238 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
ECHINOSPHAERITES AND CHRISTIANIA FAUNAS. 
The position of the Echinosphaerites beds in the American Ordovi- 
cian section can not be said to be definitely established. The knowl- 
edge which we have of these beds is due largely to Dr. Ulrich and to 
Dr. Bassler (98), and by the former of these investigators the fossil is 
reported as occurring at three horizons, one below and two above the 
Lowville. \ | | 
The evidence concerning the younger of these occurrences, in so far 
as it has been published, may be found in the description by Stose, of 
the Chambersburg — Mercersburg map-area, and in the Revision of 
the Palaeozoic Systems by Ulrich. The following section (here re- 
arranged) is given by Stose (118). 
Feet. 
10. Soft yellowish green sandstone with few fossils, said to 
be of Eden species 1200+ 
9. Black carbonaceous shale, with Climacograptus spinifer, 
Corynoides calicularis, Leptobolus insignis, Triarthrus 
becki, ete., in lower 100 feet. 800+ 
8. Shale and thin-bedded limestone with many small 
fossils, including Triarthrus becki, Cryptolithus tessella- 
tus, Ampyx, Caryocaris, etc. 150+ 
All the above strata are referred to the Martinsburg shale. 
7. Caleareous shale and shaly limestone, with Christiania 
trentonensis, Plectambonites asper, P. pisum, Oxoplecia, 
Parastrophia hemiplicata, ete. Echinosphaerites in the 
upper ten feet. 150+ 
6. Dark gray, largely thin-bedded limestone with Nidu- 
lites favus, Ampyx, Plectambonites asper, ete. 237+ 
5. Dark gray limestone in which Echinosphaerites is very 
common, Ampyx, Receptaculites, Oxoplecia, and 
brachiopods also common. 60+ 
4. Grayish dense thin-bedded limestone with Tetradiwm 
cellulosum, Zygospira recurvirostris, ete. 150+ 
These limestones above are all grouped as the Chambersburg 
limestone. 
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