Miscellaneous. 61 2. " Notes on the Polyzoa of tho AVeiilock Shales, Wenlock Lime-stone, and Shales over the Wenlock Limestone. From material supplied by CI. Maw, Esq., F.L.S., F.G.S." By G. R. Vine, Esq. Communicated by Dr. H. C. Sorby, F.R.S., Y.P.G.S. The author has received from Mr. Maw about 1| hundredwei2:ht of materials washed out of the Wenlock deposits of Shropshire, representing the contents of from (3 to 8 tons of unwashed material. From this material he extracted the specimens of Plants, Actinozoa, Echinodermata, Crustacea, and Polyzoa ; and he gave a tabular synopsis of the species and their distribution, with the addition of types from the Wenlock Limestone and of the species of Brachiopoda referred to in a paper by Messrs. Maw and Davidson in the 'Geological Magazine 'for 1^81. With regard to the Polyzoa, the author remarked that below the Cretaceous series the two great divisions of Chilostomata and Cyclo-stomata do not hold good, and suggested that the classiiicatiou of Palaeozoic Polyzoa should be based on the arrangement and character of the cells, in combination with habit. The forms characterized in the present paper were Stomatopora dissimilis^ Vine, and vars. elongata and compressa, Ascodictyon stellahim, Nich. & Eth., A. radi-ciforme^ sp. n., A. filiforme, sp. n. ?, Spiropora regularis, sp. n., 8. intermedia, Vine, Diastopora consimilis, Lonsd., Ceriopora, Goldf., Hornera crassa, Lonsd., H.? delicatula, sp.n., Folypora't prohlematica, sp. n., Fenestella prisca, Lonsd., G/auconome disticha, Goldf., Ptilo-dicfi/a lance^olata^ Lonsd., P. Lonsd(dei, sp. n., (=: P. lanceoJata auctt.), P. scalpcllum, Lonsd., P. interporosa, Vine, and P. minuta. Vine. MISCELLANEOUS. On the Postemhryonic Development of the Diptera. By M. H. VlALLANES. Among insects, it is in the Muscidae that we observe the greatest differences between tho lai-va and the perfect animal; and it is also in them that the metamorphoses that take place during the pu])al period are the most profound, which explains why exact investi-gations upon the metamorphoses of insects have been directed principally to these insects or to nearly allied animals. Having repeated the work of my predecessors *, I have been able to discover some new facts, of which I now have the honour to place a summary report before the Academy. When the larva becomes motionless and transformed into a pupa, not only does the skin of the segments answering to the head and * My investigations were made in "SX. Mihie-Edwards's laboratoiv ; thev relate to Mvsca vomitoria.