REPORT ON THE TUNICATA. 259 



At Station 315. 



Molgula grega/ria. 

 horrida, 



Boltenia legumen. 



At Station 316. 



Boltenia legumen. 



At Station 320. 



Molgula pyriform is. 

 Styela fiava. 



oblonga. 

 glans. 

 Ascidia meridionalis. 



tenera. 

 Hypobythius moseleyi. 



This list seems to show that Tunicata are very much more abundant at some localities 

 (e. g., Station 150, Station 162 and Station 320) than at others; but it must be noted 

 that in some cases, such as Kerguelen Island, the length of the list is caused, to a 

 certain extent, by the much greater time spent by the expedition in investigating that 

 region. Some of the areas in the above list, however, at which there were a large number 

 of observing stations, show singularly few Ascidians. For example, in the eastern portion 

 of the North Atlantic, and off the east coast of South America, only a single species was 

 obtained in each locality. Then again, only three species were found in the South Pacific 

 Area, and only two in the North Pacific. On the other hand, some much smaller areas 

 have a long list of species, — for example, fifteen species were obtained in the neighbour- 

 hood of Kerguelen Island, and twenty-three in the area comprising Australia and New 

 Zealand. 



In the table given below, the geographical regions already made use of have been 

 grouped together to form seven great areas, namely: — the North Atlantic, the South 

 Atlantic, the Southern Ocean (the region lying to the south of the Indian Ocean, and 

 including Kerguelen Island), the seas of the Malay Archipelago (the area lying between 

 Australia and China), the North Pacific, the South Pacific, and the shores of the southern 

 end of South America. This last area lias been separated from the South Atlantic and 

 South Pacific Oceans, to which it should strictly belong, because of the large number of 

 Tunicata found in the neighbourhood of Cape Horn, and the difficulty of dividing them 

 into an east coast and a west coast series. 



As the species are arranged in systematic order, this table shows at a glance the 

 distribution of any particular species, genus, or family in the great ocean basins. 



(zool. CHALL. EXP. PART XVII. 1882.) R 34 



