspect of a complete sphere, which may be either perfectly transparent or more or less coloured with chlorophyll-granules, or opaque through the ingestion of food-particles. GENUS HOLOPHRYA. 499 Holophrya discolor, Ehr. Body ovate, pointed posteriorly, about twice as long as broad ; cilia long, disposed in widely separated longitudinal rows ; parenchyma green or colourless. Length 1-240". Has.—Pond water. Holophrya tarda, Quenn. PL. XXVI. Fics. 59 AND 60. Body when extended nearly three times as long as broad, elongate- pytiform, somewhat flask-shaped, rounded posteriorly, tapering gradually towards the narrower and truncate anterior extremity; cuticular surface finely ciliate, striate longitudinally ; body in contraction subspherical, with the longitudinal striations obliquely set; contractile vesicle postero- terminal ; endoplast elongate-ovate, stationed a little in front of the con- tractile vesicle. Length 1-300". Has.—Salt water. This as yet single known salt-water species of the genus Holophrya is figured and described by August Quennerstedt in his “ Bidrag til Sveriges Infusoriefauna,” contributed to the ‘Acta Universitatis Lundensis’ for the year 1865. So far as its external contour and the relative form and position of the endoplast and contractile vesicle are concerned, it would appear to be most nearly related to the Lolophrya Kessteri of Mereschkowsky next described. Holophrya Kessleri, Mereschk. Body contractile and variable in form, elongate-ovate, subcylindrical, sometimes slightly wider anteriorly, about twice as long as broad ; cuticular surface alternately grooved and ribbed longitudinally, finely ciliate through- out ; parenchyma transparent or with a yellowish tinge ; contractile vesicle large, posteriorly situated; endoplast band-like, subcentral. Length 1-170" to 1-130". Has.—Fresh water: Lake Onega (Mereschkowsky), among aquatic vegetation. This species is distinguished, according to Mereschkowsky,* by the ribbed char- acter of the cuticular surface and the band-like contour of the endoplast, both of which characters are nevertheless shared by the salt-water //olophrya tarda of A. Quennerstedt. When viewed end-on, these longitudinal ribs are found to range from twenty-five to thirty in number, the animalcule under such circumstances presenting an almost melon-like appearance. It does not appear that these ribs become obliquely twisted when the animalcule is contracted, as obtains in . darda. Holophrya brunnea, Duj. Body elongate-cylindrical, equally rounded at the two extremities, two and a half times as long as broad ; colour brown. Length of body 1-125". HAsB.—Pond water. This form, in common with Holofhrya ovum and H. discolor, assumes after feeding a subglobose or perfectly spherical contour. * Studien iiber Protozoen des nordlichen Russland,’ ‘ Zeitschrift fiir Wissenschaftliche Zoologie,’ Bd. xvi., 1878. 500 ORDER HOLOTRICHA. Supplementary Species. The Holophrya coleps of Ehrenberg, thus characterized :—‘‘ Body oblong, cylindri- mo cal, rounded at both extremities ; colour whitish. Length 1-430" to 1-280" ”— is identified by Stein with the Co/eps inermis of Perty, and elevated by him to the rank of a new genus, distinguished by the name of //agiopogon. Holophrya lateralis, S.K. Pui. XXVI. Fic. 46. Body cylindrical, evenly ovate or elliptical, a little over twice as long as broad ; cuticular cilia conspicuous, arranged in numerous closely approxi- mated, even, longitudinal rows; contractile vesicle lateral, situated a little in advance of the median line; endoplast inconspicuous; endoplasm enclosing innumerable, minute, spherical corpuscles, in addition to the ordinary digestive vacuoles. Length 1-100". HaB.—Fresh water: Bombay (H. J. C.). An animalcule answering to the above diagnosis, and possessing the charac- teristic terminal oral and anal apertures of the genus /olophrya, is figured and briefly described, without name, in the manuscript notes kindly placed at the author’s disposal by Mr. H. J. Carter. The species differs essentially from all previously described members of the genus in the lateral instead of terminal location of the contractile vesicle. The flexibility of the integument of this type was demonstrated by the flattened or contorted shapes it assumed in passing and pressing against confervoid filaments or other objects in the water. Genus VI. OTOSTOMA, Carter: Animalcules free-swimming, ovate, subcylindrical, entirely ciliate ; oral aperture inferior, subterminal, conducting to a short, recurved, indurated pharynx, the contour of which, in profile, resembles that of a human ear ; anal aperture, endoplast, and contractile vesicles conspicuous. Excepting for the peculiar conformation of the pharyngeal tube, the single type of this genus corresponds essentially with the genus Vassw/a ; a still more marked divergence in the same direction is noticeable in Cohn’s new generic type, He/ico- stoma, next described. Otostoma Carteri, S.K. PL. XXVI. Fics. 55-58. Body ovate, rounded at each extremity, not quite twice as long as broad, slightly narrower anteriorly; oral aperture situated in a depression on the ventral surface, at a distance of about one-third of the length of the entire body from the anterior extremity; pharyngeal tube ear-shaped, longitudinally plicate, recurved towards the posterior extremity ; anal aperture postero-terminal ; cilia of cuticular surface short and even, dis- posed in fine parallel longitudinal lines; endoplast fusiform, subcentral ; contractile vesicles two in number, separate from one another, often, as in Paramecium aurelia, exhibiting a stellate outline. Length 1-100". Has.—Fresh water, among JVztella: Bombay (H. J. C.). Mr. H. J. Carter, in his brief description of this interesting form,* having omitted to confer upon it any other than a generic title, the author has much pleasure in * ¢ Ann. Nat. Hist.,’ Feb. 1856. GENUS HELICOSTOMA. 501 connecting the name of its discoverer with its future specific denomination. Although, as already intimated, the contour and habits of the animalcule agree closely with those of Wassu/a and LHeélicostoma, certain points have been recorded by Mr. Carter concerning its developmental manifestations which invite special atten- tion. According to this observer the matured individuals become encysted within the internodes of semi-decayed Nitellz, and then split up into two, four, or eight cleavage masses, each of which is subsequently liberated from the cyst in a form altogether identical with the parent Ofostoma, but of smaller dimensions, and possess- ing at this early stage a single contractile vesicle only. This process of multiplication by encystment and segmentation, while of but rare occurrence among the more highly organized Ciliata, commonly obtains among the Infusoria Flagellata, treated upon in the preceding volume. Mr. Charles Stewart, of St. Thomas’s Hospital, has recently reported to the author the occurrence of an animalcule apparently indistinguishable from Ofostoma Carteri, from the neighbourhood of Plymouth, Devonshire. The Sisyridion cochliostoma of Ernst Eberhard * is evidently closely allied to, if not identical with, this same type. GENUS VII. HELICOSTOMA, Cohn. Animalcules free-swimming, elastic, more or less ovate, finely ciliate throughout ; oral aperture ventral, circular, conducting to a tubular pharynx, which, after proceeding obliquely backwards to the centre of the body, terminates in a helicoidal flexure. Excepting for the peculiar prolongation of the cesophagus with its terminal helicoidal flexure, this generic type corresponds closely with the genus JVassw/a, an intermediate form between the two being supplied by Mr. Carter’s genus Otostoma. Helicostoma oblonga, Cohn. Pi. XXVI. Fic. 54. Body oblong or almond-shaped, rounded posteriorly, pointed anteriorly, usually somewhat flattened, three or four times as long as broad ; cuticular surface finely striate longitudinally and transversely; cilia short and fine, evenly distributed, sometimes vibrating irregularly, and presenting a tufted aspect ; oral aperture situated at a distance of about one-fourth of the length of the whole body from the anterior extremity, pharyngeal tube continued obliquely backwards to the centre of the body, and there forming a loop- like or helicoidal twist ; endoplast subcentral ; contractile vesicle postero- terminal. Length 1-125" to 1-75". HAB.—Salt water. Movements swift, rotatory. This species, described, in company with many other interesting marine types, by Dr. Ferdinand Cohn in the ‘Zeitschrift fiir Wissenschaftliche Zoologie’ for the year 1866, is referred to by its discoverer as apparently coinciding to some extent with the Lewcophra signata of O. F. Miiller, but of which the figure and description given are not sufficiently explicit for actual identification. ‘The transverse strize of the cuticular surface, referred to in the foregoing diagnosis, are much less conspicuously developed than those taking a longitudinal direction, and are to be defined only with a careful adjustment of a high magnifying power, constituting in this respect a test-object equal to that of the cross-striation of the diatom Pleurosigma attenuatum. * * Oster-Programm der Realschule zu Coburg,’ 1862. 502 ORDER HOLOTRICHA. Fam. III. TRACHELOPHYLLID4,, S. K. Animalcules free-swimming, ciliate throughout, more or less flask- shaped; oral and cuticular cilia alike, the oral aperture perforating the extremity of the narrower anterior region, which is frequently highly elastic and extensile. GENus I. TRACHELOPHYLLUM, C,& L. Animalcules elastic, flattened, lanceolate or flask-shaped, having an attenuate neck-like portion, the apical extremity of which is separated by an annular constriction from the preceding part, and is perforated at its apex by the oral aperture, as in the genera Lacrymaria and Trachelocerca, but has no circlet of larger cilia; pharyngeal passage tubular, conspicuously developed ; contractile vesicle single, situated close to the postero-terminal anal aperture. Clapartde and Lachmann have founded the genus 77achelophyllum on the type first described by Perty under the title of Zrachelius apiculatum, separating it from the last-named generic group on account of the terminal position of the oral aperture. The animalcules are further distinguished from those of Zacrymaria, which they still more nearly approach, by their compressed form and the absence of the annular circlet of stouter cilia at the anterior or oral region. As a consequence of their flattened contour, their movement in the water differs considerably from those of the cylindrical Lacrymarie. This in the type-species, Z' apicudatum, consists chiefly of a smooth, gliding motion, after the manner of C%ilodon and Loxo- phyllum, in place of rotation on their axis as obtains in Lacrymaria and Phialina. The neck in Zrachelophyllum, while possessing a considerable amount of elasticity, is inferior in this respect to Z7achelocerca. Trachelophyllum apiculatum, Perty sp. PL. XXVI. Fics. 61 aNnpD 62. Body flattened, lanceolate ; neck long, slender, and highly extensile, nearly equal in length to the body, perforated throughout the greater portion of its length by a narrow, straight, somewhat obscure pharyngeal tract, the walls of which are faintly striate longitudinally; cuticular surface entirely but thinly clothed with moderately long cilia, whose action is somewhat irregular and independent ; contractile vesicle single, spherical or rosette-shaped, posteriorly situated ; endoplasts multiple, ovate, two or four in number. Length of body 1-144." Haxb.