278 PALEONTOLOGY OF NEW YORK. 



surfaces are covered by the zoariura. The cell tubes are sub-cylindrical, at 

 first rapidly expanding, but for the greater portion of their length the mar- 

 gins are parallel ; transverse section oval in outline, length from 1.25 to 2 

 mm., diameter .33 mm., generally arranged in alternating order, and often 

 regularly distant, on the same side of the branch 1.50 mm. ; the angle of 

 divergence from the axial tube is sometimes equal to forty-five degrees, at other 

 times they are in contact with the axis for nearly their entire length, turning 

 abruptly outward near the end, the apertures being parallel with the axis of 

 of the branch and a little constricted ; during the process of growth the 

 apertures are rectangular to the axis. Surface marked by numerous, strong, 

 transverse striae, with finer striations between, and frequently the stronger 

 striae have the appearance of prominent annulations ; the cell tubes vary in 

 their surface characters, some of them having only the prominent annula- 

 tions, others only the fine striae, while still others have both the annulations 

 and finer striations, and when well preserved they have also numerous, 

 very fine longitudinal striae. 



This species is intermediate in size between Hederella cirrhosa and Hederella 

 filiformis ; from the former it is easily distinguished by the greater size of the 

 cell tubes and the coarser appearance of the frond ; from the latter it may be 

 distinguished by the smaller diameter and greater length of the cell tubes, the 

 cells of that species being more than .50 mm. in diameter, and seldom having a 

 length of more than 1.25 mm.; the frond of this species is also much less com- 

 pact in appearance : from H. magna it is distinguished by the much smaller size 

 of the cell tubes, those of that species having a diameter of more than 1 mm. 



Formation and locality. Hamilton group, York, Livingston county, N. Y. 



Hedekella filiformis. 



PLATE LXV, FIGS. 9-11. 



Anhrpiyra jUiformU, Billisos. Caniulian .Journal, New Series, vol. 4, p. 119. 1850. 

 Hederella " Hall. Trans. Albany Institute, vol. x, p. 194. 1881. 



Report of State Geologist for 1883, p. 54. 1884. 



ZoARiUM parasitic, procumbent, attached for its entire length, consisting of an 

 elongated, sub-cylindrical primary axis, from which proceed, laterally, simple 



