1895.] Geology and Paleontology. 841 
The Extinction of Saurians.—In regard to the extinction of 
species, Mr. Charles Morris offers as an explanation of the disappear- 
ance of the Cretaceous reptiles, an indirect assault by the placental 
mammals, viz.: the destruction of the eggs, and possibly of the young, 
of the reptiles. The author points out that the mammals, equipped 
with a higher grade of intelligence than their powerful rivals, probably 
adopted new methods of attack more rapidly than the reptiles acquired 
means of defense, so that the latter eventually found themselves at a 
disadvantage in the competition for supremacy. Multitudes of prowl- 
ing creatures, small and agile, having become aware of usefulness of 
reptiles’ eggs for food, would soon bring about a perceptible diminution 
of reptilian life. Only the smaller and most prolific forms would con- 
tinue to exist, or those that developed means of hiding or otherwise 
protecting their eggs from the assaults of the hungry mammals. (Pro- 
ceeds. Phila. Acad., 1895.) 
The Geology of Cuba.—The following geological history of 
Cuba is given by Mr. Robert T. Hill. The conclusions are based on 
stratigraphic and paleontologic data obtained during a personal recog- 
noissance made in 1894. 
1. In Pre-Tertiary times, an old land existed, almost as extensive in 
area as the present Island. Whether this old land was insular, multi- 
insular, or connected with other Antillean areas on the mainland, I 
will not speculate. The submarine topography indicates that it was 
not. Its composition and structure, however, show that it was an area 
of active vuleanism accompanied by great metamorphism and eruptive 
flows. If there are preserved in it any traces of Pre-Tertiary sedimen- 
tation, they are largely overwhelmed and almost obliterated by the 
vulcanism, metamorphism and later erosion. Paleozoic, Triassic 
Jurassic and Cretaceous sediments have been reported by De Castro in 
localities, but their physical history is unknown. 
2. It is also certain that during Tertiary times, embracing the Eocene 
and Neocene periods, this ancient nuclear land, with all of its geographic 
outlines, completely subsided beneath sea-level, and that it was covered 
with limestone sediments, which were originally derived from the sea, 
not the island itself, for there is no semblance of limestone material in 
the rocks of the Pre-Tertiary land which could have furnished material 
for the Tertiary rocks. That this subsidence was profound we may 
reasonably conclude from the thickness of the older nucleal region, now 
visibly covered by the limestone beds, which have been horizontally 
elevated to a height of at least two thousand feet. In other words, the 
