570 PROCKEDINGS OF THE AMERICAN ACADEMY. 



those already enumerated from Castle Harbor form about 25 per cent 

 of the deposit ; bivalves and gasteropoda, many of them living, about 2o 

 per cent ; the remainder consist chiefly of calcareous algae, and frag- 

 ments of millepore, much Wfiter worn, with a few Serpula and Polyzoa. 

 Except for the abundance of living organisms, the resemblance of this 

 sand to the beach at Newton's Bay is striking. 



Nonsuch Scaur, between Nonsuch and Cooper's Lslands, a shoal chan- 

 nel with only two fathoms of water, has a bottom at Stations 407 and 

 408 of very distinct character, and is a good example of the shallow pas- 

 sages. The bottom is white sand with a faint yellowish tinge, jind many 

 pink fragments. It is fine, the average diameter of the fnigments being 

 about 1 mm., granular, with about 3 per cent of fine ooze. Foramin- 

 ifera, — many of them living, the most abundant being Orbitolites and 

 Polystomella, — corallines, and millepore fragments in about equal pro- 

 portions form GO per cent of the mass, the remainder being fragments of 

 bivalve and gasteropod shells, Serpula, spines and plates of echinoids, 

 Polyzoa, calcareous spicules, diatoms, and about 5 per cent of rather 

 large, rounded, amorphous calcareous fragments, evidently the coarser 

 detritus from the cliffs on the neighboring islands. Except for the 

 Foramiuifera, there are very few living organisms ; and this is appar- 

 ently an area where deposition of sand from the nearby ledges is going 

 on rapidly ; its exposed position, however, and the vigorous wave action 

 thoroughly scour the bottom. 



In Ferry Reach, the miniature artificial sound on the north of Castle 

 Harbor, the bottom is white sand. A sample near its mouth. Station 

 402, in three fathoms, is white, mottled with yellowish, rather fine, gran- 

 ular, uniform, with about 10 per cent fine ooze. Foramiuifera and their 

 casts form about 10 per cent; joints of the calcareous algae Halimeda 

 and Udotea, and their broken-down fragments, form about 30 per cent; 

 the remainder, consisting of millepores, bivalves, gasteropods, Serpula, 

 coral fragments, ostracods, echinoid fragments, holothurian plates, sponge 

 and alcyonarian spicules, diatoms, and a few radiolarians. 



At the inner, southern end of the Reach the bottom is grayish white, 

 coherent, with about 30 per cent ooze, the remaining 70 per cent con- 

 sisting of the same organisms as above, in about the same relative abun- 

 dance; whereas at the northern entrance there is less than 2 percent of 

 fine ooze, and the bottom in every way closely resembles that at Non- 

 such Scaur. 



In the small basin known as Stocks Harbor there are few ledges and 

 very little living coral. The bottom consists of grayish sand, composed 



