1885.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 505 



conspicuousness of its medullary rays, causing, in polished boards, 

 beautiful effects of silver- grain. 



Quercus rubra, var. Texana, Buckley. (Texas Red Oak.) 



Good-sized tree at San Antonio, smaller westward and very sparsely 

 scattered in hilly districts from San Antonio to the Limpio Mountains. 



Quercus Emoryi, Torr. (Emory's Oak.) 



Abundant in some of the caiions and along the southern base of the 

 Limpio Mountains 5 forms the exclusive arboreal growth of some of the 

 canons of the Chisos Mountains. In the former habitat it is a handsome 

 tree, with tall and straight stem 1 to 3 feet in diameter; in the 

 Chisos Mountains it seldom exceeds 15 inches. Wood hard and val- 

 uable as timber and fuel. 



Quercus Durandii, Buckley. 



Seen on the forks of the STueces and, what seems a form of it, in the 

 Chisos Mountains. Small tree of little importance, good for fuel, fenc- 

 ing. &c. 



Quercus Muhlenbergii, Engelm. (Chestnut Oak.) 



Large, handsome tree on the forks of the Nueces, medium-sized in 

 the canons of the Guadalupe Mountains. Wood strong and durable. 



Quercus stellata, Wang. (Post Oak.) 



Sparse about San Antonio and northwest of it ; nowhere common. I 

 found large groves of it in the hills north of Fort Concho, apparently 

 the westernmost extension of the species. Low, spreading tree, with 

 short stem 1 to 3 feet in diameter ; wood hard and durable, excellent 

 for posts, rails, ties, &c, or as fuel. 



Quercus undulata, Torr. (Wavy Oak). 



Very common, scrubby Oak in foot-hills west of Devil's Eiver, affect- 

 ing a great variety of forms. Several of the smaller forms (Shin Oak) 

 produce edible acorns of various sizes, small in the Guadalupe Mount- 

 ains, very large in the Sand Hills, which are eaten by Mexicans, raw 

 or baked. They afford excellent mast to hogs in the vicinity of settle- 

 ments. 



Q. grisea and Q. undulata deserve notice as producers of tannin. 

 They almost always bear nut-galls in large quantity. These vary in size 

 from half an inch to an inch in diameter ; they sometimes grow upon 

 the smaller twigs, but much oftener spring from the under surface of 

 leaves, generally from the midrib, more rarely froai a main lateral 

 nerve, never from the parenchyma. They are found in all stages of 

 development, at iirst oblong, pointed and reddish, later becoming 

 rounded and yellowish-white. A section of those growing on the leaves 

 shows large open spaces between the central cyst and the external 

 wall j those found on twigs are fuller and heavier. Wherever found, 

 these nut-galls always plainly show the presence of tannic acid. 