—Pond water. This animalcule is identical with the Zrachelius apiculatum of Perty. From two to as many as four nuclei or endoplasts were observed in the specimens as examined by Claparéde and Lachmann, though the former and smaller number only is ascribed to it by Wrzesniowski. ‘The character and varied aspect of the contractile vesicle under the respective conditions of systole and diastole, and during the passage of excreta through the terminal anal aperture, has formed the subject of careful investigation by the last-named authority,* the results arrived at yielding the strongest possible evidence in demonstration of the non-possession by this * A. Wrzesniowski, ‘‘ Anatomie der Infusorien,” ‘ Archiv fiir Mikroskopische Anatomie,’ Bd, v., 1869. GENUS ENCHELYODON. 503 structure of a differential bounding wall or membrane, as also of its non-occupation of a restricted position in the substance of the cortex. At the time of fullest diastole a variable number of minute transparent lacunz filled with water make their appearance round the border of the contractile vesicle, communicating to it a rosette-shaped contour, and remain as small independent vacuoles after the contents of the central reservoir have been discharged, these then coalesce, and, increasing in size, assume the same form and pursue a like course as the water globule or vacuole just discharged. ‘The food-matter, after the extraction of its nutrient properties, is collected in the form of a globular pellet at the posterior extremity of the body, and on its way towards and through the anal aperture temporarily dislodges the contractile vesicle, forcing it to a considerable distance forwards from its original position, but to which it again returns after the evacuation of the excreta. Trachelophyllum pusillum, C. & L. Body elongate, flask-shaped, the anterior or neck-like portion very little narrower than the remainder of the body, four and a half times as long as broad ; contractile vesicle single, postero-terminal ; endoplasts two in number, elongate-ovate. Length of body 1-625". HaAxb.—Stagnant water. Claparéde and Lachmann regard this form as probably identical with the Trachelius pusillus of Perty. GENUS Hi. ENCHELYODON, €.& L. Animalcules free-swimming, elastic and changeable in form; ovate or pytiform, not produced anteriorly in a neck-like manner; oral aperture apical, followed by a well-developed membranous pharynx, the walls of which are mostly longitudinally plicate; anal aperture postero-terminal ; cuticular surface finely and entirely ciliate throughout. Inhabiting salt and fresh water. In constructing this genus upon the type next described, Claparéde and Lachmann left it in some doubt whether the walls of the conspicuous tubular pharynx were simply membranous and longitudinally plicate, or whether they were indurated or strengthened by a cylindrical fascicle of rod-like teeth, as in Wassula and Prorodon. Assuming the balance of evidence to be in favour of the latter of these two hypotheses, they placed it in close vicinity to Prorodon, and from which, indeed, they represent it as differing chiefly in the greater elasticity and finer ciliation of the cuticular investment, and in its slower movements. Wrzesniowski, however, who has more recently made this type the object of a special investigation,* has decided that the pharynx is membranous and _longi- tudinally plicate, as half-anticipated by Claparede and Lachmann, this being demon- strated by the circumstance that the tube with its plications becomes bent upon itself, or in a sinuous manner, during the contractions of the animalcule. Accepting Wrzesniowsk1’s interpretation, the natural position of Lxchelyodon is evidently close to that of Zrachelophyllum, from which it would, indeed, appear to differ only in the absence of a differentiated and elastic neck-like portion. Enchelyodon farectus, C. & L. Pui. XXVI. Fics. 51-53. Body elastic, ovate and somewhat flattened, slightly narrowest anteriorly, more than twice as long as broad; pharyngeal passage long and narrow, * ¢ Archiv fiir Mikroskopische Anatomie,’ Bd. v., 1869. 504 ORDER HOLOTRICHA. extending backwards to about one-third of the length of the body, its walls plicate longitudinally, the anterior border projecting slightly beyond the front margin of the body ; contractile vesicle single, spherical or rosette shaped, situated posteriorly, close to the anal aperture; endoplast band-like, sinuous ; cuticular surface longitudinally striate ; cilia very short and fine. Length of body 1-125". HaB.—Bog water: Berlin (C. & L.). The contractile vesicle of this species has been shown by both Claparéde and Wrzesniowski to exhibit phenomena closely corresponding with what has been already described of Zrachelophyllum apiculatum, a portion of the accumulated fluid being driven at the time of systole into minute rounded sinuses, the contents of which afterwards coalesce together, and, increasing in volume, present all the characteristics of the preceding vacuole. These metamorphic phenomena exhibited by the contractile vesicle in Trachelophyllum and Enchelyodon, are directly com- parable with the stellate modifications of this same structure already recorded of the two genera Paramecium and Otostoma. As shown by Wrzesniowski, a minute pore or aperture places the central lacuna of the contractile vesicle of Evchelyodon farctus in direct communication with the outer water. The aspect of this vesicle, in its fully dilated rosette-shaped condition, showing its central pore-like aperture, is reproduced from Wrzesniowskt’s delineations at PL XXXVI. Big. 53: Enchelyodon elongatus, C. & L. Pui. XXXII. Fic. 17. Body attenuate, clavate, four or five times as long as broad, the anterior half narrowest; pharynx simple, short, and tubular; contractile vesicle single, spherical, posteriorly located; endoplast central, oval; cilia fine, short, and evenly distributed. Length unrecorded. Haz.—Salt water: Norwegian coast (C. & L.). Although not mentioned in the description, Lachmann’s figure of this species indicates the presence of several symmetrically placed reflected sete, four on each side, at the anterior extremity or oral region of the body. Should these sete really exist, this form would seem to demand a generic title separate from that of Enchelyodon for its reception. GENUS Dil, sUROTRICH AMC ci. Animalcules free-swimming, ovate or elliptical, entirely ciliate, motion of cilia irregular and independent; oral aperture apical, terminal, a single long, projecting springing-hair or seta developed at the posterior extremity. Inhabiting fresh water. The motion of the cilia in the representatives of this genus is peculiar, and serves at a glance to distinguish them from those of the ordinary Holotrichous types. Instead of vibrating in rhythmical cadence, each cilium waves in- dependently and apparently without any order, the ciliary system as a whole consequently assuming a comparatively irregular and untidy aspect. In creating the genus Uvotricha, Claparede and Lachmann remark that Professor Johannes Miiller had indicated the possible identity of their Uvotricha farcta with the Pantotrichum lagenula of Ehrenberg. M. Lieberkuhn, however, has supported them in regarding the two forms as separate. Having frequently encountered the animalcule described by Ehrenberg under the last-named title, the anthor is likewise enabled to establish its distinctness from the species introduced by the Genevan authorities, though it is obviously desirable to refer it to the same generic group. The original genus Pantotrichum of Ehrenberg includes, in addition to P. dagenula, GENUS UROTRICHA. 505 various minute entirely ciliate forms too indistinctly characterized for present identification, and in none of which is mention made of the terminal springing- hairs upon which the genus Uyotricha is mainly founded. Urotricha fareta, C.& L. Pu. XXVII. Fic. 2. Body ovate or ellipsoidal, surface of cuticle coarsely and obliquely striate ; cilia short and evenly distributed, posterior springing - hair obliquely directed when at rest, about equal to the body in length; oral aperture perforating a small circular prominence at the anterior extremity. Contractile vesicle single, spherical, posteriorly situated ; endoplast ovate, subcentral. Length 1-1250”. Hab.—Pond water and in infusions. The movements of this animalcule are of two kinds, and somewhat remarkable. In its more ordinary mode of progression it swims slowly in a forward direction, describing circles of a considerable diameter, the organs of propulsion on such occasions being the irregularly vibrating cuticular cilia; now and then, however, this more even locomotion is interrupted by a spasmodic leap to one side or in some other direction, the motion in this instance being accomplished by the posterior seta or springing-hair. According to its discoverers, the oral aperture of this species is capable of slight protrusion anteriorly in a lip-like manner, and in a way apparently according with that characteristic of Zrachelophyllum apiculatum and Enchelyodon farctum ; its walls are at the same time highly elastic, and permit the passage of food-masses almost equal in size to its own body. Urotricha lagenula, Ehr. sp. Pi. XXVII. Fic. 1. Body flask-shaped or pyriform, attenuate in front, rounded posteriorly, from one and a half to twice as long as broad; cuticular surface smooth ; cilia longest in the anterior region, moving independently; posterior spring- ing-hair always directed backwards in a straight line, exceeding the body in length; contractile vesicle single, spherical, posteriorly located. Length 1-570’. HAs.