Fauna and Flora of Cotorado.—T. 103 
a membranous tube; perianth with broadly oval segments nearly 
equal, with short turbinate tube; bracteoles linear-hispid shorter 
than the pedicels; stamens nine, anthers redish, akenes narrowly 
winged, embryo not seen. 
A low, densely branched shrub, its slender fastigiate branches 
forming a flattened summit, with the remains of dead foliage be- 
low, flowers rather conspicuous, intermixed with the projecting 
dichotomous branches. To be placed inthe virgatae section 
though the inflerescence is mainly reduced to a single terminal 
involucre. Is apparently near to E. taxifolium, Greene,Pi Honia 
Pees ke. Orcutt, No’ 1501 La Salada, Lower California, 
April, 1886. CLOo Parry. 
Pema 7I0OVS TOWARDS A LIST: OF THE 
FAUNA AND FLORA OF WET MOUNT- 
PM VALLEY, COLORADO. 7. 
(Compiled for the Colorado Biological Association.) 
In studying the problems of geographical distribution, it is es- 
pecially necessary to consider the fauna and flora of any given 
region as a whole in order to come to sound and permanent con- 
clusions. The forms of organic life are so intimately related, one 
-with another, and have so important an influence in determining 
each others distribution and development, that a mere examin- 
ation of any single group with a view to ascertaining the why 
and wherefore of its geographical range, is certain to present us 
with many apparent anomalies,which would readily be cleared up 
could we but know the distribution of other different but in this 
connection influential groups. The distribution and abundance 
of lepidoptera for instance, is most plainly influenced by the dis- 
tribution of the plants on which the larve feed, and these plants 
are again influenced by the presence or absence of fertilizing in- 
sects and by parasitic fungi, by the browsing of animals and in 
endless different ways other than those of soiland climate. It is 
supposed that thefertilization of Yucca is dependent on a little moth 
Pronuba. Now a finespecies of butterfly, Megathymus yucce, feeds 
in the larval stage upon the Yucca. Suppose that ali the Pronu- 
bas were by some means exterminated, this would effect the 
Yuccas and so the Megathymus, as well as the Yucca Aphis, and 
many other insects—so that we may say that the distribution of 
Megathymus is actually dependent of that of Pronuba. And the 
same sort of thing can be demonstrated in endless different ways 
throughout organic nature. 
The present series of lists will be prepared with these facts in 
view and it is hoped that they will form a basis for just conclusions 
respecting the origin and nature of the tauna and flora of this re- 
gion. Though necessarily at present incomplete, they will at 
least offer fuller details than have been published hitherto respect- 
ing any one region in the Rocky Mountains, while every effort 
