132 Mr. Hassall's List of Invertebrata principle ; the dead part therefore became the proper pabu-lum of the invisible seeds of the mucor transmitted by the air in respiration ; and thus Nature carries on all her works im-mutably under every possible variation of circumstance. It would indeed be impossible for such to vegetate on a living body, being incompatible with vitality, and we may be assured that decay must take place before this minute vegetable can make a lodgement to aid in the great change of decompo-sition. Even with inanimate bodies, the appearance of mould or any species of Fungi is a sure presage of partial decay and decomposition.^^ In your last number, the first of volume nine. Dr. C. Mon-tague, in his Sketch of the Class Fungi, says, page 10, "The Hyphomycetes grow on vegetable or animal substances in the course of decomposition.^^ I refer to this only to show that Col. Montagu was well acquainted with the conditions neces-sary to this singular formation. I am, yours very truly, Wm. Yarrell. Ryder Street, St. James's, March 18, 1842. XVIII. — A List of Invertebrata found in Dublin Bay and its vicinity. By Arthur Hill Hassall, Esq., M.R.C.S.L., Corresponding Member of the Dublin Natural History Society. The few invertebrate animals contained in the following list were found by me during the winter of 1 840 and spring of 1841. The Porifera and Conchifera, with but two exceptions, are purposely excluded from it ; examples of the first which I have met with having been sent to Dr. G. Johnston, and most if not all the species of the latter collected by me have doubtless been previously found, though not yet recorded, by that zealous collector T. W. Warren, Esq. For the Echino-dermata the nomenclature of Forbes is adopted, and for the Crustacea that of Leach. ECHINODERMATA. Comatula rosacea, very abundant in the channel between Dalkey Island and the mainland. The marking and colouring of young specimens obtained off Kingstown Harbour are very beautiful and delicate, very different from the coarse red colour which distin-guishes them in their mature condition. I have collected speci-mens, the diameter of which when expanded did not exceed half an inch, and in them no trace of footstalks was to be detected.
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