—Pond and marsh water. This species, apparently identical with the Pantotrichum lagenula of Ehrenberg, differs from the preceding type, not only in its larger size, but in its flask-shaped contour, in the greater development of the cilia in the anterior region, and in the uniformly straight direction of the posterior springing-hair, which has, moreover, a greater proportional length. In common with Uvotricha farcta, its movements through the water consist of slow rotation on its longitudinal axis in circles and in a forward direction, varied by occasional leaps from side to side after the manner of a Halteria or Uronema. In examples obtained from marsh water in the neighbourhood of Le Marais, Jersey, in company with Paramecium bursaria, numerous green chlorophyll-granules occupied almost the entire space of the internal endoplasm ; this colouring-matter was doubtless derived from the inception of zoospores, Thecomonads, and other chlorophylloid organisms which abounded in the same locality. The almost invariable occurrence of this form in company with Halteria grandinella, has afforded the author grounds for suspecting that Urotricha lagenula may eventually prove to be a developmental phase only of the last-named animalcule. Fam. IV. COLEPIDZ, Ehrenberg. Animalcules free-swimming, symmetrically ovate, persistent in form, ciliate throughout, oral cilia slightly larger than those of the general cuticular surface. VOL. II. D 506 ORDER HOLOTRICHA. Genus I. COLEPS, Ehrenberg. Animalcules more or less evenly ovate, persistent in shape, cuticular surface usually longitudinally and transversely furrowed, and thus divided into numerous symmetrical quadrangular facets or interspaces ; the quad- rangular facets smooth and indurated, the narrow intervening furrows soft and clothed with cilia ; oral aperture apical, terminal, surrounded with cilia, of slightly larger size than those of the general surface; anal aperture situated at the opposite or posterior extremity, the anterior and posterior margins usually mucronate. Dividing by transverse fission. Inhabiting salt and fresh water. The genus Coleps is usually cited as one of the few ciliate infusorial groups whose members may be described as perfectly symmetrical ; many of the representatives of the family of the Prorodontide or Trachelophyllide already described possess, however, an equal claim to such distinction, The cuticular ornamentation of the various species of the genus Colefs has been somewhat diversely interpreted by independent observers. Perty and Dujardin maintained the opinion that the quadrangular facets are indurated, and the narrow intervening furrows soft and clad with cilia. Claparede and Lachmann, however, upheld the view first expressed by Ehrenberg, to the effect that the furrows are indurated, and form a continuous symmetrical trellis-work, and that the quadrangular facets are of softer consistence and support the cilia. Having recently examined examples of the typical species, Coleps hirtus, with considerable care and the aid of the highest available magnifying power, the present author unhesitatingly adopts the interpretation of Dujardin and Perty. The facility and rapidity with which the animalcules of this genus divide by transverse fission is of itself a point in favour of the view here supported, for while the existence of a continuous trellis-like induration of the cuticular surface would offer a considerable obstacle to such transverse division, it takes place naturally and with the greatest ease along the line of one of the previously existing and softer intersecting furrows. Diesing, on very insufficient grounds, has proposed to separate this genus into three, abandoning the original title of Coleps altogether, and substituting in its place that of Pinacocoleps for C. incurvus, Cricocoleps for C. amphacanthus, while all the rest, including C. Airfus and Stein’s Plagiopogon coleps, are collated together under the generic name of Dzctyocoleps. The artificial character of such a plan of grouping is self-apparent. Coleps hirtus. Pl. XXVII. Fics. 3 AND 4. Body ovate, subcylindrical, more or less barrel-shaped, about twice as long as broad, rounded posteriorly, slightly narrower and truncate in front ; the anterior margin denticulate, three spinous processes or cusps developed at the posterior extremity; cuticular surface divided into quadrangular areas and presenting a reticulate aspect; endoplast spherical, subcentral ; contractile vesicle single, posteriorly situated, colour whitish or light brown. Length 1-500” to 1-400", Hazs.—Pond water, among duckweed and Conferve. This widely distributed species is subject to some variation in contour and aspect. One of these varieties having a more elongate outline has received from Ehrenberg the title of Coleps elongatus, and another, with green-tinted parenchyma, that of C. viridis ; both, however, are now accepted as being merely local phases of the present type. The active scavengering habits and voracity of Coleps hirtus have been GENUS COLEPS. 507 the subject of remark by numerous observers, a crushed Entomostracon, or any other dead or decaying organic substance contained in the water abounding with this animalcule, being surrounded and devoured with an amount of happy despatch that, comparing small things with great, would scarcely disgrace a troop of jackals collected around some desert carrion. It has been further remarked that the contour of these animalcules becomes considerably distended after their enjoyment of such a meal, a fact which of itself substantially supports the view here adopted as to induration of the quadrangular areas only of the cuticle, such a distension being altogether irreconcilable with a continuous and trellis-like hardening of the same surface. In the examples recently examined by the author, it was noted that when the animalcules were feeding or otherwise stationary, the cuticular cilia exhibit a continuous irregular and altogether independent vibratory action; the vigorous natatory movements, on the contrary, appeared to be accomplished through the agency of the more powerful oral cilia. It was further certified, in the course of this examination, that the cortex or body-substance immediately subjacent to the sculptured cuticle was independently and sparsely striate or grooved in a longitudinal direction, the body in such case, regarded independently of the external layer, presenting an elongate, ribbed, melon-like contour. During the process of transverse fission the animalcules of this species, as shown at Pl, XXVII. Fig. 4, exhibit an altogether abnormal aspect. While the two extremities retain their usual corrugated appearance, the newly developed central area, having a median constriction, is entirely smooth, or marked only by the deeper longitudinal furrows just referred to. So also, when the two moieties become entirely separated, one half of each of these remains for a considerable interval smooth and transparent, the anterior and posterior halves of the same animalcule so contrasting with one another as to suggest the simile of a smooth acorn projecting from its rugose cup. Quite recently, May 1880, the author has obtained in abundance, from a pond near Acton, in company with the Flagellate types Zxepomonas agilis and Tra- chelomonas volvocina, a variety of this form or a most closely allied species, in which no cusps whatever were developed at the posterior extremity, the size, quad- rangular corrugation, and deeper longitudinal lines or furrows being, in common with all other essential structural details, identical with what obtains in C. hértus. At the same time the consistence of the cortical layer seemed to be thinner and more transparent than usually obtains in that species, permitting a clearer view of the internal contents, which were chiefly coloured green through the ingestion of food-matter. While the comparative length and breadth in the examples examined averaged in most instances the proportions of two to one, much shorter and almost subspheroidal specimens were not unfrequently encountered. This well-marked variety should perhaps be properly referred to the genus Plagiopogon, next described. Coleps uncinatus, C.& L. Pu. XXVII. Fic. 6. Body ovate, slightly flattened ventrally, two and a half times as long as broad; the anterior margin bearing two recurved uncini on the more flattened ventral side, four acuminate cusps developed at the posterior ex- tremity. Contractile vesicle single, posteriorly situated; endoplast discoidal, central. Length of body 1-380". HAbB,—Fresh water. Coleps fusus, C. & L. PL. XXVII. Fic. 5. Body fusiform, subcylindrical, nearly four times as long as broad; the anterior margin truncate, denticulate, attenuate and pointed posteriorly ; no posterior cusps. Length 1-300". HAxB,—Salt water. De 508 ORDER HOLOTRICHA. In their brief description and illustration of this type, Claparede and Lach- mann mention that the rugose induration of the cuticular surface does not extend quite to the posterior extremity of the body, but leaves a short, soft, terminal portion exposed. This species was originally obtained by M. Lachmann at Glesnoes, on the Norwegian coast. Coleps incurvus, Ehr. Body oblong, subcylindrical, slightly curved, terminating posteriorly in five points. Length 1-430". Has.—Fresh water, among Couferve. Coleps amphacanthus, Ehr. Body shortly ovate, cuticular surface divided by transverse furrows into numerous annular indurated segments, the anterior margin unequally den- ticulate, three strong spines or cusps at the posterior extremity. Length 1-280". HaAxB.—Fresh water. GENuS II. PLAGIOPOGON, Stein. Animalcules free-swimming, persistent in shape, oval, subcylindrical, longitudinally furrowed ; oral aperture anteriorly situated, surrounded by a circle of stiff setose cilia; fine, hair-like, vibratile cilia clothing the remain- ing cuticular surface ; no apical or posterior spines; contractile vesicle and anal aperture posteriorly located. Plagiopogon coleps, Stein. Pi. XXVII. Fic. 7. Body ovate, subcylindrical, a little over twice as long as broad, longi- tudinal furrows rather widely separated, the intervening spaces finely striate transversely. Length 1-300". HaAB.—Salt and fresh water. This typical species of the genus FPlagiopogon is founded by Stein* upon the Lolophrya coleps of Ehrenberg and the Coleps inermis of Perty. As delineated by these two authorities, the animalcule resembles a Coleps hirtus devoid of posterior spines, and having its surface furrowed in a longitudinal direction only. GENUS III. POLYKRIKOS, Biitschli. Animalcules free-swimming, persistent in shape, subcylindrical or barrel- shaped; oral aperture terminal, having issuing from it a long bristle- like seta; numerous annular shortly ciliate grooves transversely encircling the body; endoplasm enclosing irregularly disposed trichocysts (?). Polykrikos Schwartzii, Biitschli PL. XXVII. Fics. 8-10. Body barrel-shaped, subcylindrical, slightly narrowed and truncate at the two extremities, about twice as long as broad ; transverse ciliary zones, eight to twelve or more in number, converging forwards on one side so as to form an obtuse angle parallel with the projection of the succeeding ring ; the border of the oral aperture four-lobed ; a long stiff seta, similar to the oral one, produced obliquely forwards from the body at a distance of about * “Prager Lotos,’ Bd. ix., 1859. GENUS ENCHELYS. 509 one-third of its entire length from the anterior extremity ; trichocysts large and conspicuous, irregularly disposed (?); endoplasts two in number, elongate-ovate, placed usually one behind the other; contractile vacuole posteriorly situated. Multiplying by transverse fission. Length 1-200". HaAB.