GEOGRAPHICAL DISTRIBUTION. 
The introductory caution as to the insufficiency of our knowledge of the 
Geographical Distribution of Simple Ascidians which was given at the commencement 
of the corresponding section in the First Part of this Eeport applies with equal if not 
even greater force to the case of the Compound Ascidians. Still it may be of use to 
future investigators if the Challenger observations, so far as they have gone, are 
recorded and tabulated here ; and the general arrangement and division into regions 
adopted in the First Part of the Report will be adhered to in order that a comparison of 
the results, in the case of the Simple and of the Compound Ascidians, may be readily 
made. In the map which will be found at the end of this Report the Geographical 
Distribution of the Simple as well as of the Compound Ascidians is indicated. 
The track of the Challenger round the world has been divided into a series of com- 
paratively short stages, so as to show roughly the localities between which the different 
observing Stations lie. These stages are arranged in the order in which they were 
traversed by the Expedition, and consequently the Stations are in chronological order, 
and the lists of species occur in the order in which they were collected. The chief 
objects of this arrangement are to show — (1) the approximate positions of the Stations at 
which Compound Ascidians were obtained, and (2) the list of species from each Station.^ 
The red circles on the map indicate the Stations at which Tunicata were obtained. 
Between England and the Canary Islands no Comj)ound Ascidians were obtained. 
Between the Canary Islands and the West Indies no Compound Ascidians were 
obtained. 
Between the West Indies and Halifax, Nova Scotia, the following Compound 
Ascidians were obtained ; — 
Off Bermuda ; shallow water. 
Botrylloides nigrum. 
Symplegma viride. 
Didemnum inerme. 
^ In the case of a few of the species the locality at which the specimens were obtained is not known. These 
species, of conrse, do not occur in the lists. 
