. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. The onca Lineage: Subdigital Fine Structure • Peterson and Williams Til. Figure 7. The third toe of A. onca. a) Shows detail of the surface of scale 7. A small keel occurs in the lower right, b) Shows detail of the hillocks, c) Is taken on scale 7; d) is from scale 11. c) and d) Illustrate the differences in spine morphology between countoured and uncountoured regions. 6b and 6c). In the hatchling, the surface of the scales is gently contoured into ridges which occur in positions corresponding to the robust lateral an
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. The onca Lineage: Subdigital Fine Structure • Peterson and Williams Til. Figure 7. The third toe of A. onca. a) Shows detail of the surface of scale 7. A small keel occurs in the lower right, b) Shows detail of the hillocks, c) Is taken on scale 7; d) is from scale 11. c) and d) Illustrate the differences in spine morphology between countoured and uncountoured regions. 6b and 6c). In the hatchling, the surface of the scales is gently contoured into ridges which occur in positions corresponding to the robust lateral and far lateral keels of the adult. There is, however, no ridge that anticipates the median keel. Mech- anoreceptors often occur in the lee of the lateral contours, and the scale bases are also contoured into low hillocks. Setae are not present on any of the third or fourth toe scales. The distal half or two-thirds of the scale surface, includ- ing the contoured ridges, is covered with spikes and prongs (for definitions see Figs. 21, 22). Shorter spikes at the margin itself grade into taller spikes proximal to the margin ( ± /x tall; ± fx in diameter). In some areas the spikes grade into forms with a more robust prong-like tip (in Fig. 8d spikes in the upper left are shown grading into prongs in the lower right). Between the con- toured ridges as well as proximally, the scale surface is covered with spines (Fig. 9b). There is continuous variation in spine height from about /u. up to the spike morphology at 5 /x. Although its shape is quite different, scale 1 is included in this series because its contouring and fine structure are com- parable to those of scales 8-24. The sur- face of the scale is covered with spikes and prongs 5-7 jx tall. b) Scales 2-7 in the juvenile have a. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may n
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