—Salt water, Norwegian coast, and also at Kiel in brackish water. This single representative species of the genus Polykrikos as established by Biitschli, accords so closely in general contour, and in the position of the mouth, with the members of the genus Co/efs, the annulation of the cuticle more particularly ap- proximating that of C. amphacanthus, that it appears desirable to retain it provisionally in the same family group. ‘The long seta projecting from the oral cleft is possibly the homologue of the seta common to various members of the Hypotrichous genus Trochilia, The feature usually regarded as the most abnormal and important in this type is the enormous size of the contained trichocysts and the perfect correspondence of these structures with the nematocysts or thread-cells of the Ccelenterata or sea- anemones and hydroid zoophytes. The impression conveyed by a reference to Butschli’s original description and drawings of these structures,* reproduced at Pl. XXVII. Figs 9 and fo, are, it must be confessed, not unmingled with the suspicion that these so-called trichocysts have an entirely adventitious origin. Their disposition within the interior of the endoplasm is altogether irregular, and such as would occur if incepted as food-material. The species, furthermore, possesses a marine habitat, and not improbably feasts upon the débris of defunct zoophytes in the same manner as the more familiar Coless hirtus preys upon the residual detritus of fresh-water organisms. The thread-cells of the Ccelenterate structures would in the former instance be extensively engulfed, and would, under such circumstances, present the aspect accredited to them by Biitschli. Until, therefore, further evidence is forthcoming proving the extrusion of these so-called trichocysts from the cuticular surface of Polykrikos, their admission in the foregoing diagnosis must be regarded as purely provisional. Fam. V. ENCHELYIDSA, S. kK. Animalcules free-swimming, more or less ovate, ciliate throughout, oral cilia slightly larger than those of the general cuticular surface; cuticle soft and flexible; oral aperture terminal or lateral; the anterior extremity of the body never prolonged in a neck-like manner. The group of the Enchelyidze, as here defined, while corresponding to some extent with that of the Enchelia and Enchelina of Ehrenberg and Stein, has a much more restricted limitation, the long extensile-necked Trachelocerce, Prorodon and its allies, and Colefs with its indurated integument, being excluded and referred to independent families. Genus I. ENCHELYS, Ehrenberg. Animalcules free-swimming, elastic and changeable in shape, pyriform or globose ; oral aperture situated at the termination of the narrower and usually oblique truncate anterior extremity ; anal aperture at the opposite or posterior termination ; surface of cuticle entirely but very finely ciliate ; cilia longer and more easily distinguishable in the region of the mouth. Inhabiting marsh and stagnant water. * * Archiv fiir Mikroskopische Anatomie,’ Bd. ix., 1873. 510 ORDER HOLOTRICHA. The animalcules of this genus, while somewhat resembling those of Holophrya, are to be distinguished from the latter by their pointed and obliquely truncate anterior extremity, and by the fringe of larger cilia that encircles the oral region. The diagnoses and figures of the several species, as given by Ehrenberg, represent them as having no cilia on the general surface of the integument, these structures, while present, being so fine that they are liable to be overlooked unless glasses of the highest defining power are employed in their examination. From Z7vichoda, with which the animalcules of this generic group also closely correspond in form and habits, they are to be distinguished by the absence of a vibratile membrane in association with the oral fossa. The genus Lvchelys of Dujardin does not cor- respond with that of Ehrenberg, but includes forms rightly referable to the genus Cyclidium. Enchelys farcimen, Ehr. Pui. XXVII. Fic. 15. Body transparent, pyriform, slightly curved, attenuate and obliquely truncate anteriorly, inflated posteriorly, about one and a half times as long as broad ; contractile vesicle single, spherical, posteriorly located; endoplast oval, subcentral. Length of body 1-1000" to 1-430". Haxs.—Stagnant water and infusions. The author has encountered a species agreeing in every respect with this form but of smaller dimensions, in hay-infusions, the largest examples not exceeding the thousandth part of an inch in length. The characteristic movements of these animalcules consisted, when feeding, of routing about, snout downwards, among the vegetable débris, as shown in the accompanying figure, and at other times of swimming slowly through the water rotating on their longitudinal axis. In common with the members of the genus /o/ophrya, this and the other species of Enchelys become considerably distorted through the inception of food-substances, that may even exceed themselves in bulk, and also assume at will an entirely spherical outline. In this latter condition the oral aperture becomes completely obliterated, the position of the contractile vesicle only under these circumstances assisting in the distinction of the anterior from the posterior region of the body. Enchelys pupa, Ehr. Body inflated, attenuated anteriorly, frequently filled with green granules. Length 1-140". Hap.—Stagnant bog water. Enchelys arcuata,C. & L. Pu. XXVII. Fic. 14. Body pyriform, attenuate anteriorly, perfectly transparent, cilia of general surface very short and fine; contractile vesicles numerous, four or five in number, arranged in an arcuate manner along the ventral margin of the body; endoplast elongate-oval, subcentral. Length 1-300”. HAB.—Bog water. Doubtful Species. The so-called Hematozoon from the blood of Ceylon red deer, described and figured by Dr. Boyd Moss in the ‘Monthly Microscopical Journal’ for October 1871, is apparently referable to the genus Lychelys. The animalcules there delineated exhibit roughly the characteristic aspect of the members of this genus, though the cilia, probably through imperfect illumination, were visible only upon the more pointed anterior half of the body. Their dimensions would appear to correspond most. closely with the smaller size of those of 2. farcimen. While the evidence given by Dr. Moss strongly favours the supposition that these ciliate GENUS METACYSTIS—PERISPIRA—ANOPHRYS. hit animalcules occupy a permanent position within the vital fluid of the mammal named, further corroborative testimony in the same direction is much to be desired. GENUS II. METACYSTIS, Cohn. Animalcules free-swimming, symmetrically ovate or elongate, persistent in form; the entire cuticular surface clothed with fine vibratile cilia, with the exception of a bare vesicular-like posterior portion; oral aperture anteriorly situated, encircled by a fringe of stouter cilia. Metacystis truncata, Cohn. PL. XXVII. Fics. 11-13. Body ovate or elongate, subcylindrical, the posterior third or fourth smooth and vesicular-like, the remaining portion transversely annulate, and finely ciliate ; the anterior extremity abruptly truncate, bearing a circlet of long, incurved cilia ; endoplast spherical, central. Length of most elongate specimens 1-900”. HaAB.—Salt water, among decaying alge. As recognized by Cohn in his description given of this species,* it would seem by no means improbable that it is identical with the marine type figured and described by O. F. Miillerf under the title of Z7ichoda paxillus, but which does not appear to have been encountered by any subsequent observer. GENUS III. PERISPIRA, Stein. Animalcules free-swimming, symmetrically ovate, persistent in shape but not encuirassed ; oral aperture at the anterior extremity ; cuticular surface entirely and finely ciliate; a raised border, bearing the adoral cilia, extending in a spiral manner from the anterior extremity round the body towards the posterior end; anal aperture and contractile vesicle postero- terminal. Perispira ovum, Stein. Pi. XXVII. Fic. 18 (?). Body ovate, longitudinally striate, about twice as long as broad, oral aperture presenting the form of a transverse fissure; endoplasm usually filled with chlorophyll-granules. Dimensions unrecorded. HAzB.—Fresh water. Stein suggests that this species is possibly identical with the Aolophryoa vum of Ehrenberg; the elastic character of the parenchyma and cuticular covering in that type, as compared with Stein’s diagnosis, would seem, however, to scarcely favour this interpretation. ‘The accompanying figure, Pl. XX VII. Fig. 18, represents an ani- malcule apparently closely allied to it if not identical with Stein’s species, delineated in the manuscript notes of Bombay Infusoria kindly placed at the author’s disposal by Mr. Carter; the conspicuously larger size of the adoral spire of cilia affords perhaps sufficient grounds for its recognition as a second species of the genus Perispira. GENUS IV. ANOPHRYS, Cohn. Animalcules free-swimming, persistent in shape but highly flexible, elongate-ovate, rounded posteriorly, the anterior extremity pointed, more or * “ Neue Infusorien im Seeaquarium,” ‘ Zeitschrift fiir Wissenschaftliche Zoologie,’ Bd. xvi., 1866. + ‘ Animalcula Infusoria,’ 1786. 512 ORDER HOLOTRICHA. less curved; oral aperture ventral, remote from the apical extremity, of oblong shape, followed by a short, tubular pharynx; cuticular surface entirely ciliate ; a fascicle of longer and stouter cilia issuing from the oral cleft ; endoplast and contractile vesicle conspicuous. According to Cohn, excepting for the absence of the minute enclosed oral mem- brane, the representatives of this genus closely correspond with those of Zrichoda as modified by Stein ; the chief distinction between the two being that, while in Z7zchoda the oral cilia form a small wreath round the subterminal buccal aperture, in Avophrys they depend in a fascicular manner from this structure. The still closer affinity of the type-form of this generic group with Co/goda is self-evident. Anophrys sarcophaga, Cohn. Pi. XXVII. Fics. 16 anp 17. Body elongate-ovate or clavate, subcylindrical, rounded posteriorly, pointed and curved anteriorly, from three to four times as long as broad ; pale amber colour ; oral aperture situated on the ventral surface at a distance of one-third of the length of the entire body from the anterior extremity, bearing a fascicle of about eight or nine large cilia; cuticular surface furrowed longitudinally and transversely ; the cilia clothing the pointed anterior extremity of larger size than those of the remaining portion of the body, which are very fine and difficult to see; endoplast central, spherical, of large size ; contractile vesicle postero-terminal. Length 1-400". Has.—Salt water, with decaying animal matter. As recognized by Cohn,* this species, excepting for the character of the oral cilia, closely resembles the Zrichoda (Leucophrys) carnium of Ehrenberg, a species occur- ring in putrescent infusions, and in water from manure-heaps; the oral aperture in this latter type would seem, however, to be more nearly terminal. Reference is made by Cohn to a long tail-like seta at the posterior extremity, but is not indicated in his drawings. The fascicle of oral cilia in rapid motion is described as present- ing the appearance of an undulating membrane. GENUS V. COLPODA, Ehrenberg. Animalcules free-swimming, persistent in shape, ovate or reniform, compressed ; oral aperture ventral, lying in a cleft-like depression at some little distance from the anterior extremity, having no undulating membrane, but giving origin to a brush-like tuft of longer cilia; pharynx absent or rudimentary ; cilia of the general surface very fine, sometimes conspicuous only towards the anterior extremity of the body. Inhabiting fresh and salt water and infusions, Colpoda cucullus, Ehr. Pu. XXVII. Fics. 19-23. Body subreniform, one and a half times as long as broad, rounded and inflated posteriorly, pointed anteriorly and recurved towards the ventral aspect ; cilia of the oral region projecting in a tongue-shaped or tuft-like manner from the oral fossa, the shorter cilia of the general surface con- spicuous only towards the anterior extremity of the body; endoplast * ¢ Zeitschrift fiir Wissenschaftliche Zoologie,’ Bd. xvi., 1866. GENUS TILLINA. 