Mr. J. Gwyn Jeffreys on Dredging among the Shetland Isles. 247 
Journal,’ ser. 2. vol. xxxiil. p. 1380, expresses the views advocated 
herein. The following is an extract therefrom :— 
** This is the classification which the writer of the criticism main- 
tains should be sustained ; and we cannot see any reasonable objection 
toit. It is perfectly just towards both M‘Coy and D’Orbigny. It 
inflicts no injustice on any other author. It is not inconsistent with 
purity of zoological nomenclature, or in any way injurious to science. 
It does not require any modification in either of the original defini- 
tions. The typical species are central and dominant forms of two 
different groups of species which together form one larger general 
group. Athyris, under this arrangement, is the generic name of 
that group which has 4. tumida for its type. Spirigera is a per- 
fectly unexceptionable name for the other group, of which the typi- 
cal form is S. concentrica. Prof. Hall’s proposed genus Meristella 
is precisely identical with the genus Athyris in its restricted sense 
(as above explained), and cannot be admitted until some good reason 
is shown for setting aside Davidson’s arrangement. It belongs to 
Prof. Hall to place this reason before the public in a clear and un- 
sophisticated manner. If he succeed in maintaining his point, then 
he will establish a classification for this group of fossils far inferior 
to that proposed by Davidson. Spirigera must be suppressed, and 
Athyris must take its place, and thus stand as the generic appella- 
tion of a group of fossils for which it is not appropriate. We hold 
that this change is not necessary; and as it would, if adopted, be 
injurious to science by affecting the purity of zoological nomenclature, 
it cannot be maintained.” 
XXX.—Fourth Report on Dredging among the Shetland Isles. 
By J. Gwyn Jerrreys, F.R.S.* 
In spite of the weather (which was worse than usual in this 
stormy region), some additional results of no slight interest 
were obtained. The three requisites of such enterprises (time, 
money, and experience) were not wanting; and the valuable co- 
operation of Mr. Norman, Mr. Waller, and Mr. Dodd, aided by 
-a good yacht and crew, and by a large stock of apparatus, left 
nothing to desire except calmer seas. Dr. Edmonston and his 
family again did all in their power to promote our endeavours ; 
and Mr. Cheyne of Edinburgh kindly placed his house at Tan- 
wick at our disposal. 
Discoveries in natural history are of several kinds, all of which 
are nearly equally important :—1. New species or forms. 2. Geo- 
graphical distribution. 3. Habits of animals, including in the 
present case those supposed to be dependent on the depth of 
water. 4. Geological relations. 5. Extraneous incidents. 
* Communicated by the author, having been read at the Meeting of the 
British Association at Dundee, 5th Sept., 1867. 
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