258 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



etructures of greater interest in these waters. Corals grow over the bottom 

 in small patches in the open sea, and, without spreading much, often rise to a 

 height of forty to fifty or more feet, like towers, and sometimes attain the 

 level of low water, forming what are called on the Brazilian coast chapeiroes. 

 At the top these are usually very irregular, and sometimes spread out like 

 mushrooms, or, as the fishermen say, like umbrellas. Some of these chapeiroes 

 are only a few feet in diameter. A few miles to the eastward of the Abrolhos 

 is an area with a length of nine to ten, and in some places a breadth of four 

 miles, over which these structures grow very abundantly, forming the well- 

 known Parcel dos Abrolhos, on which so many vessels have been wrecked. 



" I visited in my launch the northwestern part of this reef, where the 

 chapeiroes were sufliciently scattered to allow me to sail about among them. 



" Among these chapeiroes I measured a depth of sixteen to twenty metres, 

 and once, while becalmed, I found twenty metres alongside one chapeirao and 

 three metres on top. The chapeiroes, as a general thing, are rarely ever laid 

 bare by the tide. They are here, as elsewhere, of all heights and dimensions ; 

 but in no case do they reach low-water level, nor according to the testimony of 

 the fishermen and whalers, are they ever in any part uncovered. They do 

 not coalesce here to form large reefs as they do to the west of the islands. 

 When the weather is clear and cloudless, and the water calm, these chapeiroes 

 can be readily distinguished at a considerable distance. The surface of the sea 

 appears to be flecked by shadows from a sky full of scattered cloudlets, pro- 

 ducing a striking effect. The water, being shallow and clear, and with a 

 sandy bottom, is of a very light greenish tinge, like that of the Niagara River 

 at Buff'alo. The general color of the chapeiroes is brown, from their being 

 encrusted with patches of Palythoa, and their position is marked by brownish 

 spots on the surface of the sea. In the daytime a launch may sail in safety 

 among them in calm weather, and a small vessel may traverse some of the 

 chapeirao grounds without danger, but large ships are likely to find themselves 

 in a labyrinth from which escape is not easy. In windy weather the waves 

 break over the chapeiroes, but if there are white caps beside, and a cloudy sky, 

 their position cannot be made out, and it is safest to keep well away from 

 them." 



The corals collected on these reefs by Hartt are described by Yerrill.^ 

 The list is given below. 



List of Corals Collected by C. F. Hartt on the Abrolhos Reefs. 



Class, POLYPI. 

 Order, MADREPORARIA. 

 Agaricia agaricites ? M. Edw. and Haime. 

 Siderastraea stellata Yerrill, var. conferta Verrill. 



1 A. E. Verrill. Notice of the corals and echinoderms collected by Prof. C. F. 

 Hartt, at the Abroliios reefs. . . . Trans. Conn. Acad. Arts Sci., 1868, 1., p. 351-364, 

 ri. IV. 



