BRYOZOA OF WOODS HOLE REGION. 235 



into two, the Myriozoumidse to include the genus Myriozoum, and Schizoporellidse to include the 

 remainder of the group, and at the same time have merged the species of Cellepora with Schizoporella. 

 In the present paper I shall include in this family the genera Hippothoa, Schizoporella and Cellepora, 

 which are all that fall within our region. Cellepora appears to the writer to present sufficient relation- 

 ships with Schizoporella to fall within the same family, though it seems best to retain it as a separate 

 genus. 



KEY TO GENERA. 



1. Adnate, the zooecia more or less distinct and somewhat cylindrical in form, the wall thin and some- 



what hyaline, entirely without avicularia Hippoihoa. 



Encrusting or foliaceous, the zooecia contiguous to form a continuous crust, usually with avicu- 

 laria 2 . 



2. Zooecia recumbent, or, when erected, without an aviculiferous rostrum in relation with the orifice, 



Schizoporella. 



Zooecia erected, except sometimes in the very young colonies; an aviculiferous rostrum below or 

 beside the orifice Cellepora. 



Genus HIPPOTHOA Lamouroux, 1812. 



There is a distinct sinus in the posterior border of the orifice, and appendicular organs are wanting; 

 the zooecial wall is not perforated but is more or less rugose transversely ; fertile zooecia somewhat reduced 

 in size. The zooecia are always more or less distinct in young colonies, but in older stages of H. hya- 

 lina they are much crowded. 



KEY TO SPECIES. 



Zooecia prolonged at base into a tubular portion, usually distinct, not erected dii'aricata. 



Zooecia not so prolonged at base, usually forming a crust, often erected in older colonies hyalina. 



Hippothoa divaricata Lamouroux. [PI. xxiv, fig. 46, 460..] 



Lamouroux 1821, p. 82. 



Dawson 1859, p. 256. 



Packard 1867, p. 270 (Hippothoa borealis). 



Verrill 18790, p. 29. 



Whiteaves 1901, p. 100. 



Zoarium adnate on stones, shells, and occasionally on algae. Zooecia elongate pyriform, more or 

 less produced into a peduncle at the posterior end, arranged in a loose branching series; surface smooth 

 or finely striated transversely, often with a median carina; orifice rounded with a sinus in the posterior 

 margin. Ooecia globose, with an umbonate process on top, borne on somewhat dwarfed zooecia. 

 Avicularia wanting. 



Rare; taken at either end of Vineyard Sound (Fish Hawk stations 7526 and 7723) and at Crab 

 Ledge in 18 fathoms. Only small colonies of a few cells have been noted. The species is cosmopolitan 

 in its distribution. 



Hippothoa hyalina (Linne). [PI. xxiv, fig. 47, 47 a > 47 b ' 47 C -] 



Linne 1766-68, p. 1286 (Cellepora hyalina). 

 Dawson 1859, p. 256 (iepralia hyalinal). 

 Verrill and Smith 1874, p. 713 (Mollia hyalina). 

 Verrill 1879!}, p. 193, and 18790, p. 30. 

 Whiteaves 1901, p. 100 (Schizoporella hyalina}. 

 Cornish 1907, p. 77 (Schizoporella hyalina). 



Zoarium incrusting on stones, shells, algae, hydroid and Bryozoa stems, etc., in the young colony 

 forming rather regular hyaline patches, especially on flat surfaces, in older colonies very irregular, the 

 cells piled up on each other and often more or less erected, and when on stems forming rough crusts 

 resembling Cellepora. Zooecia usually elongate, subcylindrical, and attenuated posteriorly, in young 



