INTRODUCTION. 
In the Introduction to Part I. of this Keport, the accounts of the history, biblio- 
graphy, and anatomy refer not to the Ascidise Simplices alone, but to the Tunicata as a 
whole ; stdl, as the Simple Ascidians were undoubtedly discussed there more fully than 
the other groups, it seems desirable that the more important points in the history and 
the structure of the Ascidise Compositse should be given here as an introduction to the 
description of so many new species of that section of the Tunicata. 
HISTORY. 
Although Compound Ascidians belonging to the family Botryllidse were figured as 
far back as 1555 by Rondeletius, it was not until two hundred years later, when Schlosser 
• and Ellis in 1756 brought before the Royal Society their account of a species of Botryllus^ 
that anything was known of the structure of these colonies, and even then their relation- 
ship to the Simple Ascidians — some of the main points in the anatomy of which were 
known nearly two thousand years before — was not suspected. This relationship was 
made out by the conjoined efforts of several eminent naturalists who investigated the 
Tunicata during the concluding years of the eighteenth and the ojiening years of the 
nineteenth centuries. 
Gaertner as early as 1774 evidently saw the relationship of the genus Distonms, 
which he had founded, with the other Tunicata, and Renter in 1793 published similar 
views in regard to the genus Botryllus ; but it was left for Cuvier and Savigny, working 
during the first fifteen years of the present century, the former at the Simple Ascidians and 
the latter at the Compound, to demonstrate beyond all possibility of future doubt the 
close aflSnity between these two groups of the Tunicata. Up to the date of publication of 
Savigny’s immortal “ Mdmoires ” (1816), the Compound Ascidians then known had been 
confused by the majority of naturalists with the Alcyonaria or with the Sponges. 
This patient and accurate observer succeeded in determining, from material preserved 
in spirit, the complete anatomy of a large number of forms, and he founded ten genera, 
most of which are still recognised as being among the more important types of the 
Ascidise Compositse. Lamarck about the same time, on the strength of the anatomical 
