42 



IV. PELONAIADiE. 



We have now to notice the British species of a very 

 curious group of Tunicata, one which seems to have escaped 

 the observation of most naturalists, and hitherto to have 

 been omitted from systematic arrangements of the MoUusca, 

 partly through the rarity of the creatures themselves, 

 partly from the only published account of them having been 

 overlooked. These are two animals, both inhabitants of 

 the Scottish seas, one of which was first observed by Pro- 

 fessor E. Forbes, and the other by Professor Goodsir, 

 who jointly constituted for their reception the genus Pe- 

 lonaia.* Whilst in many of their characters they approach 

 the true Ascidians, especially the unattached species of the 

 genus Cynthia^ in others they indicate a relationship with 

 the cirrhograde Echinodermata. They present the remark- 

 able positive anatomical character of a union of mantle with 

 test; so that there can be little question of their right to 

 be regarded as members of a distinct family of Tunicata.-\ 

 As no account of them is to be found out of the original 

 paper, we reprint it entire : — 



" Among the Ascidian Mollusca which we have collected toge- 

 ther, with a view to a complete investigation of the British Tiini- 

 cata, are two remarkable animals, which appear to represent 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 Siphunctdus than of an Ascidia; indeed, they may be re- 



* See Jameson's Ed. New Phil. Journal, vol. xxxi. (for 1841), p. 29. 



■j- It is worthy of notice, that Mr. Macleay, in his valuable remarks on the ar- 

 rangement of the Tunicaia, (Linnasan Trans, vol. xiv.,) had hypothetically indi- 

 cated such a group as this now constituted. 



