vaughan] LITERATURE. . 69 
Santo Tomas coal beds, and noted the existence of the sands (Carrizo) 
which come above the Eagle Pass beds and carry the water supplying 
the artesian wells at Carrizo Springs. 
1889. Hill (R. T.) . A preliminary annotated check list of the Cretaceous inverte- 
brate fossils of Texas: Bull. No. 4, Geol. Survey of Texas, Austin, 1889, pp. 
xii-xxxi, 1-57. 
Contains some notes applicable to the Rio Grande region and gives 
localities for some of the fossils. 
1890. Penrose (R. A. F.). A preliminary report on the geology of the Gulf Tertiary 
of Texas from Red River to the Rio Grande: First Ann. Rept. Geol. Survey of 
Texas, pp. 3-101. 
On pages 38 to 47 a description is given of a section along the Rio 
Grande from Eagle Pass to the mouth of the river. The three points 
of special interest in this paper are: 
(1) The description of the plain character of the country. 
(2) The ammonites hitherto found at Eagle Pass are shown to occur 
along the river to near the Webb County line. 
(3) The section (page 41) of Webb bluff 3 miles below the north line 
of Webb County. Here Eocene mollusks were found. 
On page 60, in discussing the upland gravel, Penrose states that the 
gravel along the Rio Grande is frequently cemented, by a calcareous 
matrix, into a conglomerate. The pebbles of the gravel, or conglom- 
erate, are of "limestone, flint, quartz, chalcedony, agate, black obsidian, 
red pitchstone, jasper, and porphyry." 
On page 62 is a description of the Rio Grande silt. On page 63 the 
name Reynosa limestone is proposed for a hard, white, post-Tertiary 
rock occurring in the town of Reynosa, 250 miles below Eagle Pass, 
State of Tamaulipas, Mexico, at an elevation some 50 feet above the 
Rio Grande. 
1890. Hill (R. T.) . Classification and origin of the chief geographic features of the 
Texas region: Am. Geologist, Vol. V, Nos. 1 and 2. 
In No. 1 there is an Approximate Map of the Topography and Geol- 
ogy of the Texas Region. 
1891. Hill (R. T.) . The Comanche series of the Texas- Arkansas region: Bull. Geol. 
Soc. America, Vol. II, May, 1891, pp. 503-528. 
In this paper several allusions are made to the geology of the vicin- 
ity of Del Rio. On page 517 the presence of the Fort Worth lime- 
stone and the Exogyra arietina clays is announced, and on page 519 the 
occurrence there of an Equisetum and a Nodosaria is made known. 
1891. Hill (R. T.). Notes to the geology of the Southwest: Am. Geologist, Vol. 
VII, pp. 366-370. 
On page 366 Hill states that Nodosaria texana Conrad, a fossil of the 
Denison beds, and their southern continuation, the Exogyra arietina 
clays, forms great masses of limestone at Del Rio. On pages 367 and 
368 the Tertiary basin of the Lower Rio Grande is described, and the 
