renberg was doubtless right in considering this animal viviparous; but it remains to be determined whether the young are produced by gemmation or ovulation. In Spirillina foliacea I have found the highly refractive bodies I have above described as "primitive ova.” Explanation of Plate IX. Fig. 6. Specimen of Truncatulina, decalcified; a, membranous basis of shell; b, sarcode; c, ovum, with germinal vesicle and spot; d, segment or zooid destitute of ovum. 2. On the Reproduction of Ophryodendron. Ophryodendron abietinum, which I have figured in various attitudes in Pl. X., has been noticed elsewhere by Claparède and Lachmann* and myself† several years since; but it was not until the spring of the present year that I was able to discover its mode of reproduction. The animal presents the appearance of an oblong sac filled with homogeneous and finely molecular matter, and is found attached to the corallum of Sertularia pumila. From one end of the body or sac arises a proboscis, generally appearing as a short and closely-wrinkled club, but capable of being produced to a remarkable distance as a glassy ribbon surmounted by numerous twining tentacles. The sac usually shows no trace of a nucleus or contractile vesicle, nor are its contents differentiated into an external and internal tissue (ectosarc and endosarc), as in Actinophrys and others of the class ("Acinétiens") into which it has been introduced. The structure of the proboscis differs from that of the sac in the development within it, of a clear and highly refractive tissue, corresponding to the muscular element in the branches of Zoothamnium, and in the more directly contractile pedicle of Zooteirea. In the proboscis of Ophryodendron, as in the body of Epistylis, the contraction of the muscle throws its outer covering into close folds. The tentacles are formed of a continuation of the contractile tissue of the proboscis, and are covered to within a short distance of their tips by the integument. The proboscis, when extended, hangs * Etudes sur les Infusoires et les Rhizopodes, par Edouard Claparède et Johannes Lachmann. † Edin. Phil. Journal, July 1859. suspended or floating in an erect position, or slowly swims about in large curves by the continuous and very active motion of its tentacles. This animal may be called the homomorph, amongst the Protozoa, of Sipunculus Bernhardi. I have never been able to satisfy myself as to its mode of feeding, though portions of matter are occasionally seen entangled amongst the tentacles, and apparently pressed in contact with the substance of the proboscis. In the sketch of this animal appended to my notice of 1859, I figured several globular bodies within the sac, which my friend, M. Claparède, to whom I showed it, had not observed; and on further observation, I was led to consider the figure erroneous. In March last, however, the Ophryodendra (Pl. XI. fig. 1) again contained these bodies, and by a somewhat "meddlesome midwifery," I was enabled to force them from the sacs, and to find that they were living young, from four to nine in number. The young thus obtained consist of ovoid bodies of higher refractive structure than the body of the parent, and contain olive-brown corpuscles, shaped like the chlorophyll-granules of Hydra viridis. At a later stage, when the wrinkled trunk of the parent hung lax and dead, the young larvæ assumed a pyriform shape, flattened on their inferior surface (Pl. XI. fig. 2). This surface was also marked with longitudinal striæ, carrying short, soft, slowly-moving cilia or processes. Their natural mode of extrusion was not observed; but several families of them were found, each enveloped in a soft gelatinous ball, and attached to the Sertularia and other bodies. Single individuals were seen slowly moving on the zoophyte, and others attached were putting forth the rudiments of the proboscis. The proboscis was at first finely molecular, like the contents of the sac, unwrinkled and noncontractile. A few tentacles were presently put forth from its summit (fig. 3), and it gradually assumed the structure of that of the adult. The body of Ophryodendron frequently bears fusiform bodies, from one to four in number, which I have already described, and which appear to be gemmæ. 2 N VOL. II. Explanation of Plates X. and XI., figs. 1–3. Pl. X. Two cells of Sertularia pumila, on which Ophryodendra are attached,— the figure on the left side of the centre with gemma and contracted proboscis, that on the right side of the centre with proboscis extended; the trunks of two others are shown in various stages of extension. Pl. XI. figs. 1-3. Young of Ophryodendron in various stages of development. 