288 GEOLOGICAL SURVEY OF THE TERRITORIES. 
both genera represented in amber, and Clubiona (which has eight am- 
ber species) also at Oeningen. Six genera of Agalenides are found in 
the European tertiaries, and Florissant adds another, Titanoeca (with two 
species) not found there, but allied to Amaurobius, which has three am- 
ber species. There is no family of spiders so abundantly represented 
in tertiary deposits as the Theridides, more than a fourth of the European 
species belonging here, with fourteen genera. America is for once poorer 
here than the stratified deposits of Hurope, but possesses a single species 
of Linyphia, two of Theridium, and some egg cocoons referred for con- 
venience to the comprehensive genus Aranea; Linyphia possesses three 
species from amber and two from Rott; Theridium is one of the very 
richest of the amber genera, having sixteen species, while three other 
species are described from Oeningen and Aix. The proportion of repre- 
sentation is very different in the Epeirides, eight per cent. of the Kuro- 
pean fossil spiders belonging in this group, while the proportion in 
America is forty-four per cent; Florissant possessing even more species 
than the amber, including seven or more species of Epeira, one each of 
Tetragnatha and Nephila, neither of which have before been found fossil, 
and four of a new genus, Tethneus, remarkable for its stout front legs. 
Five species of Epeira are reported from the European tertiaries, two 
each from amber and from Rott, and one from Oeningen. Not only, then, 
is Florissant peculiar for its richness in species of this family, but no 
other group of spiders shows so many novelties for the tertiary fauna. 
The only Myriapod is a large species of Iulus, represented by half a 
dozen fragments, in which only the body segments are preserved. 
Finally there is an odd form of animal, which although abundant and 
tolerably preserved is still of doubtful position. It is flattened onisci- 
form in shape, the body generally arched, and appears to be formed of 
only four nearly equal segments; each of the first three bears a pair of 
long swimming (?) legs, bearing a two-jointed tarsus armed with a single 
claw; both femur and tibia are compressed, expanded, and the latter 
fringed with hairs. The first segment has a median slit anteriorly, but 
there is no sign of a head on the 30 or 40 specimens examined, although 
the anterior portion of the alimentary canal appears to be extensile, 
being frequently preserved as protruding beyond the limits of the body 
and armed at the tip with a broken chitinous ring. There are no other 
mouth parts nor signs of eyes or antenne. The abdomen is furnished 
at tip with a set of harder converging parts, which look as if they 
served the purpose of dragging the body backward. Liurvae of any 
sort are exceedingly rare in the Florissant deposits, and there is no 
group known to me to which this seems to bear any simiitude. There 
are sometimes faint indications of several joints to the abdomen, but 
when closely examined these appear to be illusory; and this would 
certainly exclude it from the Crustacea, unless indeed it belonged, as 
has been suggested to me by Prof. A. Hyatt, to a parasitic type. It is 
from 8 to 10™ long. 
Animal remains besides those of insects are rare at Florissant. The 
most abundant is a species of thin-shelled Planorbis, which is not un- 
common, and always occurs in a more or less crushed condition; it is 
the only mollusk yet found there (excepting a Physa or allied form and 
a single small specimen of a bivalve, referred to above in the section 
from the southern lake), and according to Dr. C. A. White is probably 
undescribed, although very similar to a species found in the Green River 
shales, differing from it principally in its smaller size. 
Fishes rank next in numbers. Eight species have been found, be- - 
longing to four genera; of Amiidae we have Amia scutata and A. dicty- 
