BRYOZOA 259 



FAMILY 12. CELLEPORIDAE. 



Zocecia calcareous, tubular, more or less erect, with a terminal open- 

 ing, and irregularly heaped together; colony usually incrusting, often 

 composed of many layers of cells; sometimes erect: 2 genera. 



CELLEPORA Fabricius. With the characters of the family: numer- 

 ous species. 



C. americana Osburn. Colony incrusting or rising in nodular 

 branches a few millimeters high, growing on hydroid and bryozoan stems 

 and algae; zooecia ovate, more or less erect, heaped upon one another and 

 turned in various directions; orifice circular with a notch and a rostrum 

 which overhangs it and an avieularium at its base: Long Island to Arctic 

 Ocean ; often common. 



C. pumicosa (L.). Colony massive, scabrous, composed of many lay- 

 ers of pinkish color when fresh ; zooecia subcylindrical or ovate, smooth, 

 erect, crowded; orifice round, with a thin, raised margin, immediately 

 below which a tall rostrum bearing an avicularium is often present: 

 Atlantic and Pacific coasts, covering stones and shells in shallow 

 water; common. 



SUBORDER 3. CTENOSTOMATA. 



Opening terminal and closed by an operculum of setae set in a 

 thin membrane; zooecium never calcareous but fleshy or membranous; 

 no avicularia, vibracula, or ococia: 11 families, 10 of which are marine. 



Key to the families of Ctenostomata here described: 



! Animals marine. 

 &! Colony fleshy, forming irregular, incrusting or erect masses. 



Ci Opening of zooacium not bilabiate 1. ALCYONIDIIDAE 



c 2 Opening with 2 distinct lips 2. FLUSTBELLIDAE 



Z> 2 Colony branching, either recumbent or erect. 



G! All the tentacles erect, forming a circle 3. VESICULABITDAE 



c a Tentacles not in a circle, 2 being turned back 4. VALKERIIDAE 



a.. Animals in fresh water 5. PALUDICELLIDAE 



FAMILY 1. ALCYONIDIIDAE. 



Colony fleshy or membranous, forming either an expanded and gelat- 

 inous crust on seaweed or rocks, or being erect and cylindrical or com- 

 pressed; zocecia closely joined and developing by budding from one 

 another and not from a stolon; opening closed by an invagination of the 

 tentacular sheath: 1 genus. 



ALCYONIDIUM Lamouroux. With the characters of the family: 18 

 species. 



A. mytili Dalyell. Colony an extensive gelatinous crust, cylindrical 

 or somewhat flattened, and irregular in shape and reddish, gray, or yel- 



