THE MOUNT DESERT REGION 293 



bottom is exceedingly variable, ranging all the way from 

 solid rock to shifting silt and black mud. There are swift 

 tide runs in many places, deep tide pools on the rocky outer 

 shores, and placid protected coves on the inner side of the 

 Island. All of this naturally makes for great variety in the 

 life of the region. Zoogeographically the fauna falls natur- 

 ally and strictly into the Acadian Division. 



All of the collections were made in shallow water, the 

 greatest depth at which dredgings were made being only 330 

 feet, or just down to the 100-meter line. Also, they were all 

 close to land, none of them being more than 4 miles off shore 

 and none more than 6 miles from Mount Desert Island. The 

 region studied was therefore a very limited one. 



As might be expected, practically all of the eighty-three 

 species of Bryozoa occur in Canadian waters, only five of 

 the present list not being known to occur north of Mt. Desert 

 Island in American waters. These are : 



HiPPODiPLOSiA AMERICANA (Verrill) 

 Cryptosula pallasiana (Moll) 

 Smittina novanglia n.sp. 

 Alcyoxidium parasiticum (Fleming) 

 Buskia armata (Verrill) 



Of the present list, twenty-three species have not been 

 known to occur south of Canadian waters, though their pres- 

 ence in the colder waters of the Gulf of Maine might be 

 expected. These species whose range has been extended 

 southward in this study are: 



Barextsia gracilis (Sars) 

 Tt'bulipora lobulata (Hassall) 

 DiPLOsoLEX OBELiuM (Johnston) 



OXCOUSOECIA CANADEXSIS ll.Sp. 



(= Stomatopora diastoporides, Whiteaves, pars) 



DiAPEROECIA HARMERI II. Sp. 



(= EXTALOPHORA CLAVATA, Comish ?) 



Pyripora catexularia (Jameson) 

 Amphiblestrum trifolium (S. Wood) 

 Callopora dumerilii (Audouin) 

 HipPOTHOA EXPAXSA Dawson 



