FOSSILS OF THE DEVONIAN. 201 
fragment 45™™ in diameter, preserving three air-chambers, that is closely 
related to this form; the concavity of the septa is much greater, being 15™". 
In some respects these fragments are allied to Orthoceras Bebryx Hall 
(Pal. N. Y., vol. v, pt. 2, p. 275), of the Hamilton and Chemung Groups of 
New York, but appear to belong toa distinct species. 
II. This is a more slender form than the preceding, and diminishes less 
rapidly in receding from the chamber of habitation. Transverse section 
circular. Apical angle, 5° to 6°. Chamber of habitation large, without any 
constriction as far as observed. Air-chambers numerous, having a depth of 
3™" where the diameter of the tube is 13". Septa thin, the concavity 
equal to a little less than the interspaces. Sutures transverse, straight. 
The best preserved specimen is 60™” in length, with a diameter at the 
septate end of 11™", near the mouth of the chamber of habitation of 16™", 
the chamber of habitation having a length of 35"". Surface characters un- 
known. This form is related to Orthoceras exile Hall (Pal. N. Y., vol. v, 
pt. 2, p. 290), of the Hamilton Group of New York. 
III. This fragment has three septa in a length of 25"™; transverse sec- 
tion slightly ovate, as 8 to 9; greatest diameter, 27™. Apical angle about 5°. 
Septa thin, with a concavity equal to the depth of the chambers Siphuncle 
eccentric, distant from the nearest point on the walls of the air-chambers 
about two-fifths the greatest diameter of the tube. The diameter at the 
septa is 2™™, where the major diameter of the tube is 18™™. 
The greater depth of the air-chambers and the eccentric position of the 
siphuncele distinguish this from the preceding form. 
IV. Several small fragments of an annulated species occur that are not 
unlike portions of small specimens of Orthoceras Thoas Hall (Pal. N. Y., vol. 
v, pt. 2, p. 261), of the Upper Helderberg Group. A specimen 7™™ in 
diameter has seven annulations in a distance of 21"". Septa and siphuncle 
not observed. 
V. Large annulated form, 30°" in diameter. Annulations narrow, de- 
pressed, with a broad, slightly-depressed area between them, five annula- 
tions in a distance of 30". The margins of the septa appear about midway 
between the annulations. 
