1888.] NATURAL SCIEN'CES OF PHILADELPHIA. 303 



examination of'this locality, which is made comfortable for collecting 

 and wadini^ during a partial exposure above water of some three 

 hours. All the dredgings were conlined to depths within 16 fathoms, 

 Avhich also represents the greatest sounding made by us in the la- 



goons. 



ACTINOZOA. 



Tiie true stone corals of the Bermudas are comprised, as far as we 

 now know, in some twenty-live species, the greater number of which are 

 represented l)y identical forms in the Bahaman or West Indian seas. 

 The genera thus for indicated are Oculina, Mycediimi, Astrcea, 

 SiderastrtBci, Porites, Isojihyl/ia, Mceandrina, and Dlploria. The 

 genus Madrepora, one of the commonest of the Bahaman and Flor- 

 idian corals, appears to be absent. On the south and east side of the 

 island group the outer margin of the growing reef, largely covered 

 by a serpuline and vermetus growth, approaches to within a few 

 hundred feet of the shore, where it breaks the inflowing surf into a 

 white crest. Within the line of these breakers the depth of water is 

 in places as much as ten or twelve fathoms. The brain coral (Dijylo- 

 ria) and various gorgonians develop here in great profusion, the huge 

 yellow masses of the former aj)pearing almost everywhere at depths 

 of from ten to twenty feet. Vast growths of millepore also cover the 

 -shallower bottou)s, presenting in the ensemble a wonderful garden of 

 animal development. ' This profusion of coral growth is, however, 

 surpassed on the north side, where the reef recedes to a distance of 

 some eight or nine miles from the island- shores, enclosing an exten- 

 sive body of water whose depth is in general about eight or ten fath- 

 oms, and more rarely twelve fathoms. Much the same coral growth 

 is indicated here as on the south side, the large brain corals pre- 

 ponderating l)y their masses. While, prolDably, the greatest profusion 

 of animal life is really met with on the actual edge of the growing 

 reef, this does not appear to be the case with the corals themselves. 

 At any rate, I was unable to satisfy myself that there was any marked 

 ■difference to be observed between the marginal growth and that which 

 extends gradually backward from the margin into deep water. 

 Indeed, as far as the brain-corals themselves are concerned, it ap- 

 peared to me that their largest masses were to be found some distance 

 within the bounding reef, and consquently beyond the breaking 

 action of the surf. This condition is again shown in the compar- 

 atively quiet and sheltered waters of Castle Harbor, wdiere portions 

 of the platform-bottom may be said to constitute one almost connect- 



