Bifurcation types of Cellularine Bryozoa

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Type 1 Bifurcation The zooecia occur in pairs, and not alternately on the two sides of the branch. A and B are thus at the same level, and the split separating the two branches reaches their distal ends. E,C and F,D thus form symmetrical pairs, E and F remaining in contact with one another at their proximal ends, on the basal side of A and B. -- Didymozoum (The arrangement is slightly modified in an internode which has become triserial distally by the development of an ovicell).
Type 2 Bifurcation Bifurcation occurs before a doubling of the number of zooecia takes place, the proximal end of each branch thus being uniserial. C remains in contact with the inner lobe of the proximal fork of D; and the doubling of the number of zooecia takes place at the distal ends of C and D, or of one of their successors if more than a single uniserial zooecium occurs at the proximal end of the branch. Caulibugula sp.
Type 3 Bifurcation The split extends nearly to the proximal end of the axillary zooecium, E, which is accordingly free, on its inner side, for the greater part of its length. E gives off a connecting process (c.p.) to meet the proximal end of F. In the species figured, each of the pairs E,C and F,D has a single fork, at the proximal end, divided by the common septal wall in such a way that each of the four zooecia has only a half fork, instead of a complete fork as in the other zooecia. -- Halophila johnstonae (Gray, 1843) and species of the genus Bugula. (Harmer considered Halophila to be a synonym of Bugula )
Type 4 Bifurcation The split does not extend proximally so far as in type 3, not more than half the axillary zooecium (E) being free on its inner side. The connecting process (c.p.) is given off by F, and joins the inner lobe of the fork of G, which crosses the basal side of E. -- Species of Bugula, eg B. scaphoides Kirkpatrick, 1890, and Bicellariella, and most of the species of Caulibugula, eg C. zanzibariensis (Waters, 1913).
Type 5 Bifurcation The axillary zooecium is almost completely immersed in the parent-internode, the split only reaching its distal end. The connecting process (c.p.) is given off by G and joins the inner lobe of the fork of H. -- Species of Bugula, eg B. dentata (Lamouroux, 1816), and of Caulibugula, eg C. caraibica (Levinsen, 1909).
Type 6 Bifurcation Although F is in contact with B, it appears to be derived from E, which it meets near the middle of the latter. The connection between the proximal ends of the inner zooecia of the branches is formed by the independent junction of F and G with E. The proximal ends of the zooecia are not bifurcate. Oblique joints, indicated by dotted lines and of a type common in Bugula, traverse the zooecia. Euoplozoum cirratum Busk, 1884, p.17.
Type 7 Bifurcation Resembles type 6 in the relation of G and F to E, but is peculiar in other respects. The axillary zooecium (E), which gives rise to F and G, passes into the proximal end of the branch on the side opposite to A, a relation which has not been found in any other type. B takes no part in the doubling of the number of zooecia, the proximal ends of which are not bifurcate - Kinetoskias cyathus and all the other species (4) examined.
Type 8 Bifurcation The proximal segments of F and G are in contact on the basal side of E, and are shorter than the corresponding parts of C and D; the joints traversing F and G near their proximal ends, and passing much more distally through C and D. In the species figured (Scrupocellaria ferox, Busk, 1852) the joint traverses the middle of the opesia, which is represented by dotted lines, of each of the outer zooecia C and D. In certain other species of the genus each joint passes across the proximal end of the opesia of the outer zooecium; and in others, particularly those with elongated zooecia, it passes entirely on the proximal side of the opesia of C and D. - Scrupocellaria, all species. Himantozoum may be considered to belong to this type, with which it agrees except that it is unjointed.
Type 9 Bifurcation The proximal segments of F and G are not in contact, and are shorter than the corresponding parts of C and D; the joints traversing CG and DF respectively. A rootlet-chamber occurs on the proximal segment of C or D, or of both, and the rootlet is thus given off on the proximal side of of the joint - Tricellaria spp.
Type 10 Bifurcation The proximal segments of F and G are separated by the whole width of E, and the two branches come off at different levels, that on the side of A being more proximally situated. Internodes commonly composed of three zooecia, C and D then taking on the character of A and B zooecia in the next internode. - Tricellaria spp. (figured specimen, T. dentalis var. dilatata Ortmann, 1889, p.21)
Type 11 Bifurcation Except in the fact that the proximal segments of F and G are in contact, this agrees with type 9. - Tricellaria peachii (Busk)
Type 12 Bifurcation Readily derivable from type 10 by the suppression of the proximal segments of F and G, the internode thus consisting of a single zooecium at its proximal end, connecting with its predecessor by a single chitinous joint. - Tricellaria aculeata d'Orbigny.
Type 13 Bifurcation A modification agreeing with type 12, occurring in Emma cyathus. The zoecia C and D take on the character of A and B zooecia at their distal ends.
Type 14 Bifurcation Internodes composed of three zooecia and, like the zooecia, very short. A slight modification of type 9. - Emma spp.
Type 15 Bifurcation Proximal segments of F and G in contact, much longer than the corresponding parts of J and K. The joints are on the distal sides of C and D, and traverse the zooecia FJ and GK. The joints are situated at some distance from the axil, instead of being on the same level with it, and do not traverse the opesia of any zooecium. Rootlets given off on the distal sides of the joints. - Notoplites. A modification represented, in the same genus, in the "Siboga" collection, results from the suppression of one of the joints of the bifurcation.
Type 16 Bifurcation The axillary zooecium is free on both sides distally. The zooecia F and G are not in contact with one another, but each is connected with one side of E at a point marked by the presence of a conspicuous rosette-plate (r.p.) - Cornucopina, all species examined. The zooecia are very long, and a constriction partially separates a small proximal section from the main part of the zooecium.
Type 17 Bifurcation Proximal segments of F and G in contact (rarely separated), longer than the corresponding parts of J and K. The joints are on the distal sides of C and D, lying hardly in advance of the axil, and they traverse the zooecia FJ and GK, passing through the opesia of F and G, the two inner zooecia. Rootlets given off on the distal sides of the joints. - Menipea.
Type 18 Bifurcation The internode becomes triserial by the development of a median row of two or more zooecia. The distal member of the median row (E2 in the figured specimen) behaves as an axillary zooecium. Bifurcation in other respects as in type 17. - Menipea (triserial species).
Type 19 Bifurcation Part of a sympodial colony of Menipea spicata, only one of the branches being joined at each bifurcation.
Type 20 Bifurcation Agreeing with type 8 except for the intercalation of a median series of zooecia in the internode. Amastigia kirkpatricki (Lev., MSS). n.sp.