FELON AIA, A NEW GENUS OF TUNIC ATED MOLLUSKS. 435 



XII.— ON PELONAIA, A NEW GENUS OF TUNI- 

 CATED MOLLUSKS, WITH DESCRIPTION OF 

 TWO SPECIES. By Edward Foebes and John 



GOODSIR* 



Among the Ascidian Mollusca which we have collected to- 

 gether, with a view to a complete investigation of the British 

 Tunicata, are two remarkable animals, which appear to repre- 

 sent a very natural genus as yet unrecorded. They differ from 

 their allies in the tribe chiefly by their not being fixed, and 

 by their form, which reminds one more of that of a Sipuncnlus 

 than of an Ascidia ; indeed they may be regarded as analogues 

 of certain Sipunculidee, and in that point of view the details of 

 their forms and structure are of much interest to the naturalist. 



They are both of a cylindrical shape, having their orifices 

 on the same plane, elevated on papillose eminences at one ex- 

 tremity of the body. No rays or tentacula surround either of 

 the orifices. The posterior extremity of each terminates in 

 a blunt point. They live buried in mud, quite unattached to 

 any other body, and are extremely apathetic animals, present- 

 ing scarcely any appearance of motion. 



We have styled the genus Fdonaia (wrikht, vaToj), and define 

 it as follows : — 



Test, cylindrical, unattached. 



Orifices, without rays, or two equal approximated papillose 

 eminences at the anterior extremity. 



Species 1. J', corrugata. Test, deep hroivn, much elongated, 

 rmhlji wrinkly d tram wt r \ely. 



' Read before the Wernerian Natural Historj Society, April 17, 1841. 



