262 SRTOZOA 



2. POTTSIELLA Kraepelin. Colony consists of stolons from which 

 at intervals single erect, 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^GMATA.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 Phylactolcemata : 



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



statoblasts without hooks. 



Z>! Lophophore nearly circular; statoblasts without float.. 1. FREDEKICELLIDAE 

 ~b a Lophophore horseshoe-shaped ; statoblasts with float .... 2. PLUMATELLIDAE 

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



hooks 3. CKISTATELLIDAE 



FAMILY 1. FREDERICELLIDAE. 



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 



Kig. 430 



Fredericeila sultana. to 22 tentacles: 1 American species. 

 A, colony (Davenport). _ .. ,_., . . . ,_ . .. TT 



B, statobiast F. sultana (Blumenbach) (F. walcottn Hyatt; 



(Siissw. F. Deut.). _ _ _ TT _ ._.... ,.. 



F. pulchernma 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 Paludicella erecta," by E. Potts, Proc. Acad. Nat. Sci., 1884, p. 213. 

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

 Essex Inst., Vols. 4 and 5, 1866-1868. 



