I! Williams.] FAUNAL DISSECTION OF THE DEVONIAN. 45 
[Devonian fossils of the formations outcropping in that region. The 
(first attempts to define the separate faunules and to apply names to 
• them were imperfect on account of the absence then of any knowledge 
as to the range, distribution, and relative abundance or rarity of the 
[component species. These statistics were gathered as the investiga- 
tions progressed. Although those first attempts at classification on 
the new basis are now superseded by classification based on the full 
appreciation of the laws of shifting of faunas, the record of the steps 
by which the progress has been made will indicate how from the study 
of conspicuous local phenomena broad general laws have been devel- 
oped. 
INTRODUCTION OF A FAUNAL CLASSIFICATION OF THE 
DEVONIAN SYSTEM. 
Bulletin No. .*> of the U. S. Geological Survey, On the Fossil Faunas 
of the Upper Devonian along the Meridian of 7(3° 30', etc. (Cayuga 
Lake meridian), was issued in 1884. In it is given an analysis of the 
faunas of the section, from the Genesee shale near the head of the 
lake to the Barclay coal in Bradford County, Pa. 
The classification of the formations was based upon the changes 
exhibited in the faunas, and the following faunas were recognized, in 
ascending order, viz : 
1. Genesee slate fauna. 
2. Portage group; 1,300 feet, including the Ithaca fauna and several faunules. 
3. Chemung; 1,200 feet, with separate faunules. 
4. Catskill rocks. 
The Portage included the lower beds with the Cardiola fauna, and 
the upper part was observed to be nearly or wholly barren. Second- 
ary faunas of the Portage group were recognized and named as follows: 
1. Cladochonus fauna (No. 48, sec. 1113, p. 11). 
2. Spirifer lsevis fauna (sec. 1101, p. 12). 
(Both of these were traced eastward as to origin.) 
3. Lingula fauna (Ithaca shale, No. 6, sec. 1106, p. 14). 
4. Hamilton recurrent fauna (No. 14 N. sec. 1102 N, p. 15). 
5. Cryptonella fauna (sec. 1105, p. 17). 
6. Ithaca fauna proper, Spirifer mesicostalis zone (1102 B, HOT, p. 18 and p. 20). 
(This was traced to the eastward.) 
6a. Recurrent Portage (Cardiola speciosa fauna; 1168, p. 20). 
7. Discina fauna, a recurrent Genesee shale fauna (mentioned on pp. 20 and 30). 
(This was traced westward for its origin.) 
8. Spirifer laevis recurrent fauna (pp. 20 and 30). 
9. Lingula fauna (1162 A and B). 
10. Orthis tioga; typical Chemung fauna (1172 D, 1165-67, p. 23). 
11. Heliophyllum halli zone (coral zone; 1167 E,H, p. 24). 
12. Catskill. 
The investigation was described as the first of a series of articles 
on the comparative paleontology of the Devonian and Carboniferous 
faunas. The manuscript of the bulletin was prepared ami sent to 
