44 PROCEEDINGS OF THE NATIONAL, MUSEUM vol.87 



is a more robust species that differs in that all of its dimensions are 

 greater: The zooecial diameter (0.7 mm.) is twice that of the former; 

 the length of the zooecia is 2.5 mm, they bud at an angle less than 

 30°, and their number in 5 mm. is 2 ; the main axis from which the 

 branches emerge at an angle of 60° is strongly and more uniformly 

 developed; and the branching is less uniform. The basal part of an 

 old zoarium consists of an almost solid mass of radiating tubes in 

 which all trace of the method of branching is lost. An interesting 

 feature of the branching is that at intervals of about 4 mm., groups 

 of 4 or 5 short, wide tubes are developed on alternate sides. 



H. thedfordensis is similar to H. nicholsoni, but in the latter a single 

 zooecium emerges alternately from each side of the branch. 



Occurrence. — Middle Devonian: Thedford (cotype), Arkona, etc., 

 Ontario (Arkona and Widder shales); Livingston County, Kashong 

 Creek (Ludlowville) ; 3 miles west of East Bethany (Centerfield 

 shale), Averys Creek and Hamburg (Wanakah shale), and VA miles 

 southeast of East Bethany (cotype) (Kashong shale), all in New 

 York; 2}^ miles southwest of Sylvania, Ohio (Silica shale) (cotype); 

 abandoned shale pit, Alpena Portland Cement Co. quarry (Genshaw 

 formation) and Thunder Bay quarry (Alpena-Dock Street clay), all 

 in Traverse group of Alpena County, Mich. 



Cotypes—V.S.'NM. Nos. 26572, 54101, 87927-87931, 87983, 87984. 



HEDERELLA NICHOLSONI, new species 



Plate 4, Figures 8, 8'; Plate 12, Figure 4 



Though resembling H. helderbergia in its general proportions, H. 

 nicholsoni may be recognized by its broad tubes 2 mm. long and 

 0.6 mm. thick issuing from the main axis at an angle of about 35° 

 and usually remaining free throughout the entire length. Branch- 

 ing is rather regular, occurring at intervals of 5 to 6 mm. at angles 

 less than 45° ; 2}2 to 3 zooecia may be found in 5 mm. H. thedfordensis 

 is similar but has somewhat larger zooecia and particularly more 

 closely arranged tubes, which in budding give rise to clusters of 

 4 or 5 on alternate sides. 



This specific name is in honor of Dr. H. A. Nicholson, eminent 

 pioneer student of American Paleozoic corals and Bryozoa. 



Occurrence. — Middle Devonian: 18-Mile Creek (holo type), Wanakah, 

 Athol Springs, Elma, and Bay View (Wanakah shale), 3 mUes west 

 of East Bethany (Centerfield shale), all in New York; Rockport 

 Quarry, Alpena County, Mich. (Traverse-Upper Bell shale) (para- 

 type). 



Holotype aiidparatype.—V.S.'N.M. Nos. 72800, 73060, 78159, 87937- 

 87939. 