513 spherical, subcentral; contractile vesicle spheroidal, of large size, posteriorly located. Length of body 1-280". HAsB.—Fresh water and infusions. The distinction between this form and the Colpoda cucullus of Dujardin, or Colpidium cucullus cf Stein, is explained in the description given of the last-named species. Although appearing under ordinary magnification, and formerly pronounced to be ciliated only at the anterior extremity, there is no longer room for doubt that the entire surface of the body of this animalcule is also finely ciliate. The multiplica- tion by fission of this species has been described at length by the last-named author, this process in all instances, according to Stein’s observations, being preceded by encystment. Within its cyst the animalcule divides variably into either two, four, eight, or as many as sixteen, spore-like bodies, which ultimately escape through the rupture of the wall of their prison-house in a form which, while smaller, is in all respects identical with that of the parent animalcule. Similar reproductive pheno- mena have been recorded in connection with the genus O/ostoma, but are at the same time rare among the Ciliata, though of almost universal occurrence among the more simple Flagellata. No act of conjugation or fusion of two animalcules is mentioned by Stein as necessarily preceding the process of encystment and sporular form of multiplication as above described. Colpoda parvifrons, C. & L. Body ovate, nearly twice as long as broad, rounded at both extremities but widest posteriorly, the anterior end not recurved ventrally ; the outer surface of the body distinctly though finely ciliate; contractile vesicle posteriorly situated but not precisely terminal as in C. cucullus. Length of body 1-600". 'HAB.—River water: Spree, near Berlin (C. & L.). Colpoda pigerrima, Cohn. PL. XXVII. Fic. 24. Body elliptical, pointed at each extremity, about three times as long as broad, the anterior end most attenuate and curved towards the ventral aspect ; oral cleft at a distance of about one-third of the entire length of the body from the anterior extremity; cuticular surface subdivided by longitudinal and transverse striations into minute quadrate areas ; cuticular cilia very short and fine, of equal size throughout, oral cilia forming a projecting recurved tuft ; contractile vesicle situated close to the base of the oral cleft. Length 1-780". HAB.—Sea water with decaying animal matter. The greater proportional length, surface ornamentation, and position of the contractile vesicle readily distinguish this type from the two preceding species. GENUS VI. TILLINA, Gruber. Animalcules free-swimming, persistent in shape, subreniform; oral aperture ventral, followed by a long, curved pharynx; cuticular surface entirely clothed with very fine vibratile cilia, a circle of longer cilia developed round the oral aperture and continued down the pharyngeal passage ; endoplast and contractile vesicle conspicuous. 514 ORDER HOLOTRICHA. Tillina magna, Gruber. PL. XXXII. Fic. 13. Body subreniform or bean-shaped, compressed, rather over twice as long as broad ; an irregular, broad, lobate process developed from the dorsal aspect of the posterior extremity and interrupting the symmetry of this region; oral aperture ventral, subcentral, followed by a tubular, strongly recurved pharynx, whose walls are conspicuously ciliate throughout ; oral and pharyngeal cilia considerably larger than those covering the general cuticular surface ; cuticular surface smooth, or finely and sparsely striate longitudinally, its deeper layer apparently striate radially, an aspect due most probably to the enclosure of trichocysts; endoplast elongate-ovate, situated in the anterior body-half; contractile vesicle posteriorly located, intrenching partly on the irregular lobate process. Length 1-125”. HaB.—Fresh water. This species, described by Dr. August Gruber, together with several other interesting forms, in the ‘ Zeitschrift fiir Wissenschaftliche Zoologie,’ Bd. xxxv., 1879, and translated in the ‘ Journal of the Royal Microscopical Society’ for April 1880, is regarded by its discoverer as exhibiting a type of structure intermediate between Paramecium and Colpoda. In the peculiar form of pharynx, however, it much more closely approaches Conchophthirus, but is necessarily referred to the present family group on account of the more conspicuous development of the oral cilia. Reproduction accompanied by encystment and subdivision into four equal spore-like masses after the manner of Co/foda, has been observed. In the accompanying drawing the anterior and posterior regions have been accidentally reversed. Fam. VI. TRACHELOCERCIDS, S.K. Animalcules free-swimming, flask-shaped or elongate, soft and flexible, ciliate throughout, the oral cilia slightly exceeding in size those of the general cuticular surface; the anterior extremity usually prolonged in a neck-like manner, an annular groove or furrow often present near the apical extremity ; oral aperture terminal or subterminal. Genus I. TRACHELOCERCA, Ehrenberg. Animalcules highly elastic and changeable in form, the anterior portion produced as a long, flexible, narrow, neck-like process, the apical termination of which is separated by an annular constriction from the preceding part, and is perforated apically by the oral aperture; the entire cuticular surface finely and evenly ciliate, a circle of longer cilia developed round the oral region. Anal aperture postero-lateral or subterminal. Contractile vesicles usually multiple, irregularly distributed. Inhabiting fresh and salt water. The diagnosis of the genus Zrachelocerca as above given, and as constructed in accordance with the results of more recent investigation, differs materially from that first introduced by Ehrenberg. In accordance with the representations of this last- named authority, the cuticular surface of the animalcules of this genus was entirely devoid of cilia, and the oral aperture, instead of being situated at the apical extremity of the anterior neck-like prolongation, as is now determined, was pronounced to be located in the annular groove that separates the extreme anterior portion from the GENUS TRACHELOCERCA. 515 remainder of the body, and which antero-lateral position of the mouth forms the essential characteristic of the genus Prialina. By Dujardin, and Claparéde and Lachmann, it has been considered desirable to amalgamate the genus Z7achelocerca with that of Lacrymaria, and to retain the last- named title only, the single hitherto well-characterized member of the former genus T. olor, being represented by them as differing too slightly from the ordinary Lacrymarie to claim independent generic recognition. It has been decided here, however, to retain both of these two titles, numerous animalcules being now known that form collectively two natural groups, between which it is easy to discriminate when thus separated, but whose specific identification would be attended with much inconvenience were they collectively compared. In pursuance of this decision, all those forms are retained in the genus Zrachelocerca which agree with Z? olor in the possession of a specially elongate and highly extensile neck-like anterior portion, in mostly having several irregularly distributed contractile vesicles, and in the usually subterminal position of the anal aperture. In Lacrymaria, on the other hand, as typified by the Z. Zagenula of Claparéde and Lachmann, there is no specially elongate and elastic neck, the contractile vesicle is single and postero- terminal, and the anal aperture exactly terminal and immediately behind the con- tractile vesicle. It is further a fact of note that all the short-necked specific forms hitherto discovered, and here referred to the genus Lacrymaria, are strictly inhabi- tants of salt water. While thus readily distinguishable in their adult conditions, a developmental phase of Zrachelocerca olor is presently shown to correspond in a remarkable manner with the typical adult condition of Lacrymaria lagenula, Trachelocerea olor, Mill. sp. PL. XXVII. Fics. 29-31. Body subfusiform, usually attenuate posteriorly, the neck-like anterior portion exceedingly elastic and contractile, often, in extension, equal to four or five times the length of the body ; cuticular surface finely ciliate, obliquely striate in two directions ; contractile vesicles two or three in number ; endo- plast double, with a distinct endoplastule. Length of extended body 1-140’. HAB.—Fond water. This species was one of the earliest known infusorial forms, it having been first figured and described by Baker in the year 1752 under the title of the “ proteus,” while in Miiler’s works it receives the three names of Vibrio proteus, V. olor, and V. cygnus ; its relegation to the genus Zvachelocerca was subsequently accomplished by Ehrenberg. The aspect of the animalcules of this species, as they swim gracefully through the water, extending and contracting their attenuate and wonderfully exten- sile necks, or thrusting them from side to side in search of food among the con- fervoid filaments or vegetable debris which they usually affect, is, as implied by its specific title, not unlike that of a swan, or is perhaps still more suggestive of the restored figures of the long-necked mesozoic P/estosauri, contained in popular geological treatises. It has been frequently observed by the present author that two individuals of this species are almost invariably found in close proximity, and appear to be guided in all their movements by a certain com- munity of action. The Zrachelocerca viridis, T. linguifera, and T. biceps, and also the Lacrymaria proteus of Ehrenberg, are regarded by Clapartde and Lachmann as varieties only, or imperfectly observed examples, of this exceedingly protean and variable species. In this manner the first-named is distinguished merely by the presence of engulfed and incorporated chlorophyll-granules ; 7: diceps would be a monstrosity with a double neck, or a zooid undergoing longitudinal fission ; while the variety with a rounded posterior extremity, described under the title Lacrymaria proteus, probably represents an animalcule whose contour is abnormally rounded and inflated by the ingestion of food-particles. The Zrachelocerca linguifera of Perty, said to differ from 7: o/or in the form of the oral region, which is described as being surmounted by a movable flap or tongue-like process, practically corre- 516 ORDER HOLOTRICHA. sponds with the normal aspect of this region in the present species. Claparéde and Lachmann observe of the terminal oral region of this animalcule that the circlet of oral cilia is capable of being adpressed against the distal extremity, and assists in the prehension of food-particles. Under high magnification the walls of the conical oral fossa are shown to be longitudinally striate, and are probably plicate in a manner closely corresponding, though in a more marked degree, to what obtains in the two genera Zrachelophyllum and Enchelyodon. In a gathering containing this animalcule, 7: o/or, in abnormal abundance, examined by the author so recently as February 1880, it was