294 THE ATLANTIC. [chap. v. 



ordinary horny and halicliondroid forms, although they have 

 a considerable vertical range, are most abundant in the coral- 

 line zone. In the Atlantic, hexactinellid sponges are very 

 abundant to depths of about a thousand fathoms along the 

 coasts of Portugal and Brazil. These forms, which occur in 

 the fossil state in the earlier Paleozoic rocks, and, represented 

 by the Yentriculidse and allied families, abound in the chalk 

 and greensand, show in a marked degree the wide extension in 

 space at the jDresent day of a very uniform abyssal fauna, the 

 same or very similar species of the genera Apkrocallistes, Far- 

 rea, Hyalonema, Eu2)lectella, Iloltenia, and Rossella being appar- 

 ently cosmopolite, l^early all the deep-sea sponges of all or- 

 ders are stalked, or provided with beards or fringes of radiating 

 spicules, or otherwise supplied with means of supporting them- 

 selves above the surface of the soft ooze in which they grow. 



Among the Coelenterata the Ilydrozoa are not very fully 

 represented at great depths. To this rule, however, some sin- 

 gular exceptions occur. In many of our deepest dredgings, 

 where there was a great lack of carbonate of lime, and animal 

 life appeared to be very scarce, the curved horny tubes of what 

 is probably a species of the genus Stej)hanoscyj)hns was found 

 adhering to the ear-bones of whales or to concretions of iron 

 and manganese ; and on two occasions in the North Pacific, at 

 depths of 1875 and 2900 fathoms, w^e captured a giant of the 

 class, a species of Moiiocaulus with a stem upward of two me- 

 tres long, and a head three or four decimetres across the crown 

 of extended tentacles. 



True corals referable to the Madreporaria are not abundant 

 in deep water. According to Mr. Moseley's report, about ten 

 genera reach a depth of 1000 fathoms ; four genera are found 

 at 1500 fathoms ; and a single species extends practically through 

 all depths, ranging from 30 to 2900 fathoms. In the Atlantic 

 especially deejD-sea corals are sparsely scattered : two or three 

 species of the genus CaryophylUa are among the most com- 



