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Show 250 MESSRS. SCLATER AND SALVIN [Apr- 22, lessened by the discovery of this fibre on the whole alimentary canal of the Tench* (Tinea vulgaris), after I had observed that this is not tbe case in some other cyprinoid fishes. Such facts tend to weaken the value in systematic zoology of the character afforded by the muscular sheath of the oesophagus. But whatever structure proves constant cannot be devoid of importance, however difficult the explanation may be; and, so far as m y limited observations have gone, it is always easy to distinguish between certain orders of Mammalia, and these from birds and reptiles, simply by the muscular fibre of the oesophagus. For example, in the Quadrumana the striped muscular fibre stops short of the cardia, while in the Rodentia this fibre extends quite to that part of the stomach, as has been more particularly described of these and other vertebrates in the ' Proceedings' of this Society (1842, p. 63 et seq.). Hence it seems desirable to add this character, for as much as it may be worth, to the descriptions already known respecting such Mammalia as may have a questionable position in systematic zoology. The Aye-Aye is one of these; for it has been alternately placed among the Rodentia and Quadrumana. And by the courtesy of Mr. Flower I have examined for striated muscle about an inch of the cardiac end of the oesophagus of this animal, preserved in spirit of wine. The results were entirely negative. Not a single striped muscular fibre appeared, although the whole thickness of the oesophagus was examined, from the outer part of the preparation to the plaster with which it had been artificially distended ; in short, nothing of muscular tissue but the smooth variety could be found. And thus, so far as regards this point, the oesophagus of the Aye-Aye is as unlike that of Rodentia as it is like that of Quadrumana-a fact which tends to support the latest and now general conclusion as to the affinities of this singular animal. 2. On Venezuelan Birds collected by Air. A. Goering. By P. L. SCLATER, M.A., Ph.D., F.R.S., and OSBERT SALVIN, M.A., F.L.S.-Part IlLf (Plate XVIII.) Mr. Anton Goering's present collection was principally formed the vicinity of the Lake of Valencia, into which district he has made * Since this fact first came to m y knowledge, through the last edition of Professor Beale's excellent work on the Microscope, in which Weber is quoted as the observer, I have examined the intestines of the Tench, and found the striated muscidar fibre on the greater part of its alimentary canal. The primitive muscular fascicles of the oesophagus, stomach, and intestines presented an average diameter of TJrg. of an inch, while those of the dorsal and ventral muscles measured as much as lri-g-. Thus the striated fibres of the hollow muscles are only about one-fourth the thickness of those of the ordinary voluntary muscles ; and this agrees with my old measurements in fishes and other vertebrates, tabulated in the ' Proc. Zool. Soc' (1842, p. (58). t See Part I., P. Z. S. 1868, p. 165; Part II, P. Z. S. 1868, p. 626. |
