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Show 1894.] AN ABNORMAL VERTEBRAL COLUMN OF M E BELL-FROG. 477 5. Notes on a particularly Abnormal Vertebral Column of the Bull-frog; and on certain other Variations in the Anuran Column. By W. BLAXLAND B E N H A M , D . SC (Lond.), Hon. M.A. (Oxon.), Aldricliian Demonstrator in Comp. Anat. in the University of Oxford. [Received April 4, 1894.] (Plate XXXIII.) Among the skeletons of Ranch mugiens which are kept in spirit and used for class purposes at Oxford I came across one specimen which exhibited certain striking abnormalities. Like the rest of the vertebral columns this had not been entirely macerated, so that the vertebra? were still connected by connective tissue; and as the outlines of the vertebra? were not well defined, the specimen looked at a first glance merely slightly curved-the curvature being more marked on the ventral than on the dorsal surface. I have had drawings made of this column, natural size, viewed from below and from above. (See Plate XXXIII.) There are the normal number of transverse processes on each side, viz. eight, but it will be noticed how curiously these eight are distributed. There are only six separate vertebral pieces (A, B, C, D, E, F ) , three of them being " compound vertebrae " and showing more or less distinct signs of their fusion. The first " piece " consists of the normal " atlas" fused with the second vertebra, which possesses the usual pair of transverse processes. The second piece (B) consists of 2 | vertebras ; on the right side it carries two transverse processes, on the left three. The next two vertebral pieces appear to be perfectly normal vertebrae, each with a pair of transverse processes, and, as far as can be judged, they are symmetrical. The fifth vertebral piece (E) consists of 1| vertebrae, and bears two trausverse processes on the right side, and only one on the left-thus it is the complement of the second piece. The last, or ninth, vertebra is normal and articulates with a normal urostyle. The separate vertebral pieces, which present abnormalities, are drawn the natural size ; but their side views are represented twice the natural size. The first piece (A), figs. 3-6, consisting of "atlas" and second vertebra, is asymmetrical; the fusion is greater on the right than on the left side, for on the latter there is a large intervertebral foramen, just in front of the transverse process, whilst on the right side there is an extremely small perforation through which' even a very fine needle will not pass, and it is scarcely likely that the " hypoglossal" nerve could issue here. O n this side, however, the neural arch of the " atlas " is less extensive than on the left; and it is possible that the first spinal nerve, instead of issuing between the vertebrae, passed in front of the arch, for there is |