98 



inhabiting great depths, — from fifty to two hundred fathoms, — 

 to the great pressure of which its structure is said to be adapted, 

 is here found in great abundance some feet above low water 

 mark, where it is daily left by the tide. At a locality called 

 Bucknam's Point, a large rock was found covered with this 

 species on its under side. Of the Holothurise, — Psolus, Cuvieria, 

 Botryodactyla, Orcula, and Synapta, also the starfishes Solas- 

 ter endeca, S. papposa, Crihella rosea, C. oculata, and others, 

 were found at various points between half tide and low water 

 mark; that is, in the third and fourth sub-regions of the littoral 

 zone. Here, also, were pelagic moUusca, Pecten Islandicus, 

 ModioIaricB, Mya truncata, Chiton albus, Fusus Islandicus, 

 Buccinum undatum, etc. The eggs of the last mentioned 

 species, in large masses resembling ears of maize, were found 

 abundantly under the edges of rocks. Each mass of these eggs 

 is the product of a dozen or more individuals of the species, an 

 arrangement probably for the greater security of the eggs. 



The same proximity of pelagic species to the shore is noticed 

 among the Algae. I will mention only the Nullipores, which 

 live at fourteen fathoms and over in Massachusetts Bay, but 

 which at Grand Manan form the sea bottoms from low water 

 mark to five fathoms. 



The cause of this might at first be sought for in the great rise 

 and fall of the tides which are well known to occur in the Bay 

 of Fundy. At Eastport the tide retires five fathoms ; and it 

 might be said that a species living at the depth of five fathoms 

 would thus be left at spring tides above low water mark. But 

 this does not account for the circumstance, since on those 

 shores we find the same divisions of the littoral zone, inhabited 

 by the same common species of littoral mollusks which inhabit 

 our whole New England coast, Litlorince, Acmece, PurpurcB; 

 the only difference being that the divisions are there of much 

 greater extent. 



Thus each of the four subdivisions of the littoral zone in the 

 vicinity of Boston has a vertical range of three feet, while at 

 Eastport it has a range of seven feet, still the common or cha- 

 racteristic shells of the respective sub-regions are the same in 

 each locality. 



The Algee likewise mark the sub-regions, and at low water the 