observed that a form corresponding in external contour with the marine Lacrymaria lagenula of Claparéde and Lachmann, was equally plentiful; furthermore, that every intermediate con- dition, having gradually lengthened and more or less flexible neck-like prolonga- tions, were intermingled, the two extreme forms being thus closely amalgamated with one another. Finally, by patient watching, the short, stiffnecked Zacrymarialike zooids were found to develop into the long and graceful necked Zrachelocerce, the primary simply flask-shaped zooid gradually acquiring a distinct attenuate and extensile neck, the two being thus demonstrated to be transitional phases only of the same species. ‘The observation of this type being still further prolonged, it was at length determined that the short-necked zooids were the derivatives by transverse fission of an ordinary long-necked animalcule, and represented the hinder moiety of the fissive process pending the subsequent rapid development of the characteristic neck, Trachelocerea versatilis, Mill. sp. PL. XXVII. Fic. 33. Body attenuate fusiform, pointed posteriorly ; neck long and _ thread- like, its distal extremity expanded and conspicuously ciliated underneath ; cilia of the general cuticular surface exceedingly fine and difficult to detect. Length, when extended, I-40"; retracted, 1-120". In the autumn of the year 1870, a salt-water species of Zrachelocerca was obtained by the author at Bognor, Sussex, evidently identical with the form briefly characterized as above by both O. F. Miiller and Dujardin under the respective titles of Zrichoda and Lacrymaria versatilis. Unfortunately, the amount of attention requisite for the framing of a more complete diagnosis was not bestowed upon it at the time. Compared with Z: olor, with which Perty has proposed to identify this species, it may, however, be stated that the body was much more narrow and attenuate, and the distal extremity of the neck or oral region proportionally thicker ; the subter- minal circle of oral cilia was likewise observed to be more obliquely set, a circum- stance communicating to this region, when seen in profile, the aspect of being ciliated underneath, attested to by the authorities quoted. In the great length and elasticity of the neck-like prolongation this species rivals the form previously described. The salt-water Zrachelocerca sagitta of Ehrenberg, briefly described as of fusiform contour, with a very long neck, colour white, head terminal and opaque, length 120”, would seem to correspond closely with Zvachelocerca versatilis, or may be identical with Cohn’s Z: phenicopterus. Trachelocerca phcenicopterus, Cohn. Pri. XXVII. Fic. 32. Body elongate, ribbon-like, flattened, highly elastic and retractile, finely annulate transversely, prolonged anteriorly into an attenuate, trans- parent neck, and posteriorly into a long, pointed, tail-like portion; oral aperture terminal, circular, witha rigid annular border, followed by a funnel- shaped pharyngeal cleft ; the distal end of the neck slightly widened, its GENUS LACRYMARIA. Bay extremity abruptly truncate ; contractile vesicles multiple, lineally disposed. Length of body when most extended 1-24", retracted I-60", Has.—Salt water. The rigid annular border surrounding the apical extremity in this form would seem to take the place of the conical prominence in the ordinary species, unless it is that Cohn’s figure and description apply to examples in which at the time of examination this usually conspicuous structure was concealed by invagination. Although a single contractile vesicle only is seen in the figure here reproduced from Cohn’s original account of this species,* the two other examples delineated by this authority exhibit respectively two and eight of these structures, and which in the last instance are disposed at even intervals throughout the centre of the thicker central region of the body. In one example the endoplasmic layer has a vacuolar or reticulate aspect somewhat analogous to that of Zrachelius ovum. Trachelocerca tenuicollis, Quenn. Body elongate-lanceolate, pointed posteriorly; neck long and very slender, scarcely dilated at the apex; cuticular surface finely ciliate, feebly striate longitudinally ; contractile vesicle posteriorly situated ; endoplast subcentral. Length in extension 1-75". HaAB.—Salt water. GENUS II. LACRYMARIA, Ehrenberg. Animalcules free-swimming, more or less cylindrical, clavate or flask- shaped, moderately elastic, the anterior end narrowest, the apical extremity conical in outline, and separated from the remaining portion of the body by an annular constriction, the intervening region not produced into a separate, slender, and highly elastic neck-like region, as in Trachelocerca ; oral aperture surrounded by one or more ciliary circlets, perforating the apical extremity of the anterior -conical prolongation ; the cuticular surface finely and entirely ciliate ; contractile vesicle single, postero-terminal ; anal aperture situated immediately behind the contractile vesicle. Mostly inhabiting salt water. The Lacrymaria lagenula of Claparéde and Lachmann is here adopted as the type-form of this genus, to which two additional forms possessing the same broad general characters are here added. The Lacrymaria proteus, L. olor, L. gutta, L. rugosa, L. tornatilis, and L. farcta, of Ehrenberg, Perty, and Dujardin, are long flexible-necked animalcules, referable, so far as it is possible to identify them, to the genera Zrachelocerca and Amphileptus. Lacrymaria lagenula, C.& L. Pui. XXVII. Fic. 34. Body clavate or flask-shaped, attenuate anteriorly, nearly four times as long as broad ; cuticular surface obliquely striate, finely and entirely ciliate, a single circlet of longer cilia surrounding the oral region ; contractile vesicle single, spherical, postero-terminal ; endoplast elongate-oval, subcentral. Length of body 1-350". Has.—Salt water: Norwegian coast (C. & L.). As suggested by its discoverers, the contour of this animalcule corresponds remarkably with that of a soda-water bottle, the posterior inflated portion answering * Neue Infusorien im Seeaquarium,”’ ‘ Zeitschrift fiir Wissenschaftliche Zoologie,’ Bd. xvi., 1866. 518 ORDER HOLOTRICHA. to the body, the more attenuate anterior portion to the neck, while the conical extremity, separated off by the annular ciliated groove or furrow, may be said to represent the cork. Under the name of Lacrymaria versatilis Quennerstedt * has figured and described a marine animalcule which agrees closely with the form under notice, excepting that its contour is slightly more slender and attenuate, the length equalling as much as six times that of the greatest breadth. It has the same elon- gate, bottle-shaped contour; the cuticular surface is obliquely channelled or striate in a similar manner, and the endoplast and contractile vesicle correspond similarly in both character and position. Quennerstedt proposes to identify this variety, or possibly independent type, with the Z7ichoda versatilis of O. F. Miller, which is, however, undoubtedly rightly referable to the preceding genus. ‘This is shown both by Miiller’s description in the following terms of the movements of the animalcule in the water: “ Motus natando celerrimus, collum hinc et tline pro lubitu adirigit,? and by his additional indication in the figures of the species of the attenuate and extensile character of the neck. Lacrymaria coronata, C.& L. Pu. XXVII. Fic. 28. Body elongate-clavate, slightly narrowed anteriorly, nearly five times as long as broad; two ciliary circlets developed around the apical extremity, the anterior one bearing the longest cilia, each occupying an annular sroove or furrow; surface of cuticle obliquely striate, entirely and finely ciliate ; contractile vesicle spherical, postero-terminal ; endoplast elongate, band-like. Length of body 1-150". HAB.—Salt water, Norwegian coast. The double circlet of cilia at the apical extremity and band-like form of the endoplast, independently of the greater porportionate length of the body, assist in distinguishing this type from the preceding one. ‘The characteristic apical region only of this animalcule is delineated in the accompanying figure. Lacrymaria Cohnii, S.K. Pui. XXVII. Fics. 25-27. Body highly elastic and changeable in form, when extended oblong cylindrical, slightly broader and somewhat truncate anteriorly, about four times as long as broad, contracting from this to an almost spherical con- tour, the posterior third often flattened out and twisted like the blade of a ship’s screw ; surface of cuticle finely ciliate throughout, faintly striate lon- gitudinally ; body usually opaque through the enclosure of numerous fat- like corpuscles; contractile vesicle largely developed, postero-terminal. Length 1-240". HaxB.—Salt water. The above specific title is herewith conferred upon the form figured and described by Cohn, in his ‘ Neue Infusorien im Seeaquarium,’ 1866, under the title of Zacry- maria lagenula C. & L. From this last-named type it is evidently totally distinct. The flask-like contour, with a tapering anterior extremity distinctive of that form, would appear to be never assumed by the present animalcule, but in its place a highly remarkable screw-like shape, which would scarcely have escaped the attention of Claparéde and Lachmann in connection with their species ; the surface of the cuticle in Cohn’s type is, further, entirely wanting in that conspicuous oblique striation, and the general substance of the body would appear to be much more soft and con- tractile. The figures given by Cohn, here reproduced, entirely support the views here held relative to the invertile nature of the apical portion of the conical anterior * « Sveriges Infusoriefauna,’ tab. i. fig. 5, 1867. GENUS PHIALINA. 519 prolongation ; in two instances this part, Figs. 26 and 27, is shown to project con- spicuously beyond the oral fringe of cilia, while in the other, Fig. 25, these cilia seem to issue from the apical extremity itself, an aspect which would necessarily result from the withdrawing inwards of this structure. The Z7vichoda ambigua of O. F. Miller * would seem to agree with this type in the flattened screw-like contour of the posterior region of the body, and is possibly identical with it. At the same time the body of Miuiller’s species would appear to have a more elongate and vermiform shape, and it is apparently not capable of contracting into a globular form. Like the present species, it is an inhabitant of salt water. GENUS III. PHIALINA, Ehrenberg. Animalcules free-swimming, subcylindrical or flask-shaped, slightly elastic, narrowest anteriorly, a portion of the apical region separated from the rest of the body, as in Tvachelophyllum and Lacrymaria, by a circular groove, and bearing a circlet of longer, usually reflected cilia; the oral aperture situated in the anterior annular groove, and not terminal as in the two last-named genera; cuticular surface finely and entirely ciliate ; contractile vesicle single, adjacent to the postero-terminal anal aperture. With the exception of the antero-lateral, instead of apical position of the mouth, the animalcules of this genus correspond essentially with those of Zacrymaria, and, unless the exact position of this aperture is seen and determined, are liable to be confounded with them. Phialina vermicularis, Ehr. Pi. XXVII. Fics. 36. Body subcylindrical, ovate or pyriform, narrowest anteriorly, two and a half times as long as broad, the apical portion in advance of the annular furrow short and broadly cylindrical, its anterior margin truncate and bear- ing a single circlet of cilia, these cilia usually directed backwards ; oral aperture opening on the annular furrow; surface of integument smooth, finely and entirely ciliate; contractile vesicle single, spherical, postero- terminal; endoplast ovate, subcentral, obliquely directed. Length of body 1-240". HaAs.