io6 



SCIENCE. 



[Vol. XXI. No. 525 



and other species, but whetlier for the seeds or soft, juicy pulp I 

 could not determine, possibly for both. 



Many of the small mammals and rabbits were given to gnawing 

 the inside from the various species of globular cacti, which fur- 

 nished a large quantity of pulpy material, with plenty of moisture. 

 Several large specimens of these cacti were found that were mere 

 shells The mice, having entered from below, and without dis- 

 turbing the position or appearance of the plant, had carried away 

 all but the thorns and woody exterior. 



Deer and antelope were rather common on the plains be- 

 low camp, and, as they were seen daily and some individuals 

 recognized by certain peculiarities, it was plain that if they left 

 the region in search of water, it was not often or for any length 

 of time, but more probably that they drew a large part of their 

 moisture from their food. The different species of cacti and 

 agave were frequently found with large pieces bitten out of them 

 by these animals. The latter plant especially seemed to supply 

 them with a large part of the necessary moisture. 



The Indians and Mexicans living in the arid portions of the 

 peninsula of Lower California told me that the rabbits and quail 

 of those regions did not breed during dry seasons, the latter re- 

 maining in flocks throughout the spring and summer. This state- 

 ment was verified by my own observations in the spring of 1887. 

 No young quail or rabbits were seen, though the adults were 

 everywhere abundant. 



This habit may extend to other species in this region, as young 

 birds seemed to me to be remarkably rare during the dry season 

 mentioned. 



Whether this habit arises from the fear that suitable food for 

 the young may be wanting or that water in larger quantities than 

 is to be obtained would be necessary for their early existence, I 

 am unable to say. 



Off the west coast of the peninsula, between 28° and 29° north 

 latitude, are two islands — Cerros and Guadalupe — both of which 

 are inhabited by large herds of wild goats, the descendants of 

 domestic animals placed there by the whalers for the benefit of 

 shipwrecked sailors ; there are also quite a number of deer on 

 Cerros. 



On both of these islands water is found in small quantities. But 

 during dry seasons this becomes so scarce that the large herds of 

 Guadalupe especially suffer considerably. The sealers of that 

 coast told me, however, that during seasons of little rain the goats 

 drank sea-water and managed to exist until better times. This 

 story was looked upon as a sailor's yarn, without foundation, until 

 endorsed, in part at least, by my brother, who returned from a 

 trip along the coast of the peninsula in June, 1892. 



Goats were found on Natividad Island, a small island south of 

 Cerros, which is known to contain no fresh water. As they were 

 out of fresh meat, a few were shot for use on board the schooner, 

 and a kid about one-third grown was captured and taken on 

 board as a pet. Fresh water was offered it, supposing it would 

 be a very acceptable variation to its fare of dry weeds; but, strange 

 to say, after the first sip, it shook its head in disgust, and turned 

 away. Sea-water, however, was accepted and regularly drunk. 

 Gradually it formed a liking for fresh water, and at the end of a 

 month would not pay any attention to salt water. That goats 

 are rather scarce on Natividad would indicate that they did not 

 thrive on sea-water; yet those that were killed by my brother 

 were fat and in every way in good condition. 



The story that prairie-dogs have in each colony one or more 

 burrows reaching to water has been widely spread and is probably 

 not without foundation; but that such is the case wherever prairie- 

 dogs are found is by no means true. I witnessed the sinking of 

 a well in southwestern New Mexico, in the midst of a very large 

 colony of these rodents, the supposition being that, where "dogs" 

 were so abundant, water could not be far from the surface After 

 a depth of over two hundred feet had been reached, the work 

 was given up and the bottom reported as the dryest spot in New 

 Mexico. In sinking to this depth, several strata of tough, slaty 

 clay were cut that would have undoubtedly proved an impassible 

 barrier lo any burrowing rodent, had it even penetrated to that 

 depth. 



