136 



BULLETIN OF THE BUREAU OP FISHERIES. 



—Per 



-PL 



-NL 



;  V.-'- '■■: ->; -■■ '^•Ztecv^&F^ 



---P5 



112 



P6T 



113 



114 



Fig. hi. — Cross section of piece of shell. X s° approximately. 



Fig. 1 1 2.— Section through prismatic layer. X 45- 



Fig. 113. — Cross section through ligament. X 26. 



Fig. 114. — Cross section through edge of mantle. X 35. Fixed in Gilson fluid and stained with Delafield hematoxylin and 

 congo red. 



Abbreviations. — GL, granularlayer; HyL, hyaline layer; IF, inner fold; 1L, inner layer containing a few groups of calcium 

 crystals; MF, middle fold, showing origin of periostracum (Pit) from its outer edge; Mus, muscle fibers; AX, nacreous layer; 

 OF, outer fold; PB, pigmented bands; Per, periostracum; PL, prismatic layer. 