—Pond water. The lateral position of the mouth of this animalcule has been very clearly indicated by Ehrenberg, but, as intimated by Claparede and Lachmann, the figure referred to most probably depicts an example observed at the moment of engulfing food, the organ at other times being difficult to recognize. By Ehrenberg and various earlier writers the cuticular surface of P%zalina, as in the case of Lacrymaria, Trachelocerca, and other forms, is described as being entirely glabrous. More recent observation, assisted by the employment of superior magnifying lenses, has, however, determined the presence of fine cilia throughout its whole extent. The aspect of Phialina vermicularis, with its reflected anterior circlet of larger cilia only visible, has been not inaptly compared with that of a minute Echinorhynchus. Doubtful Species. The Phialina viridis of Ehrenberg, Pl. XX VII. Fig. 37, is suspected by Claparéde and Lachmann to be a coloured variety only of P. vermicularis; according to Ehrenberg’s figures, however, the body also is differently proportioned, the posterior * © Animalcula Infusoria,’ p. 200, pl. xxviii. figs. 11-16, 1786. 520 ORDER HOLOTRICHA. extremity being slightly narrower than the shoulder portion of the bottle-shaped body, while the projecting neck is more attenuate. Colour bright green. Length 1-288", GENUS IV. MARYNA, Gruber. Animalcules ovate or cup-shaped, with an anterior projecting funnel- shaped neck, which is cleft on its ventral aspect and fringed along its anterior edge with a single row of long cilia; finer vibratile cilia distri- buted over the whole cuticular surface ; oral aperture situated at the base of the anterior cleft, followed by a fissure-like pharyngeal passage. Habits social, secreting and inhabiting a common tubular zoothecium, to the walls of which they are not permanently united. Maryna socialis, Griiber. PL. XXXII. Fics. 11 AND 12. Zoothecium dichotomously branched, granular and finely striate trans- versely, narrower or constricted at the commencement of each bifurcation ; colour light brown or yellowish; contained zooids projecting slightly from their respective thece ; cup-shaped, one and a half times as long as broad ; the posterior border rounded, the anterior one truncate, with a centrally developed, ventrally cleft, funnel-like neck, a cleft on the ventral aspect of the anterior border corresponding with that in the neck; pharynx continued backwards to within a short distance of the posterior border; ante- rior wreath of cilia very long and fine; contractile vesicle situated near the termination of the ventral cleft ; endoplast unobserved. Length 1-165”. HaB.—Salt water. The position of this animalcule is obviously near Zacrymaria and Phialina, from both of which it most conspicuously differs in its social habits and construction of a common zoothecium. A translation of the original description of this species, as figured and described by Dr. Gruber,* in common with various other interesting infusorial forms, is given in the ‘ Journal of the Royal Microscopical Society ’ for April 1880. STACilis) (52, Bosh eel vo 331 % lonsicolliso 7.7) .e cseeeon 35 Pa OVatay- cc. Upsaees ae a5 os Steimitt es) s40 samccee nt Sen Muscle or Nerve-fibres in Stylonychia BLVAMIWS co se) seo, | hoo ueeeh © eaeege ten anORES Mycetozoa “2, a, prt A2ZVTORLLO2.470 WiyxOMyCeteS' 2. - anh en 42 IO 75020470 INassulay sa" “in. acy Senne seuss 494 Wpuy NAMLDISUA® 5.05 Saar ~ ae 495 Nassula conica Bre oy hc 495 - elegans 495 906 INDEX. PAGE Massila flava 2 2c) ss os) ee st eos. | (Onbrydina py e. UALCTILIAN Ae co Mew somes: eans - 400,| | Opurydium haba py vs MMCLOStomata .° ae. se 496 | Ophrydium Aed@ .. » ornata aa ge: 494 | Ophrydium Eichornii > FUDENS) Ge we «2 «s a» 495 | | Opkryaium longipes Nepbroselams {cf 1.) a0 me». “4og | Opbrydium-sessile.: olivacea .. 405 5 versatile Nerve-fibres or Muscle in Stylonychia Ophryodendridee mytilus .. ao) Jen Be, Vas ws ~oo2. |) Ophryedendron ig Noctiluca.. som del Meo Me An EYoy/ ss abietinum 5 AAAS 2 on ey. eine ESOT, < Belgicum E Noctilucide .. Meet este L400) 4 multicapitatum .. Nothopleurotricha setifera een rss 704 pedicellatum EVRCLERSLE SUULDIER ac. asm. Se.pen |, «2. 2k Ophryodendron pedunculatum PAELGLUCTUS? ae yee eet cage weal os STO ” COLGMORIAIS | Ocak eal) oes 5 CO gyoeryanus 55) SSS IVES OV AES He" ies gaara baa OO WELOX sn bon) © tb est. Gen whol aeeesO MIUtADIS 20° Sc) ea pee S250 obliqua EE sh one et. WA eiadrata yh, Vince ori a rostrata Sat) So oe a0 OS SECU ere! Weng haut pwsule tes. 253 (WENT) ga GOA) “Bay ooh VI Onychaspis polystyla tr ass wate fost OS Onychodromus pL coh dd Brave Ihiel motte.) 3200 STANGIS yr wan Wee See 760 ” Opalina PE Rd thee wer, coat ey PERRO ICAU atab sty ack) hee Ss (SOS SP CUMIGIACA 60 tre cn lee 6a. IS OL Opalina discoglosst Some Nice Me Che ee Gnu Opalina intestinalis Be ay ios es OS OBAUHETMEALTA! in, ce atm, vat 564 » lumbrict : 565, 571 55 TUE tues) Peay Seis es, eS OS i HOEAOS 2) | ate Ses OS Opalina obtrigona,.., 5° ss. as... . 502 Opalina planariarum .. 4 0 569 Fe POLY WLOF DG ss at ud ts, GOO DL Map DTOLUICER ee nes dene | Ge Gee AGOS Opalimatanardny 2 se coe Tee esl 559 OGEMNGTECUTUR 66 sin ag es 573 RL MUSTIIULES. | TRE cee pepe vs? Lede EGR . uncinata .. Pe dee fil Opalinidze ; 476, 481, 556 Opalinopsis octopi.. eae eeh Pern et atOO eA sepiolae pebiceiw at) 2c 1st000 Ooeccwlana gel heer he Mie xe vas EO “5 ATEDIGGla Sea Sate in. LOOT op AUMGHIACAY Gio aac) Gey. veh \o 7EE i berbemma’ 55 orth antl cs. 7 RL 33 eylindrata 6) bade c. ss: W713 5 hospes sin Sil povle 714 3 Iichtenstemit ns) 9... 712 53 WUCLOSIGHIA A cn, aur, en PTR nutans al cms. ean, lO stenostoma ot ie A ye Ophidomonas JG ee ee Cte mine i ea, DAA - JENCHSISH tact iel ruse) (CAA. - sanguinea (mE Tos..: 244) Ophionella ee Nee wrt 734 ” DICtAST Lice sacs seme ge ease. 297-54. Ophryodendron porcellanum x6 sertulariz .. Ophryoglena A atta 7 acuminata G2eca) a. Ophr -yoglena citreumt - Jlavicans .. LVISEO-VITENS Ophryoglena oblonga : Wrzesniowskii.. Ophryoglenidze Ophryoscolecidze ie Ophryoscolex 35 “sen sn es i inermis ~ ae Opisthodon niemeccensis Opisthotricha a . 9 parallela . aii 5 similis Organization of Infusoria Orthonectida .. Otostoma as Carteri Oxyrrhis .. ee eo as MALIN sm .. —-sveycates Oxytricha.. zeruginosa Oxytricha affinis é a auricularis .. a caudata.., s. = crassa Oxytricha fallax 55 ferruginea Oxytricha flava op Susca = gibba % Kesslerz.. Oxytricha macrostyla micans .. Oxytr tcha multipes x mystacea ci parallela Oxytricha pellionella Oxytricha pernix .. Oxytricha platystoma Oxytricha retractilis ss rubra Oxytricha scutellum + sordida .. Oxytricha strenua .. 3 tubicola .. re urostyla.. PELOTON fae, ale oe Oxytrichide Bet eho? call eles Pachytrocha esis cothurnoides Panophrys chrysalis Panophrys chrysalis AS conspicuad - Yarcias. Panophrys flava flavicans Panophrys g griseola Oe es paramecioides So) ss a rubra e sordida.. 5 zonalis .. Pantostomata .. Pantostomata- Dimastiga . -Monomastiga + -Polymastiga ve Pantotrichum lagenula.. .. .. Paramecidz Paramecium ., 35 aurelia e bursaria ., Paramecium caudatum - chrysalis .. a GWE a0 ¥ colpoda S compressum ae CUEULTUS "ex re Paramecium glaucum .. Paramecium inversum = y kolpoda Paramecium marinum .. , Paramecium microstomum .. Ee NUCLEUS = 6" al Boe 9 ovale Paramecium putrinum .. Paramecium stomioptycha .. Paramonadidz Paramonas a deses ie globosa Y @ibinn) Boe ar si stellata Peranema globulosa 35 protracta Peridinidz Peridinium is rr zequale _ apiculatum .. Peridinium arcticum .. « 33 Carolinianum Peridinium chilophenum Peridinium cinctum 35 cornutum .. 5 corpusculum 3 Cypripedium - depressum .. _ divergens . INDEX. PAGE 771 | Peridinium furca .. 789 a fuscum 765 Pe Susus 768 3 inaqguale .. 759 ry, zmerme Fe lineatum 729 macrocer os 729 E monadicum 533 = monas 534 x pulvisculus 496 | Peridinium reticulatum .. 534 2 sanguineum BA ie 534 5 spiniferum .. .. a Seyi =p splendor-maris .. . 534 55 tabulatum - 534 | Pertdintum uberrimum =, 534 5 vorticella 496, 534 | Perispira .. aa) 534! 5 ovum 534 | Peritricha.. 35 | Peritromide 262 | Peritromus fe 232 5 Emme .. 305 | Peronospora infestans 505 | Petalomonas Bey ie 483 5 abscissa .. 483 _ ervilia 483 *5 irregularis -- 486 3 mediocanellata ba Usk 3 sinuata 488, 542 | Petalotricha Be ae SES 5 ampulla 5p Akteys) - spiralis 583 | Phacus i we 538 » longicaudus 488 », pleuronectes 488 3) pycum 537 5 triqueter 488 | Phalansteriidz 488 | Phalansterium te. ou 577 sf consociatum .. 488 digitatum 488 Phalansterium intestinum as 540 | Phascolodon p 367 ss vorticella .. 370 | Phialina “ 371 5 vermicularis 370 “A viridis 370 | Phialonema e 370 cyclostomum oe 225, 431 Phyllomitus nc 375 93 undulans 441 | Physarum tussilaginis 447 | Physemaria*® os «1 as 451 | Physomonas : 449 . marina oe 454 ee socialis 462 | Pinacocoleps 450 | Placus . 446 5 striatus 462 | Plagiomastix .. 443 | Plagiopogon ‘ 618 a coleps Aga) | Plagiopyla =- .: « 453 v4 Carteri 5. Ay ee ea ic 287, 361 746 519 519 Me 908 INDEX. PAGE PAGE Plasiopyla fusca «.. “<. ses 539 | Podophrya infusionum.. .. 819 - NASUEA a be 538 e Leichtensteinil 818 Plagiotoma Ati an 583 - libera 5 814 Plagiotoma acuminata ie 490 55 limbata Foleo ad ests 816 S blattarum .. 580 Lyngbyi 815 i lateritia 585 - THOUS Sis 5 San Was ete 821 Plagiotoma lumbrici 583 phryganidarum .. 818 Plagiotricha : 77K Podophrya pusilla .. 826, 827 - affinis.. 772 | Podophrya pyrum .. Oe 819 strenua WD Bs quadripartita~ .. .. 820 Planicola.. 5 705 Semis Aa 655 ae 815 ingenita 717 Podophrya THDIE Tae bes 847 Platycola ee 721 2 truncata a 825 - decumbens 731 ee Wrzesniowskii .. .. 817 as dilatata .. 731 | Podostoma Ss 224 Ss gracilis 732 A filigerum 225 se longicollis 732 | Polykrikos rome linbieual iste 508 5 mollis (fer! a auricwlaria U5... -toeea. 859 4 regularis.. 731 a SChwartzil ca. Uuct ayes 508, 860 53 striata 732 | Polyceca Ae iA IGG 360 sn truncata.. Te is dichotoma: . i. .steidan) Gees Platytheca 5 202.\' Polystomata 2.7 97s! (hse eine eee *5 micropora 2020) Polytoma es... —.c 301 Pieurochilidium mers 540 | Polytoma ocellata .. 304 strigilatum fo bass: 5401) Polytomatuyella, 9... i. ae? Decweeeneene Pleuromonadidz : 2AQ | POlyloma UIVeEnS. 2. “en. ‘sein ces pee PICHhOMONAS Te.) sc es. Aan = oe ee . 248, | Polytomidz " 301 + jaculans .. 249, Poteriodendron petiolatum . 278 PICOROMEM A Ls. s ide wee eecses ee 542 | Preservative Fluid for Infusoria, &c. << soos ‘5 chrysalis 543 | Proaulax . 463 Pleuronema citrellus 545 Proboscella 549 Pleuronema coronata 544 Ke vermina 549 Pleuronema crassa . 543 | Prorocentrum .. 461 + cyclidium .. 545 + lima.. 462 Pleuronema marina 46 543 a MUCANS Gee ee 461 a MAGANS Is) To ies) oe. bien ot 5ABii| tele MON OCCT ULMELOLLIALN, fen sete 462 Pleuronemide.. 