Astronomy. 17 
through Tennessee to the southern and eastern limits of the Ohio 
drainage. The facies of the groups of species which this part of 
the Ohio drainage contains stamps them as of a different fauna 
from those north. 
The petite drainage area is anomalous, it atone 184 spe- 
cies, according to describers—but half of which, however, are any 
thing more than varieties wo genera, of 30 "deseri ive species, 
are not found elsewhere — Schizostoma and Tulosto 
these kinds, with the peculiar seve of Goniobasis, ‘bilan toa 
different fauna from many of the Unionide associated with them. 
he region contains the Unio possi in the Altamaha ane ee 
The only other spinous Unio, U. collinus, occurs in New River, 
es on the western slope of the Appalachians, pi to the 
rth. 
‘dibing of the species never present any varieties that could be 
taken for distinct species. This is true, among the Ohio types, of 
U. tuberculatus, Bes satebeits U. irroratus, U. anodontoides, U. 
cornutus, U. rectus, U. triangularis, Margitana dehiscens, and 
others. Many presi species are exceedingly variant and have 
led to the naming of many so-called species that are only varie- 
ties, 
The in the second part of this important paper will be 
published 1 in Sthe following number of this Journal. 
IV. ASTRONOMY. 
1. Elements of Comet VII, 1881 a —Professor Boss of 
_ the Dudley Observator ry has computed the following elements of 
‘Comet VII, 1881 (Swift), from observations made by him on 
November 20, 28 and December 10. 
T = 1881, November 17°41 Washington Time. 
= 116" 30°. 
\ log q = 0°2841 
This comet is remarkable for its great perihelion distance. The 
following Ephemeris may be _ ervice, in case the comet does not 
prove too faint for observatio 
Siete jor eee perp 
1882. log A. parr 
Jan, 7 23h i 368 + ‘ 07’ 0°3050 
11 38 43 +18 19 0°3265 eH 
15 40 15 +16 44 0°3469 25 
23 43 52 +14 07 0°3843 20 
31 48 00 +12 04 0-4171 ‘17 
Brightness November 20 taken as unity. 
The Longitude of Morrison Observatory, Glasgow, Mo.; by 
Professor. R. Easrman, U. 8, N., and Professor H. 8. Prrre HETT, 
Astronomer at Morrison Obser -vatory, now of Washington Uni- 
