INTRODUCTION. 9 



whom, Baster [' Opusc. Subsec.' i (1760)], described 

 a single species, probably a Mol</nl<<, wliicli he named 

 Ascidium, and thus this name was introduced into the 

 nomenclature. 



In the 12th edition of the ' Systema Naturae ' [vol. i, 

 pt. 2], which appeared in 1767, only six kinds of simple 

 Ascidians are included, three of which appear to have 

 been added by Linnasus himself. They are placed in 

 the class Vermes, under the generic denomination of 

 AsciJici , a modification of Baster's name. The com- 

 pound forms are contained in the genus Alcyonium, 

 but there are only three or four species introduced. 



In the 'Zoologica Danica' [1788-1816] Otto Fred. 

 Miiller described and figured twenty species [of AsciiUtr 

 and one , Distoma], many of the figures being very 

 characteristic and the descriptions full and accurate, 

 as is usually the case in the works of this admirable 



t/ 



observer. Otho Fabricius gave eight species in his 

 ' Fauna Grcenlaiidica ' (1780). 



After this time many distinguished naturalists 

 enriched the fauna with additional species. Amongst 

 them may be mentioned Peron (1804), Lesueur and 

 Desmarest (1804-17), Savigny (1816-22), Cuvier 

 (1817), Chamisso (1819), Macleay (1823), Quoy and 

 Gaimard (1825-35), Lesson (1830), and Delle Chiaje 

 (1841) ; and as a consequence of the combined efforts 

 of these and other naturalists there were 147 species 

 introduced in the second edition of Lamarck's ' Histoire 

 naturelle des Aiiimaux sans Vertebres ' [1835-43]. 

 Since then many species have been added to the list, 

 but it is not necessary in this monograph, devoted as 

 it is to the British species only, to enter further into 

 this branch of the subject than to observe that large 

 as the number may be of the known Tunicata, there 

 can be no doubt that a great many foreign species yet 

 remain to be discovered. In fact [while the pelagic 

 forms have attracted much attention], little has been, 

 done, comparatively, in the sedentary species. 



We shall now turn our attention to the British 



