560 NEW YORK STATE MUSEUM 



of the lower part of the Skiddaw slates in the Lake district has 

 for a long time been known to have more species in common 

 with that of the Quebec shales than with the other English 

 graptolite faunas. Nicholson and Lapworth described numerous 

 forms from these interesting beds and concluded that the lower 

 Skiddaw slates, or the zone of Tetragraptus b r y o - 

 noides, corresponds to the principal zone of the Quebec beds, 

 which is the Main Point Levis zone of Gurley. These lower 

 Skiddaw slates they considered as contemporaneous with the 

 lower Arenig, and therefore placed the zone near the base of 

 the lower Siluric. 



Lately, the graptolite fauna of the Skiddaw slates has been 

 carefully investigated by Miss Gr. L. Elles. 1 Miss Elles con- 

 cludes that the Skiddaw slate fauna, " though it is more closely 

 related to the fauna of the Quebec group of Canada than to that 

 of any English beds, is still more nearly related to the Swedish 

 fauna; for, while of the whole 59 species, 25 are common to the 

 Skiddaw slates and the Quebec, and only 14 common to the Skid- 

 daw slates and the two other English areas, no less than 34 

 species are common to the beds of Sweden and the Skiddaw 

 slates." The fact of the greater resemblance of the Skiddaw 

 and Swedish faunas can not be held, however, to vitiate the con- 

 clusion of the homotaxy of the Quebec or Levis and of the 

 Skiddaw zones; for it is only natural that, in homotaxial beds 

 the English and Swedish faunas which flourished in closely 

 adjoining geographic regions should have more forms in com- 

 mon than the Skiddaw and the far distant Levis faunas. The 

 writer believes that, considering the great difference in relative 

 distances, the great number of forms which are common to the 

 Skiddaw and Levis beds, and which comprise one half of all the 

 Skiddaw species, is as conclusive proof of the homotaxy of 

 these latter beds as the greater number of common species 

 is of the English and Swedish; beds. This argument is aided by 

 the consideration that the Levis fauna has not by far been as 

 thoroughly studied as the Skiddaw and Swedish faunas, because 



x Quar. jour. geol. soc. 1898. 54:463fiC. 



