6 The Hawaiian Rat. 



"The live rats were kept at my home in Honolulu in the hope 

 that they would breed. No. 9016 and her mate were in one cage, 

 and the second female in another. 



"On June nth, the desired result not being obtained, the 

 second female was added to the pair. She, however, would hold 

 no converse with either of them, taking possession of their sleep- 

 ing box and showing a disposition to quarrel if either approached. 

 Her presence, though, appeared to excite the male, who finding 

 his approaches were repulsed by the stranger, confined them to 

 his mate. 



"About June 21st, finding that No. 9016 was pregnant, she 

 was removed to the other cage, but seemed unable to produce her 

 young and died on the 28th. 



"I thought the other female was mating about a month ago 

 (September, 1915), but nothing has happened since. There are 

 now on hand, alive, two males and one female. 



"The cages are boxes of comparatively soft wood, with tops 

 and sides removed, and completely covered on the outside with one- 

 half inch mesh wire. It had surprised me that the rats never 

 made any attempt to gnaw through the wood. For the first few 

 days of their captivity they tried to bite through the exposed wire. 



"They have taken readily to any food we have given them, 

 and are fond of fish and grain. A crab's leg was wasted, as they 

 seemed unable to crush the shell. 



"Popoia islet is a flat piece of raised coral reef, varying in 

 height above the sea from four to seven feet. The area is only 

 three acres. It is just about a furlong from the main shore, the 

 intervening depth reaching eight feet. There is little question 

 that at one period it was joined to Oahu, as there are many places 

 along the shore of Kailua Bay where the formation is exactly 

 similar. The separation may have taken place through depression, 

 but was more probably due to the wave action or dissolution of the 

 reef rock from other causes not yet explained. The islet is rapidly 

 being worn away at present, as may be observed from some of the 

 enclosed prints (Pis. XI, XII). 



"The surface of Popoia is broken abruptly by man}- hollows, 

 approximately twenty by thirty feet in size and one to three feet 

 deep, and is honey-combed in all directions by small vertical and 



horizontal holes. In every hollow examined soil of volcanic ori- 



[256] 



