Dr. W. Nylander on new Chemical Tests for Lichens. 1 69 



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 ovate, 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 Argulus which we have just described was first 

 found in the lakes of Jemtland by Dr. C. L. Nystrom, on both 

 the Coregonus and the Grayling. The species of Coregonus 

 which is most generally met with there hCJavaj-etus, 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 Dais- 

 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. Nystrom^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 offish. 

 [To be continued.] 



Wy\\.—Notul(B Lichenologicce. No. IX. 

 By the Rev. W. A. Leighton, B.A., F.L.S. 



Dr. Nylander, 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- 



