Nickerson. — Scales of Lepidosteus, 
PLATE IV. 
Fig. 23. Portion of section of scale and overlying tissue from a fish 460 mm. 
long. X 362. See description of Figure 22, Plate III. 
« 24. Base of spine beginning to be imbedded in the outer layers of the scale. 
From fish 190 mm. long. 370. 
« 25. <An oblique section through the base of a spine partly imbedded in the 
scale. From a fish 300 mm. long. X 387. 
“ 26. Section through a spine having an abnormally shaped tip. > 105. 
“ 27. Surface view of posterior extremity of a scale freed from soft tissues by 
treatment with caustic potash, showing loosened cap on point of 
spine. X 75. 
«“ 28. Longitudinal section through a scale of a fish 190 mm. long. X 44. 
« 29. Longitudinal section through a scale of a fish 287 mm. long. X 25. 
« 30. A representation of a portion of the surface of a scale of a fish 257 mm. 
long. The dotted lines show the positions of Haversian (or Volk- 
mann’s) canals beneath the surface.  X 31. 
“31. Outlines of several scales of a fish 300 mm. long. The dots indicate the 
positions of the spines on four scales. X 6}. 