Prairie-dogs are undoubtedly fond of water when it can be 



obtained. I have frequently, in Colorado, found their colonies 

 near streams, to which well-beaten trails led, and where large 

 numbers were seen drinking daily. But where water is not to be 

 obtained, they seem to be able to subsist upon what moisture they 

 can get from the dry, scanty vegetation of the arid regions in 

 which they live. A. W. Anthony. 



Denver, Colo., Feb. 7. 



Bad-Air Indicator. 



Permit me to suggest, through your columns, something de- 

 sirable to be invented if it be within the limits of science to pro- 

 duce it, namely, an automatic and reliable indicator of bad air. 

 I do not in the least know whether such a thing can be made, and 

 must admit that the only chemist to whom I have proposed the 

 matter sees no way to construct it, but it is possible that some one 

 might see his way clear to it. My idea is to have a plain circular 

 disc, which might be made ornamental, which should be one or 

 two feet in diameter, which should be placed on the walls of a 

 room or hall, and the surface of which should be pure white 

 when the air of the room is reasonably pure, but which should 

 become discolored by the presence of bad air, and the color of 

 which should deepen or darken in proportion as the impurity in 

 the air increased. It seems to me that such an indicator, plainly 

 making its announcement before the eyes of all, would be valuable. 

 It may be said that our sensations are suflScient indicators of the 

 presence of foul air, but this. I think, is not so, and the vitiation 

 of the air in many a hall is so gradual and insidious that the great 

 number of people may, without knowing it, be gradually forced 

 to breath air which is most poisonous, and nearly every particle 

 of which — to state the matter plainly — has been previously many 

 times breathed into and out of other people's lunge. Cannot some 

 substance orsurface be so chemically prepared as to give this, the 

 above- mentioned, indication? Is not here a good chance for the 

 chemist and inventor? C. H. Ames. 



Boston, Mass, Feb. Id. 



On Chelydra serpentina. 

 The snapping tortoise is not one that appeals to many as an 

 animal of which to make an attractive pet. His appearance and 

 his manner of receiving advances are decidedly against improve- 

 ment of a reputation that contains little of the good. There is a 

 widespread opinion that he is quite intractable, utterly savage 

 and ferocious, and without redeeming traits. My own ideas on 

 the subject, however, have been greatly modified by the behavior 

 of a seventeen-inch specimen kept in a tank in a corner of one of 

 the rooms in this museum, where he furnished a good deal of 

 entertainment for visitors, during the summer and autumn of 

 last year. The sulkiness brought with him gradually vanished 

 until he began to take food from long forceps; later he would 

 accept meat from the fingers; and still later would come out of 

 the tank for something to eat. Eventually he gained confidence 

 enough to traverse a forty foot room for a sparrow, a mouse, or 

 a snake that might be offered. He seized the food held out for 

 him in his jaws, turning his head to one side, if necessary, to do 

 so with advantage, then he turned himself about and, high on 

 his legs like a little elephant, with the hinder inch or two of his 

 tail bearing on the floor, marched gravely back to his miniature 

 pond. Sometimes the fur or feathers of prey stood up or covered 

 his eyes so as to prevent seeing distinctly. No matter, the jaws 

 never loosened their grip and their owner blundered along bang- 

 ing against anything in the way till from one side or the other he 

 at last managed to get into the water. Wherever food was given 

 him, his only place to eat it was under the surface in his tank. 

 Firmly held between the jaws whatever he wished to eat was 

 torn in pieces by the claws of his fore feet, or, if too tough for 

 tearing, it was at least reduced to such shape as admitted of 

 swallowing entire. After a time ' Snap," as he was named, be- 

 came rather too familiar, coming out of his retreat at all times, 

 whether called or not, whenever one entered the room. If a stu- 

 dent came in and took a seat at a table, Snap was pretty sure to 

 plant himself under the chair or at the feet of the newcomer to 

 remain for an hour, more or less, as pleased him. Pushed aside, 



