Phylum V. MOLLUSCOIDEA. 



Under the term Molluscoidea, Milne Edwards included the Bryozoa and 

 Tunicata, of which the first had been previously regarded as Zoophytes, and 

 the second as Molluscs. Huxley afterwards assigned the Brachiopoda to the 

 same phylum. The Tunicata have more recently been regarded as an in- 

 dependent animal type, and as possible progenitors of the Vertebrate phylum. 

 Their remains, however, are unknown in the fossil state. Bryozoans, also 

 called Polyzoa, are by some authors regarded as constituting a distinct phylum 

 of invertebrates, but are here retained in association with Brachiopods. 



The typical Molluscoidea either secrete a calcareous shell, or are invested 

 with a membranaceous or corneous covering. The respiratory organs lie 

 anterior to the mouth, and are in the form of tentacles or fleshy spiral 

 ai^pendages. The mouth conducts into a closed alimentary canal. The 

 nervous system is highly organised, and proceeds from a central ganglion, 

 situated in most cases between the mouth and the anus. Reproduction is 

 either sexual or, in Bryozoa, also takes place by budding. The ontogeny of 

 the Molluscoidea is most nearly comparable with that of the Annelids. 



All of the Molluscoidea are water inhabitants ; the Bryozoans are largely, 

 and the Brachiopods exclusively, marine forms. 



Class 1. BRYOZOA Ehrenberg.i 



Small, almost always composite animals forming by gemmation variously shaped 

 colonies, each zooid of tvhich is enclosed in a membranaceous or calcareous doiible- 



^ Literature: d' Orhigny, A., 'PsX^outologie. francaise; Terrain cn'tace, vol. v., 1850-51. — Hagenoio, 

 F., Die Bryozoen der Maestriclier Kreidebildung. Cassel, 1851. — Haime, J., Description des 

 bryozoaires fossiles de la formation jurassique. Mi'in. Soe. Geol. de France, 2nd ser. vol. v., 1854. 

 —Busk, O., Catalogue of Marine Polyzoa in the Collection of the British Museum (Parts i. and ii., 

 Cheilostomata), 1852-54. (Part iii., Cyclostomata), 1875. — Busk, G., Monograph of the fossil 

 Polyzoa of the Crag. Palaeont. Soc, 1859. — Oabb, W. M., and Horn, G. H., Monograph of the 

 fossil Polyzoa of the Secondary and Tertiary Formations of North America. Journ. Acad. Nat. Sci. 

 Philad., 2nd ser., vol. v., 1862. — Beissel, I., Ueber die Bryozoen der Aachener Kreidebildung. 

 Haarlem, 1865. — Reuss, A. E., Several important papers in Denkschr. Akad. Wis.s. Wien, vols, 

 xxiii., xxxiv. , 1863-74 ; and Palaeontographica, vol. xx., 1872-74. — Manzoni, A., Several im- 

 portant contributions on Tertiary Bryozoans in Denkschr. Akad. Wiss. Wien, 1869-78, vols, 

 xxix.-xxxviii. — Waters, W. A., Numerous papers on Tertiary and Recent Bryozoa in Ann. and 

 Mag. Nat. Hist, and Quar. Journ. Geol. Soc, 1879-92. — Iflncks, T., History of the British Marine 

 Polyzoa, 2 vols., 1880. — -Vine, G. R., Reports on fossil Polyzoa. British Assoc. Reports, 1881-85. 

 — (jlrich, E. 0., American Palaeozoic Bryozoa. Journ. Cincinnati Soc. Nat. Hist., v.-vii., 1882-84. 

 — Busk, G., Report on Polyzoa. Scient. Results Challenger Exped., Zoology, vols. x. and xvii., 

 1884-86. — Hall, J., Lower Helderberg, Corniferous, and Hamilton Bryozoa (Palaeont. N.Y., vol. 

 vi.), 1886. — Ulrich, E. 0., Palaeozoic Bryozoa. Geol. Survey Illinois, vol. viii., 1890. — Ulrich, 

 E. 0., Lower Silurian Bryozoa. Geol. Survey Minnesota, Final Report, vol. iii., 1892. — Canu, F., 



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