3. On Dendrophrya radiata and D. erecta (nov. gen. et sp.). The Rhizopodous animals to which I have given the name of Dendrophrya are found plentifully on Sertularias, Flustras, Fuci, and stones, in low water pools at Granton Quarry, near Edinburgh. There are two species, D. radiata and D. erecta. D. radiata. Its general appearance is that of a small shelly mass, from the borders of which radiates a system of branched membranous tubes, more or less coated with mud or other matters. In young specimens the central shell is absent, and the animal presents the appearance of an irregular system of branches radiating from a centre. The shape of the adults is very various, and depends on the surface to which they are attached; they attain sometimes a diameter of nearly a quarter of an inch, though generally much smaller. The shell is not acted on by acids, and is therefore siliceous. The animal itself can seldom be detected, as it lies concealed within its central flinty stronghold and the complicated system of earthworks surrounding it. D. erecta. In this species, found on stones, the branched, membranous, and mud-clothed tubes, instead of creeping over the surface to which the animal is attached, spring upwards and outwards, as in Pl. XI. fig. 4. Delicate pseudopodia, linear or forked (figs 4. and 5), are readily observed to protrude themselves from the extremities of the branches, accompanied sometimes by lobular processes of the sarcode of the animal. The patelloid shell of D. erecta may be easily detached from its seat, and its tenant, a small patch of semitransparent sarcode, scooped out with a flat-pointed needle and transferred to the stage of the microscope. It differs from the sarcode of other Rhizopods in being filled with delicate short fibres instead of the usual molecular matter, and contains, both within the shell and tubes, the highly refractive bodies I have mentioned in a former paper as ova. Explanation of Plate XI. Fig 4. Dendrophrya erecta seated on a portion of stone, and showing pseudopodia projecting from summits of branches. Fig. 5. Summit of one of the tubes of D. erecta, with projecting lobes of sarcode and pseudopodia. 4. On Lecythia elegans (nov. gen. et sp.) This animal, of which I give drawings in Pl. XII. fig. 10, is found on Sertularia pumila. It is exceedingly minute, and requires high microscopic power and careful adjustment of light for its accurate definition. The body is flask or carafe-shaped, mounted on a long, fine, rigid pedicle, and enclosed in a closely fitting envelope. The summit of the body is dilated, and furnished with a variable number of long, slender, divergent processes or tentacles, which appear to correspond with those of Actinophrys. When the tentacles are contracted, they become capitate, and assume the form of a bossed crown, as shown in the figure. Appendix to Cionistes reticularis (Kionistes retiformis), printed at p. 91. This zoophyte resembles the Sertulariadæ in the simple columnar form of its non-tentacled reproductive polyps, and forms the connecting link between these organs in the Tubulariada and Sertulariadæ. It exhibits the most degraded form of the reproductive polyp, previously to the latter being altogether dispensed with and the generative sacs being developed directly from the polypary. Thus we have, in the chain of degradation,— Generative sacs or medusoids attached to ordinary ali- } mentary polyp, as in Generative sacs attached to reproductive alimentary polyp, which differs from ordinary alimentary polyp in having fewer tentacles Clava, Coryne, &c. Podoc ryna Generative sacs attached to reproductive polyp with rudi-Hydractinia mentary mouth and tentacles, as in echinata. Generative sacs attached to reproductive polyp without) Eudendrium mouth or tentacles; summit of polyp surmounted by a confertum cluster of large thread-cells, as in (Alder). Generative sacs or medusoids attached to reproductive) Cionistes, polyp without mouth, tentacles, or cluster of thread-Sertularia, cells, as in Campanularia. Reproductive polyp divided longitudinally into several Eudendrium portions, each surmounted by its cluster of large thread- arbusculum cells; sperm-sacs formed, as in Hydra, by simple dila- (T. S. W.), tation of the ectoderm; each division of polyp trans- E. capillare? formed into a "moniliform" sperm-sac, as in (Alder). Atractylis (T. S. W.), Hydractinia (Alder and T. S. W.), Cordylophora (Allman). Generative sacs or medusoids attached to the polypary, as in It will thus be seen that there is a very gradual transition from the alimentary polyp to the reproductive polyp, and from the latter to the simple generative sac. Professor Allman's term "blastostyle," applied to the reproductive polyp, is apt to mislead, as it indicates that the alimentary and reproductive polyps are not homologous parts. Still more decidedly does that accomplished naturalist confuse the homology of these parts by applying the same term to the branched pedicle of the aggregated generative sacs of Tubularia indivisa, which is merely formed of the conjoined and elongated pedicles of the individual sacs. It is impossible to construct any classification of the Hydroid Zoophytes on the form or position of their generative sacs or medusoids, as these vary not only in different species of the same genus, but also in males and females of the same species. Thus, in Eudendrium rameum the sperm-sacs are moniliform, the egg-sacs single; the former are attached to the alimentary polyp, the latter to the polyp and also to the polypary. In Hydractinia, although the generative sacs generally spring from the reproductive polyps, they are also found attached to the polypary; and in a most interesting species of this genus lately discovered by Mr Alder, medusoids spring from the latter part of the zoophyte. In Atractylis ramosa, T. S. W. (Eudendrium ramosum, Van. Ben.), the medusoids, the males and females of which differ in shape, spring from the polyps, from club-shaped bodies, and from |