444 Bulletin American Museum of Natural History. [Vol. XXXV, 



located almost anywhere in the oyster, but chiefly in the mantle, and perhaps 

 often thrown off and lost when the sac is ruptured. (See Figs. 38 and 39.) 



The pearly growths of irregular form attached to the inside of the 

 shell are of course caused by injuries of various kinds to the shell. It is 

 now believed that pearls formed in the fleshy parts of the pearl oyster result 

 chiefly from cestode parasites around which the oyster secretes a layer of 

 epithelial tissue within which the pearl is eventually formed. 



The inception at La Paz of an original method of pearl oyster cultiva- 

 tion is of more than passing interest, as the application of that method to 

 the growing of pearl oysters in our own waters may be quite within the limits 

 of possibility. 



Spiny Lobster (Panvlirus intcrruptus). — This large and valuable species 

 is apparently common along the west coast of the Peninsula wherever there 

 are rocky shores and reefs. Portions of their dried shells are common on 

 the beaches in many localities, indicating a wide distribution. 



At San Bartolome Bay, about 330 miles south of the United States and 

 Mexican boundary lines, there were at the time of our visit four camps of 

 fishermen engaged in lobstering, with two men at each camp. The camp 

 at the entrance near the anchorage had 30 pots in use which were set in 

 from one to twenty-five fathoms, according to the condition of the weather — 

 the lobsters being found close to the shore in smooth weather. The pots 

 are set outside the Bay in the vicinity of rocky ledges which are covered with 

 kelp; they are four feet long, two feet wide at the bottom by one foot at 

 the top, where the entrance is placed near one end. A pot of this kind 

 will fill nearly full of lobsters. Both ends have narrow compartments at the 

 bottom for ballast. (Fig. 12.) 



The bait is principally abalones which are left attached to the shells, 

 tied in small bunches with wire and suspended in the center of the pot. 

 Fishes are also used to a small extent as bait. (Figs. 13, 14.) 



The pots are made of lath, 1\ inches wide and \ inch thick, the framework 

 being heavier. Two men working together catch about a ton a week for 

 which they receive 4c. a pound. The camps at San Bartolome were supposed 

 to be visited weekly by a small steamer of the International Fisheries Com- 

 pany of Los Angeles, but at the time of our visit in March the steamer was 

 three weeks overdue and most of the catch had spoiled. The fishermen were 

 nearly out of fresh water and they would have been under the necessity of 

 going to Cedros Island, about thirty-five miles distant, had we not furnished 

 them with a supply from the ship. When we returned to San Bartolome 

 late in April there was but one camp of these fishermen remaining, as the 

 locality was desolate and totally without fresh water. The steamer was 

 again long overdue and the fishermen short of water and provisions. The 



