188 THE DEPTHS OF THE SEA. [CHAP. iv. 



more than we yet do of the extension both in time 

 and space of the fauna of deep water before we can 

 come to any certain conclusion on these questions. 



Dredging across the entrance of the Strait of Gib- 

 raltar in 477, 651, and 554 fathoms. Stations 31, 32, 

 and 33, with a bottom temperature of 10'3, 10'l, 

 and 10 '0 respectively, many remarkable forms were 

 dredged, including a very elegant sponge, apparently 

 allied to, if not identical with, Oscar Schmidt's, 

 Caminus vulcani, and some beautiful forms of the 

 Corallio-spongia3, which will be noticed in a future 

 chapter. Station No. 31 yielded a sponge form 

 which recalled the branching heather-like CladorMza 

 of the cold area off Eseroe. Chondrocladia mrgata 

 (Fig. 36) is a graceful branching organism from 

 twenty to forty centimetres in height. A branching 

 root of a cartilaginous consistence, formed of densely 

 packed sheaves of needle-shaped spicules bound 

 together by a structureless organic cement, attaches 

 the sponge to some foreign body, and supports it 

 in an upright position; and the same structure is 

 continued as a solid axis into the main stem and the 

 branches. The axis is made up of a set of very definite 

 strands like the strands of a rope, arranged spirally, 

 so as to present at first sight a strong resemblance to 

 the whisp of Hyalonema ; but the strands are opaque, 

 and break up under the point of a knife ; and under 

 the microscope they are found to consist of minute 

 needle-like spicules closely felted together. The soft 

 sponge substance spreads over the surface of the axis 

 and rises into long curving conical processes, towards 

 the end of which there is a dark greenish oval mass 

 of granular sponge matter, and the outline of the 



