WHITE.] SPECIES WITHIN THE FORMATION AND FIELD. 771 



Big Flats ^ north of Watertank Station, Fort Lookout,' and a number 

 of the old drifts ^to the westward, made in the early part of the cen- 

 tury, will be considered in connection with the special discussion of 

 the Dauphin Basin. 



5. The lifth category includes plants from the "Buck Mountain" 

 coal or a coal (the Twin coal) supposed to ))e its equivalent at Swatara 

 Gap at Middle Creek,* Ebony colliery' north of Newcastle, Altamont 

 colliery No. 2,'' Locust Mountain and Sharp Mountain gaps," near 

 Tamaqua. and at the Pottsville Gap. 



SPECIES AND THEIR OBSERVED DISTRIBUTION WITHIN THE 

 FORMATION AND FIELD. 



In order to avoid the repetition of names which would result from 

 an enumeration of the species from each locality or bed, the plants 

 from the Pottsville formation in the region of Pottsville and west- 

 Avard in the Southern Anthracite lield, exclusive of the Dauphin 

 Basin, will be combined in ojie list, with a table showing their dis- 

 tribution so far as yet ol)served in that foi-mation. Since the eco- 

 nomic interest of the problem of stratigraphic paleontology centers 

 primarily about the Lykens coals, the localities affording plants from 

 the roof shales directly in connection with these coals, as detinitely 

 correlated between the large mines, are placed tirst. From an eco- 

 nomic standpoint thev constitute a typical paleontologic representa- 

 tion of the productive coal-bearing horizons, just as the Pottsville 

 Gap section affords a typical paleontologic section of the formation 

 as a avIk^Ic. Since, also, it is at once clear that the species commonly 

 in association with the lower Lykens coals are largely different from 

 those over the upper Lykens coals, the principal coals of the mining- 

 region are naturally divided paleobotanically into tA\o groups: An 

 upper group, including coals 1-3, and a lower group, containing 

 Lykens coal No. i and the remaining lower portion of the formation. 



For the sake of easier comparison, the plant-bearing horizons A-M,* 

 in ascending order, in the Pottsville Gap section, are placed next. To 

 the right of these are a number of columns representing isolated devel- 

 opments of supposed Lower Lj^kens age; and beyond these are a few 



1 PI. CLXXX, .station 26. Atlas Southern Anthracite Field, Pt. Ill, mine sheet xxvi. 



-PI. CLXXX, station 27. Atla.s Southern Anthracite Field, Pt. Ill, mine sheet xxvi; I't. VI, 

 columnar-section sheet viii, section 11; Pt. Ill, mine .sheet xxvi. 



^Pl. CLXXX, stations 28-32. Atlas Southern Anthracite Field, Pt. Ill, mine sheets xxvi and xxvii. 



<P1. CLXXX, station 34. Atlas Southern Anthracite Field, Pt. II, mine sheet xiii; Pt. IV B, columnar- 

 .section sheet x, section 4; Pt. VI, cross-section sheet xiii, section 22. 



''PI. CLXXX, station 35. Atlas Southern Anthracite Field, Pt.II, mine sheet vi; Pt.V, cro.ss-scction 

 sheets v-viii, section 17. 



«P1. CLXXX, station 37. Atlas Southern Anthracite Field, Pt. II, mine slieet vi; Pt.IV, coliunnar- 

 section sheet ix; Pt.V, cross-.section sheet viii, section 16. 



'PI. CLXXX, .stations 38 and 39. Atlas Southern Anthracite Field, Pt. I, mine sheet iii, cross-section 

 sheet iii, section 12, columnar-.section sheet iii; Pt. II, mine sheet iv. 



^The application of letters to the ])lant beds of tlie tyiic section is only for convenience of reference 

 in this report. The letters are not introduced lu the nnmcnclatural sen.se, and are not intended for 

 permanent use. They are, therefore, not to bi confused with the nomenclature of the coals in the 

 Panther Creek Basin or other portions of the anthracite regions. 



