BRYOZOA OF WOODS HOLE REGION. 207 



Of characteristic southern species we have almost no representatives. Barentsia 

 discreta, which ranges along our coast to the southward and is known from the South 

 Atlantic, is perhaps one. Anguinella palmata finds its northern limit for American 

 waters in Buzzards Bay, probably, as it is rare and of small size, while farther south it 

 grows abundantly. Perhaps Hippuraria elongata should be added to the list, as it is 

 comparatively scarce at Woods Hole and very common at Beaufort, N. C. It seems 

 probable that others among those now known only from local waters will be found in 

 the future to be more widely distributed. 



Our Bryozoa fauna is thus seen to be typically a northern one, since fully one-half 

 of the species are characteristically northern or even arctic in their range. In addition 

 to this about another fourth of the number have such a wide distribution that we may 

 call them cosmopolitan, since they occur in one or more of the great oceans besides the 

 North Atlantic. 



The region embraced in the survey above mentioned includes Vineyard Sound 

 between a line drawn from East Chop to Falmouth Heights and one from Gay Head 

 to Sow-and-Pigs Reef, and Buzzards Bay above a line drawn from Sow-and-Pigs Reef 

 to the Hen-and-Chickens Lightship. This region has been thoroughly and systemat- 

 ically dredged during the summers of 1903 to 1909, inclusive, by the United vStates 

 Bureau of Fisheries vessels Fish Hawk and Phalarojje. In all, 458 dredging sta- 

 tions were established, and many of these have been repeatedly redredged. Within 

 this same region shore collections have been made at various points, and the piles of 

 docks in the various harbors have been repeatedly scraped for material. For the pur- 

 pose of comparison, collections have been made at certain other points within easy reach 

 but situated outside of the region above described. These points are as follows: Crab 

 Ledge, a few miles east of Chatham, on Cape Cod; Great Round Shoal fishing ground, 

 east of Great Point, Nantucket; Nantucket Harbor; and Muskeget Channel. Besides 

 these collections I have been able to examine some material taken by Mr. Vinal Edwards 

 off Sankaty Head, Nantucket, and some collected by the United States Fish Commission 

 35 years ago on the Nantucket Shoals. 



Throughout this whole region the water is comparatively shallow, in no place 

 reaching a depth greater than 25 fathoms, while over the greater part of the area the 

 depth ranges rather uniformly between 6 and 15 fathoms. As might be expected from 

 this, the species which are characteristic of deeper waters are lacking from our fauna. 

 A considerable portion of the bottom of Vineyard Sound is a tide-swept desert of shifting 

 sand, unfavorable for the growth of Bryozoa, but where rock ledges appear, and espe- 

 cially near the shores in the zones of red and brown algae, they are abundant. The 

 bottom of Buzzards Bay is largely mud covered, the ebb and flow of the tide not produc- 

 ing sufficient current to carry away the silt deposited by the streams which empty into 

 the bay. Naturally such a bottom is unfavorable to the growth of encrusting or sessile 

 animals, and the Bryozoa over a large part of the bay are poorly represented. The 

 piles in the harbors afford usually the best collecting grounds. 