542 | Prorodon .. a 491 Pleurotricha ons ea abauats 782 - armatus .. 492 a CCMinata. 25.) leh mebepeus- man 759 5 edentatus 493 5 grandis Benoa tT SEG ow . STISCUS 05 cies, | Soe en ee + FanceOlatames cyt fess Sues LOS ef margaritifer .. 493 - Pleurotricha setifera 784 “5 GRATES) aes. es) | an cee Pleotia vitrea 317 i NIVEUS, ss. Yi. aan se ae Plesconia affinis sarttee 800 teres 492 93 CHATON? oF sei, ey. pee bee 2000 Prorodontidze oe ba on es ; 491 a longiremis -» 800 | Proterospongia Sey. head) Stan 9s ae 5 radiosa bo REO | PEAS UAE? on Moe Se ee sa mb ” scutum TO TgtSOO Gl! PAL OL USL A. in ites lad ta © t08) pea Ssubrotumda ... .« .»» ». 600 | Protoceratium.. ot 859 Podocyathus a6 827 = aceros 859 MIGOCMA, nl) we onc wen FOS Protococcus chalybius 381 Podophrya 813 a turgidus 381 - astaci 819 Protomyxomyces coprinarius 472 “ Buckei .. 822 | Protoperidinium 2 ae (ates 859 + carchesii 818 i pellucidum 859 as conipes S05.) “RLOtOSpOnsia: splendidum Rhizo-Flagellata Rhizomonas a ‘3 verrucosa .. Rhodessa grimselina Rhopalura Rhyncheta a oS cyclopum Salpingceeca .. : amphora 3 amphoridium ampulla A Boltoni ny) campanula.. A Carteri 5 Clarkii Salpingeca Clarkit Salpingceca convallaria An cornuta - curvipes te cylindrica .. 5 fusiformis .. Be gracilis \ infusionum.. INDEX, PAGE 541 541 541 861 272 314 313 399 399 375 554 554 725 727 729 727 Spongasteriscus Salpingceca inquillata 1 longipes 3 marina Fr minuta cf napiformis ., 5 oblonga . petiolata Ff pyxidium a ringens rp Steinii ; teres Eee 55 tintinnabulum ., 5 tuba + urceolata Wallichi Salpingeecidee a Salpistes .. Be 6 castaneus Scaphidiodon .. i ne navicula .. Schizopus norvegicus Schizosiphon socialis Scyphidia .. a 3 Fromentellii ‘ie es inclinans Scyphidia tnclinans Scyphidia Jimacina a physarum = rugosa Scytomonas Fi! a pusilla Sztsyridion cochliostoma Solenophrya crassa Sparotricha vexillifer Spherophtyaly.7 2. FS hydrostatica % magna Spherophrya parameciorum Spherophrya pusilla “ sol 5 55 stentorea .. - stylonychiz 5 urostyle .. Sphenomonas 23) jaa + we op octocostata Pe quadrangularis Spirillum .. be Spirochona eg _ gemmipara .. F Scheuteni .. 5 tintinnabulum Spiromonas ee Pe angustata .. - distorta 5 volubilis Spirostomide .. Spirostomum Be 33 ambiguum 5 fErESies Spirostomum filum Uirens ” ULVeSCCUS « g1o PAGE Spongasteriscus quadricornis 229 tetraceras -. 229 Sponges, Nature and Affinities 143° 194 SpPOngida =. cs: ws ae. A soa S105 Spongocyclia .. . Meer cae) B22 Be charybdea age? oe oo de ZAG 5 GYCIOIGES setarco iee) et 2 3 CWIDHECA Kose cn a ani tomy eae “3 orthogona 229 scyllaca 229 Spongomonadidze 3 284 Spongomonas .. .. «. ‘s 286 = GISCUS 7 dees, og pee dae @ZOT a IMCESEMMANS Aes. ps, 6 se 2O7 + sacculus .. 288 uvella See’ Spontaneous Generation 118-142 Spumella.. .. 305 : guttula 305 Spumella neglecta .. eee 305 ~ VEEUOS doe ig WR Pe a BROS Spumella vivipara .. Sales 306 Spumella vulgaris Oirrnn ote «an a BOs Spumellidze 305 Squamulina scopula Bay Ooi 160 SSUCUILLIE JERI IRED we ns en os, we EO, 5 ‘platystoma Ce ae oe MEN Se Peter. SEMEOG ort ee Se. ies 588 Stentor albus .. aa aaa He 596 Stentor amethystinus .. .. .. .. 861 Stentor anceps Boise bat 596 Stentor auriculay “25 5. 6. 2 & 595 » Barretti : “ 593 SEUIOF CUCUILUS se ae, ee ms 596 Stentor ceeruleus 593 Stentor teformis 596 » elegans 596 » jimbriatus .. 596 By J USCUS 596 Stentor igneus as, ena ei mics con eth Oe Stentor Miillert aye 590 Stentor multiformis Ser Avie cos ye ide aos Stentor nanus Ge) Leasvepel a. ees eee) £500 Stentor niger .. . 594 » pediculatus 596 5» polymorphus 590 Stentor pygm@us Se GR Mesa Stentor Reeselii ia Oee o Mac eet dete MG OR Stentor roseus 596 Stentoridz ; 588 Stephanomonadidz 465 Stephanomonas.. «. ©.. 466 =F) locellus ne 466 Sterromonas eae cane LEPINE 420 Buell, Go oe sd) Bn A x HOUMMICINA vee.) se 420 SEChOGH ta ane mane anne CT Esher 0 7475 Stichocheta cornuta 776 95 pediculiformis 775 Stichotricha AF 775, op aculeata 777 cp cornuta 776 fe marina 778 _ remex .. VA 5 secunda 776 INDEX. PAGE Stichotricha socialis 778 Strombidinopsis * 613 3 gyrans.. 614 Strombidium be 633 5 acuminatum 634 - Butschlinie. jas 634 93 caudatum 635 5 Claparedi vo egy hamennieeey: globosum aastu ae 635 Strombidium Botymorp tae ae 582 Strombidium sulcatum . c 633 E turbo imo | Soood 3 urceolare 634 viride 635 Strongylidium sf 779 crassum 779 Stylobryon Hier ee 278 5 epistyloides 279 Stylobryon instgnis 278 Stylobryon petiolatum 278 Stylochona 662 2 coronata 663 x nebalina = Alana rps 662 Stylochrysalis::.. “ws. pszie;yselbeshl meee 3 parasita .. 405 Stylocola .. : 730 A; ampulla .. 730 M striata 730 Stylonethes : 782 ¥ tardus 782 Stylonychia v4 790 Stylonychia appendiculatus 800 as echinata 783 Stylonychia fissiseta 791 Stylonychia histrio 789 es lanceolata .. 783 Stylonychia macrostyla 791 45 mytilus 790 43 pustulata 791 Styloplotes 800 appendiculatus - 800 Sub- kingdom Protozoa . »» 31-48 Sycandra raphanus 7 «DOO, gar Sycon ciliatum eee i me ce Syncrypta 413 as volvox 413 Synura ee 411 » uvella 412 Telotrochidium ere 478, 643 5 crateriforme «o ORS Tentaculifera .. eS 40, 801 35 -Actinaria a Claes 846 es “Suctofla wis. els. ke , eee Tetramitidz, -... «. dee srl oe Tetramitus a 313 * descissus 314 ar rostratus 313 - sulcatus : 314 Metraselimis< i.) <2." aeaupes 315 we cordiformis 315 Thuricola Sf dob 6 718 - folliculata .. 718 5 operculata 719 a valvata .. 718 INDEX. PAGE sBillinay eee pie » Magna.. 514 Tintinnidium .. 2 611 be: fluviatile .. 611 5 marinum .. 611 ss semiciliatum 612 Tintinnodz ao ; 603 Semtimmopsis: “en. nse ek 617 9 beroidea .. 617 Tintinnus ad 603 Ps acuminatus 606 = amphora cad Ma emanrare 606 Tintinnus ampulla Sh ee cals 610, 627 Tintinnus annulatus ... uy 'OOG Fr, campanula .. .. 617, 609 a3 GINGEIS Hees 616, 608 - cothurnia .. 608 ss GenticulatuSeess sarc ne OOr7 Ehrenbergit ..° se "h. ‘'s., O07 Tintinnus flua vialilis 1. 611 Tintinnus helix é 608 a inquilinus: 27's. 604 = lagenula oe tee 608 8 mediterraneus .. 610 mucicola 605 a obliquus 606 quadrilineatus en O07 Tintinnus spiralis .. 610, 62 Tintinnus Steenstrupii.. .... 606 > subulatwus) (55) "0° “se 605 _ urnula et ee el OOD ° Wissaw et sies. LPs lie. (G06 Bs ventricosus 609 Torquatella a 621 typica as “ss 621 Torquatellida ce 621 Mirachelide: vf «a: se oe se | Be 22 Trachelius cH WNC act ae gtr sc 522 Trachelius anas = 525 53 apiculatum .. .. oa. KO as dendrophilus .. 378, 523 - EUG xe je8 527. 5 Llobulifer 431 5 lamella iat" Pare 529 s meleagris 526 IMreaxelmelngus @yabhen 85 9 Ga. Go oo “oe 22 Trachelius pusillus 503 Aa striatus 522 a SEUCELE) ‘are ee 529 a WENGE Sere 3 wd. Oe ope yu - trichophor a 376, 52 Trachelocerca oo 6) od See ae SLY Trachelocerca biceps .. 515 linguifera 515 Trachelocerca olor Bo no doe pel aH x phcenicopterus eenaae 5 LO TeGENCLOCELCA SALLE 516 Trachelocerca tenuicollis .. 517 versatilis 516 Trachelocerca viridis 515 Trachelocercidee 514 Trachelomonas 388 acuminata « 391 Trachelomonas areolata 60, tar, Met S519) Trachelomonas armata ou Bcc on 619,e) Trachelomonas ASpera sn 0 we @rachelomonas bulla 2 s,s %) caudata bo: Se _ cylindrica. “sc - a or eurystoma .. .. . hispidayen guess ate lagenella nO OC 7) -achelomonas NLGYICANS .. ae Trachelomonas rugulosa Bee oc voly ocina %- 2. Trachelophyllidze Sot ae ES Hrachelophyllum <<) <3 2. 55 apiculatum pusillum ..., Tremella PYUNTOTMIS .. 6 Trepomonadidze : ‘EPOMIONAS) sen on xe agilis Trichoda Pea Trichoda athiopica 5 ambigua fomtss = anas Se | fae nbacaptl tos PP angulata os asiatica Trichoda carnium .. Trichoda charon Lrichoda cimex grandinella 2udex znguclinus nasamomum .. mavicula patula 7. eeomeioe GESTS Pee Epon ee 4 pellionella so Sn Drichoda pirumy” “<5 4. 2. | ss Trichoda piscis 1 we Trichoda pura we Trichoda transfuga .. “ versatilis Sc. HO Trichodina ae 5 baltica .. ‘5 digitodiscus.. Trichodina grandinella Trichodina pediculus., 5 scorpena 5 Stemi. Trichodina tentaculata . volvox UVOvax . Trichodinopsidz Trichodinopsis aia 49 paradoxa MiCHOSASTEH fo. seo ows cae pilosus ” ” Trichomonas a aaeea ee 59 batrachorum .. Trichomonas hirsuta Trichomonas limacis Trichomonas locellus i mintinNa Trichomonas vaginalis . 248, g12 Trichonema os = hirsuta Trichonemidz Trichonympha a agilis Trichonymphidz Trichophrya 5: 3 digitata epistylidis .. ify vichophrya ei ; Trichopus Eee aim ve oy dysteria Trimastigide .. Trimastix ee “— marinus Trochilia .. el raat stay Wass AAA win aes ee Ce 35 palustris .. polonica .. oe sigmoides .. .. Tropidocyathus octocostatus a Tropidocyphus Scr? ae cee t Trypanosoma .. ” 5 BEET ee) eae Mies e sanguinis Acie Stee arn Trypanosomata Undulina ranarum INDEX. PAGE 469 | Vaginicola attenuata 469 - crystallina 468 | Vaginicola decumbens 552 | Vaginicola gigantea 552 > globosa 551 - grandis 811 5 inclinata 812 = ingenita 8II 55 tincta 813 | Vaginicola valvata 758 | Vaginicola vestita . 758 | Vaginicolina 307 | Vasicola a2 5 ciliata 312 | Vibrio : ; 756 | Vibrio cygnus .. 757 » olor WEG » proteus TiS) » verminus 757 | Volvox vegetans 439 | Vorticella.. 438 alba Pe 218 Vorticella ampulla ; 219 a anastatica .. 219 “ annularis 218 | Vorticella aperta » appuncta 219 | Vorticella berberina Urceolaria .. 649 | Vorticella brevistyla 55 mitra oy 050 » campanula .. Urceolariide .. z= . O45 - chlorostigma Urceolus Alenizini .. eo 517, 5 citrina rans S459" sa. oc OO x communis » epistylidis . e S07, 3) constricta Urocentrum j Oy 59 convallaria Pe turbo .. 476, 641 is crassicaulis Wireclena cn seg sec) ous ke Lives ae ATA is cratetay =. % VGIVOX, PG, ast OSs 414 | Vorticella cratertformis Uroleptus.. 779 | Vorticella cucullus .. 35 agilis Sing doe oe tie 781 | Vorticella cyathina 5 SCIDDUS cecas wy oo an) “es | YOO; | Vorticella dilatata. 5: 55 mobilis .. oon ise 781 = dubia 5 musculus 779 elongata a piscis 780 a5 fasciculata a9 rattulus .. 780 = fluvialis .. violaceus 781 | Vorticella folliculata Uronema . 5 546 > gemella . es marinum 546 | Vorticella globularia Uronychia aA 797 “4 gracilis .. 3 transfuga 797 hamata . Urostyla .. a 764 Vorticella hians flavicans .. 766 > tnclinans A grandis .. 765 tnfusionum .. 2 viridis ig aay eae 765 Vorticella longifilum - IWieISSI pea ease mee. Sean's 204 33 mamillata Urotricha 504 4 margaritifera 7 farcta 505 | Vorticella margaritata .. lagenula 505 | Vorticella marina .. .. Uvella BA 406 45 microscopica Uvella chamemorus 267 95 microstoma .. » asjuncta 341 . monilata ‘ mn Ua 267 | Vorticella multangula .. » wvtrescens 412 55 multiformis .. = nasula Vaginicola 714 | Vorticella nebulifera 548, 5575 Vorticella nutans - patellina a DIClAY, si. ise Vorticella polymorphus » _ polypina Vorticella procumbens .. . putrinum Vorticella pyriformis op pyrum Vorticella quadrangularis Vorticella ringens .. Vorticella spectabilis s spheerica FP striata telescopica Vorticella vaginata 55 versatilts Vorticellidze Vorticellina Wagnerella cylindroconica .. LOOtMAMNIUM rc) se eel es INDEX. Zoothamnium 9 Zoothamnium Zoothamnium Zoothamnium Zygoselmidz Zygoselmis affine alternans arbuscula aselli carcini Cienkowskii .. dichotomum .. elegans gleniscum macrostylum .. marinum niveum nutans parasita ., pictum plumosum simplex .,. Spirale , 5 inzequalis 9 nebulosa LONDON : PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFORD STREET AND CHARING CROSS,