76 



4. 



Condensed Synopsis of the Orders, Sub-orders, Families, and Genera. 



The fresh-water Polyzoa admit of being divided into eight generic groups. The discri- 

 mination of these is very easy in the living animal ; but as some of the genera are founded on 

 the form of the polijjnde alone, the ccencecium not presenting one character which can be 

 employed for the purposes of distinction ; while in others the form of the entire animal is 

 so changed by death, as to render it almost utterly incapable of conveying any idea of what it 

 had been, we are in most instances obliged to examine the animal in a living state before we 

 can form any safe opinion as to even the genus to which it belongs. 



The following is a condensed synopsis of the orders, sub-orders, families, and genera of 

 fresh-water Polyzoa : 



Okdeks.* 



Sub-Obders. 



Families. 



Geneua. 



Eh 



1-:; 



o 



o 

 -< 

 (^ 



K 

 Ph 



O 



O 



LOPHOPEA. 



v_ 



f Coenoeciutn "| 



free, loco- LCristatellid^. 

 motive. I 



Cristatella. 



/'Coenoecium massive ; 1 



ectocyst g^latinoid ; p^^^.^^^^jj^_ 



'' Lopbopbore 



witb two 



long arms. 



CcEnoecium 1 „ 

 rooted. I Plomatellid^. 



statoblasts orbicular, i 

 witb marginal spines. J 



Ccencecium sacciform; 

 ectocyst gelatinoid ; 

 statoblasts oval, des- 

 titute of spines. 



Ccencecium tubular, ] 

 tubes united ; ec- 

 tocyst pergamenta' 

 ceous. 





Lophopus. 



Alcyonella. 



Ccencecium tubular,| 



tubes distinct ; ec- \ ni i n 



, ' , / Plumatella. 



tocyst pergamenta- 



ceous. 



Arms of Jo- 1 

 phopbore > 

 obsolete. J 



URNATELLEA. 



PALUDICELLEA. 



Urnatellid^. 



PALUDICELLIDiE. 



Fredericella. 



Urnatella. 



Paludicella. 



* For tbe characters of the Orders and Sub-Orders see Table, 



