THE HEDERELLOIDEA BASSLER 47 



a combination of characters quite different from other species of 

 Hederella. 



Occurrence. — Devonian: 40 miles above mouth of Hay River, 

 Canada. 



Plastoholotype.—V.S.lslM. No. 54214. 



HEDERELLA ALPENENSIS GROUP 



This group, typified by an abundant species in the Traverse group 

 of Michigan and represented by 10 species, is characterized by the 

 regular arrangement of the branches, with short, closely spaced 

 zooecia dividing so frequently that a central tube is not developed. 

 Species of Reptaria have a somewhat similar aspect, but their zooecia 

 arise so regularly from the basal portion of the opposite one that they 

 form a symmetrical branch of two rows of parallel tubes in contact. 



HEDERELLA ALPENENSIS, new species 



Plate 3, Figures 1-6 



Zoarium incrusting brachiopods, cup corals, massive bryozoans, and 

 other organisms, often spreading over several square centimeters. It 

 consists of a compactly arranged set of short zooecia springing alter- 

 nately from the side of the opposite preceding one, thus leaving no 

 definite central tube. The zooecia are of equal length (1.1 mm.), 

 arising at such a slight angle as to remain often in contact and almost 

 parallel to each other. Width of zooecia 0.4 mm., with 4 to 5 occur- 

 ring in 5 mm. Branching occurs frequently at intervals of about 3% 

 mm. and at an angle of 60°. 



Occurrence. — Middle Devonian: Long Lake near Alpena and El 

 Cajon Beach, Alpena County (cotype) (Genshaw formation) aban- 

 doned shale pit, Alpena Portland Cement Co., Alpena County, etc. 

 (cotype) (Upper Ferron Point formation), Petoskey Cement Co., 

 Petoskey (cotype), and Bay View (Gravel Point limestone), % mile 

 southeast of 4-mile Dam, 7-niile Dam (Norway Point formation) 

 (cotype), and % mile northwest of Bolton, Alpena County (Alpena 

 limestone), all in Traverse group of Michigan; 2% miles southwest of 

 Sylvania, Ohio (Silica shale); Milwaukee, Wis. (Milwaukee-Lind- 

 wurm). 



Cotypes.—V. S.^.M. Nos. 54086, 54108, 54111, 54113, 87971-87975. 



HEDERELLA AEQWDISTANS. new species 



Plate 9, Figtjee 6 



This well-marked species, occurring as incrustations on cophalopod 

 shells over areas as large as 10 sq.cm., is characterized by its regularly 

 branching habit at right angles from the main axis at a distance of 

 about 3 mm. The main axis is composed of a single row of tubes 



