THE HEDERELLOIDEA — BASSLER 51 



averaging 1.5 mm. in length, 0.35 mm. in width, and about 4 in 5 mm. 

 Rapid prohferation on alternate sides of the single initial tube of a 

 branch and its successors quickly increase the number of rows so that 

 as many as 10 may occur at a bifurcation. 



Although related to H. conferta in growth features, the shorter and 

 less strongly marked zooecia of H. clarkei arranged in many rows mil 

 easily distinguish it. The specific name is in memory of the late 

 Dr. John M. Clarke, eminent student of Devonian paleontology. 



Occurrence. — Hamilton (Centerfield shale): 3 miles west of East 

 Bethany, N. Y. 



Holotype.— U.S.N. M. No. 87987. 



HEDEKELLA CALVINI, new species 



Plate 9, Figure 2 



Zoarium attached to a flat frond of Fistulipora and consisting of 

 rather broad branches dividing rather regularly at intervals of about 

 5 mm. at an angle of less than 30°, composed of flattened zooecial tubes 

 about 2 mm. in length and 0.4 mm. in width budding from the main 

 axis at such a low angle as to remain in contact throughout their length 

 and so frequently as to show 4 or more rows in a single branch. The 

 apertures are narrow, transversely elliptical ; 2 K zooecia occur in 5 mm. ; 

 surface ornamentation of very delicate transverse lines. Branches in 

 the older part of the zoarium so close together as to foixn soUd in- 

 crustations. The broad branches dividing at small angles and the four 

 or more rows of zooecia in close contact in most of the branches 

 readily distinguish tliis fine species, named in honor of the late Dr. 

 Samuel Calvin, leading student of Iowa geology and paleontology. 



Occurrence. — Devonian (Cedar Valley formation): Davenport, Iowa. 



Holotype.— U.S.N. M. No. 54091. 



HEDERELLA MAGNA GROUP 



The robust zoarium of Hederella magna, consisting of a thick, rather 

 infrequently branching tubular axis from which large ventricose but 

 usually short zooecia emerge at close intervals alternately to right and 

 left, has a type of growth shared by the nine forms here classified under 

 this heading. 



HEDERELLA MAGNA Hall. 1881 



Plate 3, Figures 9, 10 



Hederella magna Hall, Trans. Albany Inst., vol. 10, p. 195, 1883 (abstract, 

 p. 195, 1881); Rep. State Geol. New York, 1883, p. 55, 1884.— Hall and 

 Simpson, Pal. New York, vol. 6, p. 280, pi. 65, fig. 15, 1887.— Whiteaves, 

 Contr. Can. Pal., Geol. Surv. Canada, vol. 1, pt. 5, p. 382, 1898. — Bassler, 

 in Cleland, Wisconsin Geol. Nat. Hist. Surv., Bull. 21, sci. ser. 6, p. 55, pi. 6, 

 fig. 6, 1911.— Stewart, Geol. Surv. Ohio, aer. 4, Bull. 32, p. 26, pi. 1, fig. 19, 

 1927. 



