BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. Ill 



to (Amphioplus abdita (Verrill)), which was taken at about the same time by Mr. G. M. 

 Gray and by our own collectors on the Fish Hawk, and has since been dredged by us 

 on several occasions. It appears, indeed, that this species is not uncommon in local 

 waters, and the same has proved to be true of the holothurian Caudina arenata, which 

 was previously regarded as very rare locally. 



Reference to the comparative table on page 88 shows that the phylum of Echino- 

 dermata is very poorly represented in the Woods Hole region, as compared with each of 

 the other localities which have been considered. For the phylum as a whole we have 

 the following figures : Woods Hole, 24(4-1?); Eastern Canada, 71; Plymouth, 36; Irish 

 Sea, 35; Triest, 37. 



In the case of the Asteroidea and Ophiuroidea in particular, these figures are uni- 

 formly higher for the other stations than for Woods Hole. Again, our own list is the 

 only one among them which is completely lacking in crinoids, for even Antedon has not 

 thus far been met with in our waters. 



Fourteen of our 24 echinoderms are common to Whiteaves's list for eastern Canada, 

 while only 2 (perhaps only 1) are common to the Plymouth list. 



In making any comparisons between these faunal lists, the usual allowance must be 

 made for the widely different areas to which they relate, as well as to the widely different 

 ranges in depth. Comparisons with Plymouth or with Trieste appear to be much fairer 

 than with either of the other regions, so far as area is concerned. 



The average number of species of echinoderms dredged at the 458 regular stations 

 of the Survey was 1 .9. The species which was encountered with greatest frequency was 

 Asterias jorbesi, which was recorded from 206 of the stations. The only ones which 

 were recorded from as many as one-fourth of the total number of stations are: 



Number of stations. 



Asterias forbesi 206 



Echinarachnius parma 170 



Arbacia punctulata 156 



Henricia sanguinolenta 118 



Owing to the comparatively large size of most members of this phylum, and to the 

 very limited number of species which occur in local waters, it seems likely that our list 

 of echinoderms is particularly complete. If additions are made subsequently, it will 

 probably be among the ophiuroids and the holothurians, some of which are of small 

 size and given to burrowing or to concealment in crevices of stones, etc. It is likely, too, 

 that our dredging records for this group are fairly free from errors of omission or con- 

 fusion of one species with another. Reference should be made, however, to certain 

 mistakes of identification, which we believe to have been made at first. 



(1) It is probable that during the early days of the work the younger specimens of 

 Asterias vulgaris and A. forbesi were sometimes confused in the field. So far as this con- 

 fusion may relate to Vineyard Sound, the results can not be serious, since our later and 

 more accurate exploration of the Sound has shown that both species occur throughout 

 practically its entire length. As regards Buzzards Bay, specimens of Asterias vulgaris 

 were recorded from five stations within its interior, which it has been decided to leave out 

 of consideration in plotting the distribution chart for this species. The records have, 



o See Clark, in Science, Jan. 24, 1908, and Sumner, in American Naturalist, May, 1908. According to Dr. Clark, Mr. Gray's 

 specimen was taken in August. 1907 (exact date no! stated). Our own first specimen was dredged on Aug. 6. 1907. Here, then, 

 is a most perplexing question of priority! 



