ASCIDIA. 65 



c lateral. Reproductive <.>r</anx ovaries usually 

 coufiued to the left side. 



The Axriiliniii of Baster, there can scarcely be any 

 doubt, is a (.'yntJna. But the Linneeaii genus Am-uHa 

 undoubtedly comprised both true Axeidix and Ci/utlil;r. 

 There can, therefore, be no doubt as to the propriety 

 of giving precedence to the name Axridia over that of 

 Phallusia of Savigny, which has been pretty exten- 

 sively adopted by naturalists, though it was not used 

 until many years after the date of the twelfth edition 



/ / 



of the ' Systema Naturae ' ; and indeed were there any 

 doubt respecting the genera included in that work the 

 priority of Asn'tlio is sufficiently established by the 

 employment of that name by Miiller and Fabricius in 

 their respective works quoted in the above synonymy. 

 Much of the internal structure of the Ascidi& has 

 been worked out by Cuvier, Savigny, and others, 

 though not with that minuteness which science now 

 requires. Professor Huxley has also done much and 

 earnestly in this field of inquiry, but the detailed 

 results of the labours of this able anatomist have not 

 been given to the world. We have therefore thought 

 it necessary, in the following account of the anatomy 

 of the Ascidiae, to go pretty fully into the subject, and 

 more especially as the structure of these, the more 

 highly organised, Tunicates, will not infrequently be 

 used throughout this work as a standard of comparison 

 by which to estimate the structural differences of the 



various groups. 



The test of Ascidia is firm, thick, and elastic, and 

 more or less transparent ; it is usually smooth, though 

 not infrequently coarse, aculeated, or scabrous, and occa- 

 sionally covered with extraneous matter. It is some- 

 times delicately coloured, but is more frequently of a 

 watery tint. It is attached to the mantle only at the ex- 

 tremities of the respiratory tubes, and at the point where 

 it receives blood-vessels. The mantle in some species 

 is ornamented with vivid colours, and is well supplied 

 with muscular fibres which run in various directions. 



5 



