262 BRYOZOA 



2. PoTTSlELLA Kiaepelin. Colony consists of stolons from which 

 at intervals single ei'ect, cylindrical zooids arise; opening terminal: 1 

 species. 



P. erecta* (Potts). Length of zooid 1.5 mm.; number of tentacles 

 about 20: Montgomery County, Pennsylvania. 



Order 2. PHYLACTOL^MATA.f 



Lophophore oval or horseshoe-shaped; epistome present, projecting 

 over the mouth; statoblasts present, which usually have a broad mar- 

 ginal band of air cells called the float which sustains them in the water: 

 in fresh water; 3 families and about 30 species, 7 American. 



Key to the families of PhylactolcBmata : 



Oi Colony branched, provided with an opaque chitinous or hyaline cuticula ; 

 statoblasts without hooks. 

 6i Lophophore nearly circular; statoblasts without float. .1. Fredericellidae 



1)2 Lophophore horseshoe-shaped; statoblasts with float 2. Plumatellidae 



Co Colony massive, secreting a gelatinous base ; statoblasts with float and 



hooks 3. Cristatellidae 



Family 1. FEEDERICELLIDAE. 



Colony tubular, branched in form of antlers; lophophore oval; 

 cuticula opaque and brown, rarely gelatinous and hyaline; tentacles not 

 over 24; statoblasts dark brown, elliptical, with- 

 out float : 1 genus. 



1. Fredericella Gervais. Colony dendritic 

 and either recumbent or erect, attached either 

 entirely or partially to the under surface of 

 stones or sticks in ponds and streams, usually in 

 dark places; lophophore oval, bearing usually 20 

 Frederweha sultana. to 22 tentacles: 1 American species. 

 ' ^^ B^statolnasf ^'^ * F. sultana (Blumenbach) {F.walcottii Hyatt', 



(Siissw.F.Deut). ^^ pulclierrima Hyatt; F. regina Leidy) (Fig. 



430). Form of colony differs in different localities, consisting of inter- 

 twining branches which adhere to the substratum or form a dense clump : 

 cosmopolitan. 



Family 2. PLUMATELLIDAE. 



Colony consists either of cylindrical tubes which are either branched 

 or form massive clumps or of hyaline, recumbent, lobed tubes, or of 

 hyaline erect, slightly lobed sacs ; tentacles 40 to 60 on a horseshoe-shaped 



* See "On Taludicella erecta," by E. Totts, Proc. Acad. Nat. Sci., 1884, p. 213. 

 t See "Observations on Polyzoa, Suborder Phylactolsemata," by A. Hyatt, Proc. 

 Essex Inst., Vols. 4 and 5, 186G-1S68. 



