58 PROCEEDINGS OF THE NATIONAL, MUSEUM vol.87 



because they remain in contact seem to relate this species to the H. 

 parallela group. 



Occurrence. — Middle Devonian (Traverse-Genshaw formation): 

 Long Lake near Alpena, Mich. 



Holotype—U.S.^M. No. 54106. 



HEDERELLA TRISERIATA, new species 



Plate 2, Figure 3 



This species is similar to H. parallela in the development of a long 

 median tube that extends for some distance before it terminates as a 

 zooecium, so that the branch appears to be made of three parallel 

 rows. Compared further with H. parallela, the zooecial tubes are 

 shorter and broader, averaging 1.6 mm. in length, with a width of 

 about 0.4 mm. and an angle of budding of 25°. The branch is about 

 1.3 mm. wide and divides more frequently and at an angle of 45°; 3 

 zooecia occur in 5 mm. 



Occurrence. — Devonian (Snyder Creek shale): Fulton, Mo. 



Holotype.— V.S.N. M. No. 25462. 



HEDERELLA VARSOVIENSIS, new species 



Plate 9, Figure 1 



The fragmentary zoarium forming the holotype of this species 

 incrusts a Fenesirellina and seems to belong to the H. parallela group 

 because of the narrow branches with parallel zooecial tubes in its 

 early stages, but later it forms compact masses by frequent division. 

 The initial branches are only about 1 mm wide and divide at con- 

 siderable intervals, often 9 mm; later division occurs at close intervals 

 (3 mm.) and at such a low angle that a fan-shaped expansion of closely 

 set tubes results. The tubes average 2 mm. in length, 0.35 mm. in 

 width, and 2 to 3 occur in 5 mm. Their surface ornamentation is a 

 very delicate but distinct transverse annulation. 



Occwrrgnce .—Mississippian (Warsaw hmestone): Warsaw, 111. 



Holotype.— U.S.N. M. No. 54098. 



HEDEROPSIS, new genus 



Zoarium externally similar to Hederella but distmguished internally 

 by the presence of a weU-defined longitudinal septum within the zo- 

 oecial tubes along their basal side. In some tubes this septum or carina 

 is jomed at nght angles by transverse partitions at regular intervals, 

 thus dividing the base of the zooecium into two series of parallel 

 compartments. The purpose of the septum and compartments is 

 unknoxvn, but as they appear in at least six species having other 

 characters in common it is beheved they form a good generic character. 



Genotype: Hederopsis typicalis, new species. Devonian (Onon- 

 daga, Hamilton). 



