. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 246 Mr. J. A. Ryder on the twice at each of the points c and c and along the line a, h^ where the middle limb of the ^ rests. The only point which now remains to be discussed is the imbrication of the scales. This is also as readily accounted for as the delimitation of the scale-forming areola3, s, s, s, and their trilinear arrangement in three directions in the convex surface of the integument by means of the mechanical hypo- thesis here outlined. If we were to make a longitu
. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 246 Mr. J. A. Ryder on the twice at each of the points c and c and along the line a, h^ where the middle limb of the ^ rests. The only point which now remains to be discussed is the imbrication of the scales. This is also as readily accounted for as the delimitation of the scale-forming areola3, s, s, s, and their trilinear arrangement in three directions in the convex surface of the integument by means of the mechanical hypo- thesis here outlined. If we were to make a longitudinal transverse section through a fish along the ])lane of the letters c, c, c, or c', c', c' of fig. 1, we should get a section like fig. 2, Fig. 2. Ym. 3. B 3- 3 3 4 S 6 7 P. ?'} in which the myotomes M, M, M, &c. (fig. 2) were again found to be V-shaped on either side of the medial axis or vertebral column, c, c (fig. 2). This proves that the myotomes are really cones fitting into one another, and that, if we suppose the first one to be inserted into the base of the skull along the line A^ B (fig. 2), that point becomes the anterior fulcrum or point d^appui oi the whole muscular system. The tensions thus developed upon tlie skin along the successive myocommata 1, 2, 3, &c. (fig. 2) are such that the integument would be flexed inward opposite each myocomma as shown in the next figure on a larger scale, which represents the foldings of the integument at the surface of a part of fig. 2. Here in fig. 3 the myocommata m, i', m^ i\ ???, &c. are seen to be inserted upon tlie internal face of the epidermis. The membrane »2, ?«, w, »?, acted upon by the muscular fibres of the myotomes M, JVIjM, wHl have the effect of pulling the / integument inward / in the direction of /-i' the arrows «', ^', from the linear ' V ^ v \ i^ '' points of attach- ment of the myocommata to the integuments at ^', «', t', toward the vertebral bodies V, V, V. In this manner will be deve- lo
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