28 PROCEEDINGS OF THE NATIONAL MUSEUM vol.87 



the illustrations for much unpublished work on the stony Bryozoa. 

 The present contribution is the first to appear under this grant. Most 

 of the type specimens herein described are the property of the U. S. 

 National Museum. 



The general characters of this suborder and its genera are described 

 below. Then follow in order the descriptions of species, faimal Usts 

 showing geological and geographical distribution, and finally a table 

 of measurements for use in the separation of species. 



Order CYCLOSTOMATA Busk 

 Suborder Hederelloidea Bassler, 1934 



Zoarium usually incrusting but sometimes rising into soHd branches 

 composed of tubular zooecia with perforated walls derived from a 

 bulbous ancestrula, as in typical Cyclostomata. Zooecia of individual 

 tubes, budded from the lateral wall of the preceding zooecium, the 

 ends of each separated by a plate, probably perforated; apertures 

 transversely elliptical and terminal equaling the diameter of the 

 zooecial tubes. 



Family REPTARIIDAE Simpson, 1897 



Family characters as for the suborder. 

 Range. — Middle Silurian to Mississippian. 



Genus HEDERELLA Hall, 1881 



Zoarium attached to various foreign organic objects and rarely to 

 pebbles or other inorganic substances, branching, consisting of a 

 tubular axis composed of the earlier part of successive zooecia from 

 which the zooecia bud laterally, alternately to right and left; tubes 

 annulated transversely and finely striated longitudinally; apertures 

 terminal, transversely elliptical (fig. 14, A, B). 



Genotype. — Alecto canadensis Nicholson, 1874. Middle Silurian to 

 Mississippian. 



Genus HERNODIA Hall, 1881 



Zoarium as in Hederella but consisting of linear series of elongated 

 club-shaped zooecia with no central tubular axis, budding alternately 

 from about the middle of the sides of preceding zooecia; each zooecium 

 gives rise to one or more daughter zooecia (fig. 14, C). 



Genotype. — H. humifusa Hall, 1881. Upper Silurian, Devonian. 



