66 FOUNDERS OF OCEANOGRAPHY 



squeezed to see if it had a Belemnite's bone in its back " — 

 all in vain — no such " living fossil " was found. 



One of the greatest discoveries of the " Challenger " 

 expedition was the remarkable Cephalodiscus, dredged in 

 the Strait of Magellan from 246 fathoms. It is a gregarious 

 member of the Hemichordata related to Bhahdopleura and 

 Balanoglossus , and it buds o£f new individuals which all live 

 together in the cavities of a hollow gelatinous coenoecium, 

 which they have jointly secreted. It has been shown that 

 the regions of the body and the divisions of the coelom corre- 

 spond closely with those of Balanoglossus, and that there is 

 a tubular notochord extending forwards from the pharynx 

 to strengthen the proboscis region. 



Amongst the Tunicata many remarkable new abyssal 

 forms were obtained, which have added greatly to our know- 

 ledge of the range of structure in the group. For example, 

 the new genus, Octacnemus, first described by Moseley, has 

 a much reduced and degenerate branchial sac, and has re- 

 quired the formation of a new family. Then, again, several 

 distinct genera, Pharyngodictyon amongst Compound As- 

 cidians, and Culeolus, Fungulus, and Bathyoncus amongst 

 Ascidise Simplices, have the branchial sac simplified by the 

 total absence of the system of fine inter-stigmatic vessels, the 

 result being that the wall of the organ is reduced to a net- 

 work of very large meshes, in most cases strengthened by 

 branched and curved calcareous spicules. These are all of 

 them abyssal forms, and no such structure of the branchial 

 sac has been found in shallow- water Ascidians. Very 

 many of the deep-sea Ascidians, including the new genera 

 Culeolus, Fungulus, Ascopera, Hypohythius, and Coryn- 

 ascidia, are pedunculated, as if they required to be supported 

 upon stalks above the soft ooze in which their bases are 

 entangled and upon which the animals evidently feed. 

 The intestines are found distended with, in some cases, 

 Globigerina and in others Radiolarian or Diatomaceous 

 ooze. Amongst pelagic Tunicates a noteworthy form is a 



