ILLUSTRATIONS. 



Plate I. 



Lauding pearl shell at Jolo. 



Plate II. 

 Fig. 1. Jolo pearling llret. 



2. Pearl diver In the water. 



.3. Pearl diver coming out of the water. 



Plate III. 



Philippine gold lip pearl shell ( Margarit'ifcra maxima Jamson). 



Fig. 1. Inside view. 

 2. Outside view. 



Plate IV. 



Philippine black lip pearl shell (Marganlifera iiiaygnritifera Linnseus). 



Fig. 1. Inside view. 

 2. Outside view. 



Plate V. 



Fig. 1. Section tl}rough ctutor of Philippine pearl, showiiin an cncv^tcd cestode. 



2. Section through, a Pliilippine pearl, showing a calcified cestode in the 



center. 



3. Section through a Philippine jiearl which had a grain of sand in the 



colter. It is also shown how a perfectly round pearl may become irreg- 

 ular and how it may be peeled to form a perfectly round pearl. 



Plate VI. 



Fig. 1. Culture pearls from the pearl farm in the Bay of -\go, .lapan. 

 2. Pearls, found at Siasi Island in Tacloban shells. 



Text Figures. 



Fig. 1. Spermatozoa and ova of Philippine pearl oyster. 



(a) Micropyle, througli wliich the spermatozoa enters the ova. 



(6) Nucleus. 



(c) Nucleolus. 



{(l) Spermatozoa of male. 



2. Cestode from center of a Philippine pearl. 



3. A bit of shell in wdiich a pearl valued at 500 pesos was hidden. The x 



indicates the spot where the pearl was hidden. 



4. The same shell as in fig. 3, but cracked open showing the pearl. 



5. Exact sizes of pearls from 0.129(i to 1.944 grams (2 to 30 grains) in weight. 



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