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Show 1869.] MR. G. GULLIVER ON THE OESOPHAGUS OF THE AYE-AYE. 249 These points may be determined by future observations. It will be noticed that the extremities of the fins and tail of the Premnas are attenuated to what appears to be the utmost degree consistent with cohesion of their molecules. April 22, 1869. The Viscount Walden, President, in the Chair. Mr. G. Dawson Rowley, F.Z.S., exhibited some specimens of British- killed Pipits, and made the following observations upon them :- I have the pleasure to exhibit a series of Water-Pipits (Anthus aquaticus) and Rock-Pipits (Anthus obscurus), all shot or taken near Brighton, in spring and autumn plumage, male and female respectively, showing the distinction between the two species in the several states. Only two or three of the former have ever been, I think, noticed in print as found in the British isles, and considerable confusion has existed in collections respecting them. I have at times observed each one doing duty for the other. A. aquaticus is not very common; but it visits the south coast regularly in the spring, moves on to breed, and again stops with ns a few weeks on its return in autumn. In spring it has a blue tinge on the back, with a vinous one on the chest, underparts greenish ; in the autumn dress these are lost, and the underparts turn pure white. The outer tail-feather also changes from buff to white. Males differ little from females. A communication was read from Mr. Thomas Graham Ponton, F.Z.S., containing a criticism of the arrangement of the shells of the genus Mangelia adopted by Reeve in his 'Monograph/ in which it was pointed out that the seventy species of this group given in the ' Conchologia Iconica' ought to be distributed amongst the genera Defrancia, Cythara, and Mangelia. Mr. Ponton gave a list of the species which he considered referable to each of these three genera, and proposed to assign one to Defrancia, fifty-three to Cythara, and sixteen to Mangelia. The following papers were read :- 1. On the Muscular Sheath of the Cardiac End of the CEso-phagus of the Aye-Aye {Chiromys madagascariensis). By GEORGE GULLIVER, F.R.S. Among the many inexplicable structural arrangements of organs is that of the comparative distribution of the striped muscular fibre to the same part in different orders; and the obscurity is not |