THE HEDERELLOIDEA — BASSLER 35 



This graceful species incrusts crinoid stems, cup corals, and other 

 organisms where its branches cover several square centimeters. 

 The zoarium consists of a narrow single tubed main axis from which 

 slightly curving zooecial tubes, 1){ mm. long and 0.3 mm. wide, emerge 

 alternately and regularly at an angle of 30° to 45° at intervals aver- 

 aging 1 mm. Branching of the main axis occurs at long intervals 

 usually, but in one regularly growing specimen 7% mm. was the 

 average distance. Two or three zooecia occur in 5 mm. measuring 

 in the usual manner, although this number is doubled when, as in 

 rare cases, all the zooecial budding occurs on the same side of a branch. 



H. concinna is a related but more delicate species, while H. cana- 

 densis has also smaller and shorter zooecia. 



Occurrence. — Middle Devonian: West Bloomfield, York, and Skan- 

 eateles Lake (Ludlowville shale), Athol Springs, etc., Erie County 

 (Wanakah shale), 1% miles south of East Bethany (Tichenor lime- 

 stone), 3 miles west of East Bethany (Centerfield shale), and Pavilion 

 (Moscow shale), all in New York; Arkona and Thedford, Ontario 

 (Widder shale); 3}^ miles west of Charlestown, Ind. (Silver Creek 

 dolomite); and Partridge Point, 3 miles south of Alpena, Mich. 

 (Traverse-Partridge Point formation). 



Plesiotypes.—U.S.'NM. Nos. 54105, 87905-87910, 87956. 



HEDERELLA FILIFORMIS (BiUlnga, 1869) 



Plate 1. Figures 1-6' 



Aulopora filiformis Billings, Can. Journ., new ser., vol. 4, p. 119, 1859. — Nichol- 

 son, Pal. Prov. Ontario, p. 42, figs. 11a, b, 1874. 



Hederella filiformis Hall, Trans. Albany Inst., vol. 10, p. 194, 1883 (abstract, 

 p. 194, 1881); Rep. State Geol. New York, 1883, p. 54, 1884.— Hall and 

 Simpson, Pal. New York, vol. 6, p. 278, pi. 65, figs. 9-11, 1887.— Whiteaves, 

 Contr. Can. Pal., vol. 1, p. 211, pi. 29, fig. 1, 1897.— Grabau, Bull. Buffalo 

 Soc. Nat. Sci., vol. 6, p. 179, fig. 77a, 1899. — Bassler, in Cleland, Wisconsin 

 Geol. Nat. Hist. Surv., Bull. 21, sci. ser. 6, p. 55, pi. 6, figs. 1-3, 1911. 



Hederella canadensis Hall and Simpson (part). Pal. New York, vol. 6, pi. 65, 

 figs. 1, 6, 8, 1887. — Grabau and Shimer, North Amer. Index Foss., p. 120, 

 fig. 179a, 1907.— Stewart, Geol. Surv. Ohio, ser. 4, Bull. 32, p. 28, pi. 1, 

 figs. 16, 17, 1927. 



Although several distinct species were first figured under this name, 

 there is Httle doubt that the specimens here selected for illustration 

 agree in all respects with BilHngs' original Aulopora filiformis. These, 

 like the original type are incrusting Spirijer mucronatus thedfordensis, 

 where they occur in zoaria of several centimeters in diameter composed 

 of a unilinear axis, 0.5 mm. wide, branching almost at right angles at 

 intervals of about 5.5 mm. Short, shghtly curved, rapidly expanding 

 zooecial tubes about 1 mm. long arise at an angle of about 45° on 

 alternate sides of the branch; surface of tubes delicately annulated; 

 apertures transversely oval, opening upward; 4 zooecia in 5 mm. 

 measuring along a straight branch. 



