178 Puget Sound Marine Sta. Pub. Vol. 1, No. 16 



pod fauna were obtained, with complete data on the habitats from which 

 they were secured. 



The San Juan region of Puget Sound consists of a group of islands 

 separated by glaciated channels from 20 to 90 fathoms deep. These chan- 

 nels are the chief points of entrance and escape for the tide waters of the 

 Gulf of Georgia, a body of water lying directly to the north. The water 

 rushes thru the narrow channels at a velocity of 7 to 10 or more miles per 

 hour, thus sweeping the rocky points and the bottom clean of debris and 

 furnishing an excellent habitat for brachiopods. These animals are sessile 

 '?i the mature stage and are generally confined to rocky shores and bottoms. 

 In this study a situation thruout which the same physical conditions of en- 

 vironment persist is called a habitat. 



Four species of brachiopods were found at various depths (table 1) 

 in the region studied.* On account of its wide distribution, i. e., its pres- 

 ence in many habitats, Terebratalia obsoleta Sowerby was selected for 

 this study. Collections were made from the strand line to 90 fathoms. 

 The specimens from along the strand line and to a depth of about two 

 fathoms were made from a canoe, those from below the water being taken 

 by means of a scraper with a net attached. The collections from deejD 

 water were taken by means of a dredge, which was worked from the deck 

 of a steam trawler. 



Table 1. Showing depth at which species were found and depth of maxi- 

 mum abundance 



Species Range in depth Maximum abundance 



Laqueus Jeffrey si Dall to 50 fathoms 30 fathoms 



Terebratulina unguicula Carpenter .30 to 60 fathoms 50 fathoms 



Hemithyris psiltacea Gmelin 30 to 90 fathoms 90 fathoms 



Terebratalia obsoleta Sowerby .... to 90 fathoms 80 fathoms 



When the collections were made complete data were taken as to depth, 

 character of the bottom, exposure to wave action, tidal currents, and other 

 physical conditions which might have some bearing on the problem. All 

 of the specimens taken were saved. The localities at which the collec- 

 tions were made are numbered consecutively on the map (plate 30). 



The specimens from locality No. 1, on the east shore of Turn Island, 

 were obtained from about the mean tide line down to two fathoms below 

 the low tide line. These specimens lived where they were subjected to 

 strong wave action and to strong tidal currents. The currents here and at 

 Cattle Point are the strongest in the vicinity of San Juan Island. 



4These species were kindly identified by Dr. Wm. H. Dall, of the National 

 Museum, Washington, D. C. 



