NICKERSON. — Scales of Lepidosteus. 
= LO: 
ite 
12. 
13. 
14, 
15. 
16. 
PLATE II. 
Section through the axis of a spine papilla in which secretion has begun. 
From fish 150 mm. long. > 3887. 
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. 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. 
Section (prepared by grinding) through scale of fish 300 mm. long, from 
S P. Bartlett. Xx 31 
Section through posterior margin of decalcified scale from fish 300 mm. 
long pe LoS: 
