[huntsman] the ASCIDIAN FAMILY CAESIRIDAE 215 



At the present time we classify germ plasms on the basis of their 

 properties determined indirectly. We may look forward to having at 

 some time in the future a knowledge of their structure as a basis for 

 classification. Such knowledge will be the outcome of analysis or 

 synthesis of the germ plasms. While there is no immediate prospect 

 of our being able to analyse and synthesize these in the direct chemical 

 fashion, there is already well under way an indirect analysis and 

 synthesis of germ plasms, namely, in the elucidation of the Mendelian 

 phenomena. When work in this comparatively new field shall have 

 become sufficiently extensive it will provide the foundation for a 

 much better system of classification. 



Early History of the Family 



Baster (1760) appears to have been the first author to describe a 

 member of this family, and, believing his animal, which was found on 

 the coast of Holland, to be new, he gave it the name Ascidium. This 

 was adopted by Linnaeus in the 12th edition of his Systema Naturae, 

 under the altered spelling Ascidia, as the name for all the sea-squirts 

 which he knew. Later, when the group of sea-squirts was subdivided, 

 the name with variable spelling came into general use for the whole 

 group, as (in English) Ascidians. 



Raster's species has not been recognized since his time. It was 

 probably the same form as described in 1846 by P. J. van Beneden 

 under the name Ascidia ampulloides. If this can be determined 

 there seems no good reason why Raster's name Ascidium should not 

 come into use for the group of species that includes A. ampulloides. 



Pallas in 1776 and 1787 described an Ascidia globularis from the 

 Kara sea. We have shown that this belongs to the genus Rhizomol- 

 gula, instituted by Ritter in 1901 for specimens from Alaska, and it 

 now appears that there is just the one species of this genus, which was 

 not rediscovered until more than a century had elapsed. In the 

 last twenty years its distribution has been quite well worked out. 



In 1816 Savigny described from the Red Sea a species of Ascidian 

 which he named Dione, which he placed in a new genus Cynthia, and 

 for which he made a special tribe, the Cynthiae Coesirae. In 1822 

 Fleming erected this tribe into a genus, using the name Caesira and 

 indicating Savigny 's species as the type. Until Baster's form is 

 cleared up, the genus Caesira is to be considered the oldest in the 

 family, and hence gives its name to the latter. 



In 1825 MacLeay described the new genus and species Cystingia 

 griffithsii from material obtained in the Canadian arctic. This has 



