110 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



often go for a mile or more inland without seeing a single 

 specimen, but when an exposed lava ridge or a barren field of 

 lava is encountered, where conditions are such that very little 

 other vegetation will grow, specimens will occur abundantly. 

 The probable reason for this is that the species of Cereiis are 

 shaded out as soon as any considerable amount of other vegeta- 

 tion appears. Plate VI. Endemic. 



C. sp. — BiNDLOE IsL. : Heller. Probably C. sclerocarpus 

 ace. to Rob. (1), 180. No specimens of Cereus were seen by 

 any of the members of our party when this island was visited. 



Opuntia Raf. 



O. galapageia Hensl. Mag. Zool. and Bot. I. 467, t. 14, f. 2 

 (1837); Rob. (1), 180. — Abingdon Isl. : common on lava 

 beds to 1000 ft., occasional above this elevation to 1300 ft. The 

 specimens from the lower parts form trees 8-10 ft. high and 

 have the branches closely arranged, giving the crown a very 

 dense appearance, while those from the upper parts have the 

 branches rather loosely arranged. In general the specimens 

 from the upper parts are much infested with lichens, and have 

 a more sickly appearance than do the specimens on the lower 

 parts, (no. 3001). Champion Isl. : specimens low, with very 

 thick trunks, and apparently very much more abundant than on 

 the adjacent shores of Charles Island, (no. 2098). Charles 

 Isl. : abundant below 500 ft., occasional to 1300 ft. on the west 

 side of the main mountain. One of the specimens from this 

 place is peculiar in that the fascicles are made up mostly of 

 capillary bristles but in addition have one or two long pungent 

 spines. There are fewer Opuntias here than on most of the 

 other larger islands, a fact that is probably due to the presence 

 of cattle, hogs, and burros which eat the smaller and less pro- 

 tected specimens. Duncan Isl. : occasional at 450 ft., 

 abundant around 1000 ft., especially on the floor of the main 

 crater, occasional to 1250 ft. The specimens on this island 

 have the branches openly arranged and often covered with 

 various species of lichens. See Plate X. Gardner Isl. (near 

 Hood Isl.) : an interesting variation of this species occurs 

 here in that some of the specimens are stemless and have the 

 branches procumbent. One individual of this kind was found 

 growing immediately underneath a specimen with a stem 6-7 



