NicksRson, — Scales of Lepidosteus, 
Fig. 23. 
no 
ES 
PLATE IV. 
Portion of section of scale and overlying tissue from a fish 460 mm. 
long. X 862. See description of Figure 22, Plate IIT. 
Base of spine beginning to be imbedded in the outer layers of the scale. 
From fish 190 mm. long. X 370. 
An oblique section through the base of a spine partly imbedded in the 
scale. From a fish 300 mm. long. x 887. 
Section through a spine having an abnormally shaped tip. X 105. 
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. 
Longitudinal section through a scale of a fish 190 mm. long. X 44. 
Longitudinal section through a scale of a fish 287 mm. long. X 25. 
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. 
Outlines of several scales of a fish 300 mm. long. The dots indicate the 
positions of the spines on four scales. X 6%. 
