Dr. W. Nylander on new Chemical Tests for Lichens. 169 
The two testicles are small, ovate, and extend some distance 
beneath each of the tail-lobes. The seminal vesicle in the pos- 
terior part of the trunk is oblong oyate, and sends forth on either 
side a capacious backwardly directed ductus deferens, which 
opens at the extremity of the trunk. The accessory glands, which 
no doubt exist, I have not been able to discover. Of the external 
organs of generation, which are much more complicated than in 
A. foliaceus, I have already given an account. 
The species of Argu/lus which we have just described was first 
found in the lakes of Jemtland by Dr. C. L. Nystrém, on both 
the Coregonus and the Grayling. The species of Coregonus 
which is most generally met with there is C./avaretus, Linn.; and, 
according to the verbal communications I have received, it is on 
this species that A. coregoni was found, although it undoubtedly 
affects other species of that genus. Mag. H. Widegren has 
found and sent me several specimens from salmon-lakes in Dals- 
land, taken also from Coregonus lavaretus, and has asserted, 
moreover, that it occurs on Salmo trutta in the Vettern. The 
species is probably widely spread over Scandinavia. 
In Dr. Nystrém’s already cited “Observations on the River-fauna 
of Jemtland,” on p. 19, are the following remarks with reference 
to Argulus coregoni :—One of the parasites of the Gwyniad is re- 
markable from the fact of its giving a preference to a particular 
fish. An unusually large species of Argulus fastens itself at cer- 
tain times in summer, in large numbers, on the Gwyniad, and 
also, though less readily, on the Grayling. Almost every fish 
has, during this time, one or several of these blood-suckers on its 
body, which bite it till the belly is quite drained of the blood. 
The fishes then hurry in crowds to certain parts of the lake 
where probably the currents are colder, and fall in large quanti- 
ties into the nets which are there spread for them. This fishery 
lasts but a short time, perhaps two days only, but produces 
during*that time in some localities several tons of fish. 
(To be continued. } 
XXVII.—Notule Lichenologice. No. IX. 
By the Rev. W. A. Lricuton, B.A., F.L.S. 
Dr. Nytanper, with his usual skill and sagacity, has recently 
discovered two new chemical tests or criteria which are likely to 
prove of great value in the study of Lichens, not only in the 
discrimination of many difficult and closely allied species, but 
also in associating varieties with their proper species, and in 
some instances in defining the affinities of genera. These tests 
are applied to the thallus ; and their usefulness is at once demon- 
