NICKERSON. — Scales of Lepidosteus. 
10: 
Ll, 
PLATE IL 
Section through the axis of a spine papilla in which secretion has begun. 
From fish 150 mm. long. X 887. 
Optical section of spine broken off from scale of a young Lepidosteus 
300 mm. long. x 387. 
Tip of spine loosened by use of caustic potash ; a, before treating with 
hydrochloric acid; b, after applying acid. X 137. 
Section through posterior edge of ascale from a fish 300 mm. long (52 
months old), showing portions of imbedded bases of four spines. X 200, 
Base of alost (resorbed?) spine, which had been surrounded by ganoin 
before the latter was destroyed by decalcification. From fish 460 mm. 
long. x 198. 
Bection (prepared by grinding) through scale of fish 300 mm. long, from 
S P. Bartlett. x 31 
Section through posterior margin of decalcified scale from fish 300 mm. 
long. x 198. 
