THE HEDERELLOIDEA^ BASSLER 67 



Except for the wall structure, H. ? cooperi may be distinguished from 

 other species of Hernodia by its short (2 mm.) rapidly expanding 

 zooecia (0.6 mm. wide at distal end, budding at angle of 25°, with 

 2 to 3 in 5 mm.) and its branching at short but regular intervals (3 mm.) 

 at an angle of more than 45°. With continued growth only a small 

 opening is left between the branches, which disappear in old speci- 

 mens leaving all the tubes in contact. 



Occurrence. — Middle Devonian: Averys Creek, Erie County, N. Y. 

 (Ludlowville-Wanakah shale); Rockport quarry, Alpena County 

 (Traverse-Upper Ferron Point formation), 1.6 miles north of Nor- 

 wood, Charlevoix County (Petoskey formation). Thunder Bay 

 quarry, Alpena (Alpena limestone-Dock Street clay), all in Traverse 

 group of Michigan. 



Holotype.—\J.S.l<iM. No. 94586. 



HERNODIA 7 MONAHANI, new species 



Plate 15, Figure 3 



Hederella cfr. canadensis Monahan, Amer. Midi. Nat., vol. 12, No. 10, p. 388, 

 pi. 3, fig. 2, pi. 4, fig. 2, 1931. 



This new species is named in honor of Joseph W. Monahan, whose 

 early death lost to science an enterprising student of Devonian 

 paleontology. It occurs as an excavation in the surface of a cepha- 

 lopod (Mitroceras) preserved in the Museum of the Buffalo Society of 

 Natural Sciences as No. 13342. 



Gutta-percha squeezes of this mold indicate a well-marked species 

 of either Hederella or Hernodia, which is of interest further in that it 

 comes from Silurian rocks. As the illustration on plate 15 shows, the 

 zooecia bud very regularly and alternately from a median axis, but 

 the preservation is not good enough to enable one to determirie 

 whether this axis is formed of the caudal extremities of the tubes as 

 in Hernodia or an elongate tube that gives rise on each side to buds as 

 in Hederella. 



In H. ? monahani branching is rather regular, at intervals of not less 

 than 6 mm. and at angles of about 45°. The zooecia are small, 

 cornucopia-shaped, bending outward in a curve, at an angle of 45°, 

 averaging 1.3 mm. in length, 0.4 mm in width, and 4 in 5 mm. measur- 

 ing along one side of the axis. 



Occurrence. — Silurian (Cayugan-Bertie limestone): Near Buffalo, 

 N. Y. 



Plastoholofype.— U.S.N. M. No. 87883. 



