^48 Mr Anderson’s Corrections for the Effects of Humidity 
5. II. reversa — Shell transversely wrinkled, subcylindrical, with a fine 
apex. ^ Serpula reversa, Mont. Test. Brit. p. 508. Upon shells and crabs, De- 
vonshire, Montagu. On corals, Zetland. 
This shell resembles the preceding in the variableness of its mode of growth. 
In some cases, there are three or four whorls placed laterally, making a 
diameter of half an inch, others have the smaller end projected, and the 
larger end coiled. Montagu’s specimens reached to j^th inch in diame- 
ter at the aperture. Those which I possess are smaller. The same au- 
thor, states, “ the animal is a Terebella, with branched, ciliated tentacula 
(branchiae), spotted with crimson, which, when spread, almost surrounds 
a double funnel-shaped proboscis (lid), placed one within the other, the 
stalk of Avhich is long and slender, and originates on the left side, below 
the tentacula : this in some is green, others reddish ; the interior funnel 
is cut in deep longitudinal striae ; external one ciliated round the mar- 
gin : on the right side, corresponding with the proboscis, is a short cy- 
lindric appendage.” It is probable, that, when our knowledge of the struc- 
ture of the animals of the Serpuladae shall have become more extensive, 
and better fitted to regulate their methodical distribution, the* present 
species will be transferred to a station near Vermilia intricata. 
The plan which I have adopted, in this monograph of British 
Testaceous Annelides, appears in a peculiar manner calculated to 
promote an acquaintance with our recent and extinct animals, by 
exhibiting the connecting links between the ancient and modern 
species ; and the zoological characters of the different geognos- 
tical epochs of the Earth’s history. Other genera of testaceous 
and crustaceous animals are even better fitted to promote the 
end in view, than those which are here employed. We may 
particularly refer to the unrestricted genera Nautilus, Terebra- 
tula, and Echinus. The last of these presents a peculiarly 
tempting subject for a monograph, to those who have access to 
authentic documents in reference to the fossil species. 
Manse of Flisk, ) 
nth May 1824. | 
Art. VI. — New Corrections for the Effects of Humidity on 
the Formula for measuring Heights hy the Barometer. By 
Adam Ar^derson, A. M. F. R. S. E. Rector of the Aca- 
demy of Perth. 
The method of measuring heights by the barometer is at 
once so simple and expeditious, that, if the results deduced by 
