190 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
' While failing to see on what ground Dr. Frazer extended his conclu- 
sions, based upon examination of a single locality in Cuba, to Jamaica, 
Porto Rico, and the Windward Islands, it may be possible that some 
of the rocks of the Sierra Maestra range of Cuba are of a Pre-Cretaceous 
age, although Kimball has shown that the diorites have overflown the 
Tertiary. Personally, I have failed to find any Pre-Cretaceous crys- 
tallines in the localities cited. 
Dr. W. Bergt has also strongly advocated the existence of an Archean 
plexus at the foundation of San Domingo,’ another of the Great 
Antilles. Unfortunately, while his argument is strong, like Frazer’s 
it is largely hypothetical, and not founded upon extended field work. 
The substance of his conclusions is as follows. 
Bergt had before him the following rocks from the southern and 
southwestern parts of San Domingo : — Crystalline schists: horn- 
blende gneiss; pyroxene granulite; fine-grained typical hornblende 
schist ; chloritic hornblende schist, thin laminated, phyllite-like, folded ; 
garnet amphibolite, augite-bearing, eclogite-like ; chloritic schist, ete. 
Older eruptive rocks: normal mica granites, having the appearance 
poth of mountain granite and vein granite ; protegene granites with the 
most distinct evidences of pressure; hornblende granites, even macro- 
scopically so rich in large quartz grains that it is impossible to confound 
them with syenite; syenite subordinate ; diorite, quartz-diorite, “ Blue- 
beache"; diabase ; quartz-diabase ; picrite, olivine rock, serpentine. 
Younger eruptive rocks : basalts in doleritic, anamesitic, and basaltic 
development, the latter compact and of the nature of a finely porous 
lava ; andesites; on the small island of Alta Vela also trachytes. 
He concludes that, “while according to Gabb, San Domingo forms 
an exception, showing none but young eruptive rocks with very old ap- 
pearance, the above series shows quite normally the well known petro- 
graphic and geologic contrast between older and younger eruptive rocks. 
The eruptive rocks designated above as ‘older’ differ plainly by their 
state of preservation, by transpositions and new mineral formations, 
from the volcanic rocks; they do not even resemble the transition rocks 
distributed all over America (propylites, Andes diorites, etc.).” 
Bergt also concludes that the older eruptive rocks of San Domingo 
are not the causes of the mountain movements, but, on the contrary, 
were themselves subjected to such movements, and bear the traces of 
1 On the Geology of San Domingo, by Dr. W. Bergt. Sitzungsberichte und 
Abhandlungen der naturwissenschaftlichen Gesellschaft Isis in Dresden, Jahrgang 
1897, Juli bis December, Dresden, 1898, pp. 1-7. 
