Sub-Kingdom V. MOLLUSCOIDEA. 
UnpDeER the term JMolluscoidea, Milne-Edwards included the Bryozoa and 
Tunicata, of which the first had been previously regarded as Zoophytes, and 
the second as Mollusks. Huxley afterwards assigned the Brachiopoda to the 
same phylum. These three classes form a group intermediate in position 
between the Worms and Mollusks, and are considered by many zoologists as 
directly related to the one or the other. The Tunicata have more recently 
been regarded as an independent animal type, and as the probable progenitors 
of the Vertebrates. To the palaeontologist, however, they are devoid of 
practical interest, owing to their total lack of hard parts. 
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 
appendages. 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 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 I. BRYOZOA. Ehrenberg.! 
Small, almost always composite animals forming by gemmation variously shaped 
colonies, each zovid of which is enclosed in a membranaceous or calcareous double- 
1 Literature : 
d@’ Orbigny, A., Paléontologie Francaise ; Terrain cretacé, vol. V., 1850-51. 
Hagenow, F., Die Bryozoen der Maestricher Kreidebildung. Cassel, 1851. 
Haime, J., Description des Bryozoaires fossiles de la Formation jurassique (Mem. Soc. Geol., France, 
2nd ser. vol. V.), 1854. 
Busk, G., Catalogue of Marine Polyzoa in the Collection of the British Museum (Parts I. and IL., 
Cheilostomata), 1852-54. (Part III., Cyclostomata), 1875. 
Busk, G., Monograph of the fossil Polyzoa of the Crag (Palaeont. Soe.), 1859. 
Crabb, 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 Aachner Kreidebildung. Haarlem, 1865. 
Reuss, A. E., Several important papers in Denkschr. d. Wiener Akad., vols. XXIII, XXXIV. 
1863-74 ; and Palaeontographica, vol. XX., 1872-74. 
Manzoni, A., Several important contributions on Tertiary Bryozoans in Denkschr. d. Wiener Akad., 
vols. XXIX., XXXI., XXXVII., XXXVIII., 1869-78. 
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