114 THE VOYAGE OF H.M.S. CHALLENGER. 



traversed by the ship. As might be naturally expected, at some spots, such as the 

 localities of the dates March 16, 1875 (North Pacific), November 5, 1875 (South Pacific), 

 February 12, 1876 (South Atlantic), and April 13, 1876 (North Atlantic), specimens 

 and species were more abundant than at others. These regions are widely distant, and 

 their richness may have depended upon varied causes, or may have been accidental. 



It will be useful now to group the above localities at which pelagic Tunicata were 

 obtained into geograj^hical regions, as is done below — the object being to show the 

 Tunicate fauna of each of these great regions as made known by the Challenger 

 investigations. 



In the North Atlantic the following four genera and eighteen species were collected : — 



Pyi'osoma spinosum. 

 atlanticum. 

 giganteum. 

 sp. 

 Doliolum denticulatum. 

 challengeri. 

 ehrenhergi. 

 tritonis. 



sp. (blastozooid). 

 Salpa democratica-mucroriaia. 

 musculosa. 

 echinata. 



runcinata-fusiformis. 

 quadrata. 

 cylindrica. 

 cordiformis-zonaria. 

 sp. 

 Appendicularia sp. 



In the South Atlantic the following four genera and nine species were collected : — 



Pyrosoma atlanticum. 



giganteum (?). 

 spinosum. 

 sp. 

 Doliolum sp. (blastozooids). 

 Saljia democratica-mueronata. 

 cordiform,is-zonaria. 

 Tuncinata-fimformis. 

 Appendicularia sp. 



