212 PROCEEDINOS OF THE NATIONAL MUSEUM. vol. xxvu 



much to bo hoped that records will l)e published concerning the 

 occurrence of the various species in the Central, Southern, and 

 Pacilic States. The writer will be glad to receive references to or 

 sej^arate copies of such published records. To facilitate the publica- 

 tion of such records the following sj^noptic key to the fresh-water 

 Bryozoa is given. This includes a single species ( Vrctorella j>avida) 

 unrecorded for America, which may be found here in the future. 

 The key and list are based on the classification of Kraepelin (1887). 



SYNOPTIC KF.Y TO SPECIES. 



a. Anus opening inside the tentacular corona; tentac^les incapable of complete retrac- 

 tion ( Endoprocta) Urnatella gracilis. 



act. Anus opening outsidt^ the tentacular corona, which is capaljle of being retracted 

 (Ectoprocta). 

 b. Zooecia shari^ly separated from each other; no epistome (Gymnola?mata). 

 c. Stock consists of cylindrical zooecia and long stolons, which latter enlarge at 

 interyals to giye I'ise to new cylindrical zooecia. The zooecia by lateral bud- 

 ding produce stolons or new zooecia directly. Aperture terminal. 



Yictorella pavida. 

 cc. Stock consists of cylindrical zooecia, stolons, and irregular swellings, %vhich 

 constitute winter l)uds. The zooecia do not produce lateral buds. Aper- 

 ture terminal Pottsiella erecta. 



ccc. Zooecia club-shaped; no stolons; aperture lateral I'dludicella. e'ltrenbergii. 



hh. Zooecia confluent ; epistome present (Phylactohemata). 

 (/. Statoblasts without hooks, rounded at ends. 



d. Tentacles 20-22, arranged nearly in a circle; statoblasts without peripheral 



float Frcdericella sultana. 



dd. Tentacles 40-60, arranged in the form of a horseshoe. Free ellii^tical stato- 

 blasts with a peripheral float (Plumatella). 

 e. Colony with vertical as well as horizontal branches. 

 /. Cuticula thick and brown, with a keel that broadens at aperture. Free 

 statoblasts elongated; i)roportions 1:1.53 tol:2. 8 .Plinnatdlaprinceps. 

 ff. Cuticula rarely browned or keeled. Free statoblasts nearly circular, 



1:1 to 1:1.5 Plumatella jjoly7norpha. 



ee. Horizontal branches only. Cuticula delicate, colorless, hyaline. Ele- 

 yated aperture-cone wrinkled and bespreckled with white. Free 



statoblasts nearly circular Plumatella punctata. 



cfc'. Statoblasts without hooks; acutely pointed at both ends. 



Popli opus cristallinus, 

 cfc'r' . Statoblasts with hooks. 



d' . Stock compound, composed of many rosettes of individuals. A thick gela- 

 tinous l:)ase secreted Pectinatella magnifica. 



d'd' . Stock caterjjillar-like, with a broad sole but no gelatinous base. 



Cristatella mucedo. 



ECOJ.OGY OF THE FRESH- WATER BRYOZOA. 



The fresh-water Bryozoa live in all kinds of fresh waters and are 

 indeed among the most ubiquitous of aquatic animals. They are found 

 in stagnant pools and in rushing rivers, although particular species 

 favor special habitats. The ditferent species of Plutnatella occur in 

 varied habitats. Paludicella and Pectinatella favor running water and 

 Ziophopus^ Cristatella^ and Plumatella polymorpha fimgosa favor quiet 



