Mr. A. H. HassalPs Catalogue of Irish Zoophytes. 363 membranaceous and cellular lungs without any gills for the first class ; either gills in the early part of life^ then cellular lungs in their adult state^ or gills or some branchial apparatus^ coexisting with cellular lungs through the whole of life, for the second y and gills only, without lungs, for the third class. Norton House, Stockton-on-Tees, kvAW 10th, 1841. [Note. — Mr. Owen nowhere assumes that the nose, as an absolute zoo-logical character, is equal in importance to the lungs ; but believing, with other Comparative Anatomists, that the air-bladder of the fish is essentially a lung, and being able to trace its assumption of the true pulmonary struc-ture within the undoubted limits of the class of Fishes, he is not disposed to allow the respiratory organ to be so important, in relation to the classifica-tion of the Lepidosiren, as the nasal organ, which manifests no essential al-teration of structure in the class of Fishes ; but exhibits, throughout that class, a marked distinction from the structure of the nose in Reptiles. Mr. Owen's arguments for the essentially ichthyic character of the Lepidosiren are based upon the cumulative evidence of its dermal, dental, osseous, di-gestive, sensitive and generative systems, rather than on any single and ar-bitrarily chosen character. — See his 'Conchiding Observations,' Linn. Trans,, vol. xviii. p. 350 ; also the Proceedings of the Microscopical Society at p, 211 of our present volume, containing Mr. Owen's examination of the structure of the teeth, which he finds to be altogether such as is peculiar to Fish. The new naming of the genus we cannot approve. — Ed.] XXXIX. —Supplement to a Catalogue of Irish Zoophytes. By Arthur Hill. Hassall, Esq. Read before the Natural History Society of Dublin, November 6th, 1 840. [Concluded from p. 287.] Valkeria imhricata. " Cells in dense clusters, irregularly scattered on the polypidom," cylindrical. Plate VIII. fig. 2. I have added to the usual definition of this species the word cy-lindrical, as the form of the cells is the most important practical point of distinction between it and the preceding species. Valkeria imbricata, in the first stage of its formation, consists of a single layer of cells spread over the surface to which it is attached (usually Facus vesiculosus), and not rising from it in the form of an inde-pendent polypidom. In this stage of its growth it constitutes the Bowerbankia dens a c f Dr. Farre. This fact I have ascertained from a comparison of Dr. Farre's figure and description of that species with it, and its concurrence witli these is so close as not to admit of a doubt upon the subject. Bowerbankia densa is, therefore, not a distinct species, but merely a condition of the well-known one, Val-keria imbricata. Although the examination of numerous specimens of F. imbricata which I have made has resulted in the eradication of B. densa as a distinct species, I yet must not omit to notice the admirable memoir published in the 'Philosophical Transactions,' u})on this and an allied species by Dr. Farre, the gentleman by whom Bowerbankia densa was first described and figured as a di-
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