SUMMARY OF RESULTS. 5 
the great Corniferous coral reef of the east, occur at the upper horizon, and 
Syringopora perelegans, of the same formation in New York, ranges through- 
out the group in Nevada. The occurrence of rare species and those of 
limited range in the eastern Devonian is not an unusual feature, as we 
find Lingula Lena, Strophodonta Patersoni, Chonetes hemispherica, Productus 
truncatus, ete. The Trilobita also show the great range of the two species 
heretofore regarded as restricted to certain localities, viz, Proctus Halde- 
mani and P. marginalis, and also the more widely distributed Phacops rana. 
Among species of a greater range there is the well-known Pterinea flabella 
in association with other forms of the Upper Helderberg formation at the 
Lower Devonian horizon; and Sanguinolites rigidus and S. ventricosus, of the 
Chemung Group, occur in the upper beds of limestone. The Gasteropoda 
are shown by Platyostoma lineatum, so abundant in the Hamilton formation 
of New York, and eight species of Platyceras, five of which are identical 
with eastern species, as are the four species of Tentaculites and the minute 
Styliola fissurella representing the Pteropoda. 
The fortunate discovery of the interior of a dorsal valve of a rather 
large species of Lingula, L. Whitei, affords the means of comparison of the 
same parts of the shell with a Silurian and recent species of this genus, and 
proves the great structural similarity of the three species so widely sepa- 
rated in geologic time (Plate xxi, figs. 18, 19, 20). 
The fauna of the White Pine shale in the White Pine District is in 
many respects a peculiar one, combining as it does species ranging from the 
e 
Middle Devonian into the Lower Carboniferous. The stratigraphic position 
of the shale is at the summit of the Devonian system and at the base of 
the Carboniferous; it is overlain in the Eureka District, where the section is 
unbroken, by a massive belt of conglomerate before the limestones carrying 
the Lower Carboniferous fauna appear in the section. The strongly- 
marked Carboniferous species are, Spiriferina cristata, Retzia radialis, Athyris 
sublamellosa, and Cardiomorpha Missouriensis ; these are associated, at the 
same horizon, with such Devonian species as Discina Lodensis, Productus 
subaculeatus, Amboccelia umbonata, Rhynchonella (L.) quadricostata, Aviculopecten 
catactus, and Lunulicardium fragosum. 
Messrs. Hall and Whitfield (Geol. Expl. Fortieth Par., vol. iv, p. 201) 
