MAMMALS OF THE MEXICAN BOUNDARY. l21 



petvred for the first tiino since leaving the Lesna and Co!)ota moun- 

 tains. This agave was only seen in the Tnle Mountains of Arizona 

 and Sonora. The plant is about the size of Agave lechuguilla 

 Torrey, with something- of the a])pearance of Agaoe applanata 

 parryi (Engelmann) Mulford. The broad leaves have fleshy mar- 

 gins and remarkably stout, deflected spines, which spring from the 

 margins of the leaf, which is similar to that of parry'i in shape, glau- 

 cons, and armed with an indurated terminal spine about 25 mm. in 

 length. The flower-stalk is 1 to 3 meters in height and resembles that 

 of Agave applanata parrijl. It was not seen in flower. Mesquites 

 here grow to a considerable size, in canyons, and develope a spread- 

 ing habit of growth, the branches forming elbows which reach the 

 ground and are often buried in the sand, the extremities again ascend- 

 ing. The ])alo vercle is uncommon; but the small-leaf horse bean is 

 abundant, growing up the mountain slo^jes and canyons, as well as on 

 arroyos, though sparingly in the hills. The Sonoran ironwood as- 

 cends to the mountain tops. In the bed of a sandy arroyo the indigo 

 thorn, in one instance, became a tree one-third meter (1 foot) in 

 diameter and 7.3 meters (21 feet) in height. Eehhiocactus ividiseni^ 

 which was not seen west of the Sonoyta, was here replaced by EcJilno- 

 cactus lecontei^ which was not seen east of Quitobaquita, where both 

 occurred. A cactus was first found here, growing in the form of a 

 mound, like a pyramid of cannon balls, each as large as a coconut. 

 It occupied smooth slopes of bare ground, covered with small chips 

 of volcaiiic rock. There were other new forms of cacti, among 

 them a coarse Cylindropuntia having whitish spines; this first ap- 

 peared in the Sierra de la Salacla, and, in the desert ranges to the 

 westward, became the prevailing cactus and the chief food plant of 

 the mountain sheep. A very singular plant is TerehinthiiH niicro- 

 pthylla (Gray) Rose {Bursera microphylla. Gray), which has the ap- 

 pearance of a stout, woody shrub, but is so soft and spongy that when 

 a plant dies it melts down like a cactus and goes to pieces instead of 

 drying hard in its natural form. 



Reptiles. — It was said by several members of the surveying party 

 that gila monsters of a kind different from those at San Bernardino, 

 Monument No. 77 {Heloderma satipectum, Cope), were numerous in 

 the Tule and Tina j as mountains, which were surveyed in xA.pril and 

 May. At the time of our visit (February) the only reptile much m 

 evidence was the Uta stanshuriana^ which is often active when the 

 temperature is quite low : but Mr. Joe H. Wlieeler, who was the 

 most accurate observer of the civilian employees of the survey, wrote 

 me, in April, 1893, that he found : 



Lizards, very large, IS to 24 inches in lengtli : bucks of u hriek-red oolor ; 

 legs and head blaclv ; tail gray or granite color, and not very tapering; belly 

 and breast reddish, and gray tinted on sides. 



