‘ 
26 SCTE NCE 
There was still a rich and wide field open for inves- 
tigation in the study of the Monticuliporidae; and 
care should be taken first to ascertain with the new 
and more scientific means the true relations and 
affinities of the species described previous to 1881. 
Mr. Whiteaves exhibited a choice series of recent 
Polyzoa for comparison with the fossils described in 
the paper. 
Ottawa field-naturalists’ club. 
Dec. 20.— Mr. James Fletcher read a paper entitled 
‘Notes on the Flora ottawaensis, with special refer- 
ence to the introduced plants,’ which was explana- 
tory of the lists of plants hitherto published by the 
club, and in which the non-indigenous species are 
not indicated. Mr. Fletcher first defined the district 
from which the plants had been collected, and which 
lies within a circle of twelve miles radius. He then 
noted certain of the more interesting of rare or intro- 
duced species, and presented lists tabulating the lat- 
ter plants under the headings of ‘ Aggressive species,’ 
‘Species able to perpetuate themselves indefinitely,’ 
‘Species dying out after short periods,’ ete. An 
animated discussion ensued, confined principally to 
the conditions affecting introduced plants, and the 
spreading of certain species. 
Philosophical society of Washington; Mathematical section. 
Dec. 19. —Mr. M. H. Doolittle gave a paper on the 
rejection of doubtful observations, in which obsery- 
, [VoL. IIL, No. 4 , 
ing-errors were sharply divided into two classes, — 
those resulting from blunders in recording, pointing 
on wrong objects, neglect of essential precautions in 
instrumental adjustment, etc.; and those resulting 
from an unusual accumulation of similar elements of 
error. The latter class, because by their magnitude 
in one direction they indicate that the remaining ob- 
servations are in error in the opposite direction, he 
proposed to call instructive errors, and claimed that 
the larger they were the more instructive, and the 
greater the necessity of retaining them. In practice, 
however, the best rule with suspected observations is 
to reject them when they exceed the limit of error pos- 
sible to the ‘instructive’ class, and when they fall 
within it to assign a weight proportional to the 
chance that the error belongs to the latter class, and 
not the former. As the law of distribution of the 
former class of errors (if any such law exist) is very 
different from the recognized law of the latter class, 
these questions cannot be decided by computation 
with a ‘criterion,’ but must be left to the judgment. 
Prof. A. Hall gave as a general result of the debate 
of this vexed question by Peirce, Airy, De Morgan, 
Stone, Glaisher, Chauvenet, Gould, Winlock, and 
others, that every one can devise a criterion that suits 
himself, but it will not please other people. Hestrong-- 
ly opposed using such machinery in the discussion 
of observations as eliminated the knowledge. and 
judgment of the investigator, and giving to results a 
fictitious accuracy by any sweeping rejection of dis- 
cordant data. 
INTELLIGENCE FROM AMERICAN SCIENTIFIC STATIONS. 
GOVERNMENT ORGANIZATIONS. 
Geological survey. 
Topographical field-work. — Mr. H. M. Wilson, in 
charge of one of the topographical parties in Prof. 
A. H. Thompson’s Wingate division, surveyed, dur- 
ing the season of 1883, about ten thousand square 
miles in north-western New Mexico and north-eastern 
Arizona. The area covered by his work lies between 
parallels of latitude 36° and 37°, and extends from 
meridian 109° to 111°. He also worked some smaller 
detached areas outside of the limits thus indicated. 
This region has hitherto remained a terra incognita, 
partly on account of its aridity and barren condition, 
and partly on account of the difficulty of traversing 
it. So little has been known of it, that within the 
area surveyed by Mr. Wilson a small mountain range 
has been indicated as occupying two places on the 
Same map. On the engineer’s map of 1879 it is called 
Calabesa Mountains in the northern place, and Squash 
Mountains in the southern; and, on the land-office 
map for 1882, both areindicated without names. Mr. 
Wilson’s work proves that they are one and the same, 
occupying a position very close to that assigned to 
the Squash Mountains. ; 
On the 11th of September Mr. Wilson and one of his 
men made the ascent of Navajo Mountain (called 
by the Indians Nat-sis-aii), and they are probably: 
the first white men who have ever stood upon its 
summit. Navajo Mountain lies on or near the line 
between Utah and Arizona, and is a dome-shaped 
mass rising about four thousand feet above the gen- 
eral level of the surrounding country, and sixty-five 
hundred feet above the beds of the San Juan and 
Colorado rivers, which are close to its base, the for- 
mer on the north, and the latter on the west. Its ele- 
vation above sea-level is ten thousand four hundred 
feet. It slopes abruptly, especially on the east, to a: 
plateau of six to seven thousand feet, which extends 
south-eastward for fifteen or twenty miles to the 
cafion where Mr. Wilson left his pack-train in camp.: 
This was on a trail that leads to Fort Defiance, vid 
the north side of the Mesa de la Vaca and the valley 
of the Rio de Chelly. Another trail leads south- 
ward to Mo-eu-kap-i (a Mormon settlement) and to 
Oraybe and the other Moqui villages. From a point 
a few miles south of the Navajo Mountain, a third 
trail leads westward to Lee’s Ferry, on the Colorado 
River. Mr. Wilson thinks there is also a trail leading’ 
to the mountain from the north-west. He says all 
the trails in this section are exceedingly rough and 
difficult to travel, on account of the numerous cafions, 
of five hundred to a thousand feet in depth, which 
are cut into the red sandstones (triassic?) that form the 
