However, a careful consideration of the subject leads to the belief that there has been no serious decrease in the length of time that the Arab and Indian divers remain under water, and that either the writers were misinformed or that the individual cases reported were extremely exceptional. Ibn Batuta’s instance of one to two hours could easily be caused by a mistake in copying Arabic manuscript, or in the translation. The case related by Diemerbroeck in which a pearl diver remained submerged half an hour, is more perplexing, especially as the physician reports that this was done under his own observation. The numerous reports of five or six minutes may have been based on a very exceptional case. These statements are viewed as highly incredible by men who have spent scores of years at the fisheries. A man may remain submerged for several minutes, but the conditions are vastly different from the activities of pearl-gathering at a depth of ten fathoms, where the pressure of the water is nearly thirty pounds to the square inch, and the slightest exercise is fatiguing. Unless the time is taken by a watch, it is easy to overestimate the stay; the seconds pass very slowly when one is waiting momentarily for the appearance of the diver’s head above the water, and certainly to the nearly exhausted fisherman with straining chest and palpitating heart, the last few seconds must seem extremely long indeed. An instance is noted in which an Arab diver remained submerged seventy-one seconds, and on his reappearance, naïvely inquired if he had not been down ten minutes. It seems doubtful whether the 110 seconds herein noted has been greatly exceeded, in recent years at least, by Arab or Indian divers, who do not appear to equal the semi-amphibious natives of the South Sea islands in their exploits. One of the most curious features of the pearling industry is the manner in which the fishermen secure supplies of drinking water. In the vicinity of Bahrein, numerous fresh-water springs exist at the bottom of the gulf in depths of two or three fathoms, and the fishermen dive into the depth of the salt water down to where the fresh water is springing forth and there fill a skin or other suitable receptacle which they bring to the surface. By running a pipe down near the bottom in the vicinity of one of these springs, an abundance of fresh water may be pumped into the boat. Three species—or at least three varieties—of pearl-bearing oysters are obtained in the Persian Gulf. These are known locally as _mahar_, _sudaifee_, and _zinni_. Of these, the _mahar_ or Lingah oyster, which corresponds to the Ceylon pearl-oyster, yields the greatest quantity of pearls, and those of the finest quality. It measures three or three and a half inches in diameter, and is found in deeper water than the others. The _sudaifee_ and the _zinni_, which are larger, yield pearls in much smaller quantities than the _mahar_.